CN116914275A - Battery core and battery - Google Patents
Battery core and battery Download PDFInfo
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- CN116914275A CN116914275A CN202310999904.9A CN202310999904A CN116914275A CN 116914275 A CN116914275 A CN 116914275A CN 202310999904 A CN202310999904 A CN 202310999904A CN 116914275 A CN116914275 A CN 116914275A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a battery cell and a battery. The battery cell comprises a pole piece, wherein the pole piece comprises a current collector and a functional layer arranged on at least one functional surface of the current collector; the functional layer comprises a first active layer and a second active layer which are stacked along the direction far away from the current collector; in the length direction of the current collector, the first active layer comprises N first parts and M second parts which are arranged in a staggered manner, wherein N is more than or equal to 1, and M is more than or equal to 1; the first part comprises a silicon-based material and a conductive agent wrapping at least part of the surface of the silicon-based material; the second portion and the second active layer each comprise a carbon-based material; in the battery cell, the first part comprises a straight section, and the second part comprises an arc section. When the battery core is applied to a battery, the energy density of the battery can be improved, lithium is not easy to separate out in the charge and discharge process of the battery, and the cycle performance of the battery is improved.
Description
Technical Field
The invention relates to the technical field of new energy, in particular to a battery cell and a battery.
Background
With the advent of the 5G age and the rapid development of lithium ion battery technology, people put higher demands on the energy density, the rapid charging capability and the charge-discharge rate of lithium ion batteries, and in particular, put higher demands on the rapid charging capability of lithium ion batteries.
However, under the condition of quick charge, the existing lithium ion battery with quick charge capability can generate the problem of black spot lithium precipitation at the circular arcs on two sides of the lithium ion battery along with the increase of the charge and discharge times of the battery, so that the circulating water jump of the lithium ion battery can be caused, the problem that the expansion failure and the like of the lithium ion battery can be caused due to the stupefied circular arcs can be caused, and the service life of the lithium ion battery is greatly reduced.
Disclosure of Invention
The invention provides a battery cell, which not only can improve the energy density of a battery, but also is not easy to separate lithium in the charge and discharge process of the battery, thereby being beneficial to improving the cycle performance of the battery.
The invention provides a battery which comprises the battery core, so that the battery has excellent energy density and cycle performance.
The invention provides a battery cell, wherein the battery cell comprises a pole piece, and the pole piece comprises a current collector and a functional layer arranged on at least one surface of the current collector;
the functional layer comprises a first active layer and a second active layer which are stacked along the direction far away from the current collector;
in the length direction of the current collector, the first active layer comprises N first parts and M second parts which are arranged in a staggered manner, wherein N is more than or equal to 1, and M is more than or equal to 1;
The first part comprises a silicon-based material and a conductive agent wrapping at least part of the surface of the silicon-based material;
the second portion and the second active layer each comprise a carbon-based material;
in the cell, the first portion includes a straight section and the second portion includes an arcuate section.
The cell as described above, wherein the length of the second portion is 2-5mm.
The battery cell as described above, wherein the silicon-based material is 30-90% by mass and the conductive agent is 10-50% by mass based on the total mass of the first portion.
The battery cell as described above, wherein the first portion further comprises first particles, the first particles being coated on at least a portion of the surface of the silicon-based material;
the first particles comprise hard carbon particles.
The battery cell as described above, wherein the mass ratio of the silicon-based material to the first particles is (30-70): (70-30).
The battery cell as described above, wherein the total mass percentage of the silicon-based material and the first particles is 55-99% and the mass percentage of the conductive agent is 2-10% based on the total mass of the first portion.
The battery cell as described above, wherein the sphericity of the first particles is 0.8-1; and/or the number of the groups of groups,
The first particles are provided with micropores, and the pore diameter of the micropores is 100nm-1.5 mu m; and/or the number of the groups of groups,
dv50 of the first particle C 0.5-5 μm.
The cell as described above, wherein the conductive agent comprises conductive carbon black.
The cell as described above, wherein the conductive agent further comprises carbon nanotubes comprising single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
The cell as described above, wherein the conductive carbon black has a Dv50 Electric power 200nm to 1.5 mu m; and/or the number of the groups of groups,
the pipe diameter of the multi-wall carbon nano-pipe is 5-20nm, and the length-diameter ratio is (100-180): 1, a step of; and/or the number of the groups of groups,
the pipe diameter of the single-wall carbon nano-tube is 1-5mm, and the length-diameter ratio is (109-150): 1.
a cell as described above, wherein the silicon-based material has a Dv50 of Si The method meets the following conditions: 3 μm<Dv50 Si <8μm。
The battery cell as described above, wherein the functional layer further includes a third layer disposed on a surface of the first active layer remote from the second active layer;
the third layer includes a conductive agent and a binder.
The battery cell as described above, wherein the thickness of the third layer is 0.5-5 μm; and/or the number of the groups of groups,
the thickness of the first active layer is 3-12 μm.
The invention provides a battery, which comprises the battery cell.
The battery core has a special structure and a special composition, so that when the battery core is applied to a battery, the energy density of the battery can be improved, the phenomenon of lithium precipitation of the battery in the charge-discharge cycle process can be reduced, and the cycle performance of the battery can be improved.
The battery provided by the invention comprises the battery core, and is suitable for wide popularization and application due to excellent energy density and cycle performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings that are required to be used in the description of the embodiments of the present invention or the related technologies are briefly described below. It is evident that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
Fig. 1 is a schematic structural diagram of a prior art cell;
FIG. 2 is a side view of a pole piece in a first embodiment of the invention;
FIG. 3 is a side view of a pole piece in a second embodiment of the invention;
FIG. 4 is a schematic diagram of the structure of a silicon-based material, a conductive agent, a first particle, and a carbon-based material according to some embodiments of the present invention;
FIG. 5 is a side view of a pole piece in a third embodiment of the invention;
fig. 6 is a side view of a pole piece in a fourth embodiment of the invention.
