CN111916679A - Method for preparing graphite cathode of lithium ion battery - Google Patents
Method for preparing graphite cathode of lithium ion battery Download PDFInfo
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- CN111916679A CN111916679A CN202010819877.9A CN202010819877A CN111916679A CN 111916679 A CN111916679 A CN 111916679A CN 202010819877 A CN202010819877 A CN 202010819877A CN 111916679 A CN111916679 A CN 111916679A
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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
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- C—CHEMISTRY; METALLURGY
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- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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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
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- 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 method for preparing a graphite cathode of a lithium ion battery, which comprises the steps of providing first graphite particles, second graphite particles, third graphite particles and fourth graphite particles, wherein the D50 of the first graphite particles is 0.5-0.7 micrometer, and the D90 is 0.9-1.1 micrometer; wherein the D90 of the first graphite particle is the same as the D50 of the second graphite particle; the D90 of the second graphite particle is the same as the D50 of the third graphite particle; the D90 of the third graphite particle is the same as the D50 of the fourth graphite particle; the fourth graphite particles have a D90 less than five times the D50 of the first graphite particles. The first graphite particles, the second graphite particles and the third graphite particles are mixed according to a preset mass ratio to obtain a first slurry, and the graphite cathode prepared by the method has high energy density, rate capability and cycle performance.
Description
Technical Field
The invention relates to a method for preparing a graphite cathode of a lithium ion battery.
Background
The invention researches the particle size distribution and the matching relation of various graphite particles to prepare the structured negative electrode of the natural graphite.
Disclosure of Invention
The invention provides a method for preparing a graphite cathode of a lithium ion battery, which comprises the steps of providing first graphite particles, second graphite particles, third graphite particles and fourth graphite particles, wherein the D50 of the first graphite particles is 0.5-0.7 micrometer, and the D90 is 0.9-1.1 micrometer; the second graphite particles have a D50 of 0.9-1.1 microns and a D90 of 1.3-1.5 microns; the third graphite particles have a D50 of 1.3-1.5 microns and a D90 of 1.8-2.0 microns; the fourth graphite particles have a D50 of 1.8-2.0 microns and a D90 of 2.4-2.6 microns. Wherein the D90 of the first graphite particle is the same as the D50 of the second graphite particle; the D90 of the second graphite particle is the same as the D50 of the third graphite particle; the D90 of the third graphite particle is the same as the D50 of the fourth graphite particle; the fourth graphite particles have a D90 less than five times the D50 of the first graphite particles. Mixing first graphite particles, second graphite particles and third graphite particles according to a preset mass ratio to obtain first slurry, mixing second graphite particles, third graphite particles and fourth graphite particles according to a preset mass ratio to obtain second slurry, and mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio to obtain third slurry; and coating the first slurry, the second slurry and the third slurry on a current collector in sequence, and drying to obtain the graphite negative electrode. The graphite cathode prepared by the method has higher energy density, rate capability and cycle performance.
The specific scheme is as follows:
a method of making a graphite anode for a lithium ion battery, the active material of the anode comprising first, second, third and fourth graphite particles, wherein the first graphite particle has a D90 which is the same as the D50 of the second graphite particle; the D90 of the second graphite particle is the same as the D50 of the third graphite particle; the D90 of the third graphite particle is the same as the D50 of the fourth graphite particle; the D90 of the fourth graphite particles is less than five times the D50 of the first graphite particles; the method comprises the following steps:
1) providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.5 to 0.7 microns and a D90 of 0.9 to 1.1 microns; the second graphite particles have a D50 of 0.9-1.1 microns and a D90 of 1.3-1.5 microns; the third graphite particles have a D50 of 1.3-1.5 microns and a D90 of 1.8-2.0 microns; the fourth graphite particles have a D50 of 1.8-2.0 microns and a D90 of 2.4-2.6 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4-6: 4-6;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3-5: 3-5;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3-5: 3-5;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector and drying to obtain the graphite negative electrode.
