CN113839084A - Battery core and battery - Google Patents
Battery core and battery Download PDFInfo
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- CN113839084A CN113839084A CN202111150449.2A CN202111150449A CN113839084A CN 113839084 A CN113839084 A CN 113839084A CN 202111150449 A CN202111150449 A CN 202111150449A CN 113839084 A CN113839084 A CN 113839084A
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- 239000011248 coating agent Substances 0.000 claims abstract description 89
- 238000000576 coating method Methods 0.000 claims abstract description 89
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 22
- 239000013543 active substance Substances 0.000 claims abstract description 14
- 239000011149 active material Substances 0.000 claims description 78
- 239000011247 coating layer Substances 0.000 claims description 67
- 239000002245 particle Substances 0.000 claims description 36
- 239000010410 layer Substances 0.000 claims description 29
- 239000011888 foil Substances 0.000 claims description 20
- 238000009826 distribution Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 claims description 7
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 6
- 229910001593 boehmite Inorganic materials 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 26
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 26
- 238000001556 precipitation Methods 0.000 abstract description 9
- 239000011267 electrode slurry Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 239000006258 conductive agent Substances 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000007731 hot pressing Methods 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 239000002985 plastic film Substances 0.000 description 3
- 229920006255 plastic film Polymers 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 2
- 229920003123 carboxymethyl cellulose sodium Polymers 0.000 description 2
- 229940063834 carboxymethylcellulose sodium Drugs 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000283070 Equus zebra Species 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000002931 mesocarbon microbead Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
The application provides an electric core and a battery, wherein the electric core comprises a negative plate and a positive plate which are oppositely arranged; the positive plate comprises a current collector, and the surface of the current collector comprises a first area and a second area which are sequentially adjacent; the negative plate is provided with a negative pole tab and a first negative pole active layer adjacent to the negative pole tab; the second area of the positive plate is arranged opposite to the first negative active layer; the first area is provided with a first coating, the second area is provided with a second coating, the second coating is provided with a third coating, the second coating comprises a first active substance, and the third coating comprises a second active substance. The cell can reduce the possibility of lithium precipitation in the edge area of the negative electrode of the lithium ion battery close to the tab.
Description
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a battery core and a battery.
Background
With the rapid development of lithium ion battery technology, lithium ion batteries are more and more widely applied to portable mobile electronic devices such as notebook computers and smart phones, and the requirements of people on the charging speed of the batteries are higher and higher. At present, under the condition of high-rate quick charge of a lithium ion battery, lithium is easy to be separated from the edge area of a negative electrode of the lithium ion battery close to a lug, so that the service life of the lithium ion battery is short.
Disclosure of Invention
The embodiment of the application provides an electric core and a battery, and solves the problem that lithium is easy to separate out in the edge area of a negative electrode of a lithium ion battery close to a pole lug.
In order to achieve the above object, in a first aspect, an embodiment of the present application provides an electrical core, including a negative electrode tab and a positive electrode tab, where the negative electrode tab and the positive electrode tab are oppositely disposed; the positive plate comprises a current collector, and the surface of the current collector comprises a first area and a second area which are sequentially adjacent;
the negative plate is provided with a negative pole lug and a first negative pole active layer adjacent to the negative pole lug;
the second area of the positive plate is opposite to the first negative active layer;
the first region is provided with a first coating, the second region is provided with a second coating, the second coating is provided with a third coating, the second coating comprises a first active substance, and the third coating comprises a second active substance.
Optionally, the median particle size of the first active material is less than the median particle size of the second active material.
Optionally, the negative electrode sheet comprises a hollow foil region at the head and a first active material coating region connected with the hollow foil region;
the negative electrode tab is arranged in the empty foil area;
the first negative active layer is disposed in the first active material coating region.
Optionally, the negative electrode sheet includes a second active material coated region, a third active material coated region, and an empty foil region between the second active material coated region and the third active material coated region;
the negative electrode tab is arranged in the empty foil area;
the first negative electrode active layer is respectively arranged in the areas of the second active material coating area and the third active material coating area close to the negative electrode tab.
Optionally, the first negative active layer comprises a fourth coating layer and a fifth coating layer arranged in a stacked manner;
the fourth coating comprises a third active;
the fifth coating includes a fourth active.
Optionally, the sum of the thickness of the second coating layer and the thickness of the third coating layer differs from the thickness of the first coating layer by a value in the range of-10 to 10 μm.