Reference numerals illustrate:
1: a current collector;
22: a second active layer;
23: a carbon layer;
211: a first portion;
212: a second portion;
2110: a silicon-based material;
2111: a conductive agent;
2112: a first particle;
2020: a carbon-based material.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the present invention, all the definitions of "length" and "width" refer to the "length L direction" and "width W direction" of the negative electrode current collector. Taking the surface of the negative current collector (two surfaces with the largest area and opposite arrangement in the negative current collector) as a rectangle as an example, the length L direction of the current collector refers to the direction in which the largest side length of the current collector surface is located, and is denoted as the x direction; the width W direction of the current collector is the direction in which the smallest side length of the current collector surface is located, and is referred to as the y direction. For example, the present invention defines the length of the second portion as L1, which means that the dimension of the second portion in the length direction of the current collector is L1. Meanwhile, the thickness H direction of the current collector is referred to as the z direction.
Fig. 1 is a schematic structural diagram of a cell in the prior art. As shown in fig. 1, when the conventional battery cell is used in a lithium ion battery, as the charge and discharge times of the lithium ion battery are increased, a pole piece of the battery cell expands, and as the pole piece expands continuously, the expansion stress of an arc area of the pole piece is difficult to release outwards, so that the stress of the arc area is accumulated continuously, a diaphragm is extruded, electrolyte in the arc area is lost, and finally, the problem of lithium precipitation in the arc area occurs.
In view of this, fig. 2 is a side view of a pole piece according to a first embodiment of the present invention; FIG. 3 is a side view of a pole piece in a second embodiment of the invention; FIG. 4 is a schematic diagram of the structure of a silicon-based material, a conductive agent, hard carbon particles, and a carbon-based material according to some embodiments of the present invention; FIG. 5 is a side view of a pole piece in a third embodiment of the invention; fig. 6 is a side view of a pole piece in a fourth embodiment of the invention. As shown in fig. 1-6, a first aspect of the present invention provides a battery cell, the battery cell including a pole piece, the pole piece including a current collector and a functional layer disposed on at least one surface of the current collector;
the functional layer includes a first active layer and a second active layer 22 stacked in a direction away from the current collector;
In the length direction of the current collector, the first active layer comprises N first parts 211 and M second parts 212 which are arranged in a staggered way, wherein N is more than or equal to 1, and M is more than or equal to 1;
the first portion 211 comprises a silicon-based material 2110 and a conductive agent wrapped around at least a portion of the surface of the silicon-based material;
the second portions 212 and the second active layer 22 each include a carbon-based material 2020;
in the battery cell, the first portion 211 extends in the horizontal direction, and the second portion 212 is arc-shaped.
It can be understood that the electrode plate can be a negative electrode plate, the battery cell also comprises a positive electrode plate and a diaphragm, and the battery cell can be obtained by winding after the positive electrode plate, the diaphragm and the negative electrode plate are stacked.
The positive electrode sheet and the separator are not particularly limited, and may be those commonly used in the art, respectively.
In the negative plate of the present invention, the functional layer may be provided on any one surface of the current collector 1; the functional layers may be provided on both surfaces of the current collector 1, respectively.
When the functional layer is provided on one surface of the current collector 1, the negative electrode sheet of the present invention includes the current collector 1, the first active layer, and the second active layer 22 in this order in the lamination direction; when the functional layers are respectively provided on both surfaces of the current collector 1, the negative electrode sheet of the present invention sequentially includes the second active layer 22, the first active 21 layer, the current collector 1, the first active layer, and the second active layer 22 in the lamination direction.
It will be appreciated that the first active layer of the present invention may include the first portion 211, the second portion 212, and the first portion 211 … … connected to each other in order in the length direction of the current collector 1. In the cell, the first portion 211 extends along the horizontal direction, the second portion 212 is an arc transition portion when winding, that is, winding is performed along the length direction of the current collector 1, and the first active layer sequentially includes the first portion 211 (straight section), the second portion 212 (arc section), the first portion 211 (straight section), and the second portion 212 (arc section) … …. The present invention is not particularly limited as long as the first portion 211 including the straight section can be transitionally included, and in some embodiments, the arc section may be a circular arc section.
The present invention is not limited to the length of the first portion 211 and the second portion, the length of the first portion 211 may be greater than the length of the second portion, the length of the first portion 211 may be less than the length of the second portion, and the length of the first portion 211 may be the same as the length of the second portion. Typically, the length of the second portion is greater than the length of the first portion 211,
in the first portion 211 of the present invention, the conductive agent 2111 may be coated on the entire surface of the silicon-based material 2110 or may be coated on a part of the surface of the silicon-based material. Among them, the silicon-based material 2110 has excellent capacity, contributing to an improvement in energy density of the battery. The silicon-based material 2110 of the present invention may be a silicon-based material 2110 commonly used in the art, and for example, the silicon-based material 2110 may be at least one of SiC, siOx, and silicon nitride. The conductive agent 2111 may improve the conductive performance of the first portion 211, and since the conductive agent 2111 has a hardness less than that of the silicon-based material 2110, when the conductive agent wraps at least a portion of the surface of the silicon-based material, the conductive agent 2111 may reserve an expansion space for the silicon-based material, and when the silicon-based material expands, the silicon-based material may first press the conductive agent 2111, thereby preventing the pole piece from being excessively expanded, and improving the cycle performance of the battery.
In the present invention, the second portion 212 and the second active layer 22 each include a carbon-based material 2020, and the carbon-based material 2020 is excellent in stability and low in cost as compared with the silicon-based material 2110. The carbon-based material 2020 of the present invention may be the carbon-based material 220 commonly used in the art, for example, the carbon-based material 2020 may be at least one selected from artificial graphite, natural graphite, and mesophase carbon microspheres.
In the present invention, the specific composition of the second portion 212 and the second active layer 22 may be the same or different. When the second portion 212 is identical to the specific composition of the second active layer 22, the second portion 212 and the second active layer 22 may be formed by an integral arrangement.
