CN120109157B - Battery cells, battery devices, and power-consuming devices - Google Patents

Abstract

The present application relates to a battery cell, a battery device, and an electrical device. The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a first electrode sheet and a second electrode sheet, which are stacked along the thickness direction. Each of the first electrode sheet and the second electrode sheet includes a coating portion and a tab portion. The coating portion is provided with an active material layer, and the tab portion is connected to the coating portion and extends outward from the coating portion along the width direction of the battery cell. One of the first and second electrode sheets is a positive electrode sheet, and the other is a negative electrode sheet. The positive electrode sheet includes an olivine-structured lithium-containing phosphate. The coating portion of the positive electrode sheet has a first dimension along the length direction, and a second dimension along the width direction. The ratio of the first dimension to the second dimension is 4 to 7. The electrolyte includes lithium bis(fluorosulfonyl)imide, and the mass content of lithium bis(fluorosulfonyl)imide in the electrolyte is 1% to 15%. The battery cell of the present application can improve the fast charging capability and cycle performance.

Description

Battery cell, battery device and electricity utilization device

The present application claims priority from patent application PCT/CN2025/071045 entitled "battery cell, battery device and power device" filed on month 2025, year 01, and 07, the entire contents of which are incorporated herein by reference.

Technical Field

The application relates to a battery cell, a battery device and an electric device.

Background

The battery cell has the characteristics of high capacity, long service life and the like, and is widely applied to electronic equipment such as mobile phones, notebook computers, battery cars, electric automobiles, electric airplanes, electric ships, electric toy automobiles, electric toy ships, electric toy airplanes, electric tools and the like. As batteries have made great progress, higher demands are being made on the performance of the batteries. However, the quick charge capability and cycle performance of the battery cells need to be further improved.

Disclosure of Invention

The application provides a battery cell, a battery device and an electricity utilization device, wherein the quick charging capability and the cycle performance of the battery cell can be further improved.

In a first aspect, an embodiment of the present application provides a battery cell, the battery cell includes an electrode assembly and an electrolyte, the electrode assembly includes a plurality of first electrode plates and a plurality of second electrode plates, the first electrode plates and the second electrode plates are stacked along a thickness direction of the battery cell, the first electrode plates and the second electrode plates each include a coating portion and an electrode ear portion, the coating portions are provided with active material layers, the electrode ear portions are connected to the coating portions and extend out of the coating portions along a width direction of the battery cell, one of the first electrode plates and the second electrode plates is a positive electrode plate, the other is a negative electrode plate, the active material layers of the positive electrode plates include lithium-containing phosphate of an olivine structure, a dimension of the coating portion of the positive electrode plates along a length direction of the battery cell is a first dimension, a dimension of the coating portion of the positive electrode plates along the width direction is a second dimension, a ratio of the first dimension to the second dimension is 4 to 7, the electrolyte includes lithium difluorosulfimide, and a mass content of lithium difluorosulfimide in the electrolyte is 1% to 15%.

In the embodiment of the application, the ratio of the dimension of the coating part in the positive electrode plate along the length direction to the dimension of the coating part in the positive electrode plate along the width direction is 4 to 7, the length of the coating part is relatively long, which is favorable for bearing relatively more positive electrode active materials, and is favorable for enabling a battery cell to have relatively higher energy density, in the case of the battery cell having the laminated structure, an electron transmission path is possibly longer, so that the internal resistance is higher, the heat generation is increased, the conductivity of lithium-containing phosphate is poorer, the internal resistance is further increased, the heat generation is increased, the heat generation phenomenon is aggravated along with the increase of the charging multiplying power, and the quick charging is unfavorable, while the lug part of the embodiment of the application is arranged on at least one side of the coating part along the width direction, so that the transmission path of electrons in the coating part is shorter, the ohmic resistance can be reduced, and the lithium salt of the electrolyte further comprises 1 to 15 percent of lithium difluorosulfimide, so that the ion conduction capability of the electrolyte can be higher, the internal resistance of an electrochemical system can be reduced, and the embodiment of the application is favorable for reducing the heat generation capability of the cell and the heat generation and the circulation capability of the battery cell by comprehensively reducing the lug part and the electrolyte through the design.

In some embodiments, the lithium salt further comprises lithium hexafluorophosphate, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis-fluorosulfonyl imide is 0.5 to 4, alternatively 1.2 to 2, based on the mass of the electrolyte. The lithium salt is beneficial to improving the lithium ion conducting capacity of the electrolyte, improving the dynamic performance of the battery monomer, reducing the hydrofluoric acid content in the electrolyte, improving the performance of the solid electrolyte membrane at the negative electrode side, and improving the quick charging capacity and the cycle performance of the battery monomer.

In some embodiments, the mass content of lithium bisfluorosulfonyl imide in the electrolyte is 3% to 12%. The lithium salt with the mass content is beneficial to improving the quick charging capability and the cycle performance of the battery monomer.

In some embodiments, the electrolyte has a conductivity of 10mS/cm to 13mS/cm at room temperature. The migration rate of lithium ions in the electrolyte is high, the internal resistance of the battery monomer can be further reduced, so that the heat generation is reduced, and the quick charging performance of the battery monomer can be improved.

In some embodiments, the electrolyte further comprises an organic solvent, including a chain carboxylate solvent. The chain carboxylic ester solvent improves the conductivity of the electrolyte at room temperature, is beneficial to migration of lithium ions and improves the quick charging capability of the battery monomer.

In some embodiments, the mass content of the chain carboxylate solvent in the electrolyte is 5% to 30%. The chain carboxylate solvent with the mass content can improve the conductivity of the electrolyte and is beneficial to improving the quick charging capability of the battery monomer.

In some embodiments the first pole piece is such that n is from 0.5 to 1.0W 1/W2, n represents the number of all of the tab portions on the same side of the coating portion, W1 represents the average dimension of the tab portions in the length direction, and W2 represents the dimension of the coating portion in the length direction. The connection area of the lug part and the coating part is relatively large, and the overcurrent area of the lug part is relatively large, so that the direct-current resistance and the heat generation are reduced, and the quick charging capability is improved.

In some embodiments, W2 is 300mm to 650mm, and/or n x W1 is 150mm to 650mm.

In some embodiments, the first pole piece includes a plurality of pole ears that can promote overcurrent capability, facilitating improved quick charge capability.

In some embodiments, the first pole piece has at least two pole ears on the same side of the coating portion, and the distance between two adjacent pole ears along the length direction is greater than 0 and less than or equal to 300mm. The arrangement can improve the overcurrent capacity and is beneficial to improving the quick charging capacity.

In some embodiments, the plurality of tab portions of the first pole piece are located on both sides of the coating portion in the width direction. The above arrangement makes the electron transfer path shorter, which is advantageous for improving the quick charge capability.

In some embodiments, all of the tab portions of the first pole piece are located on the same side of the coating portion in the width direction. The arrangement can improve the overcurrent capacity and is beneficial to improving the quick charging capacity.

In some embodiments, the dimension of the coated portion of the first pole piece in the width direction is greater than 0 and equal to or less than 300mm. The above arrangement makes the electron transfer path shorter, which is advantageous for improving the quick charge capability.

In some embodiments, the battery cell further includes a first electrode terminal connected to the tab portion of the first electrode tab, the first electrode terminal disposed on at least one side of the electrode assembly in the length direction. The first electrode terminal and the tab part are arranged at different sides, so that the promotion of the internal space of the battery cell in the width direction is facilitated, and the energy density of the battery cell is improved.

In some embodiments, the battery cell further includes a second electrode terminal connected to the tab portion of the second electrode tab, the second electrode terminal disposed on at least one side of the electrode assembly in the length direction. The second electrode terminal and the tab part are arranged at different sides, so that the promotion of the internal space of the battery cell in the width direction is facilitated, and the energy density of the battery cell is improved.

In some embodiments, all the tab portions of the first pole piece are located on the same side of the coating portion, all the tab portions of the second pole piece are located on the same side of the coating portion, the tab portions of the first pole piece and the tab portions of the second pole piece are located on two sides of the coating portion in the width direction respectively, the first electrode terminal and the second electrode terminal are respectively located on two sides of the electrode assembly in the length direction respectively, the first electrode terminal and the second electrode terminal are arranged in a staggered mode in the width direction, the first electrode terminal is arranged close to the tab portions of the first pole piece, and the second electrode terminal is arranged close to the tab portions of the second pole piece. The above arrangement makes the electron transfer path shorter, which is advantageous for improving the quick charge capability.

In some embodiments, the electrode assembly includes two first electrode terminals, and the two first electrode terminals are disposed at both sides of the electrode assembly in a longitudinal direction. The above arrangement makes the electron transfer path shorter, which is advantageous for improving the quick charge capability.

In some embodiments, the electrode assembly includes two second electrode terminals, and the two second electrode terminals are disposed at both sides of the electrode assembly in a length direction. The above arrangement makes the electron transfer path shorter, which is advantageous for improving the quick charge capability.

In some embodiments, the battery cell further includes a first adapter member positioned between and connecting the first electrode terminal and the tab portion of the first pole piece. The first adapter is more favorable for connecting the first tab and the first electrode terminal. The first adapter can improve the overcurrent capacity, reduce the heat generation and improve the quick charging capacity of the battery cells.

In some embodiments, the first transfer member includes a first transfer portion extending in a length direction and connected to the tab portion, and a second transfer portion connected to the first transfer portion and protruding from the first transfer portion in a width direction and connected to the first electrode terminal. The first switching portion and the second switching portion can promote the overcurrent capacity between the lug portion and the first electrode terminal, reduce heat generation and improve the quick charging capacity of the battery cell.

In some embodiments, the tab portion includes a first region connected to the first adapter, the ratio of the dimension of the first region along the length to the dimension of the tab portion along the length being 0.5 to 1. When the first tab meets the above conditions, the contact area between the first tab and the first transfer member is relatively large, so that the overcurrent capacity of the first tab is relatively high, the ohmic resistance is relatively low, and the quick charging capacity of the battery cell is improved.

In some embodiments, the tab portion is disposed on at least one side of the coating portion in the width direction of the battery cell, and the tab portion extends in the length direction with a gap between the tab portion and the coating portion, and the battery cell further includes a heat conduction member disposed at least in the gap. The heat conduction component can conduct heat generated by the lug part, the heat generated by the lug part is quickly transferred, and the ablation risk of the heat to the separator in the electrode assembly is reduced.

In some embodiments, the battery cell further includes a case housing the electrode assembly and the electrolyte, wherein the thermally conductive member extends to the case to contact the case. The thermally conductive member is capable of rapidly transferring heat generated by the tab portion to the case, reducing the risk of heat ablating the separator in the electrode assembly.

In some embodiments, the thickness of the battery cell is 10mm to 30mm. When the thickness of the battery monomer is in the range, the thickness of the battery monomer is relatively small, so that the rapid heat dissipation inside the battery monomer is facilitated, and the risk of thermal runaway is reduced.

In some embodiments, the battery cell further includes a case including two first case parts opposing each other in a thickness direction, a second case part opposing each other, and a third case part connected by the first case part, the second case part including first and second walls disposed continuously in the thickness direction, the first and second walls being welded. The area of the second shell part is relatively small, the expansion degree is relatively small, the welding seam is positioned on the second shell part, and the risk of leakage of the battery monomer can be reduced.

In some embodiments, the thickness of the housing is 0.1mm to 0.5mm. When the thickness of the shell is in the range, the shell is relatively thin, so that the shell can radiate heat rapidly, the risk of aggravation of side reaction caused by heat accumulation in a system is reduced, and the cycle performance of the battery cell is improved.

In some embodiments, the olivine structured lithium-containing phosphate comprises lithium iron phosphate. The cycling stability of the lithium iron phosphate is excellent, and the cycling performance of the battery monomer can be improved.

In some embodiments, the positive electrode plate comprises a positive electrode film layer, the single-side coating weight of the positive electrode film layer is 250mg/1540.25mm ² to 330mg/1540.25mm ², when the single-side coating weight of the positive electrode film layer is in the range, the heat generation amount in the unit area of the positive electrode plate can not be excessively large, and the energy density and the quick charging capability of the battery cell can be both improved.

In some embodiments, the positive electrode film layer has a compacted density of 2.30g/cm ³ to 2.70g/cm ³ at 0% charge state of the battery cell. And because the positive electrode active material of the positive electrode film layer is closely piled, the contact resistance between particles is smaller, and the resistance of the pole piece can be further reduced, thereby reducing the heat generation under the rapid charging and improving the rapid charging capability and the cycle performance of the battery monomer.

In some embodiments, the coating portion of the negative electrode tab includes a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes a first negative electrode film layer disposed on a surface of the negative electrode current collecting portion and a second negative electrode film layer connected to a side of the first negative electrode film layer facing away from the negative electrode current collecting portion, wherein a volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is equal to or greater than a volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer. According to the embodiment of the application, the particle size of the second negative electrode film layer is relatively smaller, so that the solid phase transmission path of lithium ions can be shortened, the rapid charging performance is improved, the problem of surface chromatography lithium of the negative electrode plate can be solved, and the cycle performance of a battery monomer is improved.

In some embodiments, the carbon-based material of the first negative electrode film layer is granular, and has a volume average particle diameter Dv50 of 9.5 μm to 18.5 μm, and when the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is in the above range, on one hand, the solid phase transmission path of lithium ions can be shortened, the rapid charging performance can be improved, and on the other hand, the material is not easy to agglomerate in the preparation process, and the stability of the material can be improved.

In some embodiments, the carbon-based material of the second negative electrode film layer is particulate, having a volume average particle diameter Dv50 of 7.8 μm to 14.3 μm. When the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer is in the above range, the solid phase transmission path of lithium ions can be shortened, and the rapid charging performance can be improved.

In some embodiments, the carbon-based material of the first negative electrode film layer comprises at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer comprises artificial graphite.

In some embodiments, the coating portion of the negative electrode tab includes a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material, wherein the negative electrode film layer includes a first negative electrode film layer disposed on a surface of the negative electrode current collecting portion and a second negative electrode film layer connected to a side of the first negative electrode film layer facing away from the negative electrode current collecting portion, wherein a volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is smaller than a volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer. According to the embodiment of the application, the particle size of the second negative electrode film layer is relatively smaller, so that the solid phase transmission path of lithium ions can be shortened, the rapid charging performance is improved, the problem of surface chromatography lithium of the negative electrode plate can be solved, and the cycle performance of a battery monomer is improved.

In some embodiments, the carbon-based material of the second negative electrode film layer is granular, and the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer is 9.5 μm to 18.5 μm, and when the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer is in the above range, on one hand, the solid phase transmission path of lithium ions can be shortened, the rapid charging performance can be improved, and on the other hand, the material is not easy to agglomerate in the preparation process, and the stability of the material can be improved.

In some embodiments, the carbon-based material of the first negative electrode film layer is particulate, having a volume average particle diameter Dv50 of 7.8 μm to 14.3 μm. When the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is in the above range, the solid phase transmission path of lithium ions can be shortened, and the rapid charging performance can be improved.

In some embodiments, the carbon-based material of the second negative electrode film layer comprises at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer comprises artificial graphite.

In some embodiments, the single-sided coating weight of the negative electrode film layer is 120mg/1540.25mm ² to 180mg/1540.25mm ², and when the single-sided coating weight of the negative electrode film layer is in the range, the heat generation amount in the unit area of the negative electrode pole piece is not excessive, and the energy density of the battery cell can be improved.

In some embodiments, the negative electrode film layer has a compacted density of 1.30g/cm ³ to 1.65g/cm ³ at 0% charge state of the battery cell. The compaction density of the negative electrode film layer is beneficial to improving the energy density of the battery cell when the compaction density of the negative electrode film layer is in the range, and as the negative electrode active materials of the negative electrode film layer are closely stacked, the contact resistance between particles is smaller, and the resistance of the pole piece can be further reduced, thereby reducing the heat generation and improving the quick charging capability and the cycle performance of the battery cell.

In a second aspect, the embodiment of the present application further provides a battery device, including the battery cell according to any one of the embodiments of the first aspect of the present application.