Optionally, the sum of the thickness of the second coating layer and the thickness of the third coating layer ranges from 30 μm to 80 μm; the thickness of the second coating layer accounts for 30% to 70% of the sum of the thicknesses of the second coating layer and the third coating layer.
Optionally, the particle size distribution of the first active material satisfies: d10 is more than 3.5 mu m and less than 6.5 mu m, D50 is more than 12 mu m and less than 17 mu m, and D90 is more than 22 mu m and less than 34 mu m;
the particle size distribution of the second active material satisfies: d10 is more than 5 mu m and less than 10 mu m, D50 is more than 15 mu m and less than 20 mu m, and D90 is more than 35 mu m and less than 48 mu m.
Optionally, the compacted density of the second coating layer is greater than the compacted density of the third coating layer.
Optionally, the positive plate is further provided with a sixth coating layer, and the sixth coating layer is adjacent to the second coating layer and the third coating layer;
optionally, the material of the sixth coating layer comprises at least one of ceramic and boehmite.
Optionally, the first active material comprises at least one of lithium cobaltate, lithium manganate, lithium iron phosphate and ternary material;
the second active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials.
Optionally, the surface of the current collector further includes a third area, the third area is a blank foil area, and a positive tab is disposed on the third area.
In a second aspect, an embodiment of the present application provides a battery, including the battery cell according to the first aspect.
In the embodiment of the application, the battery cell comprises a negative plate and a positive plate, and the negative plate and the positive plate are oppositely arranged; the positive plate comprises a current collector, and the surface of the current collector comprises a first area and a second area which are sequentially adjacent; the negative plate is provided with a negative pole tab and a first negative pole active layer adjacent to the negative pole tab; the second area of the positive plate is arranged opposite to the first negative active layer; the first area is provided with a first coating, the second area is provided with a second coating, the second coating is provided with a third coating, the second coating comprises a first active substance, and the third coating comprises a second active substance. By adjusting the dynamic performance of the first active material and the second active material, the possibility of lithium precipitation in the edge area of the negative electrode of the lithium ion battery close to the pole ear can be reduced.
Drawings
For a clear explanation of the technical solutions in the embodiments of the present application, the drawings of the specification are described below, it is obvious that the following drawings are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the listed drawings without any inventive effort.
Fig. 1 is one of schematic structural diagrams of a positive electrode plate in a battery cell provided in an embodiment of the present application;
fig. 2 is a second schematic structural diagram of a positive plate in a battery cell provided in an embodiment of the present application;
fig. 3 is a third schematic structural diagram of a positive plate in a battery cell provided in the embodiment of the present application;
FIG. 4 is a schematic diagram of a prior art pole piece construction;
fig. 5 is a schematic structural diagram of a battery cell provided in an embodiment of the present application;
fig. 6 is one of schematic structural diagrams of a negative electrode sheet in a battery cell provided in an embodiment of the present application;
fig. 7 is a second schematic structural diagram of a negative electrode plate in a battery cell provided in an embodiment of the present application;
fig. 8 is a third schematic structural diagram of a negative electrode tab in a battery cell provided in an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. On the basis of the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without any creative effort belong to the protection scope of the present application.
Referring to fig. 1 and 5, an electric core provided in an embodiment of the present application includes a negative electrode tab and a positive electrode tab, where the negative electrode tab and the positive electrode tab are disposed opposite to each other; the positive plate comprises a current collector 4, and the surface of the current collector 4 comprises a first area and a second area which are sequentially adjacent;
the negative plate is provided with a negative pole tab 6 and a first negative pole active layer 7 adjacent to the negative pole tab;
the second region of the positive electrode sheet is arranged opposite to the first negative electrode active layer 7;
the first region is provided with a first coating 1, the second region is provided with a second coating 2, the second coating 2 is provided with a third coating 3, the second coating 2 comprises a first active substance, and the third coating 3 comprises a second active substance.
In a specific example, the surface of the current collector of the positive plate further includes a third area, the third area is a blank foil area, and the third area is provided with a positive tab.
In the case that the pole piece is a positive pole piece, the current collector 4 may be made of aluminum foil; the shape of current collector 4 may be rectangular. In a specific example, the first negative electrode active layer 7 includes a negative electrode active material including at least one material of artificial graphite, natural graphite, composite graphite, mesocarbon microbeads, soft carbon, carbon nanomaterials, and hard carbon.