It will be appreciated that the functional layers of the present invention (first portion 211, second portion 212, and second active layer 22) may also include binders and thickeners. Wherein the binder in the first portion 211, the second portion 212, and the second active layer 22 are each independently a binder commonly used in the art, and illustratively, the binder may be selected from at least one of polyvinylidene fluoride (PVDF), acrylic-modified PVDF, carboxylic acid-modified PVDF, styrene-butadiene rubber, acrylic-modified styrene-butadiene rubber, polymethyl methacrylate (PMMA), and Polyimide (PI); the thickener in the first portion 211, the thickener in the second portion 212, and the thickener in the second active layer 22 may each independently be a thickener commonly used in the art, and illustratively, the thickener may be at least one selected from the group consisting of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone.
The functional layer of the negative electrode sheet sequentially comprises a first active layer containing a silicon-based material 2110 and a conductive agent and a second active layer 22 containing a carbon-based material 2020 along the direction far away from the current collector 1, and the energy density of the negative electrode sheet can be effectively improved because the first active layer contains the silicon-based material 2110 with high specific energy, and the stability of the negative electrode sheet can be effectively improved because the second active layer 22 arranged outside the negative electrode sheet contains the carbon-based material 2020 with excellent stability; further, the conductive agent 2111 in the first portion 211 is wrapped on at least part of the surface of the silicon-based material 2110, so that an expansion space can be reserved for the silicon-based material 2110 while the conductivity of the silicon-based material 2110 is improved, the phenomenon that a pole piece expands due to expansion of the silicon-based material 2110 in the cycle process of a battery is avoided, and further, the cycle performance of the pole piece can be effectively improved, meanwhile, the electrolyte can be stored in micropores of the conductive agent 2111, the liquid retention amount of the first active layer is improved, more electrolyte is arranged in the first active layer, further, the polarization phenomenon generated by the reaction of the silicon-based material 2110 can be reduced, the dynamic performance of the pole piece is improved, and further, the phenomenon that lithium is separated out from the surface of the pole piece is reduced; meanwhile, the second part 212 comprising the carbon-based material 2020 with excellent stability is arranged at the arc-shaped position of the battery core, the first part 211 comprising the silicon-based material 2110 with high specific energy is arranged in the horizontal direction, and the first part 211 and the second part 212 are arranged in a staggered manner, so that the energy density of the battery core can be improved, the expansion of the arc-shaped region is smaller than that of the horizontal direction, the anode piece is prevented from being excessively expanded in the arc-shaped region in the circulating process, the continuous accumulation of stress caused by the fact that the stress cannot be released outwards freely in the arc-shaped region is avoided, the phenomenon that electrolyte is lost due to the fact that the diaphragm is extruded is avoided, lithium precipitation in the arc-shaped region is avoided, and the circulating performance of the battery is improved.
It is understood that the length of the second portion 212 may be sized according to the actual winding process. Typically, the length of the second portion 212 may be 2-5mm.
In some embodiments of the present invention, as shown in fig. 4 and 5, the silicon-based material 2110 is 30-90% by mass and the conductive agent 2111 is 10-50% by mass, based on the total mass of the first portion 211.
In the present invention, when the content of the silicon-based material 2110 and the content of the conductive agent 2111 in the first portion 211 satisfy the above ranges, the conductive agent 211 can be more fully wrapped on the surface of the silicon-based material 210, so that not only the conductivity of the silicon-based material 210 can be better improved, but also an expansion space is more fully reserved for the silicon-based material 210; and more conductive agent 211 can further improve the liquid retention of the first active layer, improve the dynamic performance of the first active layer, and avoid the phenomenon of pole piece lithium precipitation. Therefore, the first active layer with the composition can further improve the comprehensive performance of the pole piece, and further improve the electrochemical performance of the battery.
It is to be understood that the second portion 212 and the second active layer 22 may also include the conductive agent 2111 in the present invention, and the content and type of the conductive agent 2111 in the second portion 212 and the second active layer 22 are not limited in the present invention. The conductive agent 2111 in the second portion 212 and the second active layer 22 may be the same kind as or different from the conductive agent 2111 in the first portion 211. In some embodiments, the mass ratio of the conductive agent 2111, the carbon-based material 2020, the binder, and the thickener in the second portion 212 and the second active layer 22 may be (0.5 to 3): (80-99): (0.5-5): (0.5-3).
In some embodiments, the first portion 211 further includes a binder in an amount of 3-10% by mass and a thickener in an amount of 2-10% by mass, based on the total mass of the first portion 211.
As shown in fig. 4 and 6, in some embodiments of the present invention, the first portion 211 further includes first particles 2112, which are coated on at least a portion of the surface of the silicon-based material;
the first particles comprise hard carbon particles.
In the present invention, when the first portion 211 further includes the first particles 2112, the first particles 2112 and the conductive agent 2111 may be coated on the surface of the silicon-based material 2110 together, so as to improve the conductive performance of the silicon-based material 2110; and since the first particles 2112 (e.g., hard carbon particles) are spherical particles, the accumulation of the first particles 212 may create a large number of voids, and the voids created by the first particles 2112 may also be reserved for expansion of the silicon-based material 2110; meanwhile, the micropores of the first particles 2112 can further improve the liquid retention of the first portion 211, reduce the polarization of the reaction of the silicon-based material 2110 in the first portion 211, and improve the dynamic performance of the first portion 211. It should be noted that the first particles 2112 can also provide capacity to the negative electrode sheet, thereby increasing the energy density of the battery.
The active layer of the present invention, in which the silicon-based material 2110, the first particles 2112 and the conductive agent 2111 are blended, may be thinner than the active layer of the prior art, in which the carbon-based material 2020 (e.g., graphite particles) is blended with the silicon-based material 2110, contributing to further increasing the volumetric energy density of the negative electrode sheet; compared with the prior art, the silicon-based material 2110 in the active layer can be dispersed more uniformly and concentrated, and when the silicon-based material 2110 expands, the stress generated by the expansion of the silicon-based material 2110 can be uniformly dispersed, so that the phenomenon that the negative electrode plate deforms due to overlarge local expansion stress of the negative electrode plate caused by the expansion of a single silicon-based material 2110 is prevented.
