CN113889597A - Pole piece and lithium ion battery - Google Patents
Pole piece and lithium ion battery Download PDFInfo
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- CN113889597A CN113889597A CN202111153157.4A CN202111153157A CN113889597A CN 113889597 A CN113889597 A CN 113889597A CN 202111153157 A CN202111153157 A CN 202111153157A CN 113889597 A CN113889597 A CN 113889597A
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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
- 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
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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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- 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
Abstract
The invention provides a pole piece and a lithium ion battery. The invention provides a pole piece, which comprises a current collector and an active layer arranged on at least one functional surface of the current collector, wherein the pole piece is obtained after rolling by a roller, the roller and the active layer comprise N mutually corresponding areas in the direction parallel to the axis of the roller, N is a positive integer greater than or equal to 1, and the pole piece comprises: in the active layer, the plastic strain of the region corresponding to the region of minimum deflection in the roll is epsilonp1Plastic strain epsilon of the zone corresponding to the zone of maximum deflection in the rollp2，1.0<εp1：εp2<1.07. According to the invention, according to the different deflection of the different areas of the roller, the plastic strain of the active layer in the corresponding area is designed, which is beneficial to making up the problem of poor consistency of the thickness of the pole piece caused by rolling, thereby relieving the lithium separation condition of the lithium ion battery and improving the cycle performance of the lithium ion battery.
Description
Technical Field
The invention relates to a pole piece and a lithium ion battery, and relates to the technical field of lithium ion batteries.
Background
With the development of lithium ion batteries, consumers have increasingly high demands on charging speed, endurance time, safety performance and the like. At present, pole pieces in the lithium ion battery are compacted through a rolling process so as to reduce the volume of the pole pieces, improve the energy density of the lithium ion battery and ensure the smooth and flat surface of the pole pieces.
However, due to the fact that the rollers are used for a long time and stressed unevenly, the rollers in different areas are different in abrasion and deflection, when the pole pieces are rolled by the rollers, uneven thickness of the rolled pole pieces is prone to occur, on one hand, the pole pieces are poor in cohesiveness in the subsequent formation process, lithium precipitation of the lithium ion battery is caused, the cycle performance of the lithium ion battery is reduced, on the other hand, the overall thickness of the lithium ion battery manufactured by cutting the thin parts into the pole pieces is reduced, and the production yield of the lithium ion battery is reduced. Therefore, how to solve the problem of poor consistency of the thickness of the pole piece caused by the deformation of the roller is paid more and more attention.
Disclosure of Invention
The invention provides a pole piece, which is used for solving the problem of poor consistency of the thickness of the pole piece caused by deformation of a roller.
The invention also provides a lithium ion battery comprising the pole piece, and the lithium ion battery has better cycle performance.
The invention provides a pole piece, which comprises a current collector and an active layer arranged on at least one functional surface of the current collector, wherein the pole piece is obtained after rolling by a roller, the roller and the active layer comprise N mutually corresponding areas in the direction parallel to the axis of the roller, and N is a positive integer greater than or equal to 1;
wherein, in the active layer, a plastic strain of a region corresponding to a region of the roll in which the deflection is minimum is εp1Plastic strain epsilon of the zone corresponding to the zone of maximum deflection in the rollp2，1.0<εp1：εp2<1.07。
The invention provides a pole piece, which comprises a current collector and an active layer arranged on at least one functional surface of the current collector, wherein the current collector is generally in a sheet shape, the functional surfaces of the current collector are two surfaces with larger opposite areas in the current collector and are used for realizing the load of the active layer, specifically, the upper surface and the lower surface are formed in the length direction and the width direction of the current collector, the active layer is arranged on one or two functional surfaces of the current collector, fig. 1 is a rolling schematic diagram of the pole piece, as shown in fig. 1, in the preparation process of the pole piece, firstly, active layer slurry is prepared and coated on the two functional surfaces of the current collector to obtain an active layer 200, then, the active layer 200 and the current collector 100 are rolled by a roller 300 to obtain the pole piece, the roller is in a cylindrical