CN210349968U - Pole piece and lithium ion battery - Google Patents
Pole piece and lithium ion battery Download PDFInfo
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- CN210349968U CN210349968U CN201921789094.XU CN201921789094U CN210349968U CN 210349968 U CN210349968 U CN 210349968U CN 201921789094 U CN201921789094 U CN 201921789094U CN 210349968 U CN210349968 U CN 210349968U
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 56
- 239000011149 active material Substances 0.000 claims abstract description 50
- 230000004048 modification Effects 0.000 claims abstract description 38
- 238000012986 modification Methods 0.000 claims abstract description 38
- 239000011888 foil Substances 0.000 claims abstract description 33
- 239000011800 void material Substances 0.000 claims abstract description 5
- 239000010410 layer Substances 0.000 claims description 180
- 239000000463 material Substances 0.000 claims description 55
- 229910052744 lithium Inorganic materials 0.000 claims description 46
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 44
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 26
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- 229910002804 graphite Inorganic materials 0.000 claims description 22
- 239000010439 graphite Substances 0.000 claims description 22
- 239000002245 particle Substances 0.000 claims description 11
- 239000011247 coating layer Substances 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 4
- 229920000058 polyacrylate Polymers 0.000 claims description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 4
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical class 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 239000011345 viscous material Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 description 18
- 239000011248 coating agent Substances 0.000 description 12
- 238000000576 coating method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 11
- 238000003466 welding Methods 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 230000002035 prolonged effect Effects 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 239000006258 conductive agent Substances 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 239000002270 dispersing agent Substances 0.000 description 3
- 238000009830 intercalation Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910013361 LiNixCoyAl1-x-yO2 Inorganic materials 0.000 description 1
- 229910013421 LiNixCoyMn1-x-yO2 Inorganic materials 0.000 description 1
- 229910013427 LiNixCoyMn1−x−yO2 Inorganic materials 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- -1 nickel cobalt aluminum Chemical compound 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
Images
Classifications
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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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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The present disclosure relates to a pole piece and a lithium ion battery. The pole piece includes: a current collector layer with a void foil area at the edge; the active material layer is arranged on the surface of the current collector layer and does not overlap with the empty foil area; and the modification layer is arranged on the surface of the current collector layer, provided with the active material layer, and is positioned between the active material layer and the empty foil area.
Description
Technical Field
The disclosure relates to the technical field of batteries, in particular to a pole piece and a lithium ion battery.
Background
A lithium ion battery is a secondary battery, i.e., a rechargeable battery, which mainly operates by movement of lithium ions between a positive electrode and a negative electrode.
The lithium ion battery is used as a source of clean power and clean electric power, the aim of green sustainable development in China is met, and the position and the universality of the lithium ion battery in the new energy industry are increasingly prominent. At present, lithium ion batteries are widely used in various electronic products such as mobile terminals, electric tools, electric vehicles and the like.
How to improve the service life and the use safety of the lithium ion battery is a key subject for the research and development of technicians in the field.
SUMMERY OF THE UTILITY MODEL
The embodiment of the disclosure provides a pole piece and a lithium ion battery, so as to improve the service life and the use safety of the lithium ion battery.
According to an aspect of the embodiments of the present disclosure, there is provided a pole piece, including:
a current collector layer with a void foil area at the edge;
the active material layer is arranged on the surface of the current collector layer and does not overlap with the empty foil area;
and the modification layer is arranged on the surface of the current collector layer, provided with the active material layer, and is positioned between the active material layer and the empty foil area.
In some embodiments, the modification layer is a stress buffer layer in contact with the active material layer.
In some embodiments, the electrode sheet is a negative electrode sheet, the modified layer is a negative electrode modified layer, and the material of the negative electrode modified layer comprises lithium titanate.
In some embodiments, the electrode sheet is a negative electrode sheet, the modified layer is a negative electrode modified layer, the material of the negative electrode modified layer comprises uniformly mixed lithium titanate and graphite, or the material of the negative electrode modified layer comprises graphite particles coated by a lithium titanate coating layer.