The surface of the current collector 4 comprises a first surface and a second surface, a first area is arranged on each of the first surface and the second surface of the current collector 4, and a first coating 1 is arranged on each first area. A projection of the first area of the first face of the current collector 4 on the current collector 4 may overlap a projection of the first area of the second face of the current collector 4 on the current collector 4.
In a specific implementation, the second region may be provided on only one surface of the current collector 4, or may be provided on both surfaces of the current collector 4.
As an example, referring to fig. 1, the positive electrode sheet shown in fig. 1 is provided with a second region on only one surface of a current collector 4, the second region is provided with a second coating layer 2, and the second coating layer 2 is provided with a third coating layer 3. The sum of the thicknesses of the second and third coating layers 2 and 3 may be equal to the thickness of the first coating layer 1.
As another example, referring to fig. 2, the positive electrode sheet shown in fig. 2 is provided with second areas on both sides of the current collector 4, and a projection of the second area of the first side of the current collector 4 on the current collector 4 may overlap with a projection of the second area of the second side of the current collector 4 on the current collector 4. In this embodiment, the pole piece can be made by zebra coating.
In the embodiment of the application, the battery cell comprises a negative plate and a positive plate, and the negative plate and the positive plate are oppositely arranged; the positive plate comprises a current collector, and the surface of the current collector comprises a first area and a second area which are sequentially adjacent; the negative plate is provided with a negative pole tab and a first negative pole active layer adjacent to the negative pole tab; the second area of the positive plate is arranged opposite to the first negative active layer; the first area is provided with a first coating, the second area is provided with a second coating, the second coating is provided with a third coating, the second coating comprises a first active substance, and the third coating comprises a second active substance. By adjusting the dynamic performance of the first active material and the second active material, the possibility of lithium precipitation of the lithium ion battery cathode in the edge area close to the tab can be reduced.
Optionally, the kinetic properties of the first active substance are greater than the kinetic properties of the second active substance.
Specifically, the first active material may be lithium cobaltate, and the second active material may be lithium manganate. Optionally, the first active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, and ternary material. The second active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate and ternary material. The kinetic properties of the first active material can be made larger than those of the second active material by controlling the particle size or the content of the first active material and the second active material, and the like.
The smaller the kinetic performance of the active material in the positive electrode sheet, the less lithium ions are released per unit time, but the smaller the kinetic performance of the active material in the positive electrode sheet, the smaller the charging rate of the battery will be. In the embodiment of the application, the third coating is arranged on the second coating, and the kinetic performance of the second active material in the third coating is smaller than that of the first active material in the second coating, so that the lithium ions released by the positive plate in the second area of the positive plate in unit time can be reduced on the premise of considering the charging speed of the battery. The second area of the positive plate is arranged opposite to the first negative active layer of the negative plate, which is adjacent to the negative pole tab, namely, the lithium ions received by the area adjacent to the negative pole tab in unit time are reduced, so that the possibility of lithium precipitation of the edge area of the negative pole of the lithium ion battery, which is adjacent to the tab, is reduced.
In specific implementation, the negative electrode tab can be arranged at the end part of the negative electrode plate, and only one side of the negative electrode tab is adjacent to the first negative electrode active layer; the negative pole utmost point ear also can set up the intermediate position at the negative pole piece, and the both sides of negative pole utmost point ear all are adjacent with first negative pole active layer.
As an example, referring to fig. 6, the negative electrode sheet includes a blank foil region 8 at the head and a first active material coating region 9 connected to the blank foil region 8; the negative electrode tab is arranged in the empty foil area 8; the first negative electrode active layer is disposed in the first active material coating region 9.
As another example, referring to fig. 7, the negative electrode sheet includes a second active material coated region 10, a third active material coated region 11, and an empty foil region 8 between the second active material coated region 10 and the third active material coated region 11; the negative electrode tab is arranged in the empty foil area 8; the first negative active layer is disposed at regions of the second active material coated region 10 and the third active material coated region 11 near the negative electrode tab, respectively.
Another embodiment of the present application provides an electric core, including a positive plate and a negative plate, where the negative plate and the positive plate are oppositely disposed, the positive plate includes a current collector, and a surface of the current collector includes a first region and a second region that are sequentially adjacent to each other; the negative plate comprises a negative pole lug and first negative pole active layers, the first negative pole active layers are arranged on two sides of the negative pole lug, and the second area of the positive plate and the first negative pole active layers on two sides of the negative pole lug are oppositely arranged. The second area of the positive plate is arranged opposite to the first negative active layers on two sides of the negative pole lug, so that lithium ions received by the area adjacent to the negative pole lug in unit time can be reduced, and the possibility of lithium precipitation of the edge area of the negative pole of the lithium ion battery close to the lug is reduced.