In the present invention, since the first particles 2112 can also provide capacity to the negative electrode sheet to increase the energy density of the battery, the content of the silicon-based material 2110 in the first portion 211 can be appropriately reduced in order to save production costs without affecting the energy density of the battery. Illustratively, the mass ratio of the silicon-based material 2110 to the first particles 2112 may be (30-70): (70-30). Meanwhile, when the mass ratio of the silicon-based material to the first particles meets the range, the first particles can reserve more expansion space for the silicon-based material, so that the cycle performance of the pole piece is improved, the pole piece has excellent cycle performance and energy density, and meanwhile, the production cost of the pole piece is reduced. Further, the mass ratio of the silicon-based material 2110 to the first particles 2112 may be (30-50): (50-70).
In some embodiments of the present invention, the total mass percent of the silicon-based material 2110 and the first particles 2112 is 55-99% and the mass percent of the conductive agent 2111 is 2-10% based on the total mass of the first portion 211.
In the invention, when the total mass content of the silicon-based material and the first particles is in the above range, more capacity can be provided, and the energy density of the pole piece can be further improved, and the conductivity of the pole piece can be improved by the specific content of the conductive agent 2111, so that when the total content of the silicon-based material and the first particles and the content of the conductive agent 2111 meet the above range, the pole piece provided by the invention has more excellent cycle performance and energy density.
When the first portion 211 further includes a binder and a thickener, the mass percentage of the binder may be 2-8% and the mass percentage of the thickener may be 2-40% based on the total mass of the first active layer.
In the present invention, the first particles 2112 may be further selected in order to better enhance the electrochemical performance of the battery.
For example, in some embodiments of the invention, the sphericity of the first particles is 0.8 to 1.
In the present invention, sphericity is used to characterize the morphology of the first particle. Sphericity can be tested by testing methods commonly used in the art. When the sphericity of the first particles is 0.8-1, the first particles are closer to the sphere or are spherical in morphology, more pores are generated when the first particles are stacked, more expansion space can be reserved for the silicon-based material, and then the cycle performance of the pole piece can be further improved.
In some embodiments of the invention, the first particles 2112 have micropores with a pore size of 100nm to 1 μm.
In the present invention, when the pore diameter of the micropores of the first particles 2112 is within the above range, it is possible to store more electrolyte while increasing the capacity of the first portion 211, to increase the wettability of the first portion 211, and to further increase the dynamic performance of the first portion 211.
Further, dv50 of first particle 2112 C 0.5-5 μm.
When the particle size of the first particles 2112 is within the above range, more pores can be accumulated without affecting the capacity of the first portion 211, more space is reserved for the expansion of the silicon-based material 2110, and the electrochemical performance of the cell can be further improved.
The composition of the conductive agent 2111 can be further selected so as to further improve the electrochemical performance of the negative electrode sheet. In particular, the composition of the conductive agent 2111 in the first active layer may be further selected to improve the electrochemical performance of the negative electrode sheet.
The conductive agent 2111 of the present invention may be a conductive agent 2111 commonly used in the art, for example, the conductive agent 2111 may be at least one selected from conductive carbon black, graphite, graphene, carbon nanotube, metal conductive powder, carbon nanofiber, and ketjen black, wherein the conductive carbon black may be acetylene black and/or ketjen black; the carbon nanotubes may be single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
The invention can further select the type of the conductive agent 2111 in the first part 211 so as to improve the electrochemical performance of the negative electrode plate and further improve the electrochemical performance of the battery cell.
In some embodiments of the present invention, when the conductive agent 2111 includes conductive carbon black, a cell having excellent electrochemical properties can be obtained.
Further, the conductive agent 2111 includes carbon nanotubes including single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
Illustratively, the conductive agent 2111 may include conductive carbon black and single-walled carbon nanotubes; the conductive agent 2111 may include conductive carbon black and multi-walled carbon nanotubes; the conductive agent 2111 may include conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.
In some embodiments, when the conductive agent 2111 includes conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes, the resulting pole piece has more excellent electrochemical properties. Further, when the mass ratio of the conductive carbon black, the single-walled carbon nanotube and the multi-walled carbon nanotube in the conductive agent 2111 is (5-7): (1-2): (2-3), the conductive carbon black, the single-walled carbon nanotube and the multi-walled carbon nanotube can be better matched, so that the electrochemical performance of the negative plate is improved. Or alternatively, the first and second heat exchangers may be,
When the conductive agent 2111 includes conductive carbon black and single-walled carbon nanotubes, the obtained electrode sheet has the most excellent electrochemical properties. Further, in the conductive agent 2111, the mass ratio of the conductive carbon black to the single-walled carbon nanotube is (6-8): and (2-4), the conductive carbon black can be better matched with the single-walled carbon nanotube so as to improve the electrochemical performance of the negative plate.
In the present invention, the particle size of the conductive agent 2111 may be further selectedAlternatively, it is desirable to further reserve space for expansion of the silicon-based material 2110 while improving the conductivity of the negative electrode sheet. Illustratively, in the conductive agent 2111, the Dv50 of the conductive carbon black Electric power 200nm to 1.5 mu m; and/or the number of the groups of groups,
the pipe diameter of the multi-wall carbon nano-pipe is 5-20nm, and the length-diameter ratio is (100-180): 1, a step of; and/or the number of the groups of groups,
the pipe diameter of the single-wall carbon nano-tube is 1-5mm, and the length-diameter ratio is (109-150): 1.
further, the pipe diameter of the multi-wall carbon nano-pipe is 6-13nm, and the length-diameter ratio is (120-160): 1, a step of; and/or the number of the groups of groups,
the pipe diameter of the single-wall carbon nano-tube is 1.5-3.5nm, and the length-diameter ratio is (110-140): 1.
in the present invention, pipe diameter refers to the diameter (outer diameter) of the outer periphery, and aspect ratio refers to the ratio of length to outer diameter.