In some embodiments, the pole piece is a negative pole piece, and the modified layer is a negative pole modified layer; the material of the negative electrode modified layer comprises uniformly mixed lithium titanate and graphite, wherein the mass mixing ratio of the lithium titanate to the graphite is greater than or equal to 1/6 and less than or equal to 4/9; or the material of the negative electrode modified layer comprises graphite particles coated by a lithium titanate coating layer, wherein the particle size D50 of the graphite is more than or equal to 5 μm and less than or equal to 25 μm; the thickness of the lithium titanate coating layer is not less than 50 nanometers and not more than 100 nanometers.
In some embodiments, the thickness of the negative electrode modification layer is 0.2 micrometers or more and 71 micrometers or less.
In some embodiments, the pole piece is a positive pole piece, the modified layer is a positive pole modified layer, and the material of the positive pole modified layer is an insulating adhesive material.
In some embodiments, the material of the positive electrode modification layer includes polyvinylidene fluoride, polyacrylate, or a mixed material of a nano metal oxide and a resin.
In some embodiments, the thickness of the positive electrode modification layer is 0.2 micrometers or more and 80 micrometers or less.
In some embodiments, the width of the modifying layer is greater than or equal to 5 millimeters and less than or equal to 20 millimeters; and/or the overlapping width of the modification layer and the active material layer is less than or equal to 4 mm.
In some embodiments, the active material layer is provided on both side surfaces of the current collector layer, and the modification layer is provided on both side surfaces of the current collector layer.
According to another aspect of the embodiments of the present disclosure, there is provided a lithium ion battery, including the pole piece according to any one of the above technical solutions, and a tab connected to an empty foil region of the pole piece.
By adopting the technical scheme of the embodiment of the disclosure, the connection reliability of the tab and the pole piece can be improved, the service life of the lithium ion battery is prolonged, and the potential safety hazard is reduced.
Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of embodiments of the present disclosure with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.
The present disclosure may be more clearly understood from the following detailed description, taken with reference to the accompanying drawings, in which:
fig. 1a is a schematic cross-sectional view of a pole piece and a tab after being connected according to an embodiment of the present disclosure;
fig. 1b is a schematic cross-sectional view of a pole piece and a tab according to another embodiment of the present disclosure after being connected;
fig. 2a is a schematic cross-sectional view of a negative electrode tab and a negative electrode tab according to an embodiment of the present disclosure after being connected;
fig. 2b is a schematic cross-sectional view of a positive plate and a positive tab after being connected according to an embodiment of the disclosure;
fig. 3a is a top view of a pole piece and a tab after being connected according to an embodiment of the present disclosure;
fig. 3b is a top view of a pole piece and tab joined according to another embodiment of the present disclosure;
fig. 4a is an exploded view of the internal structure of a lithium ion battery according to an embodiment of the present disclosure;
fig. 4b is a schematic cross-sectional view illustrating an internal structure of a lithium ion battery according to another embodiment of the present disclosure;
fig. 5 is a flowchart illustrating a method for manufacturing a pole piece according to an embodiment of the disclosure.
It should be understood that the dimensions of the various parts shown in the figures are not drawn to scale. Further, the same or similar reference numerals denote the same or similar components.
Detailed Description
Various embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the embodiments is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps set forth in these embodiments is to be construed as illustrative only and not as a limitation unless specifically stated otherwise.
The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" and similar words mean that the elements preceding the word encompass the elements listed after the word, and does not exclude the possibility that other elements are also encompassed. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
In the present disclosure, when a specific element is described as being located between a first element and a second element, there may or may not be intervening elements between the specific element and the first element or the second element.
All terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
The internal structure of the lithium ion battery mainly comprises a positive plate, a positive lug connected with the positive plate, a negative lug connected with the negative plate, a diaphragm and electrolyte. The positive plate and the positive lug form a positive electrode of the lithium ion battery, and the negative plate and the negative lug form a negative electrode of the lithium ion battery. The positive plate and the negative plate are soaked in the electrolyte and are separated by the diaphragm. The separator functions to allow lithium ions to pass through freely, but not electrons, thereby preventing a short circuit between the positive and negative electrodes through the electrolyte. Lithium ions move between the positive electrode and the negative electrode by taking the electrolyte as a medium, so that the charge and discharge of the lithium ion battery can be realized. When the lithium ion battery is charged, lithium ions are extracted from the crystal lattice of the anode material and inserted into the crystal lattice of the cathode material after passing through the electrolyte, so that the cathode is rich in lithium and the anode is poor in lithium; during discharging, lithium ions are extracted from the crystal lattice of the negative electrode material and inserted into the crystal lattice of the positive electrode material after passing through the electrolyte, so that the positive electrode is rich in lithium and the negative electrode is poor in lithium.
The inventor of the application discovers that phenomena such as heating, expansion, material falling and lithium precipitation easily occur at the lug of the lithium ion battery in the related art in the process of realizing the application, so that the service life of the lithium ion battery is influenced, and safety hidden dangers are brought.
In order to solve the technical problem, the embodiment of the present disclosure provides a pole piece, a lithium ion battery, and a method for manufacturing the pole piece.
As shown in fig. 1a, an embodiment of the present disclosure provides a pole piece 100, including:
a current collector layer 1 with a void foil area 10 at the edge;
the active material layer 2 is arranged on the surface of the current collector layer 1 and does not overlap with the empty foil area 10;
and a modified layer 3 provided on the surface of the current collector layer 1 on which the active material layer 2 is provided, and located between the active material layer 2 and the void foil region 10.
Wherein the empty foil region 10 is intended for connection with the tab 4. The active material layer 2 does not overlap the empty foil region 10, which means that the active material layer 2 does not overlap the empty foil region 10 in an area in a direction perpendicular to the surface of the current collector layer 1.
In the pole piece 100 of the embodiment of the present disclosure, the modified layer 3 and the active material layer 2 are disposed on the same side surface of the current collector layer 1, the modified layer 3 is located between the active material layer 2 and the empty foil area 10, and the modified layer 3 can improve the chemical and/or physical properties of the pole piece 100 near the empty foil area 10, so as to improve the reliability of connection between the tab 4 and the pole piece 100, prolong the service life of the lithium ion battery, and reduce the potential safety hazard.
In one embodiment of the present disclosure, the modification layer 3 may be a stress buffer layer, which is in contact with the active material layer 2. The stress buffer layer can release the stress of the pole piece at the welding position of the pole lug, and the expansion and material falling are reduced.
As shown in fig. 2a, in some embodiments of the present disclosure, the pole piece is a negative pole piece 100 b. The current collector layer 1b of the negative electrode sheet 100b is made of copper foil. Graphite is used for the active material layer 2b of the negative electrode sheet 100 b. In some embodiments, the particle size D50 (which refers to a particle size with a 50% cumulative particle distribution) of the graphite and the powder OI value (which characterizes the crystallographic orientation index of the graphite) satisfy: 3.14 is less than or equal to 100/(D50+2.8 XOI) is less than or equal to 8.45, and 5 mu m is less than or equal to D50 is less than or equal to 25 mu m. In the structure of the negative electrode sheet 100b, the modified layer is the negative electrode modified layer 3b in the figure, and the material thereof includes lithium titanate. The negative electrode tab 4b connected to the negative electrode tab 100b is made of nickel.
In the lithium ion battery in the related art, the negative electrode tab is welded with the empty foil area of the negative electrode sheet. Because the binding force between graphite and copper foil is relatively small, the welding stress of the negative electrode tab and the negative electrode sheet easily causes the graphite material nearby to fall off, and the phenomenon is called material falling. In addition, welding stress may cause the negative electrode tab and the negative electrode tab to be separated at the welded portion by swelling, thereby affecting connection reliability.