structure, and for convenience, the distance of a longer side in one functional surface of the current collector is specified as the length of the current collector, the distance of the shorter side is specified as the width of the current collector, the advancing direction of the roller is the length direction of the current collector, the axial direction of the roller is the width direction of the current collector, after rolling, the plastic strain of the active layer in the area corresponding to the roller is different due to different abrasion degrees and different deflection of different areas of the roller, generally, in the active layer, the plastic strain of the active layer area corresponding to the area with smaller deflection of the roller is larger than the plastic strain of the active layer area corresponding to the area with larger deflection of the roller, and the difference between the two is larger and can usually reach 1.07-1.2 times, so that the consistency of the thickness of the pole piece is poor, in order to solve the above problems, the application adjusts the plastic strain of the active layer in the corresponding area according to the deflection of the roller in different areas, so as to improve the consistency of the thickness of the pole piece after rolling, specifically, fig. 2 is a left view of the pole piece provided by an embodiment of the invention, as shown in fig. 2, in the axial direction of the roll 300, that is, in the current collector width direction, the roll 300 and the active layer 200 include N regions corresponding to each other (one corresponding region in one broken line frame), and the plastic strain of the active layer region corresponding to the region where the roll deflection is smallest among the N regions becomes ∈p1Plastic strain epsilon of the region of the active layer corresponding to the region of maximum roll deflectionp2By reducing the plastic strain to epsilonp1The problem of poor consistency of the thickness of the active layer is solved, and the plastic strain is also called permanent strain and refers to the strain still retained by the material unit after the stress is completely disappeared, namely, the rebound effect of the region of the active layer corresponding to the region with the largest roller deflection is improved, so that the problem of poor consistency of the thickness of the pole piece caused by rolling is solved, the lithium separation condition of the lithium ion battery is relieved, and the cycle performance of the lithium ion battery is improved.
In the specific preparation process of the pole piece, the abrasion of the middle part of the roll is generally larger, the abrasion of the edge part is smaller, and further concave deflection is formed, accordingly, the edge part of the pole piece is thinner after rolling, and the middle part of the pole piece is thicker, for example, fig. 3 is a left view of the pole piece after rolling in the prior art, according to fig. 3, the thickness of the active layer positioned at two sides of the pole piece is obviously lower than that of the active layer positioned at the middle of the pole piece in the width direction of the current collector, therefore, the active layer is further divided into three regions, namely N is 3, and the plastic strain of the active layer positioned at the first region and the third region is reduced, so that the plastic strain of the active layer positioned at the first region and the third region is epsilonp1Plastic strain epsilon of the active layer in said second regionp2，1.0<εp1：εp2<1.07。
Fig. 4 is a left side view of a pole piece provided according to another embodiment of the present invention, and fig. 5 is a top view of a pole piece provided according to another embodiment of the present invention, as shown in fig. 4-5, the pole piece includes a current collector 100 and an active layer 200 disposed on one functional surface of the current collector 100, and the active layer 200 is sequentially divided into a first region 201, a second region 202, and a third region 203 in a width direction of the current collector (also in a roll axis direction)p1Plastic strain epsilon of the active layer in said second regionp2，1.0<εp1：εp2<1.07 to increase the rebound thickness of the active layer in the first and third zones to compensate for the difference in roll deflectionThe problem of poor consistency of the thickness of the pole piece is solved, fig. 6 is a left side view of the rolled pole piece according to another embodiment of the present invention, and it can be understood from fig. 6 that the consistency of the thickness of the pole piece is significantly better than that of fig. 3, and that the difference of deflection of two sides of the roll is not large, so that the plastic strains of the active layers in the first region and the third region can be the same, and in the process of preparing the pole piece, the first active layer slurry and the second active layer slurry can be prepared separately, and the first region, the second region and the third region can be divided according to the difference of deflection of the roll, and the first active layer slurry is coated on the first region and the third region, and the second active layer slurry is coated on the second region, so as to obtain the active layers with different plastic strains.