In a third aspect, embodiments of the present application further provide an electrical device, where the electrical device includes a battery device according to any of the second or third aspects of the present application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an electrical device according to some embodiments of the present application;

fig. 2 is a schematic view of a battery pack according to some embodiments of the present application;

fig. 3 is a schematic view illustrating a structure of a battery module according to some embodiments of the present application;

fig. 4 is a schematic structural view of a battery cell according to some embodiments of the present application;

fig. 5 is a schematic structural view of an electrode assembly of a battery cell according to some embodiments of the present application;

fig. 6 is a schematic structural view of a first pole piece of a battery cell according to some embodiments of the present application;

fig. 7 is a schematic structural view of a first electrode tab of a battery cell according to other embodiments of the present application;

Fig. 8 is a schematic structural view of a first pole piece of a battery cell according to still other embodiments of the present application;

fig. 9 is a schematic structural view of a first pole piece of a battery cell according to further embodiments of the present application;

Fig. 10 is a schematic structural view of a first pole piece of a battery cell according to further embodiments of the present application;

fig. 11 is a schematic structural view of a second pole piece of a battery cell according to some embodiments of the present application;

fig. 12 is a schematic structural view of a second electrode tab of a battery cell according to further embodiments of the present application;

Fig. 13 is a schematic view illustrating a structure of a battery cell according to some embodiments of the present application;

Fig. 14 is a schematic view illustrating a structure of a battery cell according to other embodiments of the present application;

Fig. 15 is a schematic structural view of a battery cell according to still other embodiments of the present application;

fig. 16 is a schematic view illustrating a structure of a battery cell according to still other embodiments of the present application;

Fig. 17 is a schematic view of the structure of an end cap, a first electrode terminal, and a first conductive fixture of a battery cell according to some embodiments of the present application;

FIG. 18 is a schematic top view of FIG. 17;

FIG. 19 is a cross-sectional view taken along line A-A of FIG. 18;

Fig. 20 is a schematic structural view of a battery cell according to still other embodiments of the present application;

fig. 21 is a schematic structural view of a battery cell according to still other embodiments of the present application.

The figures are not necessarily to scale.

The reference numerals are explained as follows:

x, thickness direction, Y, width direction, Z, length direction;

1. the power utilization device comprises a power utilization device, a battery pack, a controller, a motor, a box body, a first box body part, a second box body part, a containing space and a battery module, wherein the power utilization device comprises a power utilization device, a battery pack, a controller, a motor, a box body, a first box body part, a second box body part, a containing space, a battery module and a storage space;

7. A battery cell;

10. an electrode assembly;

11. 111, a first tab, 1111, a first end, 112, a first coating portion;

12. a second pole piece 121, a second lug 1211, a second end 122, a second coating portion;

13. A spacer;

20. A housing assembly;

21. housing, 211, first shell portion, 212, second shell portion, 2121, first wall, 2122, second wall, 213, third shell portion;

22. An end cap;

31. a first electrode terminal 311, a first electrode body 312, a first electrode protrusion;

32. A second electrode terminal;

41. a first conductive mount;

51. First adapter, 511, first adapter, 512, second adapter;

61. 611, first conductive part, 612, second conductive part;

81. A first heat conducting member.

Detailed Description

Hereinafter, embodiments of the battery cell, the battery device, and the power consumption device according to the present application are specifically disclosed with reference to the accompanying drawings. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with the given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values 1 and 2 are listed, and if maximum range values 3,4 and 5 are listed, the following ranges are all contemplated as 1 to 3,1 to 4, 1 to 5, 2 to 3,2 to 4 and 2 to 5. In the present application, unless otherwise indicated, the numerical ranges "a to b" represent a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been listed throughout, and "0 to 5" is only a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2,3, 4,5, 6,7, 8, 9, 10, 11, 12 or the like.

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.

All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method may include steps (a) and (b), and the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may further comprise step (c), meaning that step (c) may be added to the method in any order, e.g. the method may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.

The term "plurality" as used herein refers to two or more (including two).

The battery cell has internal resistance in the charging process, particularly, the electrode assembly with a longer size, although the battery cell has the advantage of energy density due to the advantage of longer size, the internal resistance of the battery cell is higher due to a long electron transmission path, the internal temperature of the battery cell is excessively increased in the charging process, the rapid charging is not facilitated, and the side reaction in the battery cell system is aggravated due to the excessively high temperature rise, so that the high-temperature cycle performance may be worsened.

In view of the above problems, the embodiment of the application designs the long-size battery cell, combines the comprehensive design of the aspect ratio of the positive electrode film layer, the tab-out mode and the electrolyte component, and improves the internal resistance of the battery cell from the viewpoint of reducing the ohmic resistance and the chemical system resistance in the battery cell. Through setting up the position of utmost point ear portion, shorten electron transmission path, reduce ohmic resistance, combine through designing electrolyte composition for electrolyte's ion conductivity is stronger, reduces electrochemical system internal resistance, with this comprehensive reduction battery monomer internal resistance, is favorable to reducing the heat generation volume, promotes battery monomer's quick charge ability and high temperature cycle performance.

The battery cell of the application is suitable for various battery devices and power utilization devices using the battery cell.

Illustratively, the electric device may be a mobile phone, a portable device, a notebook computer, an electric car, an electric toy, an electric tool, a vehicle, a ship, a spacecraft, or the like. Or, illustratively, the powered device is a spacecraft, including an airplane, rocket, space shuttle, spacecraft, and the like.

Fig. 1 is a schematic structural diagram of an electric device 1 according to some embodiments of the present application. The electric device 1 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the requirements of the power consumer 1 for high power and high energy density, a battery pack or a battery module may be employed.

The battery device is arranged inside the power utilization device 1, and the battery device can be arranged at the bottom or the head or the tail of the power utilization device 1. The battery device may be used for power supply of the power consumption device 1, for example, the battery device may be used as an operation power source of the power consumption device 1, and may also be used as a driving power source of the power consumption device 1 to supply driving power to the power consumption device 1 instead of or in part of fuel oil or natural gas. The battery device shown in fig. 1 is a battery pack 2.

The power consuming device 1 may further comprise a controller 3 and a motor 4, the controller 3 being arranged to control the battery means to power the motor 4, e.g. for the start-up, navigation and operational power requirements of the power consuming device 1 during driving.

The battery device (Battery Apparatus) may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly (Battery Cell Assembly) may include a plurality of battery cells connected in series, parallel, or series-parallel by a bus bar.

In some embodiments, the cell assembly (Battery Cell Assembly) is generally formed from an arrangement of a plurality of cells.

As an example, the Battery cell assembly may be a Battery Module (Battery Module) formed by arranging and fixing a plurality of Battery cells to form an independent Module. As an example, the battery module may be formed by binding a plurality of battery cells by a tie.

As shown in fig. 2, in some embodiments, the battery device may be a battery Pack 2 (battery Pack), the battery Pack 2 including a case 5 and one or more battery cell assemblies housed in the case 5.

As an example, the battery cell assembly may be accommodated in the case 5 by directly fixing a plurality of battery cells to the case 5.

As an example, the case 5 includes a first case portion 5a and a second case portion 5b, the case 5 having an accommodation space 5c, the first case portion 5a and the second case portion 5b being fastened such that an enclosed space is formed inside the case 5 to accommodate the battery cell assembly. The closing means covering or closing, and can be sealing or unsealing. The first housing part 5a may be a top cover or a bottom plate.

As an example, the case 5 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected with the frame, so that a closed space is formed inside the box 5 to accommodate the battery cell assembly.

In some embodiments, the tank 5 may be part of the chassis structure of the vehicle. For example, a portion of the tank 5 may become at least a portion of the floor of the vehicle, or a portion of the tank 5 may become at least a portion of the cross member and the side member of the vehicle.

As an example, the battery cell assembly may be a battery module 6, which may be accommodated in the case 5 in such a manner that the battery module 6 is fixed in the case 5.

As shown in fig. 3, the battery module 6 includes a plurality of battery cells 7.

In some embodiments, during charging of the battery device from 0% state of charge SOC to 100% state of charge SOC, the temperature of the external environment in which the battery device is located is room temperature, e.g., 25 ℃.

In some embodiments, the temperature of the external environment in which the battery device is placed during charging of the battery device or any of the battery cells comprising the battery device from 10% SOC to 80% SOC is room temperature, e.g., 25 ℃.

Illustratively, the charging step of the battery device or any battery cells constituting the battery device from 10% soc to 80% soc may be performed as follows:

charging from 10% soc to 25% soc at a constant current of 7.0C;

Charging from 25% soc to 30% soc at a constant current of 7.0C;

charging from 30% soc to 35% soc at a constant current of 7.0C;

Charging from 35% soc to 40% soc at a constant current of 7.0C;

Charging from 40% soc to 45% soc at a constant current of 6.7C;

charging from 45% soc to 50% soc at a constant current of 6.5C;

charging from 50% soc to 55% soc at a constant current of 6.0C;

charging from 55% soc to 60% soc at a constant current of 5.8C;

charging from 60% soc to 65% soc at a constant 5.5C current;

Charging from 65% soc to 70% soc at a constant 5.2C current;

Charging from 70% soc to 75% soc at a constant current of 5.0C;

Charged from 75% soc to 80% soc at a constant 4.8C current.

In some embodiments, the battery device, or any of the battery cells comprising the battery device, has a charge time from 10% state of charge to 80% state of charge of 5min to 20min, optionally less than or equal to 12min, further optionally 5min to 8min, and the temperature of the external environment of the battery device at 10% state of charge is room temperature, e.g., 25 ℃. The battery device may be charged from 10% state of charge to 80% state of charge for example by 20min、19min、18min、17min、16min、15min、14.5min、14min、13.5min、13min、12.5min、12min、11.5min、11min、10.5min、10min、9.5min、9min、8.5min、8min、7.5min、7min、6.5min、6min、5min or any two values as described above.

As shown in fig. 4 to 6, the battery cell 7 includes an electrode assembly 10 and an electrolyte,

The electrode assembly 10 includes a plurality of first electrode tabs 11 and a plurality of second electrode tabs 12, the first electrode tabs 11 and the second electrode tabs 12 are stacked along a thickness direction X of the battery cell 7, each of the first electrode tabs 11 and the second electrode tabs 12 includes a coating portion and an electrode ear portion, the coating portion is provided with an active material layer, the electrode ear portion is connected to the coating portion and extends out of the coating portion along a width direction Y of the battery cell 7, and the active material layer is not coated, wherein one of the first electrode tabs 11 and the second electrode tabs 12 is a positive electrode tab, the other is a negative electrode tab, the active material layer of the positive electrode tab includes a positive electrode active material, and the positive electrode active material includes lithium-containing phosphate of an olivine structure;

the size of the coating part in the positive electrode plate along the length direction Z is a first size, the size of the coating part in the positive electrode plate along the width direction Y is a second size, and the ratio of the first size to the second size is 4-7;

The electrolyte comprises lithium salt, the lithium salt comprises lithium bis (fluorosulfonyl) imide, and the mass content of the lithium bis (fluorosulfonyl) imide in the electrolyte is 1-15%.

For the purpose of more clear explanation of the present application, the tab portion of the first pole piece 11 is defined as a first tab 111, and the coating portion of the first pole piece 11 is defined as a first coating portion 112. The tab portion of the second pole piece 12 is defined as a second tab 121 and the coating portion of the second pole piece 12 is defined as a second coating portion 122. The electrode terminal electrically connected to the first tab 111 is a first electrode terminal 31, and the electrode terminal electrically connected to the second tab 121 is a second electrode terminal 32.

Optionally, the battery cell 7 further comprises a separator 13, the separator 13 being located between the first pole piece 11 and the second pole piece 12.

The polarities of the first pole piece 11 and the second pole piece 12 are opposite, when the first pole piece 11 is a positive pole piece, the second pole piece 12 is a negative pole piece, the first electrode terminal 31 is a positive terminal, and the second electrode terminal 32 is a negative terminal;

Or when the first electrode tab 11 is a negative electrode tab, the second electrode tab 12 is a positive electrode tab, the first electrode terminal 31 is a negative electrode terminal, and the second electrode terminal 32 is a positive electrode terminal.

The electrode assembly 10 may be a laminated structure in which a plurality of first electrode sheets 11 and a plurality of second electrode sheets 12 are laminated, and it is easier to increase the coating amount of the active material on the laminated structure so that the battery cell 7 has a relatively high energy density, compared to a wound structure, and in the embodiment of the application, the ratio of the size of the coating portion in the positive electrode sheet along the length direction Z to the size of the coating portion in the positive electrode sheet along the width direction Y is 4 to 7, and the length of the coating portion is relatively long so as to be beneficial to carrying relatively more positive electrode active material and to be beneficial to making the battery cell 7 have a relatively high energy density.

In the case where the battery cell 7 has the above-described laminated structure, the electron transport path may be long, so that the internal resistance is high, the heat generation increases, and the above-described heat generation phenomenon is aggravated as the charge rate increases, which is unfavorable for rapid charge;

The electrode lug part is arranged on at least one side of the coating part along the width direction Y, so that the transmission path of electrons in the coating part is shorter, ohmic resistance can be reduced, lithium salt of the electrolyte also comprises 1-15% of lithium difluorosulfimide, so that the ion conduction capacity of the electrolyte is stronger, the internal resistance of an electrochemical system can be reduced, and the electrode lug part and the electrolyte are designed to comprehensively reduce the internal resistance of a battery monomer, thereby being beneficial to reducing the heat generation quantity, improving the quick charging capacity of the battery monomer and further improving the high-temperature cycle performance.

In the embodiment of the present application, the dimension of the coating portion in the positive electrode sheet in the length direction Z is a first dimension, which can be understood as the length of the coating portion in the positive electrode sheet. The dimension of the coating portion in the positive electrode sheet in the width direction Y is a second dimension, which can be understood as the width of the coating portion in the positive electrode sheet. When the first electrode sheet 11 is a positive electrode sheet, W2 in fig. 6 represents the dimension of the coating portion of the positive electrode sheet in the longitudinal direction Z, and Y1 represents the dimension of the coating portion of the positive electrode sheet in the width direction Y.

The ratio of the length of the coating part to the width of the coating part in the positive electrode plate is too small, for example, smaller than 4, the loading amount of the active material is relatively small, which is not beneficial to the improvement of the energy density of the battery cell, and the ratio of the length of the coating part to the width of the coating part in the positive electrode plate is too large, for example, larger than 7, which is not beneficial to the improvement of the quick charging performance of the battery cell.

The ratio of the length of the coating portion to the width of the coating portion in the positive electrode sheet according to the embodiment of the application is 4 to 7, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7 or a range formed by any two values, and the energy density and the quick charge performance of the battery cell can be improved.

The length of the coating part in the positive electrode plate is too small, for example, under the condition of less than 300mm, the carrying capacity of the active material is relatively small, which is not beneficial to the improvement of the energy density of the battery cell, and the length of the coating part in the positive electrode plate is too large, for example, under the condition of more than 650mm, the length of the positive electrode film layer is too long, the transmission path of electrons in the length direction of the positive electrode plate is too long, the resistance is increased, and the quick charging performance of the battery cell is not beneficial to the improvement.

In some embodiments, the length of the coating in the positive electrode sheet is 300mm to 650mm, e.g., 300mm, 350mm, 400mm, 450mm, 500mm, 505mm, 550mm, 600mm, 650mm, or a range of any two of the foregoing values. Alternatively, the length of the coating portion in the positive electrode sheet is 400mm to 505mm. When the length of the coating part in the positive electrode plate meets the range, the energy density and the quick charging performance of the battery cell can be improved.

[ Electrolyte ]

In the process of charging and discharging the battery cell, active ions such as lithium ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate, and the electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

The electrolyte salt includes a lithium salt including lithium bis-fluorosulfonyl imide and may further include lithium hexafluorophosphate LiPF ₆. The lithium salt is favorable for improving the lithium ion conducting capacity of the electrolyte, reducing the internal resistance of an electrochemical system, reducing the heat generation quantity and improving the quick charging capacity and the high-temperature cycle performance of the battery monomer.

Alternatively, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium difluorosulfonimide is 0.5 to 4, alternatively 1.2 to 2.0, based on the mass of the electrolyte. The lithium salt is favorable for improving the lithium ion conducting capacity of the electrolyte, reducing the internal resistance of an electrochemical system, reducing the heat generation quantity and improving the quick charging capacity and the high-temperature cycle performance of the battery monomer.

Illustratively, the mass content of lithium hexafluorophosphate and the mass content of lithium difluorosulfimide are 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.9, 4.0 or a range of any two of the values recited above.

In an embodiment of the application, the mass content of lithium bis-fluorosulfonyl imide is 1% to 15%, alternatively 3% to 12%, based on the mass of the electrolyte. The lithium salt is favorable for improving the lithium ion conducting capacity of the electrolyte, reducing the internal resistance of an electrochemical system, reducing the heat generation quantity and improving the quick charging capacity and the high-temperature cycle performance of the battery monomer.

Illustratively, the mass content of lithium bis-fluorosulfonyl imide is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range of any two of the foregoing numerical compositions, based on the mass of the electrolyte.

In some embodiments, the electrolyte has a conductivity of 10mS/cm to 13mS/cm at room temperature. Illustratively, the electrolyte has a conductivity of 10mS/cm, 10.5mS/cm, 11mS/cm, 11.5mS/cm, 12mS/cm, 12.5mS/cm, 13mS/cm, or a range of any two of the foregoing values at room temperature.