Alternatively, referring to fig. 8, the first negative active layer includes a fourth coating layer 12 and a fifth coating layer 13, which are stacked, the fourth coating layer 12 includes a third active material, and the fifth coating layer 13 includes a fourth active material. By providing the first negative electrode active layer including the fourth coating layer 12 and the fifth coating layer 13 disposed in a stacked manner, the possibility of lithium deposition in the edge region of the negative electrode of the lithium ion battery near the tab can be further reduced by adjusting the kinetic properties of the third active material and the fourth active material, for example, by making the kinetic property of the third active material smaller than that of the fourth active material.
In particular implementations, the third active material has less kinetic properties than the fourth active material. The greater the kinetic properties of the active material in the negative electrode sheet, the greater the acceptance of lithium ions, but the greater the kinetic properties of the active material in the negative electrode sheet, the thicker the coating layer will be, resulting in a smaller energy density of the battery. By enabling the dynamic performance of the third active material to be smaller than that of the fourth active material, the receiving capacity of the pole piece for lithium ions can be improved on the premise of considering the energy density of the battery, and therefore the possibility of lithium precipitation of the edge area of the negative electrode of the lithium ion battery close to the pole lug is reduced.
In particular implementations, the median particle size of the third active material can be made larger than the median particle size of the fourth active material. The particles having a particle size distribution curve smaller than the median particle size account for 50% of the total number of particles. The smaller the particle size of the active material is, the larger the dynamic performance of the active material is, and the larger the median particle size of the third active material is limited to be larger than the median particle size of the fourth active material, so that the dynamic performance of the third active material can be smaller than that of the fourth active material, the receiving capacity of the pole piece for lithium ions can be improved on the premise of considering the energy density of the battery, and the possibility of lithium analysis of the edge area of the negative electrode of the lithium ion battery close to the pole lug is reduced.
Optionally, the difference between the sum of the thickness of the second coating layer 2 and the thickness of the third coating layer 3 and the thickness of the first coating layer 1 is in the range of-10 μm to 10 μm. Through this injecture, can make the pole piece surface comparatively level and smooth, improve the security performance of battery. Illustratively, the sum of the thickness of the second coating 2 and the thickness of the third coating 3 is equal to the thickness of the first coating 1.
Alternatively, referring to fig. 3, the positive electrode sheet may be further provided with a sixth coating layer 5, and the sixth coating layer 5 is adjacent to both the second coating layer 2 and the third coating layer 3. Optionally, the sixth coating 5 comprises an insulating material, such as ceramic, boehmite, etc. The sixth coating 5 may be provided in the third region, and the thickness of the sixth coating 5 may be equal to the sum of the thicknesses of the second coating 2 and the third coating 3.
Optionally, the particle size distribution of the first active material satisfies: d10 is more than 3.5 mu m and less than 6.5 mu m, D50 is more than 12 mu m and less than 17 mu m, and D90 is more than 22 mu m and less than 34 mu m;
the particle size distribution of the second active material satisfies: d10 is more than 5 mu m and less than 10 mu m, D50 is more than 15 mu m and less than 20 mu m, and D90 is more than 35 mu m and less than 48 mu m;
wherein D10 represents a first particle diameter, and particles smaller than the first particle diameter on the particle diameter distribution curve account for 10% of the total number of particles, D50 represents a median diameter, and D90 represents a second particle diameter, and particles smaller than the second particle diameter on the particle diameter distribution curve account for 90% of the total number of particles.
Specifically, the particles having a particle size distribution curve smaller than the median particle size account for 50% of the total number of particles. The particle size of the first active material and the particle size of the second active material are controlled to meet the distribution, so that the dynamic performance of the first active material is higher than that of the second active material, lithium ions released by the pole piece in unit time can be reduced on the premise of considering the charging speed of the battery, and the possibility of lithium precipitation of the edge area of the negative electrode of the lithium ion battery close to the pole lug is further reduced.