When the lithium ion battery is in a normal working state, lithium ions are removed from the positive plate and are embedded into the negative plate after passing through the electrolyte and the diaphragm. If the process of lithium ion intercalation into the negative electrode sheet is hindered, deposition in the form of metallic lithium occurs on the surface of the negative electrode sheet, a phenomenon known as lithium deposition. In the lithium ion battery in the related art, due to the existence of welding stress, the lithium intercalation is greatly influenced after the expansion deformation of the negative electrode tab and the negative electrode piece, so that the lithium precipitation phenomenon is generated. The process of lithium separation is irreversible, low voltage, low capacity, low service life, battery expansion and the like can be caused after lithium separation, and lithium metal is an extremely active chemical element, so that the lithium metal is extremely easy to burn and ignite.
Therefore, the service life of the lithium ion battery in the related technology is not ideal, and certain potential safety hazards exist.
In the negative electrode sheet 100b according to the embodiment of the present disclosure, the negative electrode modification layer 3b is disposed on the surface of the current collector layer 1b and between the active material layer 2b and the empty foil region 10b, and the material thereof includes lithium titanate.
Lithium titanate is known as a zero strain material, which has a lattice constant and a volume change of less than 1% when intercalating or deintercalating lithium ions. In the charge-discharge cycle, the zero strain characteristic can avoid the structural damage caused by the back-and-forth expansion of the electrode material, thereby improving the cycle performance and the service life of the electrode, reducing the specific capacity attenuation caused by the cycle, and having very good overcharge and overdischarge resistance characteristics. The lithium titanate has a high lithium ion diffusion coefficient and can be charged and discharged at a high rate. In addition, lithium titanate is not easy to generate lithium crystal branches, so that the occurrence of lithium precipitation is reduced, and a foundation is provided for ensuring the safety of the lithium ion battery.
In the negative electrode sheet 100b according to the embodiment of the present disclosure, the negative electrode modification layer 3b is used as a "buffer zone" between the graphite layer (i.e., the active material layer 2b) and the empty foil region 10b, and the volume is hardly expanded in the lithium ion deintercalation process, and the welding stress can be effectively released, so that the phenomena of material dropping, expansion and lithium precipitation caused by the welding stress in the related art can be reduced, the adhesion between the graphite layer and the current collector layer 1b is improved, the service life of the lithium ion battery is prolonged, and the potential safety hazard is reduced.
In some embodiments of the present disclosure, the material of the negative electrode modification layer 3b includes lithium titanate and graphite which are uniformly mixed. In addition, the material of the negative electrode modification layer 3b may further include some auxiliary materials, such as a solvent, a dispersant, a conductive agent, a binder, and the like. Wherein the mass mixing ratio of the lithium titanate to the graphite is not less than 1/6 and not more than 4/9.
In other embodiments of the present disclosure, the material of the negative electrode modification layer 3b includes graphite particles coated with a lithium titanate coating layer. In addition, the material of the negative electrode modification layer 3b may further include some auxiliary materials, such as a solvent, a dispersant, a conductive agent, a binder, and the like. Wherein the particle size D50 of the graphite is more than or equal to 5 μm and less than or equal to 25 μm, and the thickness of the lithium titanate coating layer is more than or equal to 50 nanometers and less than or equal to 100 nanometers.
In still other embodiments of the present disclosure, the material of the negative electrode modification layer 3b may also include only lithium titanate and some auxiliary materials, such as a solvent, a dispersant, a conductive agent, a binder, and the like.
As described above, based on the foregoing advantages of lithium titanate, the negative electrode sheet 100b of the foregoing embodiment can effectively prolong the service life of the lithium ion battery, and reduce the potential safety hazard.
In the embodiment of the present disclosure, the thickness of the negative electrode modification layer 3b is equal to or greater than 0.2 micrometers and equal to or less than 71 micrometers, preferably, the thickness of the active material layer 2b is not more than the thickness, and the negative electrode modification layer may be formed by a process of coating, baking, and then rolling. Wherein, the coating and baking processes can also be synchronously carried out in the coating and baking integrated machine.