Further, the first graphite particles have a D50 of 0.6 microns and a D90 of 1.0 microns; the second graphite particles have a D50 of 1.0 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles had a D50 of 1.9 microns and a D90 of 2.5 microns.
Further, in the first slurry, the mass ratio of the first graphite particles: second graphite particles: third graphite particles ═ 1:2.2: 4.8-5.0.
Further, in the second slurry, the mass ratio of the second graphite particles: third graphite particles: fourth graphite particles ═ 1:2.2: 4.8-5.0.
Further, in the third slurry, the mass ratio of the first graphite particles: fourth graphite particles 1: 10.8.
Furthermore, the coating thickness ratio of the first slurry, the second slurry and the third slurry is 15-20:40-50: 6-8.
Further, the binder is SBR, and the conductive agent is conductive carbon black.
The invention has the following beneficial effects:
1) the inventors found that when the particle size distribution of the graphite particles satisfies the following range, D90 of the first graphite particles is the same as D50 of the second graphite particles; the D90 of the second graphite particle is the same as the D50 of the third graphite particle; the D90 of the third graphite particle is the same as the D50 of the fourth graphite particle; when the D90 of the fourth graphite particles is less than five times the D50 of the first graphite particles, the different graphite particles can be sufficiently mixed, and the mixed particles have excellent dispersibility in the slurry;
2) the inventors have found that when the particle size of the graphite particles is such that the first graphite particles have a D50 of 0.5 to 0.7 micron and a D90 of 0.9 to 1.1 micron; the second graphite particles have a D50 of 0.9-1.1 microns and a D90 of 1.3-1.5 microns; the third graphite particles have a D50 of 1.3-1.5 microns, and in the first slurry, the mass ratio of the first graphite particles: second graphite particles: when the third graphite particles are 1:2.2:4.8-5.0, the first slurry obtains extremely high stability;
3) when the particle size of the graphite particles is that the D50 of the second graphite particles is 0.9-1.1 microns, and the D90 is 1.3-1.5 microns; the third graphite particles have a D50 of 1.3-1.5 microns and a D90 of 1.8-2.0 microns; the fourth graphite particles have a D50 of 1.8-2.0 microns and a D90 of 2.4-2.6 microns, and in the second slurry, the mass ratio of the second graphite particles: third graphite particles: when the fourth graphite particles are 1:2.2:4.8-5.0, the second slurry obtains extremely high stability.
3) The first graphite particles have a D50 of 0.5-0.7 micron and a D90 of 0.9-1.1 micron; the fourth graphite particles have a D50 of 1.8 to 2.0 microns, a D90 of 2.4 to 2.6 microns, a D90 of less than five times the D50 of the first graphite particles, and a third slurry in mass ratio of the first graphite particles: when the fourth graphite particles are 1:10.8, the third slurry obtains extremely high stability;
4) by setting a specific component ratio for different positions of the active material layer of graphite, the energy density, rate capability and cycle performance of the active material layer can be improved. The active material layer close to the current collector has lower particle size distribution, can obtain higher specific surface area of the material, and improves the lithium ion transmission path; the middle layer has a larger particle size distribution and a higher energy density; the surface layer has larger porosity and larger particle size, and the porosity among layers and the filling density of the graphite particles are balanced by setting the mass proportion of different graphite particles, so that the performance of the negative active material is optimal.
Detailed Description
The present invention will be described in more detail below with reference to specific examples, but the scope of the present invention is not limited to these examples. The graphite in the invention is natural graphite, the binder is SBR, and the conductive agent is conductive carbon black.