When the conductivity of the electrolyte at room temperature, for example, 25 ℃, is in the above range, the migration rate of lithium ions in the electrolyte is high, the internal resistance of the battery cell can be further reduced, the heat generation is reduced, and the rapid charging performance and the high-temperature cycle performance of the battery cell can be improved.

In embodiments of the present application where the electrolyte has an ionic conductivity at room temperature, e.g., 25 ℃, the electrolyte may be tested using equipment and methods well known in the art, e.g., with reference to the industry standard HG-T4067-2015.

In some embodiments, the organic solvent comprises a carbonate-based solvent.

Alternatively, the mass content of the carbonate-based solvent in the electrolyte is 10% to 80%. Illustratively, the mass content of the carbonate-based solvent in the organic solvent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80% or a range of any two of the above numerical values. The carbonate solvent with the mass content can further improve the conductivity of the electrolyte at room temperature, is beneficial to migration of lithium ions, and can reduce the high-temperature gas yield and improve the high-temperature cycle performance.

Optionally, the carbonate-based solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate. Further alternatively, the carbonate-based solvent includes one or more of dimethyl carbonate, ethylene carbonate. Still further alternatively, the carbonate-based solvent comprises dimethyl carbonate. The carbonate solvent and the chain carboxylic ester solvent are matched for use, so that the conductivity of the electrolyte at room temperature is improved, and the migration of lithium ions is facilitated.

In some embodiments, the organic solvent comprises a chain carboxylate solvent.

Alternatively, the mass content of the chain carboxylic ester solvent in the electrolyte is 5% to 30%. Illustratively, the mass content of the chain carboxylate solvent is 5%, 10%, 15%, 20%, 25%, 30% or a range of any two of the above values.

When the mass content of the chain carboxylate solvent is in the range, the viscosity of the electrolyte system is relatively small, which is favorable for migration of lithium ions, and the mass content of the chain carboxylate solvent is not too high, so that the high-temperature gas yield can be reduced, and the high-temperature cycle performance can be improved.

In some embodiments, the chain carboxylate solvents include compounds of formula I,

The compound of the formula I,

In the formula I, the compound (I),

R ₁ includes a hydrogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group,

R ₂ includes C1 to C5 alkyl or C1 to C5 haloalkyl.

The chain carboxylic ester solvent has higher conductivity, and is beneficial to improving the quick charging capability of the battery monomer.

Optionally, R ₁ includes a hydrogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further alternatively, R ₁ includes a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.

Alternatively, R ₂ includes a C1 to C3 alkyl or a C1 to C3 haloalkyl. Further alternatively, R ₂ comprises a C1 to C2 alkyl or C1 to C2 haloalkyl.

In each of the above embodiments, the haloalkyl comprises one or more of fluoroalkyl, chloroalkyl, bromoalkyl, and iodoalkyl, optionally the haloalkyl comprises fluoroalkyl.

Illustratively, the chain carboxylate solvents include one or more of the compounds of formula I-1 through formula I-8,

In some embodiments, the electrolyte further comprises an additive, which may include a negative film-forming additive, or may include a positive film-forming additive, or may include an additive capable of improving certain properties of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high temperature performance of the battery, an additive that improves the low temperature power performance of the battery, and the like.

In some embodiments, the additive comprises one or more, optionally at least two, of a carbonate additive, a sulfur-containing additive. The additive can improve the interfacial film performance of the positive electrode side and/or the negative electrode side, is beneficial to improving the quick charging performance of the battery cell and improves the cycle performance.

In some embodiments, the additive is present in the electrolyte in an amount of 0.5% to 6% by mass. Illustratively, the additive is present in the electrolyte at a mass content of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6% or a range of any two of the foregoing values.

The organic solvent, such as chain carboxylate solvent, may decompose to produce acid at high temperature to corrode solid electrolyte interface film SEI film on the surface of the negative electrode, while the additive can form compact SEI film with uniform thickness on the negative electrode side, can effectively repair SEI film, has excellent protection to the negative electrode active material, is beneficial to improving the quick charging performance of the battery cell and improves the cycle performance.

Illustratively, the carbonate additive comprises one or more of vinylene carbonate VC, fluoroethylene carbonate FEC, optionally the carbonate additive comprises vinylene carbonate VC and fluoroethylene carbonate FEC.

The vinylene carbonate VC can form a compact SEI film with uniform thickness on the negative electrode side, can effectively repair the SEI film, has excellent protection on the negative electrode active material, and is favorable for improving the quick charging performance and high-temperature cycle performance of the battery cell.

The fluoroethylene carbonate FEC can form an SEI film with relatively low impedance on the negative electrode side, can effectively repair the SEI film, has excellent protection on the negative electrode active material, and is beneficial to improving the quick charging performance and the high-temperature cycle performance of the battery cell.

Illustratively, the sulfur-containing additive includes one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butylene sulfite BS, 1, 3-propane sultone PS, vinyl sulfite ES, methyl methylene disulfonate MMDS, optionally 1, 3-propane sultone PS.

The sulfur-containing additive can effectively repair the SEI film, has excellent protection on the anode active material, and is beneficial to improving the quick charging performance and the high-temperature cycle performance of the battery cell.

Illustratively, the additives include one or more of vinylene carbonate, fluoroethylene carbonate, and 1, 3-propane sultone.

Alternatively, the mass content of vinylene carbonate VC in the electrolyte is 0.5% to 3.0%, e.g. 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3.0% or a range of any two values mentioned above. When the mass content of the vinylene carbonate VC in the electrolyte is in the range, the SEI film can be effectively repaired, the negative electrode active material is protected excellently, and the quick charging performance and the high-temperature cycle performance of the battery monomer are improved.

Alternatively, the fluoroethylene carbonate FEC is present in the electrolyte in a mass content of 0.2% to 2.5%, for example 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5% or in a range consisting of any two of the values mentioned above. When the mass content of fluoroethylene carbonate FEC in the electrolyte is in the range, the SEI film can be effectively repaired, the anode active material is protected excellently, and the quick charge performance and the high-temperature cycle performance of the battery cell are improved.

Alternatively, the mass content of 1, 3-propane sultone PS in the electrolyte is 0.5% to 2.5%, for example 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5% or a range of any two of the numerical compositions mentioned above. When the mass content of the 1, 3-propane sultone PS in the electrolyte is in the range, the SEI film can be effectively repaired, the anode active material is protected excellently, and the quick charge performance and the high-temperature cycle performance of the battery cell are improved.

In the embodiment of the application, the type and content of the inorganic component/lithium salt in the electrolyte are the meanings known in the art, and can be detected by using equipment and methods known in the art, for example, the inorganic component/lithium salt in the electrolyte can be qualitatively or quantitatively analyzed by an ion chromatography method with reference to the standard JY/T020-1996 general rule of ion chromatography method. In the embodiment of the application, newly prepared electrolyte can be taken as a sample, free electrolyte of a fresh battery can be taken as a sample, or the battery which has been discharged (discharged to a lower limit cut-off voltage so that the charged state of the battery is about 0% SOC) is reversely disassembled, and the free electrolyte obtained from the battery is taken as a sample and detected by adopting an ion chromatography analysis method.

In the embodiments of the present application, the types and contents of the organic components in the electrolyte are within the meaning known in the art, and may be detected using devices and methods known in the art, for example, qualitative and quantitative analysis of the organic components in the electrolyte by gas chromatography may be performed with reference to GB/T9722-2006 general rules for chemical gas chromatography.

In the embodiment of the application, after quantitatively and qualitatively detecting each component in the electrolyte, classifying each component, taking a chain carboxylate solvent and a carbonate solvent (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate) as constituent components of an organic solvent, calculating the mass content of each component based on 100% of the mass of the electrolyte,

The mass content of each component was calculated by taking a carbonate additive (e.g., vinylene carbonate, fluoroethylene carbonate) and a sulfur-containing additive as additives of the electrolytic solution, based on 100% by mass of the electrolytic solution.

[ First Pole piece and second Pole piece ]

As shown in fig. 7, in some embodiments, the first pole piece 11 satisfies n x W1/W2 of 0.5 to 1.0,

N represents the number of all the tab portions located on the same side of the coating portion;

w1 represents the average dimension of the tab portion in the length direction Z;

w2 represents the dimension of the coating portion in the longitudinal direction Z

Illustratively, n is W1/W2 is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or a range of any two of the foregoing values.

The first pole piece 11 satisfies n×w1/W2 to be 0.5 to 1.0, so that the connection area between the pole ear portion and the coating portion is relatively large, the overcurrent area of the pole ear portion is relatively large, the direct current resistance is reduced, the heat generation is reduced, and the quick charging capability and the high-temperature cycle performance are improved.

W1 represents the average size of the first tab 111 in the length direction Z,

When the first tab 111 is of a special-shaped structure, for example, in the width direction Y, the dimension of the first tab 111 in the length direction Z is gradually increased, and in this case, the dimension of the first tab 111 in the length direction Z may be measured at a plurality of positions, thereby calculating the average value of the dimensions of the first tab 111 in the length direction Z. Of course, the dimensions of the first tab 111 in the longitudinal direction Z may be the same value throughout, and in this case, the value may be an average value of the dimensions of the first tab 111.

The number of the first tabs 111 may be one or more, for example, n is 1 to 4, and in the case where there are a plurality of the first tabs 111, the average size of the first tabs 111 may be calculated by measuring the average size of each first tab 111, adding the average sizes, and dividing the sum by the number of the first tabs 111.

When the first tab 111 is connected to the first coating portion 112 and the first tab 111 includes the first end 1111 connected to the first coating portion 112 and n×w1/W2 satisfies the above range, this means that the cross section of the first end 1111 along the thickness direction of the first tab 111 is relatively large, the contact surface between the first tab 111 and the first coating portion 112 is relatively large, the overcurrent capability of the first tab 111 is relatively strong, and the power performance and the cycle performance of the battery cell 7 can be improved.

Optionally, the first tab 111 and the current collecting portion of the first coating portion 112 are in an integrated structure, so that the internal resistance of the first pole piece 11 is low, and the power performance and the cycle performance of the battery cell 7 can be further improved.

Alternatively, W2 is 300mm to 650mm, for example 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or a range of any two of the numerical values mentioned above.

Alternatively, n x W1 is 150mm to 650mm, e.g. 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or a range of any two of the numerical compositions mentioned above.

In some embodiments, the first pole piece 11 includes at least one first tab 111, and the at least one first tab 111 is disposed on at least one side of the coating portion in the width direction Y.

As shown in fig. 7 to 9, for example, at least one first tab 111 is disposed at one side of the coating portion in the width direction Y, in which case it can be understood that all the first tabs 111 are disposed at the same side of the coating portion in the width direction Y, which is advantageous in increasing the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7. In fig. 7, n is 1, W1 represents the dimension of the single first tab 111 in the longitudinal direction Z, and W2 represents the dimension of the first coating portion 112 in the longitudinal direction Z. In fig. 8, n is 4, the dimensions of the respective first tabs 111 are the same, and W1 represents the dimension of a single first tab 111 in the length direction Z. In fig. 9, n is 1, W1 represents the dimension of the single first tab 111 along the length direction Z, and n×w1/W2 is 1.

As shown in fig. 10, or for example, in the case where the first pole piece 11 includes a plurality of first tabs 111, the plurality of first tabs 111 are provided on both sides of the first coating portion 112 in the width direction Y.

Whether the first tab 111 is disposed on one side or both sides of the first coating portion 112, at least one, optionally at least two, for example, two, three, four, five, six, etc., and optionally four of the first tabs 111 on the same side of the first coating portion 112 in the width direction Y. This arrangement is advantageous for a uniform distribution of electrons in the first pole piece 11 and for an improved fast charging capability.

In the case where there are at least two first tabs 111 on the same side of the first coating portion 112, the distance between two adjacent first tabs 111 in the longitudinal direction Z is greater than 0 and equal to or less than 300mm, for example, 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range composed of any two of the above values. Z1 shown in fig. 10 represents a pitch of adjacent two first tabs 111 in the length direction Z.

When the distance between two adjacent first tabs 111 along the length direction Z satisfies the above range, the migration paths of electrons in the first coating portion 112 are shorter and can be uniformly distributed, which is beneficial to improving the quick charging capability of the battery cell.

In the case where the plurality of first tabs 111 are provided on both sides of the first coating portion 112 in the width direction Y, the dimension of the first coating portion 112 in the width direction Y is greater than 0 and equal to or less than 300mm, for example, 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range composed of any two of the above-mentioned values. Y1 shown in fig. 10 represents the dimension of the first coating portion 112 in the width direction Y.

In the case where the plurality of first tabs 111 are provided on one side of the first coating portion 112 in the width direction Y, the dimension of the first coating portion 112 in the width direction Y may be greater than 0 and equal to or less than 300mm, for example, 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range composed of any two of the above values.

When the dimension of the first coating portion 112 in the width direction Y meets the above requirement, the migration path of electrons in the width direction Y of the first coating portion 112 is short, and the electrons are uniformly distributed in the first coating portion 112, which is advantageous for improving the fast charging capability of the battery cell.

As shown in fig. 11, in some embodiments, the second pole piece 12 satisfies that m x W3/W4 is 0.5 to 1.0;

m represents the number of all the tab portions located on the same side of the coating portion;

w3 represents the average dimension of the tab portion in the length direction Z;

W4 denotes the dimension of the coating portion in the longitudinal direction Z.

Illustratively, m is W3/W4 is 0.5, 0.55, 0.6, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9, 1 or a range of any two of the foregoing values.

When m×w3/W4 satisfies the above range, the overcurrent area of the second tab 121 is relatively large, which is advantageous for improving the quick-charging performance of the battery cell 7.

W3 represents an average size of the second ears 121 in the length direction Z, and the average size may be calculated by measuring the size of each second ear 121 by ten-thousandth in the case where the second ears 121 are plural, for example, m is 1 to 4.

The second tab 121 is connected to the second coating portion 122, and when the second tab 121 includes the second end 1211 connected to the second coating portion 122 and m×w3/W4 satisfies the above range, this means that the cross section of the second end 1211 along the thickness direction of the second tab 121 is relatively large, the contact surface between the second tab 121 and the second coating portion 122 is relatively large, the overcurrent capacity of the second tab 121 is relatively high, and the power performance and the cycle performance of the battery cell 7 can be improved.

Alternatively, the second tab 121 and the current collecting portion of the second coating portion 122 are of an integrated structure, so that the internal resistance of the second tab 12 is low, and the quick charge capability and cycle performance of the battery cell 7 can be further improved.

When the second pole piece 12 meets the above conditions, the connection area between the pole ear part and the coating part is relatively large, and the overcurrent area of the pole ear part is relatively large, so that the direct current resistance and the heat generation are reduced, and the quick charging capability and the high-temperature cycle performance are improved.

Alternatively, W4 is 300mm to 650mm, for example 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm or a range of any two of the numerical values mentioned above.

Alternatively, m W3 is 150mm to 650mm, e.g., 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm, or a range of any two of the foregoing numerical compositions.

In some embodiments, the second tab 12 includes at least one second tab 121, and the at least one second tab 121 is disposed on at least one side of the coating portion in the width direction Y.

As shown in fig. 12, for example, at least one second tab 121 is disposed at one side of the second coating portion 122 in the width direction Y, in which case it can be understood that all the second tabs 121 are disposed at the same side of the second coating portion 122 in the width direction Y, which is advantageous in increasing the occupied space of the electrode assembly 10, thereby improving the energy density of the battery cell 7.

Or, for example, in the case where the second electrode sheet 12 includes a plurality of second electrode tabs 121, the plurality of second electrode tabs 121 are provided on both sides of the second coating portion 122 in the width direction Y.

Whether the second lugs 121 are provided on one side or both sides of the second coating portion 122, at least one, optionally at least two, for example, two, three, four, five, six, etc., and optionally four second lugs 121 located on the same side of the second coating portion 122 in the width direction Y. This arrangement facilitates a uniform distribution of electrons in the second pole piece 12 and improves the fast charging capability.

In the case where there are at least two second ears 121 on the same side of the second coating portion 122, the distance between two adjacent second ears 121 in the longitudinal direction Z is greater than 0 and equal to or less than 300mm, for example, 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range of any two of the above values.

When the distance between two adjacent second lugs 121 along the length direction Z satisfies the above range, the migration paths of electrons in the second coating portion 122 are shorter and can be uniformly distributed, which is beneficial to improving the quick charging capability of the battery cell.