In some embodiments of the invention, when the Dv50 of the silicon-based material 2110 Si The method meets the following conditions: 3 μm<Dv50 Si <When the energy density of the negative plate is 8 mu m, the cycle performance of the battery cell can be improved under the condition of ensuring the energy density of the negative plate.
In some embodiments of the present invention, the functional layer further comprises a third layer disposed on a surface of the first active layer remote from the second active layer 22;
the third layer includes a conductive agent 2111 and an adhesive.
It is understood that the negative electrode sheet of the present invention may include the current collector 1, the third layer 23, the first active layer, and the second active layer 22 in this order in a direction away from the current collector 1.
The third layer 23 is not particularly limited in the present invention, and may be a third layer 23 commonly used in the art. In some embodiments, the third layer 23 may include a conductive agent 2111 and an adhesive. Further, in the third layer 23, the conductive agent 2111 may be 40 to 75% by mass, and the binder may be 25 to 60% by mass. In some embodiments, the conductive agent 2111 may be 50 to 70% by mass and the binder may be 30 to 50% by mass in the third layer 23.
When the functional layer further includes the third layer 23 disposed on the surface of the first active layer away from the second active layer 22, the third layer 23 can improve adhesion between the first active layer and the current collector 1, which is helpful to improve conductivity of the negative electrode sheet and prolong the service life of the negative electrode sheet.
In the present invention, when the thickness of the third layer 23 is 0.5 to 5 μm, the conductivity of the negative electrode sheet can be improved and the service life of the negative electrode sheet can be prolonged without affecting the energy density of the battery.
In some embodiments of the present invention, the first active layer has a thickness of 3-12 μm, which can provide the battery cell with more excellent electrochemical properties.
The present invention may further define the positions of the first active layer and the second active layer 22, so as to simplify the preparation process while improving the electrochemical performance of the negative electrode sheet. As shown in fig. 5 or 6, in some embodiments of the present invention, the first active layer has a first end and a second end disposed opposite to each other in the length direction of the current collector 1;
the second active layer 22 has a third end and a fourth end disposed opposite to each other;
the third end extends beyond and wraps at least part of the end face of the first end; and/or the number of the groups of groups,
the fourth end extends beyond and wraps around at least a portion of the end face of the second end.
It will be appreciated that in the present invention, the first end and the third end are on the same side in the length direction, and the second end and the fourth end are on the same side.
It is understood that the third end extends beyond and wraps around at least a portion of the end face of the first end, the third end of the second active layer 22 extends beyond the first end of the first active layer, and the second active layer 22 covers at least a portion of the end face of the first end of the first active layer.
By at least a portion of the end face of the fourth end beyond and surrounding the second end is understood that the third end of the second active layer 22 exceeds the second end of the first active layer and the second active layer 22 covers at least a portion of the end face of the second end of the first active layer.
When the negative electrode sheet has the above-described structure, expansion of the negative electrode sheet can be further suppressed, and the manufacturing process can also be simplified.
Further, when the length of the second active layer 22 is 1 to 3mm longer than the length of the first active layer, the expansion of the negative electrode sheet can be further suppressed on the basis of saving the second active layer 22.
In some embodiments of the invention, the distance between the first orthographic projection of the first end on the surface of the second active layer 22 and the third end in the length direction is 0.5-1mm; and/or the number of the groups of groups,
the distance between the second orthographic projection of the second end on the surface of the second active layer 22 and the fourth end in the length direction is 0.5-1mm.
In the present invention, the first orthographic projection means a projection formed on the surface of the second active layer 22 by irradiating the first end with incident light in a direction perpendicular to the surface of the second active layer 22. The distance between the first orthographic projection and the third end is understood to be the size of the third end protruding beyond the first end.
In the present invention, the second orthographic projection means a projection formed on the surface of the second active layer 22 by irradiating the third terminal with incident light in a direction perpendicular to the surface of the second active layer 22. The distance between the second orthographic projection and the fourth end is understood to be the dimension by which the fourth end protrudes beyond the second end.
When the dimensions of the third end extending beyond the first end and/or the dimensions of the fourth end extending beyond the second end satisfy the above relationship, the expansion of the negative electrode sheet can be suppressed more effectively while saving the second active layer 22.
In some embodiments of the present invention, when the ratio of the thickness of the first active layer to the thickness of the second active layer 22 is (0.03 to 0.5): and 1, the dynamic performance of the negative plate is improved, and the expansion of the negative plate can be further reduced.
Since pores are generated by the conductive agent 2111 and/or hard carbon deposition of the first portion 211 in the present invention, when the second active layer 22 is disposed on the surface of the first portion 211 remote from the current collector 1, the second active layer 22 is easily embedded in the pores of the first portion 211. Thus, in some embodiments of the present invention, the functional layer further comprises a miscible layer disposed between the first active layer and the second active layer 22;
The miscible layer comprises first miscible parts and second miscible parts which are arranged in a staggered way;
a portion of the first miscible portion is composed of the first portion 211 and another portion is composed of the second active layer 22, the composition of the second miscible portion being the same as the composition of the second active layer 22.
That is, the negative electrode sheet of the present invention may include the current collector 1, the first active layer, the miscible layer, and the second active layer 22 in this order in the direction away from the current collector 1 in the thickness direction.
When the negative electrode sheet further includes a miscible layer, the first and second active layers 22 can be more tightly bonded, contributing to improved kinetic performance of the negative electrode sheet, and contributing to reduced expansion of the negative electrode sheet. Further, the thickness of the miscible layer may be 3 μm or less.
In some embodiments of the present invention, the positions of the third layer 23 and the first active layer may be further selected, so as to further improve the electrochemical performance of the negative electrode sheet.