Optionally, the compacted density of the second coating layer 2 is greater than the compacted density of the third coating layer 3. By making the compacted density of the second coating layer 2 greater than that of the third coating layer 3, the adhesion between the coating layers and the current collector 4 can be enhanced, reducing the possibility of the occurrence of the overpressure phenomenon.
Optionally, the sum of the thicknesses of the second and third coating layers 2 and 3 ranges from 30 μm to 80 μm, and the thickness of the second coating layer 2 accounts for 30% to 70% of the sum of the thicknesses of the second and third coating layers 2 and 3.
In particular implementations, the sum of the thickness of the second coating layer 2 and the thickness of the third coating layer 3 may be 30 μm, 40 μm, 48 μm, 52 μm, 60 μm, 77 μm, 80 μm, or the like. The thickness of the second coating layer 2 may account for 30%, 41%, 53%, 59%, 68%, 70%, etc. of the sum of the thicknesses of the second coating layer 2 and the third coating layer 3. It is understood that, when the thickness of the second coating layer 2 is 30% of the sum of the thicknesses of the second coating layer 2 and the third coating layer 3, the thickness of the third coating layer 3 is 70% of the sum of the thicknesses of the second coating layer 2 and the third coating layer 3.
Through the limitation, the lithium ions released by the pole piece in unit time can be reduced on the premise of considering the charging speed of the battery, so that the possibility of lithium precipitation of the edge area of the lithium ion battery cathode close to the pole lug is reduced.
The embodiment of the present application further provides a manufacturing method including the cell provided by the embodiment of the present application, which specifically includes:
preparing a negative plate: preparing 96.9g of graphite, 0.5g of conductive agent SP, 1.3g of binder carboxymethylcellulose sodium (CMC), 1.3g of binder Styrene Butadiene Rubber (SBR) and 150g of deionized water into slurry by a wet process; uniformly coating the negative electrode slurry on a copper foil with the thickness of 6 mu m; after baking, rolling and cutting the pole piece to obtain a negative pole piece;
positive electrode slurry 1: mixing 97g of positive electrode active material lithium cobaltate 1, 2g of conductive agent conductive carbon black and 1g of binder, adding 50g of N-methyl pyrrolidone (NMP), and stirring under the action of a vacuum stirrer until uniform and fluid positive electrode slurry is mixed;
positive electrode slurry 2: 97g of positive electrode active material lithium cobaltate 2, 2g of conductive agent conductive carbon black and 1g of binder are mixed, 50g of N-methyl pyrrolidone (NMP) is added, and the mixture is stirred under the action of a vacuum stirrer until uniform and fluid positive electrode slurry is mixed;
comparative example: coating the positive electrode slurry 1 on an aluminum foil with the thickness of 12 microns to obtain a negative electrode sheet with the structure consistent with that shown in figure 4, baking, rolling and cutting to obtain a positive electrode sheet 1;
and then winding the negative plate, the positive plate 1 and the diaphragm, packaging by adopting an aluminum plastic film, baking to remove moisture, injecting electrolyte, and forming by adopting a hot pressing process to obtain the battery core.
Example 1: coating the positive electrode slurry 1 with a first coating 1 and a second coating 2, coating the positive electrode slurry 2 with a third coating 3 to obtain a positive electrode sheet with a structure consistent with that shown in the figure 1, controlling the coating thickness of the second coating 2 and the third coating 3 according to a ratio of 1:1, baking, rolling, and cutting to obtain the positive electrode sheet 2;
and then winding the positive plate 2, the negative plate and the diaphragm, packaging by adopting an aluminum plastic film, baking to remove moisture, injecting electrolyte, and forming by adopting a hot pressing process to obtain the battery core.
Example 2: coating the positive electrode slurry 1 with a first coating 1 and a second coating 2, coating the negative electrode slurry 3 with a third coating 3 to obtain a positive electrode sheet with a structure consistent with that shown in the figure 1, controlling the coating thickness of the second coating 2 and the third coating 3 according to a ratio of 7:3, baking, rolling, and cutting to obtain the positive electrode sheet 3;
and then winding the negative electrode, the positive plate 3 and the diaphragm, packaging by adopting an aluminum plastic film, baking to remove moisture, injecting electrolyte, and forming by adopting a hot pressing process to obtain the battery cell.
The coating thickness of all the positive electrode sheets was 50 μm.