In the case where the plurality of second lugs 121 are provided on at least one side of the second coating portion 122 in the width direction Y, the dimension of the second coating portion 122 in the width direction Y is greater than 0 and equal to or less than 300mm, for example, 100mm, 120mm, 140mm, 150mm, 160mm, 180mm, 200mm, 220mm, 240mm, 250mm, 260mm, 280mm, 300mm, or a range composed of any two of the above values.

When the dimension of the second coating portion 122 in the width direction Y meets the above requirement, the migration path of the electrons in the width direction Y of the second coating portion 122 is short, and the electrons are uniformly distributed in the second coating portion 122, which is beneficial to improving the quick charging capability of the battery cell.

In the case where all the second tabs 121 are disposed on the same side of the second coating portion 122 in the width direction Y and all the first tabs 111 are disposed on the same side of the first coating portion 112 in the width direction Y, the first tabs 111 and the second tabs 121 are disposed on both sides of the coating portion in the width direction Y, respectively. The arrangement mode is more beneficial to the connection of the like pole ear parts and the electrode terminals, and assembly interference of parts with opposite polarities can not occur.

[ Shell Assembly ]

In some embodiments, the battery cell 7 further includes a case assembly 20, and the case assembly 20 has a receiving space for receiving the electrode assembly 10 and the electrolyte.

In some embodiments, the case assembly 20 includes a case, a first electrode terminal 31 and a second electrode terminal 32, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on the case.

The shell can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), an aluminum-plastic film or the like. In some embodiments, the housing may be a sealed structure or a non-sealed structure. As an example, when the case is in a non-sealing structure, the case plays a role of protecting the electrode assembly 10, and a sealing pouch for sealing the electrode assembly 10 and the electrolyte is further included between the case and the electrode assembly 10. In particular, the sealed bag may be a bag-like insulating member or an aluminum plastic film. When the case has a sealed structure, the case is used for sealing the electrode assembly 10 and the electrolyte.

As an example, the battery cell 7 may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or other shaped battery cell, and the prismatic battery cell includes a square-case battery cell, a blade-shaped battery cell, a polygonal-prismatic battery cell, such as a hexagonal-prismatic battery cell, etc., and the present application is not particularly limited.

Outer casing

In some embodiments, the housing includes an end cap 22 and a housing 21, the housing 21 being provided with an opening, the end cap 22 covering the opening. The housing 21 may be provided with one or more openings. One or more end caps 22 may also be provided.

The first electrode terminal 31 and the second electrode terminal 32 may be provided to the case 21, or the first electrode terminal 31 and the second electrode terminal 32 may be provided to the end cap 22. Alternatively, the first electrode terminal 31 and the second electrode terminal 32 are provided on the end cap 22.

The first electrode terminal 31 and the second electrode terminal 32 may be provided at the same end cap 22, for example, one end cap 22 may be provided, and the first electrode terminal 31 and the second electrode terminal 32 may be provided at a distance from each other on the end cap 22. For another example, the end caps 22 are two, the two end caps 22 are disposed opposite to each other, and the first electrode terminal 31 and the second electrode terminal 32 are disposed on each end cap 22.

The first electrode terminal 31 and the second electrode terminal 32 are provided on different end caps 22, for example, two end caps 22 are provided, the two end caps 22 are provided opposite to each other, the first electrode terminal 31 is provided on one end cap 22, and the second electrode terminal 32 is provided on the other end cap 22.

The shape of the case 21 may be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, a case 21 having a cylindrical structure may be used, and if the electrode assembly 10 has a rectangular parallelepiped structure, a case 21 having a rectangular parallelepiped structure may be used. Alternatively, both the electrode assembly 10 and the case 21 are of a rectangular parallelepiped structure.

In some embodiments, the case 21 includes two first case portions 211, a second case portion 212, and a third case portion 213, the two first case portions 211 are opposite to each other in the thickness direction X of the battery cell 7, the second case portion 212 and the third case portion 213 are opposite to each other, and the second case portion 212 and the third case portion 213 are connected by the first case portion 211, the second case portion 212 includes a first wall 2121 and a second wall 2122 disposed continuously in the thickness direction X, and the first wall 2121 and the second wall 2122 are welded. The first wall 2121 and the second wall 2122 may be welded by welding, laser welding, or the like, and may be selectively welded. Because the area of the second shell portion 212 is relatively small and the degree of expansion is relatively small, the weld is located on the second shell portion 212, which reduces the risk of leakage of the battery cells 7.

When the battery unit 7 is assembled to the box body of the battery device, the battery unit 7 is arranged in the box body, the box body comprises a first box body part and a second box body part, the first box body part is covered on the second box body part, the second shell part 212 is arranged opposite to the first box body part, the second shell part 212 is arranged close to the first box body part, and the third shell part 213 is arranged close to the second box body part. When the battery device is assembled to the power utilization device, the first box portion can be located on the upper portion of the second box portion in the vertical direction, and the second shell portion 212 is provided with a welding seam upwards, so that the risk of leakage of the battery cell 7 is reduced.

In some embodiments, the dimension of the battery cell 7 in the thickness direction X is 10mm to 30mm, for example 10mm, 12mm, 14mm, 15mm, 16mm, 18mm, 20mm, 22mm, 24mm, 25mm, 26mm, 28mm, 30mm or a range of any two of the numerical values mentioned above.

The dimension of the battery cell 7 in the thickness direction X may characterize the thickness of the battery cell 7, in other words, the thickness of the battery cell 7 is 10mm to 30mm. When the thickness of the battery cell 7 is in the above range, the thickness of the battery cell 7 is relatively small, which is advantageous for rapid heat dissipation inside the battery cell 7 and reduces the risk of thermal runaway.

In some embodiments, the thickness of the housing 21 is 0.1mm to 0.5mm, such as ,0.1mm、0.12mm、0.14mm、0.15mm、0.16mm、0.17mm、0.18mm、0.19mm、0.2mm、0.21mm、0.22mm、0.23mm、0.24mm、0.25mm、0.26mm、0.27mm、0.28mm、0.29mm、0.3mm、0.31mm、0.32mm、0.33mm、0.34mm、0.35mm、0.36mm、0.37mm、0.38mm、0.39mm、0.4mm、0.41mm、0.42mm、0.43mm、0.44mm、0.45mm、0.46mm、0.47mm、0.48mm、0.49mm、0.5mm or a range of any two values recited above. Alternatively, the thickness of the housing 21 is 0.3mm to 0.4mm.

When the thickness of the housing 21 is in the above range, the housing 21 is relatively thin, which is advantageous for rapid heat dissipation of the housing 21.

Illustratively, the first shell portion 211 has a thickness of 0.1mm to 0.5mm, such as ,0.1mm、0.12mm、0.14mm、0.15mm、0.16mm、0.17mm、0.18mm、0.19mm、0.2mm、0.21mm、0.22mm、0.23mm、0.24mm、0.25mm、0.26mm、0.27mm、0.28mm、0.29mm、0.3mm、0.31mm、0.32mm、0.33mm、0.34mm、0.35mm、0.36mm、0.37mm、0.38mm、0.39mm、0.4mm、0.41mm、0.42mm、0.43mm、0.44mm、0.45mm、0.46mm、0.47mm、0.48mm、0.49mm、0.5mm or a range of any two values recited above. Alternatively, the thickness of the housing 21 is 0.3mm to 0.4mm.

Illustratively, second shell portion 212 has a thickness in the range of 0.1mm to 0.5mm, such as ,0.1mm、0.12mm、0.14mm、0.15mm、0.16mm、0.17mm、0.18mm、0.19mm、0.2mm、0.21mm、0.22mm、0.23mm、0.24mm、0.25mm、0.26mm、0.27mm、0.28mm、0.29mm、0.3mm、0.31mm、0.32mm、0.33mm、0.34mm、0.35mm、0.36mm、0.37mm、0.38mm、0.39mm、0.4mm、0.41mm、0.42mm、0.43mm、0.44mm、0.45mm、0.46mm、0.47mm、0.48mm、0.49mm、0.5mm or any two of the numerical values set forth above. Alternatively, the thickness of the housing 21 is 0.3mm to 0.4mm.

Illustratively, the thickness of the third shell portion 213 is from 0.1mm to 0.5mm, such as ,0.1mm、0.12mm、0.14mm、0.15mm、0.16mm、0.17mm、0.18mm、0.19mm、0.2mm、0.21mm、0.22mm、0.23mm、0.24mm、0.25mm、0.26mm、0.27mm、0.28mm、0.29mm、0.3mm、0.31mm、0.32mm、0.33mm、0.34mm、0.35mm、0.36mm、0.37mm、0.38mm、0.39mm、0.4mm、0.41mm、0.42mm、0.43mm、0.44mm、0.45mm、0.46mm、0.47mm、0.48mm、0.49mm、0.5mm or a range of any two values recited above. Alternatively, the thickness of the housing 21 is 0.3mm to 0.4mm.

First electrode terminal

In some embodiments, the battery cell 7 further includes a first electrode terminal 31, and the first electrode terminal 31 is connected to the first tab 111.

In some embodiments, the first electrode terminal 31 is at least one, and optionally at least two, for example, two, three, or four, etc.

As shown in fig. 13, in some embodiments, at least one first electrode terminal 31 is disposed at least one side of the electrode assembly 10 in the width direction Y in such a manner that the migration path of electrons can be shortened, which is advantageous in improving the rapid charging capability.

For example, all the first electrode terminals 31 are disposed at one side of the electrode assembly 10 in the width direction Y.

For another example, a plurality of first electrode terminals 31 are provided at both sides of the electrode assembly 10 in the width direction Y.

As shown in fig. 14, in some embodiments, at least one first electrode terminal 31 is disposed at least one side of the electrode assembly 10 in the length direction Z.

For example, all the first electrode terminals 31 are disposed at one side of the electrode assembly 10 in the length direction Z.

For another example, the plurality of first electrode terminals 31 are provided at both sides of the electrode assembly 10 in the length direction Z, and this arrangement can shorten the migration path of electrons, which is advantageous in improving the quick charge capability.

Illustratively, there are two first electrode terminals 31, one of which 31 is disposed on one side of the electrode assembly 10 and the other 31 is disposed on the other side of the electrode assembly 10. Or, for example, the first electrode terminals 31 are four, wherein two first electrode terminals 31 are disposed at one side of the electrode assembly 10 and the other two first electrode terminals 31 are disposed at the other side of the electrode assembly 10.

The first tab 111 and the first electrode terminal 31 may be electrically connected, directly or indirectly, and when the first tab 111 and the first electrode terminal 31 are indirectly connected, the battery cell 7 may include a first adapter 51, and the first adapter 51 is located between the first electrode terminal 31 and the first tab 111 and connects the first electrode terminal 31 and the first tab 111. When the number of first electrode tabs 111 is plural, the number of first electrode terminals 31 may be divided into plural groups, and each group of first electrode tabs 111 is connected to one first electrode terminal 31.

For example, when the first electrode terminal 31 is disposed at least one side of the electrode assembly 10 in the length direction Z and the first tab 111 is disposed at least one side of the first coating portion 112 in the width direction Y, connection of the first tab 111 and the first electrode terminal 31 is facilitated by the first adapter 51 while also improving the overcurrent capability of the battery cell 7. The arrangement of the first electrode terminal 31 on one side of the electrode assembly 10 in the longitudinal direction Z also improves the utilization space of the first electrode tab 11 in the width direction Y, and improves the energy density of the battery cell 7.

In the case where the first tab 111 and the first electrode terminal 31 are disposed at different sides of the battery cell 7, respectively, the first tab 51 may include a first tab 511 and a second tab 512, the first tab 511 extending in the length direction Z, the first tab 111 being connected to the first tab 511, and the second tab 512 being connected to the first tab 511 and protruding from the first tab 511 in the width direction Y and being connected to the first electrode terminal 31.

In the case where the first tab 111 and the first electrode terminal 31 are disposed at the same side of the battery cell 7, the first tab 51 may include only the first tab 511.

In the above embodiments, the first adapter 51 may have a sheet-like structure, but may have other structures.

In the above embodiments, the first adapter 51 may include a conductive polymer or a conductive metal material, and the conductive metal material may include copper, aluminum, an alloy containing the above metal elements, or the like.

In some embodiments, the first tab 111 includes a first region connected to the first adapter 51, and a ratio of a dimension of the first region along the length direction Z to a dimension of the first tab 111 along the length direction Z is 0.5 to 1.

Illustratively, the ratio of the dimension of the first region along the length direction Z to the dimension of the first tab 111 along the length direction Z is 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, or a range of any two values.

The dimension of the first region in the length direction Z is the distance of the first tab 111 in contact with the first tab 51, and this dimension can characterize the overcurrent capability of the first tab 111. For example, when the first tab 111 and the first adapter 51 are welded, the first area is a welded area on the first tab 111.

When the first tab 111 satisfies the above condition, the contact area between the first tab 111 and the first adapter 51 is relatively large, and when welding is adopted, the welding area is relatively large, so that the overcurrent capacity of the first tab 111 is relatively high, the ohmic resistance is relatively low, and the quick charging capacity of the battery cell 7 is improved.

In some embodiments, the battery cell 7 further includes a first conductive member 61, where the first conductive member 61 is located between the first adapter member 51 and the first tab 111, and the arrangement of the first conductive member 61 can increase the overcurrent capability between the first tab 111 and the first adapter member 51, which is beneficial to improving the quick charging performance, reducing the heat generation, and improving the high temperature cycle performance of the battery cell 7.

For example, the tab portion of the first pole piece 11 is disposed at one side of the coating portion in the width direction Y, and the first conductive member 61 is disposed between the first tab portion 111 and the first tab portion 51 and connects the first tab portion 111 and the first tab portion 51.

Optionally, at least two first tabs 111 are disposed on the same side of the first coating portion 112, at least two first conductive members 61 are disposed, the first conductive members 61 are connected to the first tabs 111 in a one-to-one correspondence manner, and at least two first conductive members 61 are connected to the first adapter 51.

As shown in fig. 15, alternatively, at least two first tabs 111 are disposed on the same side of the first coating portion 112, and the first conductive member 61 may be a continuous sheet structure connected to at least two first tabs 111.

As shown in fig. 16, in the case where the first tab 111 and the first electrode terminal 31 are disposed at different sides of the battery cell 7, respectively, the first conductive member 61 may optionally include a first conductive portion 611 and a second conductive portion 612, the first conductive portion 611 extending in the length direction Z, the first conductive portion 611 connecting the first tab 111 and the first adapter 51, the second conductive portion 612 being connected to the first conductive portion 611 and protruding from the first conductive portion 611 in the width direction Y, the second conductive portion 612 connecting the first adapter 51. The structure is beneficial to improving the grouping space of the length direction Z and improving the energy density of the battery device.

In the case where the battery cell 7 does not include the first adapter 51, the first tab 111 may be connected to the first electrode terminal 31 through the first conductive member 61.

Illustratively, the first conductive member 61 has a conductive capability, and may include a conductive polymer or a conductive metal material, which may include copper, aluminum, or an alloy containing the above metal elements, or the like.

In the embodiment of the present application, the first electrode terminal 31 may be in an integral structure, may be integrally formed, or may be integrally connected by welding or other means, so that the integral structure is beneficial to reducing resistance, reducing heat generation, and improving power performance and cycle performance of the battery cell.

As shown in fig. 17 to 19, in some embodiments, the first electrode terminal 31 may include a first electrode body 311 and a first electrode protrusion 312, the first electrode body 311 being located at a side of the end cap 22 facing the electrode assembly 10, the first electrode protrusion 312 being connected to the first electrode body 311 and protruding toward a side facing away from the electrode assembly 10 and penetrating the end cap 22, alternatively, the first electrode body 311 and the first electrode protrusion 312 may be in a unitary structure. In other embodiments, the first electrode terminal 31 may include only the first electrode tab 312, and the first electrode tab 312 penetrates the end cap 22 and is connected to the tab portion.

Alternatively, the minimum sectional area of the first electrode protrusion 312 parallel to the thickness direction X is a first area, the area surrounded by the projection outer contour of the end cap 22 parallel to the thickness direction X is a second area, and the ratio of the first area to the second area is 0.02 to 0.20, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, or a range consisting of any two of the above values, and in the embodiment of the present application, the thickness direction X refers to the thickness direction X of the battery cell 7. The first area refers to the smallest cross-sectional area of the first electrode protrusion 312 of the single first electrode terminal 31, and is the overcurrent bottleneck of the first electrode terminal 31, and when the first area meets the above conditions, the overcurrent capacity of the first electrode terminal 31 is strong, which is beneficial to reducing heat generation and improving the quick charge performance and cycle performance of the battery cell.

The first electrode protrusion 312 may have a plurality of cross-sectional areas of different sizes in the thickness direction X, for example, the first electrode protrusion 312 includes a first portion, a second portion, and a third portion connected in sequence, and the cross-sectional area of the second portion is the first area if the cross-sectional area of the second portion is the smallest. Of course, the sectional area of the first electrode protrusion 312 may be the same throughout the thickness direction X.