As shown in fig. 2b, in some embodiments of the present disclosure, the pole piece is a positive pole piece 100 a. The current collector layer 1a of the positive electrode sheet 100a is typically made of aluminum foil. Specific materials of the active material layer 2a of the positive electrode sheet 100a are not limited, and for example, lithium iron phosphate, lithium nickelate, lithium manganate, lithium cobaltate, nickel cobalt aluminum ternary, nickel cobalt manganese ternary, and the like can be used. In some specific embodiments of the present disclosure, the material of the active material layer 2a of the positive electrode sheet 100a includes LiNixCoyMn1-x-yO2And modified compound thereof, LiNixCoyAl1-x-yO2And at least one of the modified compounds thereof, wherein x is more than 0 and less than 1, y is more than 0 and less than 1, and x + y is more than 0 and less than 1. In the structure of the positive electrode sheet 100a, the modified layer is the positive electrode modified layer 3a, and the material of the positive electrode modified layer 3a is an insulating adhesive material. For example, the material of the positive electrode modification layer 3a includes polyvinylidene fluoride (PVDF), Polyacrylate (PAA), or a mixed material of a nano metal oxide and a resin, or the like.
In designing a lithium ion battery, in order to prevent a short circuit of lithium deposition in the negative electrode, the capacity of the negative electrode is generally designed to be larger than the capacity of the positive electrode, for example, in one embodiment, the edge of the active material layer 2b of the negative electrode sheet 100b exceeds the edge of the active material layer 2a of the positive electrode sheet 100a by 2 mm or more and 4 mm or less.
In the lithium ion battery in the related technology, the empty foil area of the positive plate is opposite to the active material layer of the negative plate, so that the heat productivity of the area is very large, and the lithium ion battery is easy to bulge due to high-rate heat production, thereby bringing certain potential safety hazard.
The positive electrode sheet 100a according to the embodiment of the present disclosure has an insulating and adhesive positive electrode modification layer 3a provided on the surface of the current collector layer 1a and between the active material layer 2a and the empty foil region 10 a. The positive electrode modified layer 3a and the current collector layer 1a are reliably adhered, and the empty foil region 10a of the positive electrode sheet 100a and the active material layer 3b of the negative electrode sheet 100b can be spaced apart from each other, thereby effectively reducing the heat generation phenomenon in this region. In addition, the positive electrode modified layer 3a can be used as a buffer zone between the active material layer 2a and the empty foil region 10a, and can effectively reduce the influence of welding stress and processing external force on the active material layer 2a, thereby prolonging the service life of the lithium ion battery.
In the embodiment of the present disclosure, the thickness of the positive electrode modification layer 3a is not less than 0.2 micrometers and not more than 80 micrometers, preferably not more than the thickness of the active material layer 2a, and may be formed by a process of coating, baking, and then rolling. The coating and baking processes can also be synchronously carried out in a coating and baking integrated machine. Wherein the slurry concentration of the coated positive electrode modifying material is more than or equal to 1% and less than or equal to 20%, preferably more than or equal to 3% and less than or equal to 15%; the viscosity of the slurry is 1000 mPa/s or more and 5000 mPa/s or less.
In the electrode sheets (positive electrode sheet 100a and negative electrode sheet 100b) according to the above embodiments of the present disclosure, the active material layer 2 is provided on both side surfaces of the current collector layer 1, and the modified layer 3 is provided on both side surfaces of the current collector layer 1. In other embodiments of the present disclosure, as shown in fig. 1b, the active material layer 2 may be disposed on only one surface of the current collector layer 1, and the modification layer 3 may be disposed on one surface of the current collector layer 1 on which the active material layer 2 is disposed.
In the embodiment of the present disclosure, the widths of the positive electrode modification layer 3a and the negative electrode modification layer 3b may be designed to be 5 mm or more and 20 mm or less. In order to facilitate the manufacturing process, the modification layer 3 is reliably in contact with the active material layer 2, and the modification layer 3 and the active material layer 2 may overlap (i.e., the modification layer 3 and the active material layer 2 include a portion having an overlapping area in a direction perpendicular to the surface of the current collector layer 1), for example, the overlapping width is 4 mm or less.
The embodiment of the disclosure further provides a lithium ion battery, which includes the pole piece of any one of the foregoing embodiments, and a tab connected with the empty foil area of the pole piece.