In some embodiments of the present invention, the first active layer has a first end and a second end disposed opposite each other in the length direction of the current collector 1;
the third layer 23 includes a fifth end and a sixth end disposed opposite each other;
the first end extends beyond and wraps at least part of the end face of the fifth end; and/or the number of the groups of groups,
The second end extends beyond and wraps around at least a portion of the end face of the sixth end.
It will be appreciated that in the present invention, the first end and the fifth end are on the same side in the length direction, and the second end and the sixth end are on the same side.
At least a portion of the end face of the first end beyond and surrounding the fifth end is understood to mean that the first end of the first active layer exceeds the fifth end of the third layer 23 and that the first active layer covers at least a portion of the end face of the fifth end of the third layer 23.
By the second end extending beyond and wrapping around at least part of the end face of the fifth end is understood that the first end of the first active layer extends beyond the sixth end of the third layer 23 and the first active layer covers at least part of the end face of the sixth end of the third layer 23.
When the negative electrode sheet has the above-described structure, the conductivity of the negative electrode sheet can be further improved, and the manufacturing process can also be simplified.
Further, when the length of the first active layer is 6-8mm longer than that of the third layer 23, the conductivity of the negative electrode sheet can be further improved on the basis of saving the first active layer.
In some embodiments of the invention, the distance between the third orthographic projection of the fifth end on the surface of the first active layer and the first end in the length direction is 2-3mm; and/or the number of the groups of groups,
The distance between the fourth orthographic projection of the sixth end on the surface of the first active layer and the second end is 2-3mm in the length direction.
In the present invention, the third orthographic projection means a projection in which incident light irradiates the fifth end in a direction perpendicular to the surface of the first active layer, thereby forming a surface of the first active layer. The distance between the third orthographic projection and the first end is understood to be the dimension by which the first end protrudes beyond the fifth end.
In the present invention, the fourth orthographic projection means a projection in which incident light irradiates the sixth end in a direction perpendicular to the surface of the first active layer, thereby forming a surface of the first active layer. The distance between the fourth orthographic projection and the sixth end is understood to be the dimension by which the second end protrudes beyond the sixth end.
When the size of the first end extending out of the fifth end and/or the size of the second end extending out of the sixth end satisfy the above relation, the electrochemical performance of the negative electrode sheet can be further improved.
A second aspect of the present invention provides a battery comprising the above-described cell.
In the invention, the battery cell can be placed in an outer package, electrolyte is injected into the outer package, and the battery is obtained after sealing formation.
The battery of the present invention includes the above-described battery cell, and therefore, is excellent in energy density and cycle performance, and has a high user evaluation.
The technical scheme of the invention will be further described below with reference to specific examples.
Example 1
The battery of this example was prepared by a method comprising the steps of:
1) Negative plate
Mixing a conductive agent and styrene-butadiene rubber according to a mass ratio of 70:30, and then adding absolute ethyl alcohol to obtain carbon layer active slurry;
mixing silicon carbide, a conductive agent, acrylic acid modified styrene-butadiene rubber and carboxymethyl cellulose lithium according to a mass ratio of 55:38:3:4; adding deionized water as a solvent to prepare a first part of active slurry; wherein, the Dv50Si of the silicon carbide is 5 mu m, the conductive agent comprises conductive carbon black (A) and single-walled carbon nano-tubes (B), the mass ratio of the conductive carbon black to the single-walled carbon nano-tubes is 4:1, the Dv50 of the conductive carbon black is 800nm, the pipe diameter of the single-walled carbon nano-tubes is 2.76mm, and the length-diameter ratio is 127:1, a step of;
artificial graphite, conductive carbon black of a conductive agent, styrene-butadiene rubber and carboxymethyl cellulose lithium are mixed according to the mass ratio of 96:1.5:1.5:1, mixing, and then adding deionized water as a solvent to prepare a second anode active slurry;
respectively arranging third-layer active slurry on two surfaces of the copper foil by using a coating machine, and forming a third layer on the two surfaces of the copper foil after drying; the method comprises the steps that first part of active sizing agent is respectively arranged on two surfaces of a third layer far away from a copper foil at intervals, and first parts of intervals are respectively formed on the two surfaces of the third layer after drying; continuously arranging second active slurry on two surfaces of the first part far away from the third layer respectively, wherein one part of the second active slurry is arranged on two surfaces of the first part far away from the third layer, and the other part of the second active slurry is permeated into a region of the first part, where the first part is not arranged, of the interval region of the first part), and drying to obtain a negative plate containing the second part and the second active layer, wherein the drying temperature is 100 ℃;
The length of the second part is 3mm;
the thickness of the third layer is 1 μm; the thickness of the first portion was 7 μm; the thickness of the second active layer was 45 μm;
the length of the first active layer is 6mm longer than the length of the third layer;
two ends of the first active layer respectively exceed the third layer by 3mm;
the length of the second active layer is 3mm longer than the length of the first active layer;
the two ends of the second active layer respectively exceed the first active layer by 1.5mm.
2) Positive plate
Adding lithium cobaltate, conductive carbon black serving as a conductive agent and polyvinylidene fluoride into a stirring tank according to the mass ratio of 97.2:1.5:1.3, adding an NMP solvent, fully stirring, sieving with a 200-mesh sieve to obtain positive electrode active slurry with the solid content of 70-75%, respectively coating the positive electrode active slurry on two surfaces of an aluminum foil by using a coating machine, and drying at the temperature of 120 ℃ to obtain a positive electrode plate containing a positive electrode active layer.
3) Battery cell
And (3) sequentially laminating the negative electrode sheet, the diaphragm and the positive electrode sheet in the step (1) and the step (2), then carrying out winding treatment, wherein the first part comprises a straight section, and the second part comprises an arc section, so as to obtain a winding battery core, placing the winding battery core in an aluminum plastic film, baking to remove moisture, injecting a commercial electrolyte, and carrying out thermocompression to obtain the battery.
Example 2
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative electrode sheet of step 1), the thickness of the first portion was 9 μm.
Example 3
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative electrode sheet of step 1), the thickness of the first portion was 12. Mu.m.