Alternatively, the ratio of the dimension of the first electrode protrusion 312 in the thickness direction X to the dimension of the end cap 22 in the thickness direction X is 0.20 to 0.40, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40, or a range of any two of the above values, and in the present embodiment, the thickness direction X refers to the thickness direction X of the battery cell 7. The size of the first electrode protrusion 312 refers to the size of the first electrode protrusion 312 of the single first electrode terminal 31 in the thickness direction X. The dimension of the first electrode protrusion 312 in the thickness direction X may be understood as the width of the first electrode protrusion 312, and the dimension of the end cap 22 in the thickness direction X may be understood as the width of the end cap 22.

When the first electrode protrusion 312 satisfies the above condition, the size of the first electrode protrusion 312 is relatively high, which is advantageous for improving the overcurrent capability of the first electrode terminal 31, thereby improving the quick charge performance.

In some embodiments, the case assembly 20 further includes a first conductive fixing member 41, the first conductive fixing member 41 is disposed around the first electrode terminal 31 and fixedly connects the first electrode terminal 31 and the end cap 22, at least a portion of the first conductive fixing member 41 is located at a side of the end cap 22 facing away from the electrode assembly 10, and the first conductive fixing member 41 may be used to connect with an external bus bar assembly. Optionally, an insulating member may be provided between the first conductive fixing member 41 and the end cap 22 for insulation.

The first conductive fixing member 41 can further increase the overcurrent area of the battery unit 7 and the external bus assembly, thereby improving the overcurrent capacity, being beneficial to improving the overcurrent capacity of the battery device and improving the quick charging performance of the battery device.

Alternatively, a portion of the first electrode protruding portion 312 protrudes from a side of the end cap 22 facing away from the electrode assembly 10, and the first conductive fixing member 41 is disposed around the first electrode protruding portion 312.

Alternatively, the ratio of the dimension of the first conductive fixing member 41 in the thickness direction X to the dimension of the end cap 22 in the thickness direction X is 0.40 to 0.80, for example 0.40、0.42、0.44、0.46、0.48、0.50、0.52、0.54、0.56、0.58、0.60、0.62、0.64、0.66、0.68、0.70、0.72、0.74、0.76、0.78、0.80 or a range consisting of any two of the above values, and in the embodiment of the present application, the thickness direction X refers to the thickness direction X of the battery cell 7. The size of the first conductive fixing member 41 refers to the size of the single first conductive fixing member 41 in the thickness direction X. X ₁ shown in fig. 18 represents the dimension of the first conductive fixing member 41 in the thickness direction X, which can be understood as the width of the first conductive fixing member 41, and X ₂ represents the dimension of the end cap 22 in the thickness direction X, which can be understood as the width of the end cap 22.

When the first conductive fixing member 41 meets the above conditions, the size of the first conductive fixing member 41 is relatively high, which is favorable for improving the overcurrent area of the battery unit 7 and the external bus assembly, thereby improving the overcurrent capacity of the battery device, and improving the quick charging performance of the battery device.

Second electrode terminal

In some embodiments, the battery cell further includes a second electrode terminal 32, and the second electrode terminal 32 is connected to the second tab 121.

In some embodiments, the second electrode terminals 32 are at least one, optionally at least two, such as two, three, or four, etc.

In some embodiments, at least one second electrode terminal 32 is disposed at least one side of the electrode assembly 10 in the width direction Y in such a manner that a migration path of electrons can be shortened, which is advantageous in improving a quick charge capability.

For example, all the second electrode terminals 32 are provided at one side of the electrode assembly 10 in the width direction Y, in which case the first electrode terminals 31 and the second electrode terminals 32 may be provided at both sides of the electrode assembly 10 in the width direction Y, respectively, without interfering with each other when electrically connected to the tab portions, respectively.

Illustratively, there are two first electrode terminals 31 and two second electrode terminals 32, and the two first electrode terminals 31 are disposed on one side of the electrode assembly 10 in the width direction Y, and the two second electrode terminals 32 are disposed on the other side of the electrode assembly 10 in the width direction Y. Fig. 13 shows a schematic view in which the first electrode terminal 31 and the second electrode terminal 32 are disposed at both sides of the electrode assembly 10 in the width direction Y.

For another example, the plurality of second electrode terminals 32 are respectively disposed at both sides of the electrode assembly 10 in the width direction Y, and this arrangement can further shorten the migration path of electrons, which is advantageous in improving the quick charge capability. In this case, one side of the electrode assembly 10 in the width direction Y is provided with a first electrode terminal 31 and a second electrode terminal 32, and the other side of the electrode assembly 10 in the width direction Y is provided with the first electrode terminal 31 and the second electrode terminal 32.

In some embodiments, at least one second electrode terminal 32 is disposed on at least one side of the electrode assembly 10 in the length direction Z.

For example, at least two second electrode terminals 32 are respectively disposed at both sides of the electrode assembly 10 in the length direction Z, which can shorten the migration path of electrons, which is advantageous for improving the rapid charging capability. In this case, the electrode assembly 10 is provided with the first electrode terminal 31 and the second electrode terminal 32 at one side in the length direction Z, and the electrode assembly 10 is provided with the first electrode terminal 31 and the second electrode terminal 32 at the other side in the length direction Z.

For another example, there are two second electrode terminals 32, one of which 32 is provided on one side of the electrode assembly 10 in the longitudinal direction Z, and the other of which 32 is provided on the other side of the electrode assembly 10 in the longitudinal direction Z. The number of the first electrode terminals 31 is two, one of the first electrode terminals 31 is disposed at one side of the electrode assembly 10, and the other first electrode terminal 31 is disposed at the other side of the electrode assembly 10. Fig. 16 shows that the battery cell 7 includes four electrode terminals.

In this case, the first electrode terminal 31 and the second electrode terminal 32 may be provided on both sides of the electrode assembly 10 in the longitudinal direction Z, and may not interfere with each other when electrically connected to the tab portion.

As shown in fig. 20, the first electrode terminal 31 and the second electrode terminal 32 are exemplarily one each, the first electrode terminal 31 and the second electrode terminal 32 are respectively located at both sides of the electrode assembly in the length direction Z, and the first electrode terminal 31 and the second electrode terminal 32 are disposed offset in the width direction Y. Specifically, in the case where all the second tabs 121 are disposed on the same side of the second coating portion 122 in the width direction Y and all the first tabs 111 are disposed on the same side of the first coating portion 112 in the width direction Y, the first tabs 111 and the second tabs 121 are disposed on both sides of the coating portion in the width direction Y, respectively, the first electrode terminals 31 are disposed near the first tabs 111, and the second electrode terminals 32 are disposed near the second tabs 121. By the arrangement mode, the electron transmission distance is shorter, and the quick charging capacity of the battery cell 7 is improved more favorably.

The second tab 121 and the second electrode terminal 32 may be electrically connected, either directly or indirectly, and when the second tab 121 and the second electrode terminal 32 are indirectly connected, the battery cell 7 may include a second adapter member that is positioned between the second electrode terminal 32 and the second tab 121 and connects the second electrode terminal 32 and the second tab 121.

For example, when the second electrode terminal 32 is disposed at least one side of the electrode assembly 10 in the length direction Z and the second tab 121 is disposed at least one side of the second coating portion 122 in the width direction Y, the connection of the second tab 121 and the second electrode terminal 32 is facilitated by the second adapter, while the overcurrent capability of the battery cell 7 can be improved. The provision of the second electrode terminal 32 on one side of the electrode assembly 10 in the longitudinal direction Z also improves the utilization space of the second electrode sheet 12 in the width direction Y, and improves the energy density of the battery cell 7.

In the case where the second tab 121 and the second electrode terminal 32 are disposed at different sides of the battery cell 7, respectively, the second adapter may include a first connection portion extending along the length direction Z and a second connection portion connected to the second tab 121, the second connection portion being connected to the first connection portion and protruding from the first connection portion along the width direction Y and being connected to the second electrode terminal 32.

In the case where the second tab 121 and the second electrode terminal 32 are disposed at the same side of the battery cell 7, the second adapter may include only the first connection part.

In the above embodiments, the second adaptor may have a sheet-like structure, but may have other structures.

In the above embodiments, the second adapter may include a conductive polymer or a conductive metal material, and the conductive metal material may include copper, aluminum, an alloy containing the above metal elements, or the like.

In some embodiments, the second tab 121 includes a second region connected to the second adapter, and a ratio of a dimension of the second region along the length direction Z to a dimension of the second tab 121 along the length direction Z is 0.5 to 1.

Illustratively, the ratio of the dimension of the second region along the length direction Z to the dimension of the second tab 121 along the length direction Z is 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, or a range of any two values.

The dimension of the second region along the length Z is the distance the second tab 121 contacts the second adapter, and this dimension is indicative of the overcurrent capability of the second tab 121. For example, when the second tab 121 and the second adapter are welded, the first area is a solder area on the second tab 121.

When the second tab 121 meets the above conditions, the overcurrent capacity of the second tab 121 is strong, which is favorable for improving the quick charging capacity of the battery cell 7.

In some embodiments, the battery unit 7 further includes a second conductive member, where the second conductive member is located between the second adapter and the second tab 121, and the second conductive member is configured to increase the overcurrent capability between the second tab 121 and the second adapter, so as to facilitate the improvement of the quick charging performance and the reduction of the heat generation, and the second tab 121 and the second adapter, and the second conductive member and the second adapter may be electrically connected by welding. The presence of the second conductive element can significantly reduce the risk of failure caused by the direct electrical connection of the plurality of second tabs 121 and the second adapter element.

For example, the tab portion of the second pole piece 12 is disposed at one side of the coating portion in the width direction Y, and the second conductive member is disposed between the second adapter and the second tab 121 and connects the second adapter and the second tab 121.

Optionally, at least two second lugs 121 are disposed on the same side of the second coating portion 122, and the second conductive members may be in a continuous sheet structure and connected to the at least two second lugs 121, or at least two second conductive members are connected to the at least two second lugs 121 in a one-to-one correspondence manner, and the at least two second conductive members are connected to the second adaptor, so that the weight energy density of the battery cell 7 is improved.

In the case where the second tab 121 and the second electrode terminal 32 are disposed on different sides of the battery cell 7, respectively, the second conductive member may optionally include a third conductive portion extending in the length direction Z and a fourth conductive portion connecting the tab portion of the second pole piece 12 and the second adapter member, the fourth conductive portion being connected with the third conductive portion and protruding from the third conductive portion in the width direction Y, the third conductive portion being connected with the second adapter member. The structure is beneficial to improving the grouping space of the length direction Z and improving the energy density of the battery device.

Illustratively, the second conductive member has conductive capabilities, and may include a conductive polymer or a conductive metal material, which may include copper, aluminum, or an alloy containing the above metal elements, or the like.

In the case where the battery cell 7 does not include the second adapter, the second tab 121 may be connected to the second electrode terminal 32 through the second conductive member.

In the embodiment of the present application, the second electrode terminal 32 may be in an integral structure, may be integrally formed, or may be integrally connected by welding or other means, so that the integral structure is advantageous in reducing resistance, reducing heat generation, and improving power performance and cycle performance of the battery cell.

For example, in some embodiments, the second electrode terminal 32 may have a structure similar to that of the first electrode terminal 31, for example, the second electrode terminal 32 may include a second electrode body located at a side of the end cap 22 facing the electrode assembly 10 and a second electrode protrusion connected to the second electrode body and protruding toward a side facing away from the electrode assembly 10 and penetrating the end cap 22, and optionally the second electrode body and the second electrode protrusion may be a unitary structure. In other embodiments, the second electrode terminal 32 may include only a second electrode tab that extends through the end cap 22 and connects with the tab portion.

In some embodiments, the housing assembly 20 further includes a second conductive mount disposed circumferentially about the second electrode terminal 32 and fixedly connecting the second electrode terminal 32 and the end cap 22. The structural form and associated dimensions of the second conductive mount are as described in connection with the first conductive mount 41.

The second conductive fixing piece can further increase the overcurrent area of the battery monomer 7 and the external confluence assembly, so that the overcurrent capacity is improved, the overcurrent capacity of the battery device is improved, and the quick charging performance of the battery device is improved.

Heat conduction member

In some embodiments, the battery cell 7 further includes a heat conduction member disposed between the tab portion and the coating portion, the heat conduction member being capable of conducting heat generated by the tab portion, rapidly transferring the heat generated by the tab portion, and reducing the risk of ablation of the separator in the electrode assembly by the heat.

Optionally, the tab part is disposed on at least one side of the coating part along the width direction of the battery cell, and extends along the length direction and has a gap with the coating part, and the battery cell further comprises a heat conduction member disposed at least in the gap.

Optionally, the heat conducting member is further in contact with the housing 21, thereby allowing heat to diffuse from the housing 21.

As shown in fig. 21, exemplarily, the heat conductive member includes a first heat conductive member 81, the first heat conductive member 81 is disposed at a gap between the first tab 111 and the first coating part 112, and the first heat conductive member 81 is capable of conducting heat generated by the first tab 111.

Alternatively, the first heat conductive member 81 may be further disposed at a gap between the first tab 111 and the first electrode terminal 31, and in the case where the battery cell 7 includes the first adapter 51, the first heat conductive member 81 may be further disposed at a gap between the first tab 111 and the first adapter 51, or at a gap between the second adapter 512 and the coating portion of the first adapter 51.

Illustratively, the heat conductive member includes a second heat conductive member disposed in a gap between the second tab 121 and the second coating portion 122, the second heat conductive member being capable of conducting heat generated by the second tab 121.

Alternatively, the second heat conductive member may be further disposed at a gap between the second tab 121 and the second electrode terminal 32, and in the case where the battery cell 7 includes the second adapter, the second heat conductive member may be disposed at a gap between the second tab 121 and the second adapter.

The main material of the heat conduction component comprises one or more of polyimide PI and polyethylene terephthalate PET.

Positive electrode plate

For more clear description of the application, the coating part of the positive electrode plate corresponds to a positive electrode coating part, the lug part corresponds to a positive electrode lug, the active material layer corresponds to a positive electrode film layer containing a positive electrode active material, and the positive electrode coating part comprises a positive electrode current collecting part and a positive electrode film layer arranged on at least one side of the positive electrode current collecting part.

The positive electrode plate comprises a positive electrode current collecting part and a positive electrode film layer which is arranged on at least one surface of the positive electrode current collecting part and comprises a positive electrode active material. For example, the positive electrode current collecting portion has two surfaces opposing each other in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two opposing surfaces of the positive electrode current collecting portion.

The upper limit voltage for charge and the cut-off voltage of the battery cell differ according to the difference of the positive electrode active material, for example, when the phosphate material includes lithium iron phosphate, the upper limit voltage for charge may be 3.65V, the cut-off voltage for discharge may be 2.0V, or the upper limit voltage for charge may be 3.8V, the cut-off voltage for discharge may be 2.0V, and for example, when the phosphate material includes lithium iron phosphate, the upper limit voltage for charge may be 4.3V, the cut-off voltage for discharge may be 2.0V, and next, the state of the battery cell is described by taking the upper limit voltage for charge of 3.65V, the cut-off voltage for discharge of 2.0V as an example, in the embodiment of the present application, the 100% state of charge SOC and the 0% state of charge SOC of the battery cell are defined as follows,

The battery cell is charged to the charge upper limit voltage at a constant current charging rate of 0.33C, then is charged to 0.05C at a constant voltage, and corresponds to a state of 100% SOC of the battery cell, and the battery cell is discharged to the cut-off voltage at a constant current discharging rate of 0.33C, and corresponds to a state of 0% SOC of the battery cell.

In some embodiments, the positive electrode film layer has a compacted density of 2.30g/cm ³ to 2.70g/cm ³, optionally 2.40g/cm ³ to 2.55g/cm ³, at a state of charge, SOC, of 0%. For example, the positive electrode film layer has a compacted density of 2.30g/cm³、2.32g/cm³、2.35g/cm³、2.38g/cm³、2.40g/cm³、2.42g/cm³、2.45g/cm³、2.48g/cm³、2.50g/cm³、2.52g/cm³、2.55g/cm³、2.56g/cm³、2.57g/cm³、2.58g/cm³、2.60g/cm³、2.62g/cm³、2.65g/cm³、2.68g/cm³、2.70g/cm³ or a range of any two values above at 0% SOC.

The compaction density of the positive electrode film layer is beneficial to improving the energy density of the battery monomer when the compaction density of the positive electrode film layer is in the range, and the contact resistance between particles is smaller because the positive electrode active material of the positive electrode film layer is compactly stacked, so that the resistance of a pole piece can be further reduced, the heat generation under quick charge is reduced, the problem of aggravation of side reaction of a negative electrode caused by heat accumulation is solved, and the cycle performance of the battery monomer is improved.

