CN117810448A - Graphite-based negative electrode active material and negative electrode sheet - Google Patents
Graphite-based negative electrode active material and negative electrode sheet Download PDFInfo
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- CN117810448A CN117810448A CN202311867225.2A CN202311867225A CN117810448A CN 117810448 A CN117810448 A CN 117810448A CN 202311867225 A CN202311867225 A CN 202311867225A CN 117810448 A CN117810448 A CN 117810448A
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- 239000007773 negative electrode material Substances 0.000 title claims abstract description 43
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 32
- 239000010439 graphite Substances 0.000 title claims abstract description 32
- 229910021383 artificial graphite Inorganic materials 0.000 claims abstract description 113
- 239000002245 particle Substances 0.000 claims abstract description 53
- 238000005087 graphitization Methods 0.000 claims abstract description 22
- 239000011164 primary particle Substances 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims description 24
- 239000002994 raw material Substances 0.000 claims description 24
- 239000011248 coating agent Substances 0.000 claims description 21
- 239000006183 anode active material Substances 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 11
- 238000000576 coating method Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- 239000011331 needle coke Substances 0.000 claims description 8
- 238000010000 carbonizing Methods 0.000 claims description 6
- 239000000571 coke Substances 0.000 claims description 6
- 239000011265 semifinished product Substances 0.000 claims description 6
- 239000011230 binding agent Substances 0.000 claims description 5
- 239000011247 coating layer Substances 0.000 claims description 5
- 239000002010 green coke Substances 0.000 claims description 4
- 239000011163 secondary particle Substances 0.000 claims description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 15
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 15
- 230000005540 biological transmission Effects 0.000 abstract description 8
- 230000000052 comparative effect Effects 0.000 description 25
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 20
- 229910052744 lithium Inorganic materials 0.000 description 20
- 238000002360 preparation method Methods 0.000 description 13
- 238000011112 process operation Methods 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- 230000008901 benefit Effects 0.000 description 10
- 239000003822 epoxy resin Substances 0.000 description 7
- 229920000647 polyepoxide Polymers 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 6
- 238000005056 compaction Methods 0.000 description 5
- 230000003179 granulation Effects 0.000 description 5
- 238000005469 granulation Methods 0.000 description 5
- 238000011056 performance test Methods 0.000 description 5
- 239000010426 asphalt Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000002006 petroleum coke Substances 0.000 description 3
- 230000002195 synergetic effect Effects 0.000 description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000006256 anode slurry Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920001568 phenolic resin Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 239000006257 cathode slurry Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 239000005007 epoxy-phenolic resin Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/205—Preparation
-
- 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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a graphite-based negative electrode active material, which comprises artificial graphite A, wherein the artificial graphite A is primary particles, the particle size D50 of the artificial graphite A is 8-10 mu m, the graphitization degree of the artificial graphite A is 90-93%, and the tap density of the artificial graphite A is 0.95-1.05 g/cm 3 . According to the invention, by simultaneously controlling the particle size, graphitization degree and tap density of the artificial graphite A, lithium ions can be rapidly intercalated and deintercalated on the surface of the graphite-based negative electrode active material, so that the battery has excellent lithium ion transmission dynamics characteristic and good rapid charging performance, and a faster charging speed and a shorter charging time are realized.
Description
Technical Field
The invention belongs to the technical field of lithium batteries, and particularly relates to a graphite-based negative electrode active material and a negative electrode plate.
Background
Lithium batteries are a common secondary battery and are widely applied to the fields of mobile electronic equipment, electric automobiles and the like. With the increasing demands of the market on electric vehicles, people put higher and higher demands on the quick charging performance of the electric vehicles. The quick charge performance of an electric car is determined by a power battery as a power core, and the quick charge performance of the power battery depends on the quick charge capability of a negative electrode material thereof. The graphite negative electrode material has excellent conductivity and stability, however, the quick charge performance is limited, and the requirement of a quick charge battery cannot be met. Therefore, the quick charge performance of the graphite-based negative electrode active material is further improved, the requirement of a quick charge battery is met, and the method has important research significance.