Example 4
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), in the first part of active slurry, the mass ratio of silicon carbide to conductive agent to acrylic acid modified styrene-butadiene rubber to carboxymethyl cellulose lithium is 30:50:10:10;
the thickness of the first portion was 9 μm.
Example 5
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), in the first part of active slurry, the mass ratio of silicon carbide to conductive agent to acrylic acid modified styrene-butadiene rubber to carboxymethyl cellulose lithium is 85:10:2:3;
the thickness of the first portion was 9 μm;
the first active layer, the second active layer, and the carbon layer have the same length.
Example 6
The battery of this example was prepared in substantially the same manner as in example 1, except that:
In the preparation of the negative electrode sheet in step 1), dv50Si of silicon carbide was 7 μm, and the thickness of the first portion was 9 μm.
Example 7
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), dv50Si of silicon carbide is 7 mu m, and the thickness of the first part is 9 mu m;
the particle size of the conductive carbon black was 1.5. Mu.m.
Example 8
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), the thickness of the third layer is 4 mu m; the thickness of the first portion was 9 μm.
Example 9
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), silicon carbide and hard carbon particles are mixed according to the mass ratio of 3:7, and the mixture of the silicon carbide and the hard carbon particles, a conductive agent, acrylic acid modified styrene-butadiene rubber and carboxymethyl cellulose lithium are mixed according to the mass ratio of 85:5:3, a step of; 7, mixing; adding deionized water as a solvent to prepare a first part of active slurry; wherein, the Dv50Si of the silicon carbide is 5.5 mu m, the Dv50c of the hard carbon particles is 1 mu m, the pore diameter of the surface micropores of the hard carbon particles is 300-800 nm, and the Dv50 electricity of the conductive carbon black is 300nm;
Wherein the third layer has a thickness of 1 μm, the first portion has a thickness of 7 μm, and the second active layer has a thickness of 45 μm.
Example 10
The method for preparing the battery of this example was substantially the same as in example 9, except that in the preparation of the negative electrode sheet of step 1), the mass ratio of silicon carbide to hard carbon particles was 4:6.
Example 11
The method for preparing the battery of this example was substantially the same as in example 9, except that in the preparation of the negative electrode sheet of step 1), the mass ratio of silicon carbide to hard carbon particles was 5:5.
Example 12
The method for producing a battery of this example was substantially the same as in example 9, except that in the production of the negative electrode sheet of step 1), the thickness of the third layer was 2 μm, the thickness of the first portion was 9 μm, and the mass ratio of silicon carbide to hard carbon particles was 4:6.
Example 13
The method for producing a battery of this example was substantially the same as in example 9, except that in the production of the negative electrode sheet of step 1), the thickness of the third layer was 2 μm, the thickness of the first portion was 12 μm, and the mass ratio of silicon carbide to hard carbon particles was 4:6.
Example 14
The method for producing a battery of this example was substantially the same as in example 9, except that in the production of the negative electrode sheet of step 1), the thickness of the third layer was 4 μm, the thickness of the first portion was 9 μm, and the mass ratio of silicon carbide to hard carbon particles was 4:6.
Example 15
The method for manufacturing the battery of this example was basically the same as that of example 9, except that in the preparation of the negative electrode sheet of step 1), the thickness of the third layer was 2 μm;
the thickness of the first portion was 9 μm, the Dv50Si of the silicon carbide was 7 μm, the Dv50c of the hard carbon particles was 1 μm, and the mass ratio of the silicon carbide to the hard carbon particles was 4:6.
Example 16
The method for manufacturing the battery of this example was basically the same as that of example 9, except that in the preparation of the negative electrode sheet of step 1), the thickness of the third layer was 2 μm;
the thickness of the first portion was 9 μm, the Dv50Si of the silicon carbide was 7 μm, the Dv50 of the hard carbon particles was 2 μm, and the mass ratio of the silicon carbide to the hard carbon particles was 4:6.
Example 17
The battery of this example was prepared in substantially the same manner as in example 1, except that:
in the preparation of the negative plate in the step 1), in the first part of active slurry, the conductive agent comprises conductive carbon black, single-walled carbon nanotubes and multi-walled carbon nanotubes, the mass ratio of the conductive carbon black to the single-walled carbon nanotubes to the multi-walled carbon nanotubes is 7:1:2, the Dv50 electricity of the conductive carbon black is 800nm, the pipe diameter of the multi-walled carbon nanotubes is 13nm, and the length-diameter ratio is 150:1, the pipe diameter of the single-wall carbon nano-pipe is 2.76mm, and the length-diameter ratio is 127:1, a step of;
Example 18
The battery of this example was prepared in substantially the same manner as in example 1, except that:
the conductive agent is conductive carbon black, and the Dv50 of the conductive carbon black is 800nm.
Examples 19 to 27
The preparation method of the battery of this example is specifically different from that of example 1 as shown in table 1.
Comparative example 1
The battery of this comparative example was prepared in substantially the same manner as in example 1, except that: in the preparation of the negative electrode sheet in step 1), second active slurries are respectively arranged on two surfaces of the copper foil by using a coating machine, so that the negative electrode sheet containing the second active layer is obtained, and the thickness of the second active layer is 63 μm.
Comparative example 2
The battery of this comparative example was prepared in substantially the same manner as in example 1, except that: in the preparation of the negative plate, a coating machine is used for sequentially setting a third layer of active slurry and a second layer of active slurry on two surfaces of a copper foil respectively, so that the negative plate comprising the third layer and the second active layer is obtained;
wherein the thickness of the third layer is 2 μm and the thickness of the second active layer is 60 μm.