In one embodiment, the plastic strain is related to the elastic modulus, the plastic modulus, and the yield strength according to the formula shown in formula 1, and thus, the difference of the plastic strain can be achieved by adjusting the elastic modulus, the plastic modulus, and the yield strength of the active layers in different regions, specifically, the elastic modulus of the active layers in the first region and the third region is smaller than the elastic modulus of the active layer in the second region, the yield strength of the active layers in the first region and the third region is larger than the yield strength of the active layer in the second region, and the hardening modulus of the active layers in the first region and the third region is larger than the hardening modulus of the active layer in the second region.
εp＝σ/E+(σa-σ)/Ep-σaE formula 1
Wherein epsilonpFor plastic strain, E is the modulus of elasticity, EpIs the plastic modulus, σ is the yield strength, σaStress at the time of rolling.
In order to take the comprehensive performance of the lithium ion battery into consideration, the invention also provides the relationship between the elastic modulus, the plastic modulus and the yield strength of the active layers positioned in the first region and the second region and the active layer positioned in the second region, and specifically:
the elastic modulus of the active layer in the first and third regions is E1The elastic modulus of the active layer in the second region is E2，0.1≤E1：E2＜1；
The yield strength of the active layer in the first and third regions is σ1The yield strength of the active layer in the second region is sigma2，1＜σ1：σ2≤2；
The hardening modulus of the active layer in the first and third regions is Ep1The hardening modulus of the active layer in the second region is Ep2，1＜Ep1：Ep2≤5。
From the above, the skilled person can reasonably arrange the materials of the active layers in different areas to change the plastic strain of the active layers in different areas, and the skilled person knows that the active layers comprise active substances, binders and conductive agents, for example, the plastic strain of the active layer in different areas can be changed by changing the type and content of the binder, in one embodiment, the binder content of the active layer in the first and second regions may be increased, but too much binder may affect the active material content, further influencing the energy density of the lithium ion battery, therefore, the content of the binder should be kept in a certain range, the mass of the binder is 0.4-6% of the total mass of the active layer, and specifically, the mass percentage of the binder in the active layer in the first region and the third region is a.1And the mass percentage of the binder in the active layer in the second area is a2，a1≥a2And 0.6 is not less than a1≤6％，0.4≤a2Less than or equal to 5.8 percent; in another specific embodiment, the kind of the binder may be adjusted, wherein the binder is selected from one or more of polyvinyl alcohol, polyacrylic acid, sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide, the currently commonly used binders are styrene-butadiene latex SBR and polyacrylic acid PAA, the difference of the plastic strain of the active layer in different regions may be achieved by adjusting the content of the PAA, specifically, the active layer includes styrene-butadiene latex and polyacrylic acid, and the mass ratio of the styrene-butadiene latex and the polyacrylic acid is less than 0.5.
According to the difference of the pole pieces, the used active substances are different, and when the pole pieces are positive pole pieces, the active substances can be one or more of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium manganese oxide, lithium iron manganese phosphate and lithium nickel manganese oxide; when the pole piece is a negative pole piece, the active substance can be one or more of artificial graphite, natural graphite, graphite coated with a modifier, a silicon negative pole and a silicon-containing negative pole material; the conductive agent may be selected according to a conventional means in the art, for example, the conductive agent is one or more of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder, conductive fiber.
In the preparation process of the pole piece, firstly, dispersing an active substance, a binder and a conductive agent in a solvent according to a certain mass ratio to prepare different active layer slurries, respectively coating the active layer slurries on different areas of at least one functional surface of a current collector according to different deflection of a roller to obtain an active layer, and then rolling to obtain the pole piece, and the research of the inventor shows that the pole piece provided by the invention is more suitable for a negative pole piece, so that the invention also provides the mass ratio of the components in the negative pole active layer, specifically, when the pole piece is the negative pole piece, the active layer comprises 90-98% of the negative pole active substance, 0.2-4% of the conductive agent and 0.4-6% of the binder according to mass percentage, the viscosity of the negative pole active layer slurry is 7000mPa.s, and the solid content is 70-80%.