In some embodiments, the single sided coating weight of the positive electrode film layer is 250mg/1540.25mm ² to 330mg/1540.25mm ², alternatively 275mg/1540.25mm ² to 300mg/1540.25mm ². The positive electrode film layer may have a single-sided coating weight of 250mg/1540.25mm²、260mg/1540.25mm²、270mg/1540.25mm²、280mg/1540.25mm²、290mg/1540.25mm²、300mg/1540.25mm²、310mg/1540.25mm²、320mg/1540.25mm²、330mg/1540.25mm² or a range of any two of the above values.

When the single-sided coating weight of the positive electrode film layer is in the range, the heat generation amount in the unit area of the positive electrode plate is not excessive, the problem of aggravation of negative side reaction caused by heat accumulation is relieved, the cycle performance of the battery monomer is improved, and the energy density of the battery monomer can be improved.

In the embodiment of the application, the compaction density of the positive electrode film layer of the battery cell under the state of charge of 0% is the meaning known in the art, namely, the positive electrode plate is disassembled for the battery cell under the state of charge of 0%, the compaction density of the positive electrode film layer is measured, for example, a single-side coated positive electrode plate (in the case of a double-side coated electrode plate, the positive electrode film layer on one side can be wiped off firstly) is taken, a small wafer with the area of S1 is punched, the weight of the small wafer is called, the weight is recorded as M1, and the thickness H1 of the small wafer is measured. And then wiping the positive electrode film layer of the weighed positive electrode plate, weighing the weight of the positive electrode current collecting part, recording as M0, and measuring the thickness H0 of the positive electrode current collecting part. Single-sided coating weight of positive electrode film = (weight of positive electrode sheet M1-weight of positive electrode current collector M0)/S1, thickness of positive electrode film = thickness of positive electrode sheet H1-thickness of positive electrode current collector H0, compacted density of positive electrode film = single-sided coating weight of positive electrode film/thickness of positive electrode film.

In some embodiments, the positive electrode active material includes an olivine structured lithium-containing phosphate. In other embodiments, the positive electrode active material may also include lithium-containing transition metal oxides and the like, examples of which may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

In the embodiment of the application, the lithium-containing phosphate with the olivine structure can be phosphate particles or a material obtained by coating and modifying the same, for example, the lithium-containing phosphate with the olivine structure comprises phosphate particles and a coating layer, the coating layer is coated on the surfaces of the phosphate particles, for example, the coating layer comprises elements such as carbon, so that the conductivity of the phosphate particles is improved, the powder resistivity of the material is reduced, the migration rate of lithium ions is facilitated, the quick charging capability of a battery is improved, and the heat generation amount of a battery cell is reduced.

In some embodiments, the phosphate particles comprise a compound of the general formula Li _x1A_y1Me_aM_bP_1-cX_cY_z, where 0.5≤x ₁≤1.3,0≤y₁≤1.3, and 0.9≤x ₁+y₁≤ 1.3,0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5, 0≤c≤0.5, 3≤z≤5, A comprises one or more of Na, K, mg, me comprises one or more of Mn, fe, co, ni, M comprises one or more of B, mg, al, si, P, S, ca, sc, ti, V, cr, cu, zn, sr, Y, zr, nb, mo, cd, sn, sb, te, ba, ta, W, yb, la, ce, X comprises one or more of Cl, C, N, Y comprises one or more of O, F. The cycling stability of the phosphate particles is excellent, and the cycling performance of the battery monomer is improved.

Illustratively, the phosphate particles include one or more of LiFePO ₄、LiMnPO₄、LiNiPO₄、LiCoPO₄. The battery cells may be charged and discharged with the release and consumption of active ions such as Li, and the molar contents of Li are different when the battery cells are discharged to different states. In the list of LiFePO ₄、LiMnPO₄、LiNiPO₄、LiCoPO₄ and the like as the positive electrode active material, the molar content of Li is the initial state of the material, that is, the state before charging, and the molar content of Li may change after charge and discharge cycles when the positive electrode active material is applied to a battery system. In the examples of the positive electrode active material LiFePO ₄、LiMnPO₄、LiNiPO₄、LiCoPO₄ and the like in the embodiments of the present application, the molar content of oxygen O is only a theoretical state value, and the molar content of oxygen O may be changed due to lattice oxygen release, and in practice, the molar content of oxygen O may float, which is within the scope of the present application.

In an embodiment of the present application, the content of the element in the positive electrode active material is in the meaning known in the art, and may be detected using equipment and methods known in the art, for example, by inductively coupled plasma atomic emission spectrometry test, with reference to EPA 6010D-2014, and measurement using plasma atomic emission (ICP-OES, instrument model: thermo ICAP 7400). Discharging the battery monomer to a state of charge (SOC) of 0%, disassembling the battery monomer to obtain a positive electrode plate, cleaning and drying the positive electrode plate by using dimethyl carbonate (DMC), calcining at high temperature to remove impurities, weighing 0.4g of positive electrode active material, and adding 10ml (50% concentration) of aqua regia into the positive electrode active material. Then placed on a 180℃plate for 30min. After digestion on the plate, the volume is fixed to 100mL, and quantitative test is carried out by adopting a standard curve method.

In some embodiments, the positive electrode film layer further comprises a positive electrode additive, wherein the positive electrode additive comprises lithium elements, and can release lithium ions in the charging process of the battery cells, so that lithium loss is compensated, and the capacity characteristic and the cycle performance of the battery cells are improved.

In some embodiments, the positive electrode additive includes at least one of lithium ferrite particles or lithium nickelate particles.

In some embodiments, the average longest diameter of the positive electrode additive is in the range of 2 μm to 5 μm, e.g., 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any two of the compositions. When the positive electrode additive with the particle size is adopted, the stability of the positive electrode additive can be effectively improved, and meanwhile, the positive electrode additive has a good lithium supplementing effect.

In the embodiment of the application, the positive electrode plate is cut along the thickness direction of the plate to expose the longitudinal section of the positive electrode film layer, and the longest diameter of the positive electrode additive particles is determined by Scanning Electron Microscope (SEM) test on the longitudinal section of the positive electrode film layer. For example, the "longest diameter" of a particle refers to the longest straight line that passes through the center point of the particle and extends to the periphery of the particle.

In the cross section of the positive electrode film layer in the thickness direction thereof, the longest diameters of a plurality of, for example, 10 lithium-containing iron oxides are counted, and the average value thereof is calculated as the average longest diameter.

In some embodiments, the mass ratio of the positive electrode additive is 0.2% to 2.5%, such as 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.5%, or a range of any two compositions, based on the total mass of the positive electrode film layer.

When the positive electrode additive with the mass range is adopted, lithium loss can be effectively compensated.

In some embodiments, the positive electrode film layer further optionally includes a positive electrode conductive agent. The embodiment of the present application is not particularly limited in kind of the positive electrode conductive agent, and the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example. In some embodiments, the mass content of the positive electrode conductive agent is 5% or less based on the mass of the positive electrode film layer.

In some embodiments, the positive electrode film layer further optionally includes a positive electrode binder. The embodiment of the present application is not particularly limited in kind of the positive electrode binder, and the positive electrode binder may include at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluoroacrylate-based resin, as an example. In some embodiments, the mass content of the positive electrode binder is 5% or less based on the mass of the positive electrode film layer.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. As examples of the metal foil, at least one foil of aluminum, aluminum alloy, nickel alloy, titanium alloy, silver, and silver alloy may be employed. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metal material of the metal material layer may include at least one of aluminum, aluminum alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).

In some embodiments, the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collector is 3 to 10, e.g., 3, 4, 5, 6, 7, 8, 9, 10, or a range of any two of the foregoing values. Alternatively, the ratio of the thickness of the single-sided positive electrode film layer to the thickness of the positive electrode current collector is 4 to 8.

When the ratio of the thickness of the single-side positive electrode film layer to the thickness of the positive electrode current collecting part is in the above range, the quick charging capability and the energy density of the battery cell can be improved.

In some embodiments, the thickness of the positive current collector is 12 μm to 16 μm, alternatively 13 μm to 15 μm. The thickness of the positive electrode current collector is, for example, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm or a range of any two of the above numerical values.

When the thickness of the positive electrode current collecting portion is in the above range, the overcurrent capability of the positive electrode current collecting portion is excellent, and the battery cell can have a high energy density.

In the embodiment of the present application, the thicknesses of the positive electrode film layer and the positive electrode current collecting portion are in the meaning known in the art, and can be detected by using equipment and methods known in the art, for example, the thickness of the positive electrode sheet is measured by using a ten-thousandth gauge, the film layer on the surface of the positive electrode current collecting portion is removed, the thickness of the positive electrode current collecting portion is measured by using a ten-thousandth gauge, when the positive electrode film layer is coated on one side, the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collecting portion, and when the positive electrode film layer is coated on both sides, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collecting portion)/2.

The positive electrode film layer is usually formed by coating a positive electrode slurry on a positive electrode current collecting portion, drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.

The positive electrode sheet does not exclude other additional functional layers than the positive electrode film layer. For example, in some embodiments, the positive electrode sheet of embodiments of the present application further includes a positive electrode conductive layer disposed on a surface of the positive electrode current collector sandwiched between the positive electrode current collector and the positive electrode film layer. In other embodiments, the positive electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the positive electrode film layer.

Negative pole piece

For more clear description of the application, the coating part of the negative electrode plate corresponds to a negative electrode coating part, the lug part corresponds to a negative electrode lug, the active material layer corresponds to a negative electrode film layer containing a negative electrode active material, the negative electrode coating part comprises a negative electrode current collecting part and a negative electrode film layer arranged on at least one side of the negative electrode current collecting part, and the negative electrode coating part comprises a negative electrode current collecting part and a negative electrode film layer arranged on at least one side of the negative electrode current collecting part.

The negative electrode tab includes a negative electrode current collecting portion and a negative electrode film layer disposed on at least one surface of the negative electrode current collecting portion and including a negative electrode active material. For example, the anode current collecting portion has two surfaces opposing in the own thickness direction, and the anode film layer is provided on either or both of the two opposing surfaces of the anode current collecting portion.

In some embodiments, the negative electrode film layer has a compacted density of 1.30g/cm ³ to 1.65g/cm ³, optionally 1.35g/cm ³ to 1.50g/cm ³, at a state of charge SOC of 0%. Illustratively, the negative electrode film layer of the battery cell has a compacted density of 1.3g/cm³、1.32g/cm³、1.35g/cm³、1.40g/cm³、1.45g/cm³、1.50g/cm³、1.55g/cm³、1.60g/cm³、1.65g/cm³ or a range of any two of the above values at 0% charge.

The compaction density of the negative electrode film layer is beneficial to improving the energy density of the battery monomer when the compaction density of the negative electrode film layer is in the range, and as the negative electrode active materials of the negative electrode film layer are closely stacked, the contact resistance between particles is smaller, and the resistance of the pole piece can be further reduced, thereby reducing the heat generation, relieving the problem of aggravation of negative electrode side reaction caused by heat accumulation and improving the cycle performance of the battery monomer.

In an embodiment of the present application, the compacted density of the negative electrode film layer at 0% SOC of the battery cell is as known in the art, and may be detected using equipment and methods known in the art, such as the compacted density test method of the positive electrode film layer described above.

In some embodiments, the single-sided coating weight of the negative electrode film layer is 120mg/1540.25mm ² to 180mg/1540.25mm ², optionally 125mg/1540.25mm ² to 150mg/1540.25mm ². Illustratively, the single-sided coating weight of the negative electrode film layer is 120mg/1540.25mm²、122mg/1540.25mm²、125mg/1540.25mm²、128mg/1540.25mm²、130mg/1540.25mm²、132mg/1540.25mm²、135mg/1540.25mm²、137mg/1540.25mm²、140mg/1540.25mm²、145mg/1540.25mm²、150mg/1540.25mm²、155mg/1540.25mm²、160mg/1540.25mm²、165mg/1540.25mm²、170mg/1540.25mm²、175mg/1540.25mm²、180mg/1540.25mm² or a range of any two of the above values.

When the single-sided coating weight of the negative electrode film layer is in the range, the heat generation amount in the unit area of the negative electrode plate is not excessive, the problem of aggravation of negative electrode side reaction caused by heat accumulation is relieved, the cycle performance of the battery monomer is improved, and the energy density of the battery monomer can be improved.

In the present embodiment, the single-sided coating weight of the negative electrode film layer is in the meaning well known in the art, and may be detected using equipment and methods well known in the art, such as the single-sided coating weight test method of the foregoing film layer.

In some embodiments, the negative electrode active material includes a carbon-based material having high cycle stability, which can improve cycle performance of the battery cell. The anode active material is mainly a lithium-containing phosphate system with an olivine structure, the cathode active material is mainly a carbon-based material system, and the anode active material and the carbon-based material are matched for use, so that the cycle performance of the battery monomer is excellent.

Optionally, the carbon-based material comprises artificial graphite, the electric conductivity of the artificial graphite is excellent, the heat generation of the negative electrode plate can be reduced, the heat generation of the battery cell can be reduced, and the quick charging performance of the battery cell can be improved.

In some embodiments, the carbon-based material may also include natural graphite. Specifically, the carbon-based material may include artificial graphite, or the carbon-based material may include artificial graphite and natural graphite. The natural graphite has relatively good conductivity, is favorable for further reducing heat generation, and can improve the power performance and the cycle performance of the battery monomer.

In some embodiments, the anode active material may include at least one of a tin-based material and lithium titanate in addition to the carbon-based material, and optionally a silicon-based material described above. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material. Alternatively, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

The qualitative and quantitative detection of each substance or each element in the application can be carried out by using proper equipment and methods known by the technicians in the field, the related detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards and the like, and the technicians in the field can adaptively change certain detection steps/instrument parameters and the like from the detection accuracy point of view so as to obtain more accurate detection results. One detection method may be used qualitatively or quantitatively, or several detection methods may be used in combination for qualitative or quantitative determination.

For example, the present application can perform X-ray powder diffraction test and qualitative analysis on a negative electrode tab or a negative electrode active material in combination with JIS/K0131-1996X-ray diffraction analysis rule.

The artificial graphite and the natural graphite can be distinguished by SEM sectional pictures photographed by a scanning electron microscope, gaps exist among lamellar structures in the SEM sectional pictures of the natural graphite, the SEM sectional pictures of the artificial graphite are compact and have no obvious gaps, or XRD spectrograms obtained by an X-ray diffraction method are distinguished, obvious 2H phases and 3R phases exist in the XRD spectrograms of the natural graphite, and the XRD spectrograms of the artificial graphite only exist in the 2H phases.

In the embodiment of the application, the negative electrode film layer comprises at least one film layer, and can adopt a single film layer or at least two film layers. Optionally, the negative electrode film layer includes at least two film layers.

In the case where the anode film layer is a single-layer film layer, the anode active material in the anode film layer includes a carbon-based material. In the case of a single film layer, the volume average particle diameter Dv50 of the carbon-based material is 8 μm to 13 μm, alternatively 9.5 μm to 11.5 μm. Illustratively, the volume average particle diameter Dv50 of the carbon-based material is 8μm、8.5μm、8.8μm、9μm、9.2μm、9.5μm、9.8μm、10μm、10.2μm、10.5μm、10.8μm、11μm、11.2μm、11.5μm、11.8μm、12μm、12.2μm、12.5μm、12.8μm、13μm or a range of any two of the numerical compositions described above.

In the case where at least two film layers are used as the anode film layer, the anode active material in the anode film layer includes a carbon-based material. The negative electrode film layer may include two film layers, three film layers, four film layers, or even more film layers.

In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, the first negative electrode film layer is disposed on a surface of the negative electrode current collecting portion, the carbon-based material of the first negative electrode film layer includes artificial graphite, the second negative electrode film layer is connected to a side of the first negative electrode film layer facing away from the negative electrode current collecting portion, the carbon-based material of the second negative electrode film layer includes artificial graphite, and the artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer may be the same or different. When the artificial graphite of the first negative electrode film layer and the artificial graphite of the second negative electrode film layer are different, the particle sizes may be different, or the graphitization degrees may be different.

The interface between the first negative electrode film layer and the second negative electrode film layer is regular, or may be irregular, or alternatively irregular.

The negative electrode film layer comprises at least two film layers, and the layered coating is favorable for improving the quick charging performance of the battery monomer. Especially when the first negative electrode film layer and the second negative electrode film layer are different, the pore difference of the negative electrode film layer can be constructed, the lithium ion transmission tortuosity is reduced, and the quick charging performance of the battery unit is improved.