Example 1
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.5 microns and a D90 of 0.9 microns; the second graphite particles have a D50 of 0.9 microns and a D90 of 1.3 microns; the third graphite particles have a D50 of 1.3 microns and a D90 of 1.8 microns; the fourth graphite particles have a D50 of 1.8 microns and a D90 of 2.4 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.2:4.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
3) mixing second graphite particles, third graphite particles and fourth graphite particles according to a preset mass ratio of 1:2.2:4.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3: 3;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:10.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3: 3;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 15:40:6, and drying to obtain the graphite cathode.
Example 2
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.7 microns and a D90 of 1.1 microns; the second graphite particles have a D50 of 1.1 microns and a D90 of 1.5 microns; the third graphite particles have a D50 of 1.5 microns and a D90 of 2.0 microns; the fourth graphite particles have a D50 of 2.0 microns and a D90 of 2.6 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.2:5.0, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:6: 6;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio of 1:2.2:5.0, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:10.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 20:50:8, and drying to obtain the graphite cathode.
Example 3
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.6 microns and a D90 of 1 micron; the second graphite particles have a D50 of 1 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles have a D50 of 1.9 microns and a D90 of 2.5 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.2:4.9, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio of 1:2.2:4.9, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:10.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 18:45:7, and drying to obtain the graphite cathode.
Comparative example 1
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.5 microns and a D90 of 1.2 microns; the second graphite particles have a D50 of 0.9 microns and a D90 of 1.6 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles have a D50 of 2.2 microns and a D90 of 2.8 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.2:4.9, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio of 1:2.2:4.9, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:10.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 18:45:7, and drying to obtain the graphite cathode.
Comparative example 2
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.6 microns and a D90 of 1 micron; the second graphite particles have a D50 of 1 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles have a D50 of 1.9 microns and a D90 of 2.5 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:1.8:4.2, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
3) mixing second graphite particles, third graphite particles and fourth graphite particles according to a preset mass ratio of 1:1.8:4.2, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:9, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 18:45:7, and drying to obtain the graphite cathode.
Comparative example 3
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.6 microns and a D90 of 1 micron; the second graphite particles have a D50 of 1 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles have a D50 of 1.9 microns and a D90 of 2.5 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.5:6, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio of 1:2.5:6, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:12, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 18:45:7, and drying to obtain the graphite cathode.
Comparative example 4
1) Providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.6 microns and a D90 of 1 micron; the second graphite particles have a D50 of 1 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles have a D50 of 1.9 microns and a D90 of 3 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio of 1:2.2:5, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:5: 5;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio of 1:2.2:5, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio of 1:10.8, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4: 4;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector, wherein the coating thickness ratio of the first slurry to the second slurry to the third slurry is 18:45:7, and drying to obtain the graphite cathode.
Test and results
The first, second and third slurries of examples 1 to 3 and comparative examples 1 to 4 were tested, stored at room temperature for 15 hours, and the solid contents at 5cm below the surface of the slurries before and after storage were measured, and the solid content after storage/the solid content before storage was equal to the stability of the slurries, and the negative electrode and the lithium sheet were formed into an experimental battery, and charge and discharge cycles were performed 400 times at a current of 1C to measure the cycle capacity retention rate of the battery, and the results are shown in table 1.
TABLE 1
| The first size% | The second size% | The third size% | Retention ratio of circulating Capacity (%) | |
| Example 1 | 95.6 | 95.4 | 96.1 | 99.1 |
| Example 2 | 95.2 | 95.6 | 95.8 | 98.8 |
| Example 3 | 95.6 | 96.0 | 96.2 | 99.3 |
| Comparative example 1 | 88.9 | 85.7 | 86.8 | 94.8 |
| Comparative example 2 | 89.5 | 90.1 | 91.8 | 95.6 |
| Comparative example 3 | 91.5 | 92.1 | 90.6 | 95.4 |
| Comparative example 4 | 92.1 | 91.9 | 92.3 | 96.0 |
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention.