In conclusion, according to the invention, the plastic strain of the active layer in the corresponding region is designed according to the different deflection of the different regions of the roller, which is beneficial to make up the problem of poor consistency of the thickness of the pole piece caused by rolling, thereby relieving the lithium separation condition of the lithium ion battery and improving the cycle performance of the lithium ion battery.
In a second aspect, the invention provides a lithium ion battery, which includes any one of the above-mentioned pole pieces.
On the basis of the pole piece provided by the first aspect of the invention, a person skilled in the art can prepare the lithium ion battery according to the conventional technical means in the art, and the lithium ion battery prepared by using the pole piece provided by the invention is beneficial to relieving the lithium precipitation condition of the lithium ion battery and improving the cycle performance of the lithium ion battery.
The implementation of the invention has at least the following advantages:
1. according to the invention, according to the different deflection of the different areas of the roller, the plastic strain of the active layer in the corresponding area is designed, which is beneficial to making up the problem of poor consistency of the thickness of the pole piece caused by rolling, thereby relieving the lithium separation condition of the lithium ion battery and improving the cycle performance of the lithium ion battery.
2. The lithium ion battery prepared by using the pole piece provided by the invention is beneficial to relieving the lithium precipitation condition of the lithium ion battery and improving the cycle performance of the lithium ion battery.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic illustration of rolling of a pole piece according to an embodiment of the present invention;
FIG. 2 is a left side view of a pole piece according to an embodiment of the present invention;
FIG. 3 is a left side view of a rolled pole piece according to the prior art;
FIG. 4 is a left side view of a pole piece provided in accordance with yet another embodiment of the present invention;
FIG. 5 is a top view of a pole piece provided in accordance with yet another embodiment of the present invention;
fig. 6 is a left side view of a rolled pole piece according to another embodiment of the present invention.
Description of reference numerals:
100-a current collector;
200-an active layer;
201-a first area;
202-a second area;
203-a third area;
300-rolling the roller.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The pole piece provided by the embodiment is a negative pole piece, and comprises a negative pole current collector copper foil and negative pole active layers arranged on two functional surfaces of the negative pole current collector copper foil, wherein the negative pole current collector copper foil is divided into a first area, a second area and a third area in the width direction of the negative pole current collector copper foil, wherein,
the negative active layers located in the first and third regions include 96.8 parts by mass of negative active material graphite, 1.2 parts by mass of conductive agent (Super P), and 2 parts by mass of binder including styrene-butadiene latex (SBR) and polyacrylic acid (PAA), and the mass ratio of SBR: PAA ═ 1: 9;
the negative active layer located in the second region includes 96.8 parts by mass of negative active material graphite, 1.2 parts by mass of conductive agent (Super P), and 2 parts by mass of binder, the binder includes styrene-butadiene latex (SBR) and polyacrylic acid (PAA), and the mass ratio of the two is SBR: PAA ═ 1: 1.
example 2
The electrode sheet provided in this embodiment is a negative electrode sheet, and reference may be made to example 1, except that the negative electrode active layers located in the first region and the third region include 96.3 parts by mass of negative electrode active material graphite, 1.2 parts by mass of conductive agent (Super P), and 2.5 parts by mass of binder, the binder includes styrene-butadiene latex (SBR) and polyacrylic acid (PAA), and the mass ratio of the two is SBR: PAA-3: 7.
Comparative example 1
The pole piece provided by the comparative example is a negative pole piece, which comprises a negative pole current collector and negative pole active layers arranged on two functional surfaces of a copper foil of the negative pole current collector, wherein the negative pole active layers comprise 96.8 parts by mass of negative pole active material graphite, 1.2 parts by mass of conductive agent (Super P) and 2 parts by mass of binder, the binder comprises styrene-butadiene latex (SBR) and polyacrylic acid (PAA), and the mass ratio of the styrene-butadiene latex (SBR) to the polyacrylic acid (PAA) is as follows: PAA ═ 1: 1.
comparative example 2
The electrode sheet provided in this comparative example is a negative electrode sheet, and reference may be made to example 1, except that the negative electrode active layers located in the first region and the third region include 96.8 parts by mass of negative electrode active material graphite, 1.2 parts by mass of conductive agent (Super P), and 2 parts by mass of binder, and the binder includes styrene-butadiene latex (SBR) and polyacrylic acid (PAA), and the mass ratio of the two is SBR: PAA is 9: 1.