In some embodiments, the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is greater than or equal to the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer. Further alternatively, the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is larger than the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer, which is beneficial to improving the dynamic performance of the negative electrode film layer.

The particle sizes of the first negative electrode film layer and the second negative electrode film layer are different, so that the quick charging performance of the battery monomer can be improved, particularly, in the quick charging process, the overpotential of the second negative electrode film layer is generally higher, the bottleneck of quick charging mainly lies in the second negative electrode film layer, but the particle size of the second negative electrode film layer is relatively smaller in the embodiment of the application, the solid phase transmission path of lithium ions can be shortened, the quick charging performance can be improved, the problem of chromatographic lithium of the surface of a negative electrode plate can be improved, and the cycle performance of the battery monomer can be improved.

Alternatively, the carbon-based material of the first negative electrode film layer is particulate, and has a volume average particle diameter Dv50 of 9.0 μm to 18.5 μm, optionally 9.0 μm to 14.6 μm. Illustratively, the volume average particle diameter of the carbon-based material of the second anode film layer is 9.0μm、10μm、10.5μm、11μm、11.5μm、12μm、12.5μm、13μm、13.5μm、14μm、14.5μm、14.6μm、15μm、15.5μm、16μm、16.5μm、17μm、17.5μm、18μm、18.5μm or a range of any two of the above numerical values. When the first negative electrode film layer includes a carbon-based material, the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is 9.0 μm to 18.5 μm, optionally 9.0 μm to 14.6 μm.

When the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is in the range, on one hand, the solid phase transmission path of lithium ions can be shortened, the rapid charging performance is improved, and on the other hand, the material is not easy to agglomerate in the preparation process, and the stability of the material can be improved.

Alternatively, the carbon-based material of the second negative electrode film layer is particulate, and has a volume average particle diameter Dv50 of 7.8 μm to 14.3 μm, alternatively 7.8 μm to 11.3 μm. Illustratively, the volume average particle diameter Dv50 of the carbon-based material is 7.8μm、8.0μm、8.2μm、8.5μm、8.8μm、9μm、9.2μm、9.5μm、9.8μm、10μm、10.2μm、10.5μm、10.8μm、11μm、11.3μm、11.2μm、11.5μm、11.8μm、12μm、12.2μm、12.5μm、12.8μm、13μm、13.2μm、13.5μm、13.8μm、14μm、14.1μm、14.3μm or a range of any two of the numerical compositions described above. When the second anode film layer includes a carbon-based material, the volume average particle diameter Dv50 of the carbon-based material of the second anode film layer is 7.8 μm to 14.3 μm, optionally 7.8 μm to 11.3 μm.

When the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer is in the above range, the solid phase transmission path of lithium ions can be shortened, and the rapid charging performance can be improved.

When the volume average particle diameter Dv50 of the carbon-based material of the second anode film layer is in the range, on one hand, the solid phase transmission path of lithium ions can be shortened, the quick charge performance is improved, on the other hand, the material is not easy to agglomerate in the preparation process, the stability of the material can be improved, on the other hand, the anode active material in the second anode film layer and the anode active material in the first anode film layer in the volume average particle diameter range are matched, the gradient pore difference of the second anode film layer and the first anode film layer is favorably constructed, the lithium ion transmission tortuosity is reduced, and the quick charge performance of a battery monomer is improved.

In the embodiment of the present application, the volume average particle diameter Dv50 of the anode active material is in the meaning known in the art, and can be measured using an apparatus and a method known in the art, for example, the anode active material is used as a sample, and the Dv50 of the particles is measured by a Mastersizer 2000E type laser particle size analyzer according to the test standard GB/T19077-2016, and the like.

Optionally, the carbon-based material of the first negative electrode film layer further comprises natural graphite.

Illustratively, the carbon-based material of the first negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the second negative electrode film layer includes artificial graphite.

In other embodiments, the volume average particle diameter Dv50 of the carbon-based material of the second anode film layer is greater than the volume average particle diameter Dv50 of the carbon-based material of the first anode film layer. Further alternatively, the volume average particle diameter Dv50 of the carbon-based material of the second anode film layer is larger than the volume average particle diameter Dv50 of the carbon-based material of the first anode film layer, which is beneficial to improving the compaction density of the anode film layer.

The particle sizes of the first negative electrode film layer and the second negative electrode film layer are different, and the quick charging performance of the battery monomer can be improved.

Alternatively, the carbon-based material of the second negative electrode film layer is particulate, and has a volume average particle diameter Dv50 of 9.0 μm to 18.5 μm, optionally 9.0 μm to 14.6 μm. When the volume average particle diameter Dv50 of the carbon-based material of the second anode film layer is in the range, on one hand, the solid phase transmission path of lithium ions can be shortened, the rapid charging performance is improved, and on the other hand, the material is not easy to agglomerate in the preparation process, and the stability of the material can be improved.

Alternatively, the carbon-based material of the first negative electrode film layer is particulate, and has a volume average particle diameter Dv50 of 7.8 μm to 14.3 μm, alternatively 7.8 μm to 11.3 μm. When the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is in the above range, the solid phase transmission path of lithium ions can be shortened, and the rapid charging performance can be improved.

Illustratively, the carbon-based material of the second negative electrode film layer includes at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer includes artificial graphite.

In some embodiments, the negative electrode film layer further optionally includes a negative electrode conductive agent. The embodiment of the present application is not particularly limited in kind of the anode conductive agent, and the anode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example. In some embodiments, the negative electrode conductive agent is present in an amount of 5% by mass or less based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode film layer further optionally includes a negative electrode binder. In some embodiments, the mass content of the anode binder is 5% or less, based on the total weight of the anode film layer.

In some embodiments, the negative electrode film layer may also optionally include other adjuvants. As examples, other adjuvants may include thickeners, dispersants, etc., such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the mass content of other adjuvants is 2% or less, based on the total weight of the negative electrode film layer.

In some embodiments, the negative current collector may employ a metal foil or a composite current collector. As examples of the metal foil, at least one foil of copper, copper alloy, nickel alloy, titanium alloy, silver, and silver alloy may be employed. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metal material in the metal material layer may include at least one of copper, copper alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).

In some embodiments, the ratio of the thickness of the single-sided negative electrode film layer to the thickness of the negative electrode current collector is 8 to 14, e.g., 8, 9, 10, 11, 12, 13, 14, or a range of any two of the values recited above. Alternatively, the ratio of the thickness of the single-sided anode film layer to the thickness of the anode current collector is 10 to 12.

When the ratio of the thickness of the single-side negative electrode film layer to the thickness of the negative electrode current collecting part is in the above range, the quick charging capability and the energy density of the battery cell can be improved.

In some embodiments, the thickness of the negative current collector is 5 μm to 10 μm, optionally 6 μm to 8 μm. Illustratively, the thickness of the negative current collector is 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, or a range of any two values of the foregoing.

When the thickness of the anode current collecting portion is in the above range, the overcurrent capability of the anode current collecting portion is excellent, and the battery cell can have a high energy density.

In embodiments of the present application, the thickness of the negative current collector is within the meaning known in the art and can be measured using equipment and methods known in the art, for example, by washing off the film layer on the surface of the negative current collector with a solvent and measuring the thickness of the negative current collector with a ten-thousandth.

The negative electrode film layer is usually formed by applying a negative electrode slurry to a negative electrode current collector, drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, an optional conductive agent, an optional binder, and other optional auxiliaries in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

The negative electrode tab does not exclude other additional functional layers than the negative electrode film layer. For example, in some embodiments, the negative electrode tab of an embodiment of the application further comprises a negative electrode conductive layer disposed on a surface of the negative electrode current collector sandwiched between the negative electrode current collector and the negative electrode film layer. In other embodiments, the negative electrode tab according to the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[ Spacer ]

In some embodiments, the electrode assembly further comprises a separator disposed between the positive and negative electrode sheets.

In some embodiments, the separator is a separator film. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability can be used.

As an example, the main material of the separator may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited. The separator may be a single member located between the positive and negative electrodes, or may be attached to the surfaces of the positive and negative electrodes. The surface of the isolating film may be coated with inorganic particle coating, organic particle coating or organic/inorganic composite coating.

In some embodiments, the volumetric energy density of the battery cell is 380Wh/L to 450Wh/L. Illustratively, the volumetric energy density of the battery cell is 380Wh/L, 395Wh/L, 400Wh/L, 410Wh/L, 420Wh/L, 430Wh/L, 450Wh/L, or a range of any two values recited above.

In the embodiment of the present application, the volumetric energy density of the battery cell is in the meaning known in the art, and can be detected by using the apparatus and method known in the art, for example, taking the example that the battery charge upper limit voltage is 3.65V, the battery discharge cut-off voltage is 2.0V,

The battery cell was placed under 25 ℃, charged to 3.65V at a constant current of 0.33C, charged to 0.05C again at a constant voltage, discharged to 2.0V at a constant current of 0.33C, and the discharge capacity A0 at that time was recorded in units of Ah, and the length, width, and height of the battery cell (generally calculated as the housing size of the battery, excluding the electrode terminal height, and excluding the insulating film outside the housing) were measured using a caliper, and the cell volume V0, unit L, and volumetric energy density of the battery cell ved= (a0×discharge plateau voltage)/V0, unit Wh/L were calculated.

Examples

The following examples more particularly describe the disclosure of embodiments of the present application, and are intended as illustrative only since numerous modifications and variations within the scope of the disclosure of embodiments of the present application will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages and ratios reported in the examples below are on a mass basis, and all reagents used in the examples are commercially available or were obtained synthetically according to conventional methods and can be used directly without further treatment, as well as the instruments used in the examples.

Example 1

1. Preparation of positive electrode plate

The positive pole piece comprises a positive pole lug, a positive pole current collecting part and positive pole film layers arranged on two sides of the positive pole current collecting part, and the positive pole current collecting part is an aluminum foil with the thickness of 13 mu m.

The positive electrode film layer comprises lithium-containing phosphate lithium iron phosphate, positive electrode additive lithium ferrite, binder polyvinylidene fluoride (PVDF) and conductive agent acetylene black in a mass ratio of 96:1:2:1, and is formed by uniformly coating positive electrode slurry (N-methylpyrrolidone NMP serving as a solvent) on two sides of a positive electrode current collecting part, drying and cold pressing.

The single-sided coating weight of the positive electrode film layer was 300mg/1540.25mm ².

2. Preparation of negative electrode plate

The negative pole piece comprises a negative pole lug, a negative pole current collecting part and negative pole film layers arranged on two sides of the negative pole current collecting part, and the negative pole current collecting part is copper foil with the thickness of 6 mu m.

The negative electrode film layer is formed by uniformly coating negative electrode slurry (deionized water as solvent) on the surface of a negative electrode current collecting part, drying and cold pressing.

The single-sided coating weight of the negative electrode film layer was 130mg/1540.25mm ².

The negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is positioned on the surface of the negative electrode current collecting layer, and the second negative electrode film layer is positioned on the surface of the first negative electrode film layer.

The first negative electrode film layer comprises a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1, the carbon-based material of the first negative electrode film layer comprises artificial graphite and natural graphite in a mass ratio of 1:1, and the volume average particle size of the carbon-based material is 9.0 mu m.

The second negative electrode film layer comprises a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1, the carbon-based material of the second negative electrode film layer comprises artificial graphite, and the volume average particle size of the carbon-based material is 8.0 mu m.

3. Spacer member

The separator included a base film of 7 μm polyethylene film layer with a porosity of 42%.

4. Preparation of electrolyte

The electrolyte comprises an organic solvent, lithium salt and an additive.

After mixing the components of the organic solvent, lithium salt and additives are added to prepare the electrolyte.

The organic solvent comprises 10% of chain carboxylic ester solvent (ethyl acetate) and 75% of carbonic ester solvent (diethyl carbonate, dimethyl carbonate and ethylene carbonate in a mass ratio of 1:1:1), and the mass content of each component in the organic solvent is calculated based on the mass of the electrolyte.

The mass content of the additive, based on the mass of the electrolyte, was 1.5%, which included vinylene carbonate VC.

The lithium salt included 8.5% lithium hexafluorophosphate LiPF ₆ and 5% lithium bis-fluorosulfonyl imide.

The electrolyte had a conductivity of 12mS/cm at room temperature.

5. Preparation of battery cells

And stacking the positive electrode plate, the separator and the negative electrode plate in sequence, so that the separator is positioned between the positive electrode plate and the negative electrode plate to play a role in separation, a laminated electrode assembly is obtained, the electrode assembly is placed in an outer packaging shell, electrolyte is injected after drying, and the battery monomer is obtained through the procedures of vacuum packaging, standing, formation, shaping and the like, wherein the compaction density of a positive electrode film layer of the battery monomer under 0% of SOC is 2.5g/cm ³, and the compaction density of a negative electrode film layer under 0% of SOC is 1.45g/cm ³.

In example 1, four electrode terminals were used, and as shown in fig. 14, two positive electrode terminals were located on both sides of the electrode assembly in the longitudinal direction, and two negative electrode terminals were located on both sides of the electrode assembly in the longitudinal direction.

Comparative example 1 and comparative example 2

A battery cell was prepared in a similar manner to example 1, except that the length and width ratio of the positive electrode film layer was adjusted, unlike example 1.

Comparative example 3

A battery cell was prepared in a similar manner to example 1, except that the setting positions and the setting numbers of the positive electrode tabs were adjusted, unlike example 1.

Examples 2-1 and 2-2

A battery cell was prepared in a similar manner to example 1, except that the setting positions and the setting numbers of the positive electrode tabs were adjusted, unlike example 1.

Examples 3-1 and 3-2

A battery cell was prepared in a similar manner to example 1, except that the size of the welding region (first region) of the positive electrode tab and the positive electrode adaptor was adjusted, unlike example 1.

Example 4

A battery cell was prepared in a similar manner to example 1, except that the number of electrode terminals was adjusted, and one positive electrode terminal and one negative electrode terminal were used, as shown in fig. 20.

Examples 5-1 and 5-2

A battery cell was prepared in a similar manner to example 1, except that the size of the positive electrode film layer was adjusted, unlike example 1.

Performance testing

1. DC internal resistance DCR test of battery cell

Reference may be made to the method in GB/T31467 Specification for Performance test of high Power lithium ion batteries for HEVs.

For example, at 25 ℃, the battery cell was charged to 3.65V at a constant current of 0.33C, left to stand 1 min, then charged to 3.65V at a constant current of 0.05C, left to stand 30min, discharged to 2.5V at a constant current of 0.33C, the discharge capacity a ₀ at this time was recorded in units Ah, then charged to 0.5a ₀ Ah at a constant current of 0.33C, and SOC was adjusted to 50%.

After the battery cell was left at 25 ℃ for 2h seconds, the discharge was constant current discharged at 4C for 10 seconds, father U _{Discharge of electric power} 、∆I _{Discharge of electric power} was recorded, the discharge DCR data for the battery cell, R _{Discharge of electric power} =∆U _{Discharge of electric power} /∆I _{Discharge of electric power} ,

Wherein, father U _{Discharge of electric power} represents the voltage change in the discharge start 10s, father I _{Discharge of electric power} represents the current value in the discharge start 10 s.

2. Cycle performance of battery cell

Charging the battery cell to 3.65V at a constant current of 0.5 ℃, then charging to 0.05 ℃ at a constant voltage, standing for 10min, then discharging to 2.0V at a constant current of 1C, which is a charge-discharge cycle, recording the first-turn discharge capacity, standing for 10min, repeating the charge-discharge cycle until the discharge capacity of the battery cell is reduced to 80% of the first-turn discharge capacity, stopping the test, and recording the number of the cycles.

The test results are shown in Table 1.

TABLE 1

The arrangement of the positive electrode tab and the negative electrode tab in the examples and comparative examples may be of similar design.

The number of the positive electrode tabs refers to the total number of the positive electrode tabs in the same positive electrode sheet.

The short side of the positive electrode tab means that the positive electrode tab is positioned at least one side of the positive electrode current collecting part along the length direction.

The fact that the positive electrode tab is located on one side of the short side means that all the positive electrode tabs are located on the same side of the positive electrode current collecting portion along the length direction.

The long side of the positive electrode tab means that the positive electrode tab is positioned on at least one side of the positive electrode current collecting part along the width direction.

The positive electrode tab is formed on one side of the long side, which means that all positive electrode tabs are positioned on the same side of the positive electrode current collecting portion in the width direction, as shown in fig. 8.

The two sides of the long side of the positive electrode tab means that a plurality of positive electrode tabs are positioned at two sides of the positive electrode current collecting part in the width direction, as shown in fig. 10.

N is the ratio of the length of all the positive electrode tabs located on the same side of the positive electrode current collecting portion to the length of the positive electrode current collecting portion.