Claims (7)
1. A method of making a graphite anode for a lithium ion battery, the active material of the anode comprising first, second, third and fourth graphite particles, wherein the first graphite particle has a D90 which is the same as the D50 of the second graphite particle; the D90 of the second graphite particle is the same as the D50 of the third graphite particle; the D90 of the third graphite particle is the same as the D50 of the fourth graphite particle; the D90 of the fourth graphite particles is less than five times the D50 of the first graphite particles; the method comprises the following steps:
1) providing first, second, third and fourth graphite particles, the first graphite particle having a D50 of 0.5 to 0.7 microns and a D90 of 0.9 to 1.1 microns; the second graphite particles have a D50 of 0.9-1.1 microns and a D90 of 1.3-1.5 microns; the third graphite particles have a D50 of 1.3-1.5 microns and a D90 of 1.8-2.0 microns; the fourth graphite particles have a D50 of 1.8-2.0 microns and a D90 of 2.4-2.6 microns;
2) mixing the first graphite particles, the second graphite particles and the third graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a first slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:4-6: 4-6;
3) mixing the second graphite particles, the third graphite particles and the fourth graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, then adding the mixed graphite particles, and uniformly stirring to obtain a second slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3-5: 3-5;
4) mixing the first graphite particles and the fourth graphite particles according to a preset mass ratio, adding a binder into deionized water, uniformly stirring, adding a conductive agent, uniformly stirring, adding the mixed graphite particles, and uniformly stirring to obtain a third slurry; wherein the mass ratio of the active substance particles is as follows: adhesive: the conductive agent is 100:3-5: 3-5;
5) and sequentially coating the first slurry, the second slurry and the third slurry on a current collector and drying to obtain the graphite negative electrode.
2. The method of the preceding claim, the first graphite particles having a D50 of 0.6 microns, a D90 of 1.0 microns; the second graphite particles have a D50 of 1.0 micron and a D90 of 1.4 microns; the third graphite particles have a D50 of 1.4 microns and a D90 of 1.9 microns; the fourth graphite particles had a D50 of 1.9 microns and a D90 of 2.5 microns.
3. The method of the preceding claim, wherein in the first slurry, the mass ratio of the first graphite particles: second graphite particles: third graphite particles ═ 1:2.2: 4.8-5.0.
4. The method of the preceding claim, wherein in the second slurry, the mass ratio of the second graphite particles: third graphite particles: fourth graphite particles ═ 1:2.2: 4.8-5.0.
5. The method of the preceding claim, wherein, in the third slurry, the mass ratio of the first graphite particles: fourth graphite particles 1: 10.8.
6. The method of the preceding claim, wherein the first slurry, the second slurry, and the third slurry are applied at a thickness ratio of 15-20:40-50: 6-8.
7. The method of the preceding claim, wherein the binder is SBR and the conductive agent is conductive carbon black.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010819877.9A CN111916679A (en) | 2020-08-14 | 2020-08-14 | Method for preparing graphite cathode of lithium ion battery |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110690409A (en) * | 2019-10-17 | 2020-01-14 | 朱虎 | Preparation method of natural graphite-based negative electrode |
| KR20200025983A (en) * | 2018-08-29 | 2020-03-10 | 한국전기연구원 | Preparation of high density anode with reduced graphene oxide-silicon metal particle compound and fabrication of electrodes for secondary battery and process for preparing the same |
| CN111416098A (en) * | 2020-05-12 | 2020-07-14 | 朱虎 | Preparation method of lithium ion battery cathode |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20200025983A (en) * | 2018-08-29 | 2020-03-10 | 한국전기연구원 | Preparation of high density anode with reduced graphene oxide-silicon metal particle compound and fabrication of electrodes for secondary battery and process for preparing the same |
| CN110690409A (en) * | 2019-10-17 | 2020-01-14 | 朱虎 | Preparation method of natural graphite-based negative electrode |
| CN111416098A (en) * | 2020-05-12 | 2020-07-14 | 朱虎 | Preparation method of lithium ion battery cathode |
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Application publication date: 20201110 |