The negative electrode sheets provided in examples 1-2 and comparative example 2 were tested for the elastic modulus, yield strength, and hardening modulus of the active layers located in the first and third regions in the negative electrode sheet, and the negative electrode sheet provided in comparative example 1 was tested for the elastic modulus, yield strength, and hardening modulus in the negative electrode sheet, wherein the test methods for the elastic modulus, yield strength, and hardening modulus included: performing a multilayer compression experiment on the pole pieces positioned in the first area and the third area to obtain force-displacement curves of the pole pieces, and calculating through a composite material mechanics theory to obtain stress-strain lines to obtain elastic modulus, yield strength and hardening modulus, wherein test results are shown in table 1;
the negative electrode sheets provided in test examples 1 to 2 and comparative examples 1 to 2 were rolled, and the difference Δ L between the thickness of the negative electrode active layer at the thinner position and the thickness of the negative electrode active layer at the thicker position was found in table 1;
the negative electrode sheets provided in examples 1-2 and comparative examples 1-2 were cut by die cutting, the negative electrode sheets in the first and third regions, the positive electrode sheet, and the separator were wound to form a roll core, and the lithium ion battery was obtained after passing a short circuit test and then sequentially performing encapsulation, liquid injection, aging, and thermal compression molding, wherein the positive electrode sheet included a positive current collector aluminum foil and positive active layers disposed on both functional surfaces of the positive current collector aluminum foil, and the positive active layer included 96 parts by mass of a positive active material lithium cobaltate, 2.5 parts by mass of a conductive agent (Super P), and 1.5 parts by mass of a binder.
The lithium ion batteries obtained on the basis of examples 1-2 and comparative examples 1-2 were tested for energy density, capacity retention rate and lithium deposition, and the test results are shown in table 1, in which: fully charging at 0.5C, and taking the ratio of the energy E of 0.5C discharge to the cell volume V as the energy density ED; the ratio of the capacity after the charge at 4C multiplying power and the discharge at 1C multiplying power are cycled for 700 weeks to the initial capacity is used as the capacity retention ratio; and fully charging at 5.5 ℃, discharging at 0.5 ℃, dissecting the battery cell after charging and discharging for 15 times, and checking the lithium separation condition.
Table 1 test results for pole pieces and lithium ion batteries provided in examples 1-2 and comparative examples 1-2
| Example 1 | Example 2 | Comparative example 1 | Comparative example 2 | |
| E(Mpa) | 209.7 | 203.8 | 211.2 | 197.4 |
| σ(Mpa) | 78.9 | 74.4 | 69.5 | 65 |
| Ep(Mpa) | 34.5 | 33.5 | 32.3 | 31.6 |
| ΔL(μm) | 1.2 | 0.9 | 2.3 | 2.2 |
| ED(Wh/L) | 570 | 559 | 567 | 566 |
| Capacity retention rate | 82％ | 87％ | 76％ | 77％ |
| Case of lithium evolution | Does not separate out lithium | Does not separate out lithium | Separating lithium | Separating lithium |
As can be seen from the data provided in table 1, compared with comparative example 1, in the electrode sheets provided in examples 1-2, the elastic modulus, the yield strength, and the hardening modulus of the active layers located in the first region and the third region are reduced, which indicates that the plastic strain of the active layers located in the first region and the third region is reduced, and the thickness difference Δ L between the active layers located in the first region and the third region and the active layer located in the second region can be effectively reduced, so that the lithium deposition of the lithium ion battery is alleviated, and the capacity retention rate of the lithium ion battery is improved; according to the data provided in example 2, it can be seen that, in example 2, the content of the binder in the active layers located in the first region and the third region is higher, which results in a decrease in the content of the negative active material, and thus the energy density of the lithium ion battery is decreased, and therefore, those skilled in the art can reasonably set the content of the binder in the active layers; according to the data provided in comparative example 2, although the elastic modulus of the active layers located in the first and third regions is decreased, the yield strength and the hardening modulus are also decreased at the same time, and there is no improvement in the lithium-out state of the lithium ion battery.