S represents the ratio of the dimension of the first region located in the positive electrode tab along the length direction Z to the dimension of the positive electrode tab along the length direction, and can be understood as the length ratio of the first region, for example, the length ratio of the welding marks of the positive electrode tab.

The length of the positive electrode film layer of comparative example 1 is relatively small, and the electron transmission path is short, so that DCR is small, but the volume energy density requirement of the battery monomer cannot be met;

The length of the positive electrode film layer in comparative example 2 is longer, but the volume energy density is larger, but the aspect ratio of the positive electrode film layer is too large, and the transmission path of electrons in the length direction is too long, so that the internal resistance of the battery cell is higher, the heat generation is increased, and the rapid charging and the high-temperature cycle performance are not facilitated.

Compared with comparative examples 1 and 2, the aspect ratios of the positive electrode film layers of examples 1, 5-1 and 5-2 of the present application are in a proper range, the length of the positive electrode film layer is in a proper range, the transmission path of electrons in the length direction is not excessively long, the internal resistance can be reduced, the rapid charging capability of the battery cell can be improved, and the volumetric energy density of the battery cell can be improved.

The positive electrode tab of comparative example 3 is disposed on one side of the positive electrode current collecting portion along the length direction, and the transmission path of electrons along the length direction is long, so that the internal resistance of the battery cell is high, the heat generation is increased, and the rapid charging and the high-temperature cycle performance are not facilitated.

Compared with comparative example 3, the positive electrode tab of the embodiment of the application is disposed on at least one side of the positive electrode current collecting portion along the width direction, electrons are introduced into the positive electrode current collecting portion through the positive electrode tab and conducted in the positive electrode current collecting portion, and the transmission path of the electrons in the positive electrode current collecting portion is relatively short, so that the internal resistance on the positive electrode sheet is smaller, the heat generation amount is less, the side reaction of the battery caused by heat accumulation can be relieved, and the high temperature cycle performance and the quick charging performance of the battery cell are improved.

For example, in embodiment 1, the positive electrode tab may be disposed on one side of the positive electrode current collecting portion in the width direction, and for example, in embodiment 2-2, the positive electrode tab may be disposed on both sides of the positive electrode current collecting portion in the width direction, so that the high temperature cycle performance and the rapid charging performance of the battery cell can be effectively improved.

When the size of the tab on the same side is the same (n is the same as W1/W2), the electron transfer distance can be further shortened and DCR can be reduced when the positive electrode tab is provided on both sides.

Compared with example 1, the size of the positive electrode tab of example 2-1 is higher, so that the overcurrent capacity of the positive electrode tab is stronger, the heat generation is further reduced, and the high-temperature cycle performance and the quick charging performance of the battery cell can be more effectively improved.

Compared with example 1, examples 3-1 and 3-2 have the welding areas of the positive electrode tab and the positive electrode adapter adjusted, and as the welding area increases, the overcurrent capacity of the positive electrode adapter is further enhanced, the heat generation is further reduced, and the high-temperature cycle performance and the rapid charging performance of the battery cell can be more effectively improved.

In example 1, four electrode terminals are used, and in example 4, two electrode terminals are used, and as the number of electrode terminals increases, the overcurrent capacity of the electrode terminals increases, the heat generation decreases, and the high-temperature cycle performance and the quick charge performance of the battery cell can be more effectively improved.

Comparative example 4 and comparative example 5

A battery cell was prepared in a similar manner to example 1, except that the composition of the electrolyte was adjusted, in which,

The electrolyte in comparative examples 4 and 5 comprises an organic solvent, the organic solvent comprises a chain carboxylic ester solvent and a carbonate solvent in a mass ratio of 1:9, the chain carboxylic ester solvent is ethyl acetate, and the carbonate solvent comprises diethyl carbonate, dimethyl carbonate and ethylene carbonate in a mass ratio of 1:1:1.

Examples 6-1 to 6-7

A battery cell was prepared in a similar manner to example 1, except that the composition of the electrolyte was adjusted, in which,

The electrolyte in examples 6-1 to 6-7 includes an organic solvent including a chain carboxylate solvent and a carbonate solvent in a mass ratio of 1:9, the chain carboxylate solvent being ethyl acetate, and the carbonate solvent including diethyl carbonate, dimethyl carbonate, and ethylene carbonate in a mass ratio of 1:1:1.

The test results are shown in Table 2.

TABLE 2

In table 2, VC represents vinylene carbonate, and FEC represents fluoroethylene carbonate.

The adjustment of the electrolyte components has no influence on the volume energy density of the battery cell.

The lithium difluorosulfimide of comparative example 4 is excessively high in addition amount, while advantageous for improving high temperature cycle performance, rapidly releases a large amount of energy at the time of thermal runaway, possibly deteriorating use reliability, and in the case of excessively high addition amount of lithium difluorosulfimide, the SEI film on the negative electrode side may be excessively formed, increasing impedance, and being disadvantageous for rapid charging.

Comparative example 5 does not add lithium bisfluorosulfonyl imide, a large amount of lithium hexafluorophosphate is added to the electrolyte, the excess hexafluorophosphate is decomposed to generate a large amount of hydrofluoric acid HF, damage is caused to the SEI film, the SEI film is repeatedly repaired, and negative side reactions are aggravated, deteriorating cycle and DCR.

In the embodiment of the application, the mass content of the lithium bis (fluorosulfonyl) imide in the electrolyte is 1-15%, so that the HF content in the electrolyte is not too high, the SEI film formed on the negative electrode side is stable, the negative electrode active material can be well protected, the side reaction on the negative electrode side is relieved, the high-temperature cycle performance is improved, the ion conduction capability of the electrolyte is higher, the impedance of the SEI film is relatively lower, the internal resistance of an electrochemical system can be reduced, the improvement of the quick charge capability is facilitated, and because

Further, the ratio of the mass contents of the lithium hexafluorophosphate and the lithium difluorosulfimide is in a proper range, so that the internal resistance of the battery cell can be further and effectively improved, and the quick charging capability and the cycle performance of the battery cell are improved.

Additives VC and FEC can form a compact film layer with uniform thickness on the negative electrode side, can effectively repair an SEI film, play an excellent role in protecting a negative electrode active material, and are beneficial to improving the quick charging performance of a battery cell and the cycle performance.

Example 7

A battery cell was produced in a similar manner to example 1, except that the setting of the negative electrode film layer was adjusted, specifically:

The negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is positioned on the surface of the negative electrode conductive layer, and the second negative electrode film layer is positioned on the surface of the first negative electrode film layer.

The first negative electrode film layer comprises a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1, wherein the carbon-based material of the first negative electrode film layer comprises artificial graphite, and the volume average particle size of the carbon-based material is 8.0 mu m.

The second negative electrode film layer comprises a carbon-based material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber and a thickener sodium carboxymethyl cellulose in a mass ratio of 96.5:1:1.5:1, the carbon-based material of the second negative electrode film layer comprises artificial graphite and natural graphite in a mass ratio of 1:1, and the volume average particle size of the carbon-based material is 9.0 mu m.

The test results are shown in Table 3.

TABLE 3 Table 3

The embodiment of the application is suitable for single-layer negative electrode film layers and double-layer negative electrode film layers, and the volume average particle size of the carbon-based material of the first negative electrode film layer adopted in the negative electrode film layers is smaller than that of the carbon-based material of the second negative electrode film layer, so that the quick charging performance and the cycle performance of the battery cell can be improved.

Although illustrative embodiments have been shown and described, it will be understood by those skilled in the art that the foregoing embodiments are not to be construed as limiting the embodiments of the application, and that changes, substitutions and alterations may be made to the embodiments without departing from the spirit, principles and scope of the embodiments of the application.

Claims (35)

1. A battery cell, characterized in that the battery cell comprises an electrode assembly and an electrolyte,

The electrode assembly comprises a plurality of first pole pieces and a plurality of second pole pieces, the first pole pieces and the second pole pieces are arranged in a lamination way along the thickness direction of the battery unit, the first pole pieces and the second pole pieces both comprise a coating part and a pole lug part, the coating part is provided with an active material layer, the pole lug part is connected with the coating part and extends out of the coating part along the width direction of the battery unit,

One of the first pole piece and the second pole piece is a positive pole piece, the other one is a negative pole piece, and an active material layer of the positive pole piece comprises lithium-containing phosphate with an olivine structure;

The size of the coating part of the positive electrode plate along the length direction of the battery monomer is a first size, the size of the coating part of the positive electrode plate along the width direction is a second size, and the ratio of the first size to the second size is 4-7;

The electrolyte comprises lithium bis (fluorosulfonyl) imide, wherein the mass content of the lithium bis (fluorosulfonyl) imide in the electrolyte is 1-15%;

The first pole piece satisfies that n is 0.5 to 1.0 in W1/W2;

n represents the number of all tab portions located on the same side of the coating portion;

W1 represents the average size of the tab portion along the length direction;

W2 represents the dimension of the coating portion in the longitudinal direction.

2. The battery cell of claim 1, wherein the electrolyte further comprises lithium hexafluorophosphate, the ratio of the mass content of lithium hexafluorophosphate to the mass content of lithium bis-fluorosulfonyl imide being 0.5 to 4 based on the mass of the electrolyte.

3. The battery cell according to claim 2, wherein a ratio of a mass content of the lithium hexafluorophosphate to a mass content of the lithium difluorosulfimide is 1.2 to 2 based on a mass of the electrolyte.

4. The battery cell according to claim 1, wherein the mass content of the lithium bisfluorosulfonyl imide in the electrolyte is 3% to 12%.

5. The battery cell of claim 1, wherein the electrolyte has a conductivity of 10mS/cm to 13mS/cm at room temperature.

6. The battery cell of claim 1, wherein the electrolyte further comprises a chain carboxylate solvent.

7. The battery cell according to claim 6, wherein the mass content of the chain carboxylic acid ester solvent in the electrolyte is 5% to 30%.

8. The battery cell of claim 7, wherein the battery cell comprises a plurality of cells,

W2 is 300mm to 650mm, and/or n.times.W1 is 150mm to 650mm.

9. The battery cell of claim 1, wherein the first pole piece comprises a plurality of pole ears.

10. The battery cell according to claim 9, wherein at least two tab portions of the first electrode sheet are located on the same side as the coating portion, and a distance between two adjacent tab portions in the longitudinal direction is greater than 0 and equal to or less than 300mm.

11. The battery cell according to claim 9 or 10, wherein the plurality of tab portions of the first pole piece are located on both sides of the coating portion in the width direction.

12. The battery cell according to claim 9 or 10, wherein all of the tab portions of the first pole piece are located on the same side of the coating portion in the width direction.

13. The battery cell according to claim 1, wherein a dimension of the coating portion of the first electrode sheet in the width direction is greater than 0 and equal to or less than 300mm.

14. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells,

The battery cell further comprises a first electrode terminal connected with the lug part of the first pole piece, wherein the first electrode terminal is arranged on at least one side of the electrode assembly along the length direction, and/or

The battery cell also comprises a second electrode terminal, wherein the second electrode terminal is connected with the lug part of the second pole piece, and the second electrode terminal is arranged on at least one side of the electrode assembly along the length direction.

15. The battery cell of claim 14, wherein the battery cell comprises a plurality of cells,

All the lug parts of the first pole piece are positioned on the same side of the coating part, all the lug parts of the second pole piece are positioned on the same side of the coating part, and the lug parts of the first pole piece and the lug parts of the second pole piece are respectively positioned on two sides of the coating part along the width direction;

The first electrode terminal and the second electrode terminal are respectively one, the first electrode terminal and the second electrode terminal are respectively located on two sides of the electrode assembly along the length direction, the first electrode terminal and the second electrode terminal are arranged in a staggered mode along the width direction, the first electrode terminal is close to the lug part of the first pole piece, and the second electrode terminal is close to the lug part of the second pole piece.

16. The battery cell of claim 14, wherein the battery cell comprises a plurality of cells,

The number of the first electrode terminals is two, the two first electrode terminals are respectively arranged at two sides of the electrode assembly along the length direction, and/or

The number of the second electrode terminals is two, and the two second electrode terminals are respectively arranged at two sides of the electrode assembly along the length direction.

17. The battery cell of claim 14, further comprising a first adapter, the first adapter is located between the first electrode terminal and the tab portion of the first pole piece and connects the first electrode terminal and the tab portion of the first pole piece.

18. The battery cell of claim 17, wherein the first adapter member includes a first adapter portion extending in the length direction and connecting the tab portion, and a second adapter portion connected to the first adapter portion and protruding from the first adapter portion in the width direction and connected to the first electrode terminal.

19. The battery cell of claim 17 or 18, wherein the tab portion comprises a first region connected to the first adapter, the ratio of the dimension of the first region along the length direction to the dimension of the tab portion along the length direction being 0.5 to 1.

20. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells,

The tab part is arranged on at least one side of the coating part along the width direction of the battery cell, extends along the length direction and has a gap with the coating part;

The battery cell also includes a thermally conductive member disposed at least within the gap.

21. The battery cell of claim 20, further comprising a housing containing the electrode assembly and the electrolyte, wherein the thermally conductive member extends to the housing in contact with the housing.

22. The battery cell of claim 1, wherein the thickness of the battery cell is 10mm to 30mm.

23. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells, the battery cell also includes a housing including:

two first shell portions opposed to each other in the thickness direction, and

And a second shell portion and a third shell portion opposite to each other, the second shell portion and the third shell portion being connected by the first shell portion, the second shell portion including a first wall and a second wall disposed continuously in the thickness direction, the first wall and the second wall being welded.

24. The battery cell of claim 23, wherein the thickness of the housing is 0.1mm to 0.5mm.

25. The battery cell of claim 1, wherein the olivine structured lithium-containing phosphate comprises lithium iron phosphate.

26. The battery cell of claim 25, wherein the positive electrode sheet comprises a positive electrode film layer having a single-sided coating weight of 250mg/1540.25mm ² to 330mg/1540.25mm ², and/or

The positive electrode film layer has a compacted density of 2.30g/cm ³ to 2.70g/cm ³ at 0% charge state of the battery cell.

27. The battery cell of claim 1, wherein the coated portion of the negative electrode tab comprises a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, the negative electrode film layer comprising a negative electrode active material comprising a carbon-based material, wherein the negative electrode film layer comprises:

A first negative electrode film layer arranged on the surface of the negative electrode current collecting part, and

A second negative electrode film layer connected to one side of the first negative electrode film layer facing away from the negative electrode current collecting part,

Wherein the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is equal to or greater than the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer.

28. The battery cell of claim 27, wherein the cell comprises a plurality of cells,

The carbon-based material of the first negative electrode film layer is in the form of particles having a volume average particle diameter Dv50 of 9.5 μm to 18.5 μm, and/or

The carbon-based material of the second negative electrode film layer is granular, and its volume average particle diameter Dv50 is 7.8 μm to 14.3 μm.

29. The battery cell of claim 27 or 28, wherein the carbon-based material of the first negative electrode film layer comprises at least one of artificial graphite and natural graphite and the carbon-based material of the second negative electrode film layer comprises artificial graphite.

30. The battery cell of claim 1, wherein the coated portion of the negative electrode tab comprises a negative electrode current collecting portion and a negative electrode film layer disposed on at least one side of the negative electrode current collecting portion, the negative electrode film layer comprising a negative electrode active material comprising a carbon-based material, wherein the negative electrode film layer comprises:

A first negative electrode film layer arranged on the surface of the negative electrode current collecting part, and

A second negative electrode film layer connected to one side of the first negative electrode film layer facing away from the negative electrode current collecting part,

Wherein the volume average particle diameter Dv50 of the carbon-based material of the first negative electrode film layer is smaller than the volume average particle diameter Dv50 of the carbon-based material of the second negative electrode film layer.

31. The battery cell of claim 30, wherein the cell comprises a plurality of cells,

The carbon-based material of the second negative electrode film layer is in the form of particles having a volume average particle diameter Dv50 of 9.5 μm to 18.5 μm, and/or

The carbon-based material of the first negative electrode film layer is granular, and its volume average particle diameter Dv50 is 7.8 μm to 14.3 μm.

32. The battery cell of claim 30 or 31, wherein the carbon-based material of the second negative electrode film layer comprises at least one of artificial graphite and natural graphite, and the carbon-based material of the first negative electrode film layer comprises artificial graphite.

33. The battery cell of claim 27, wherein the negative electrode film layer has a single-sided coating weight of 120mg/1540.25mm ² to 180mg/1540.25mm ², and/or

The compaction density of the negative electrode film layer is 1.30g/cm ³ to 1.65g/cm ³ under the state of 0% charge of the battery cell.

34. A battery device comprising the battery cell of any one of claims 1 to 33.

35. An electric device is characterized in that, the power utilization device includes the battery device of claim 34.