Through experiments, the peel force of the positive electrode sheet in the above examples and comparative examples is shown in table 1.
| Example 1 | Example 2 | Comparative example | |
| Pole piece peel force/N | 0.1462 | 0.1456 | 0.1389 |
TABLE 1
As can be seen from the comparison of the peeling force data in table 1, when the positive plate with slightly poor kinetics is used in the upper layer, the peeling force of the positive plate in the single-sided area (i.e., the second area coated with the coating layer on only one side of the current collector 4 in fig. 1) is not significantly different from that in the comparative example, and the new structure is adopted for production, so that the negative plate is not affected.
Through experiments, the cycle performance data of the battery cells of the above examples and comparative examples are shown in table 2.
TABLE 2
As can be seen from table 2, a single surface region of the positive electrode sheet (i.e., the second region of fig. 1 in which only one surface of the current collector 4 is coated with the coating) can be coated with a new structure, so that the problem of lithium precipitation in the edge region of the negative electrode can be solved, and the capacity retention rate and the thickness expansion rate of the entire battery are both improved, especially the problem of thickness expansion.
The embodiment of the application also provides a battery, which comprises the battery core provided by the embodiment of the application. The structure and the working principle of the battery core provided by the embodiment of the application can refer to the above embodiment, and are not described again here. Because the battery that this application embodiment provided includes the electric core that this application embodiment provided, consequently have the whole beneficial effect of the electric core that this application embodiment provided.
While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (14)
1. The battery cell is characterized by comprising a negative plate and a positive plate, wherein the negative plate and the positive plate are oppositely arranged; the positive plate comprises a current collector, and the surface of the current collector comprises a first area and a second area which are sequentially adjacent;
the negative plate is provided with a negative pole lug and a first negative pole active layer adjacent to the negative pole lug;
the second area of the positive plate is opposite to the first negative active layer;
the first region is provided with a first coating, the second region is provided with a second coating, the second coating is provided with a third coating, the second coating comprises a first active substance, and the third coating comprises a second active substance.
2. The electrical core of claim 1, wherein the median particle size of the first active material is less than the median particle size of the second active material.
3. The battery cell of claim 1, wherein the negative electrode tab comprises a blank foil region at the head and a first active material coated region connected to the blank foil region;
the negative electrode tab is arranged in the empty foil area;
the first negative active layer is disposed in the first active material coating region.
4. The electrical core of claim 1, wherein the negative electrode tab comprises a second active material coated region, a third active material coated region, and an empty foil region between the second active material coated region and the third active material coated region;
the negative electrode tab is arranged in the empty foil area;
the first negative electrode active layer is respectively arranged in the areas of the second active material coating area and the third active material coating area close to the negative electrode tab.
5. The cell of claim 1, wherein the first negative active layer comprises a fourth coating layer and a fifth coating layer in a stacked arrangement;
the fourth coating comprises a third active;
the fifth coating includes a fourth active.
6. The cell of claim 1, wherein the sum of the thickness of the second coating and the thickness of the third coating differs from the thickness of the first coating by a value in a range from-10 to 10 μ ι η.
7. The electrical core of claim 1, wherein the sum of the thickness of the second coating and the thickness of the third coating ranges from 30 μ ι η to 80 μ ι η; the thickness of the second coating layer accounts for 30% to 70% of the sum of the thicknesses of the second coating layer and the third coating layer.
8. The electrical core of claim 1, wherein the first active material has a particle size distribution such that: d10 is more than 3.5 mu m and less than 6.5 mu m, D50 is more than 12 mu m and less than 17 mu m, and D90 is more than 22 mu m and less than 34 mu m;
the particle size distribution of the second active material satisfies: d10 is more than 5 mu m and less than 10 mu m, D50 is more than 15 mu m and less than 20 mu m, and D90 is more than 35 mu m and less than 48 mu m.
9. The cell of claim 1, wherein the compacted density of the second coating layer is greater than the compacted density of the third coating layer.
10. The electrical core of claim 1, wherein the positive electrode tab is further provided with a sixth coating layer, the sixth coating layer being contiguous with the second coating layer and the third coating layer.
11. The electrical core of claim 10, wherein the material of the sixth coating comprises at least one of ceramic and boehmite.
12. The electrical core of claim 1, wherein the first active material comprises at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, and ternary materials;
the second active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials.
13. The battery cell of claim 1, wherein the surface of the current collector further comprises a third region, the third region is a blank foil region, and a positive tab is disposed on the third region.
14. A battery comprising the cell of any one of claims 1 to 13.
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Application publication date: 20211224 |