Performance testing
The following performance tests were performed on the batteries of examples and comparative examples, and the results are shown in table 2;
1. performing a cyclic test on the battery at 25 ℃ according to a 1C/0.7C charge-discharge system to obtain the initial discharge capacity of the battery and the discharge capacity after 800 times of cycling, and calculating the capacity retention rate; acquiring the initial thickness of the battery and the thickness after 800 times of circulation, and calculating the circulation expansion rate;
And confirming the lithium precipitation degree of the arc-shaped region of the negative electrode plate by disassembling the battery at 100 times and 700 times, wherein 0, 1, 2, 3, 4 and 5 are used for representing the lithium precipitation degree, and the larger the numerical value is, the more serious the lithium precipitation is.
2. Energy density = capacity voltage plateau/cell length-width thickness
TABLE 1
TABLE 2
As can be seen from table 1, the battery of the embodiment of the present invention has excellent energy density and cycle performance, and lithium is not easily separated from the circular arc of the negative electrode tab after the cycle. Proved by the scheme, the problem of lithium precipitation at the arc position of the negative electrode plate of the lithium ion battery in the long-cycle process can be fully solved, so that the cycle life and the cycle expansion of the battery can be effectively improved;
specifically, as can be seen from examples 10, 27, when the negative electrode sheet includes the third layer, the energy density and cycle performance of the battery can be significantly improved; further, as can be seen from examples 8 and 22, the electrochemical performance of the battery can be further improved by further selecting the thickness of the third layer;
2. it can be seen from examples 1, 17, 18 that by selecting the kind of the conductive agent in the first part, the electrochemical performance of the battery, particularly the cycle performance of the battery, can be improved; further, it can be seen from examples 6, 7, 21 that by selecting the Dv50 electricity of the conductive carbon black in the first portion, the electrochemical performance of the battery, particularly the cycle performance of the battery, can be improved;
3. It can be seen from examples 2, 4, 5, 19 or examples 10, 24 that by selecting the composition of the first part, the electrochemical performance of the battery, in particular the energy density of the battery, can be improved;
4. from examples 7, 8, 20, it can be seen that by the Dv50 for the silicon-based material in the first part Si The electrochemical performance of the battery can be improved by selecting, especially the cycle performance of the battery is improved;
5. as can be seen from examples 9, 10, 11, 23, when the mass ratio of the silicon-based material to the first particles in the first portion satisfies a specific range, the energy density of the battery can be significantly improved without significant change in cycle performance;
it can be seen from examples 10, 25 that by selecting the sphericity of the first particles, the electrochemical performance of the battery can be significantly improved;
as can be seen from examples 10 and 26, when the particle size of the first particles satisfies a specific range, the electrochemical performance of the battery can be improved.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. The foregoing is merely illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (14)
1. The battery cell is characterized by comprising a pole piece, wherein the pole piece comprises a current collector and a functional layer arranged on at least one surface of the current collector;
the functional layer comprises a first active layer and a second active layer which are stacked along the direction far away from the current collector;
in the length direction of the current collector, the first active layer comprises N first parts and M second parts which are arranged in a staggered manner, wherein N is more than or equal to 1, and M is more than or equal to 1;
the first part comprises a silicon-based material and a conductive agent wrapping at least part of the surface of the silicon-based material;
the second portion and the second active layer each comprise a carbon-based material;
in the cell, the first portion includes a straight section and the second portion includes an arcuate section.
2. The cell of claim 1, wherein the second portion has a length of 2-5mm.
3. The cell of any one of claims 1-2, wherein the silicon-based material comprises 30-90% by mass and the conductive agent comprises 10-50% by mass, based on the total mass of the first portion.
4. The cell of any one of claims 1-2, wherein the first portion further comprises first particles, the first particles being coated on at least a portion of a surface of the silicon-based material;
The first particles comprise hard carbon particles.
5. The cell of claim 4, wherein the mass ratio of the silicon-based material to the first particles is (30-70): (70-30).
6. The cell of claim 4 or 5, wherein the total mass percent of the silicon-based material and the first particles is 55-99% and the mass percent of the conductive agent is 2-10% based on the total mass of the first portion.
7. The cell of any one of claims 4-6, wherein the sphericity of the first particles is 0.8-1; and/or the number of the groups of groups,
the first particles are provided with micropores, and the pore diameter of the micropores is 100nm-1.5 mu m; and/or the number of the groups of groups,
dv50 of the first particle C 0.5-5 μm.
8. The cell of any one of claims 1-7, wherein the conductive agent comprises conductive carbon black.
9. The cell of claim 8, wherein the conductive agent further comprises carbon nanotubes, the carbon nanotubes comprising single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
10. The cell of claim 9, wherein the conductive carbon black has a Dv50 Electric power 200nm to 1.5 mu m; and/or the number of the groups of groups,
The pipe diameter of the multi-wall carbon nano-pipe is 5-20nm, and the length-diameter ratio is (100-180): 1, a step of; and/or the number of the groups of groups,
the pipe diameter of the single-wall carbon nano-tube is 1-5mm, and the length-diameter ratio is (109-150): 1.
11. the cell of any one of claims 1-10, wherein the silicon-based material has a Dv50 Si The method meets the following conditions: 3 μm<Dv50 Si <8μm。
12. The cell of any one of claims 1-11, wherein the functional layer further comprises a third layer disposed on a surface of the first active layer remote from the second active layer;
the third layer includes a conductive agent and a binder.
13. The cell of claim 12, wherein the third layer has a thickness of 0.5-5 μιη; and/or the number of the groups of groups,
the thickness of the first active layer is 3-12 μm.
14. A battery comprising a cell according to any one of claims 1-13.
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| CN113644231A (en) * | 2021-07-15 | 2021-11-12 | 恒大新能源技术(深圳)有限公司 | Composite negative electrode sheet and preparation method thereof, and secondary battery |
| CN114464771B (en) * | 2022-02-09 | 2024-07-16 | 珠海冠宇电池股份有限公司 | Battery core |
| CN114649505B (en) * | 2022-04-07 | 2024-07-16 | 珠海冠宇电池股份有限公司 | Negative plate and lithium ion battery |
| CN116914275A (en) * | 2023-08-09 | 2023-10-20 | 珠海冠宇电池股份有限公司 | Battery core and battery |
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