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A pole piece is characterized by comprising a current collector and an active layer arranged on at least one functional surface of the current collector, wherein the pole piece is obtained after rolling by a roller, the roller and the active layer comprise N mutually corresponding areas in the direction parallel to the axis of the roller, and N is a positive integer greater than or equal to 1;
wherein: in the active layer, the plastic strain of the region corresponding to the region of minimum deflection in the roll is epsilonp1Plastic strain epsilon of the zone corresponding to the zone of maximum deflection in the rollp2，1.0<εp1：εp2<1.07。
2. The pole piece of claim 1, wherein the active layer is divided into a third layer in the width direction of the current collectorA first region, a second region and a third region, the plastic strain of the active layer being in the first and third regions being epsilonp1Plastic strain epsilon of the active layer in said second regionp2，1.0<εp1：εp2<1.07。
3. The pole piece of claim 2, wherein the active layers in the first and third regions have a modulus of elasticity less than the modulus of elasticity of the active layer in the second region, the yield strength of the active layers in the first and third regions is greater than the yield strength of the active layer in the second region, and the hardening modulus of the active layers in the first and third regions is greater than the hardening modulus of the active layer in the second region.
4. The pole piece of claim 3, wherein the active layers in the first and third regions have an elastic modulus E1The elastic modulus of the active layer in the second region is E2，0.1≤E1：E2＜1。
5. The pole piece of claim 3, wherein the yield strength of the active layer in the first and third regions is σ1The yield strength of the active layer in the second region is sigma2，1＜σ1：σ2≤2。
6. The pole piece of claim 3, wherein the active layers in the first and third regions have a hardening modulus Ep1The hardening modulus of the active layer in the second region is Ep2，1＜Ep1：Ep2≤5。
7. The pole piece of any one of claims 1 to 6, wherein the active layer comprises an adhesive, the adhesive being located in the active layer of the first and third regionsThe mass percent is a1And the mass percentage of the binder in the active layer in the second area is a2，a1≥a2And a is more than or equal to 0.6 percent1≤6％，0.4％≤a2≤5.8％。
8. The pole piece of claim 7, wherein the binder is selected from one or more of polyvinyl alcohol, polyacrylic acid, sodium carboxymethyl cellulose, styrene butadiene latex, polytetrafluoroethylene, and polyethylene oxide.
9. The pole piece of claim 7, wherein the adhesive comprises styrene-butadiene latex and polyacrylic acid, and the mass ratio of the styrene-butadiene latex to the polyacrylic acid is less than 0.5.
10. A lithium ion battery, characterized in that it comprises a pole piece according to any of claims 1 to 9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023123411A1 (en) * | 2021-12-31 | 2023-07-06 | 宁德时代新能源科技股份有限公司 | Negative electrode plate, preparation method therefor, secondary battery comprising negative electrode plate, and electric device |
| CN117038860A (en) * | 2023-10-10 | 2023-11-10 | 宁德时代新能源科技股份有限公司 | Cathode plate, electrode assembly, battery and electric equipment |
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| CN117038860A (en) * | 2023-10-10 | 2023-11-10 | 宁德时代新能源科技股份有限公司 | Cathode plate, electrode assembly, battery and electric equipment |
| CN117038860B (en) * | 2023-10-10 | 2024-04-05 | 宁德时代新能源科技股份有限公司 | Cathode plate, electrode assembly, battery and electric equipment |
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| CN113889597B (en) | 2022-08-05 |
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