In some embodiments, the lithium ion battery includes the positive tab 100a, the positive tab 4a connected to the positive tab 100a, the negative tab 100b, and the negative tab 4b connected to the negative tab 100b of the previous embodiments. The positive tab 4a and the positive plate 100a, and the negative tab 4b and the negative plate 100b may be connected by welding or by conductive adhesive. As shown in fig. 3a, the tab 4 may be a full tab in a strip-like continuous manner on one side or on two opposite sides of the pole piece 100. As shown in fig. 3b, a plurality of tabs 4 may be arranged at intervals on one side or on two opposite sides of the pole piece 100.
The lithium ion battery may be of a laminated or wound type. In which a plurality of positive electrode tabs 100a and a plurality of negative electrode tabs 100b of a laminated lithium ion battery are alternately stacked and spaced apart by a separator 5, as shown in fig. 4 a. As shown in fig. 4b, the positive electrode sheet 100a and the negative electrode sheet 100b of the wound lithium ion battery are wound layer by layer and spaced apart by a separator 5.
As shown in fig. 5, an embodiment of the present disclosure further provides a manufacturing method of a pole piece, where the method includes the following steps:
step S1: forming an active material layer on the surface of the current collector layer, wherein the active material layer is not overlapped with the empty foil area of the current collector layer;
step S2: and forming a modified layer on the surface of the current collector layer, which is provided with the active substance layer, wherein the modified layer is positioned between the active substance layer and the empty foil area.
The modified layer can improve the chemical and/or physical characteristics of the pole piece close to the empty foil area, so that the connection reliability of the pole lug and the pole piece is improved, the service life of the lithium ion battery is prolonged, and the potential safety hazard is reduced.
In some embodiments, the fabricated electrode plate is a negative electrode plate, the modified layer is a negative electrode modified layer, and the material of the negative electrode modified layer comprises lithium titanate; the step S2 includes:
coating a negative electrode modification material on the surface of the current collector layer and between the active material layer and the empty foil region;
baking the negative electrode modified material to increase the adhesion and the bonding property of the negative electrode modified material and the current collector layer;
and rolling the negative electrode modified material to increase the compactness of the negative electrode modified material.
Wherein, the coating and baking processes can also be synchronously carried out in the coating and baking integrated machine.
The materials and the dimensional parameters of the current collector layer, the active material layer and the negative electrode modification layer are selected in reference to the foregoing description, and the detailed description is not repeated here. In some embodiments, the thickness of the negative electrode modification layer is greater than or equal to 0.2 micrometers and less than or equal to 71 micrometers, and is the thickness after the rolling process.
The lithium ion battery adopting the negative plate manufactured by the method of the embodiment can effectively reduce the phenomena of material falling, expansion and lithium precipitation caused by welding stress, thereby prolonging the service life of the lithium ion battery and reducing potential safety hazards.
In some embodiments, the manufactured pole piece is a positive pole piece, the modified layer is a positive pole modified layer, and the material of the positive pole modified layer is an insulating viscous material; the step S2 includes:
coating a positive electrode modification material on the surface of the current collector layer and between the active material layer and the empty foil area;
baking the positive electrode modified material to increase the adhesion and the bonding property of the positive electrode modified material and the current collector layer;
and rolling the positive electrode modified material to increase the compactness of the positive electrode modified material.
Wherein, the coating and baking processes can also be synchronously carried out in the coating and baking integrated machine.
Wherein, the slurry concentration of the positive electrode modified material is more than or equal to 1% and less than or equal to 20%, or more than or equal to 3% and less than or equal to 15%; the slurry viscosity of the positive electrode modifying material is not less than 1000 mPa/s and not more than 5000 mPa/s.
The materials and dimensional parameters of the current collector layer, the active material layer and the positive electrode modification layer are referred to the foregoing description, and the detailed description thereof is not repeated here.
The lithium ion battery adopting the positive plate manufactured by the method of the embodiment can effectively reduce the heating at the tab. In addition, in the process of processing the positive plate and using the lithium ion battery, the influence of welding stress and processing external force on the active material layer can be effectively reduced, and therefore the service life of the lithium ion battery is prolonged.
Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.
Claims (12)
1. A pole piece, comprising:
a current collector layer with a void foil area at the edge;
the active material layer is arranged on the surface of the current collector layer and does not overlap with the empty foil area;
and the modification layer is arranged on the surface of the current collector layer, provided with the active material layer, and is positioned between the active material layer and the empty foil area.
2. The pole piece of claim 1, wherein: the modified layer is a stress buffer layer, and the stress buffer layer is in contact with the active material layer.
3. The pole piece of claim 1, wherein: the pole piece is a negative pole piece, the modified layer is a negative pole modified layer, and the material of the negative pole modified layer comprises lithium titanate.
4. The pole piece of claim 1, wherein: the electrode plate is a negative electrode plate, the modified layer is a negative electrode modified layer, the material of the negative electrode modified layer comprises uniformly mixed lithium titanate and graphite, or the material of the negative electrode modified layer comprises graphite particles coated by a lithium titanate coating layer.
5. The pole piece of claim 1, wherein: the pole piece is a negative pole piece, and the modified layer is a negative pole modified layer;
the material of the negative electrode modified layer comprises uniformly mixed lithium titanate and graphite, wherein the mass mixing ratio of the lithium titanate to the graphite is greater than or equal to 1/6 and less than or equal to 4/9; or
The material of the negative electrode modified layer comprises graphite particles coated by a lithium titanate coating layer, wherein the particle size D50 of the graphite is more than or equal to 5 microns and less than or equal to 25 microns; the thickness of the lithium titanate coating layer is not less than 50 nanometers and not more than 100 nanometers.
6. The pole piece of any one of claims 3 to 5, wherein: the thickness of the negative electrode modification layer is greater than or equal to 0.2 micrometer and less than or equal to 71 micrometers.
7. The pole piece of claim 1, wherein: the pole piece is a positive pole piece, the modified layer is a positive pole modified layer, and the positive pole modified layer is made of an insulating viscous material.
8. The pole piece of claim 7, wherein: the material of the positive electrode modification layer comprises polyvinylidene fluoride, polyacrylate or a mixed material of nano metal oxide and resin.
9. The pole piece of claim 7 or 8, wherein: the thickness of the positive electrode modified layer is more than or equal to 0.2 micrometer and less than or equal to 80 micrometers.
10. The pole piece of claim 1, wherein: the width of the modified layer is greater than or equal to 5 mm and less than or equal to 20 mm; and/or the overlapping width of the modification layer and the active material layer is less than or equal to 4 mm.
11. The pole piece of claim 1, wherein: the active material layer is arranged on the surfaces of two sides of the current collector layer, and the modification layer is arranged on the surfaces of two sides of the current collector layer.
12. A lithium ion battery comprising a pole piece according to any one of claims 1 to 11, and a tab connected to an empty foil region of the pole piece.
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| CN201921789094.XU CN210349968U (en) | 2019-10-23 | 2019-10-23 | Pole piece and lithium ion battery |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921789094.XU CN210349968U (en) | 2019-10-23 | 2019-10-23 | Pole piece and lithium ion battery |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110635106A (en) * | 2019-10-23 | 2019-12-31 | 珠海格力电器股份有限公司 | Pole piece, lithium ion battery and method for making pole piece |
| CN112086620A (en) * | 2020-09-29 | 2020-12-15 | 珠海冠宇电池股份有限公司 | Negative plate and preparation method and application thereof |
-
2019
- 2019-10-23 CN CN201921789094.XU patent/CN210349968U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110635106A (en) * | 2019-10-23 | 2019-12-31 | 珠海格力电器股份有限公司 | Pole piece, lithium ion battery and method for making pole piece |
| CN112086620A (en) * | 2020-09-29 | 2020-12-15 | 珠海冠宇电池股份有限公司 | Negative plate and preparation method and application thereof |
| CN112086620B (en) * | 2020-09-29 | 2021-11-16 | 珠海冠宇电池股份有限公司 | Negative plate and preparation method and application thereof |
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