Disclosure of Invention
The invention aims to provide a graphite-based negative electrode active material which has excellent lithium ion transmission dynamics and quick charge performance.
According to one aspect of the present invention, there is provided a graphite-based negative electrode active material comprising artificial graphite A as primary particles, the artificial graphite A having a particle diameter D50 of 8 to 10 μm, a graphitization degree of 90 to 93% of the artificial graphite A, and a tap density of 0.95 to 1.05g/cm 3 。
The invention provides a graphite-based negative electrode active material, which adopts specific artificial graphite A, wherein the artificial graphite A is primary particles, and as the surfaces of the primary particles are smooth, the lattice defects are few and certain gaps exist among the particles, a good lithium ion transmission channel is provided for lithium ions, and the rapid transmission of the lithium ions is facilitated; in addition, the particle size of the artificial graphite A is smaller, the diffusion and migration path of lithium ions can be shortened, and the transmission of the lithium ions in the negative plate is smoother, so that the lithium ion transmission efficiency of the negative plate is improved, and the problems of capacity loss and the like in the high-rate charge and discharge process are avoided; meanwhile, the artificial graphite A has proper graphitization degree and tap density, has a stable structure and proper graphite layer spacing, can ensure that the graphite fully exerts the capacity, can promote the rapid movement of lithium ions, and reduces the lithium ion transmission impedance, thereby improving the rapid charging performance of the negative plate. In summary, the particle size, graphitization degree and tap density of the artificial graphite A are controlled simultaneously, so that lithium ions can be rapidly intercalated and deintercalated on the surface of the graphite-based negative electrode active material, and the battery has excellent lithium ion transmission dynamics characteristic and good rapid charging performance, and realizes faster charging speed and shorter charging time.
Specifically, the graphitization degree G calculation formula is: g= [ (0.3440-d 002)/0.0086 ]. Times.100%, where d002 is the (002) interplanar spacing of artificial graphite A, obtained by XRD testing according to the guidelines of QJ2507-93, in nm.
Preferably, the preparation method of the artificial graphite A comprises the following operations: taking raw coke as a raw material, carrying out graphitization treatment on the raw material to obtain graphitized particles A, and then coating and carbonizing the graphitized particles A by adopting a coating agent to obtain the artificial graphite A. According to the preparation method, raw coke is used as a raw material, the raw coke has good kinetic performance advantage, and the quick charge performance and gram capacity of the product can be further improved on the premise of ensuring the good kinetic performance advantage of the raw material by graphitizing, coating and carbonizing the raw material.
Preferably, the graphitization treatment temperature is 2700 to 3100 ℃.
Preferably, the coating agent comprises at least one of epoxy resin and phenolic resin.
Preferably, the true density of the green coke is > 2.1g/cm 3 . The adoption of the raw coke raw material with higher true density is beneficial to improving the compacted density and gram capacity of the product.
Preferably, the method also comprises artificial graphite B, wherein the artificial graphite B is secondary particles, the particle diameter D50 of the artificial graphite B is 11-14 mu m, and the graphitization degree of the artificial graphite B is 93-94%; the mass ratio of the artificial graphite A to the artificial graphite B is 30-40: 60 to 70. The artificial graphite B is secondary particles and has the advantage of higher compaction density, the artificial graphite A is primary particles, the surface of the artificial graphite A is smooth, and the particle size of the artificial graphite A is smaller, so that the smooth artificial graphite A is easy to fill between gaps of the artificial graphite B, the compaction density of the graphite-based negative electrode active material is improved, on the basis, the artificial graphite A and the artificial graphite B are mixed according to a specific proportion, the artificial graphite A can be fully dispersed between the gaps of the artificial graphite B, the compaction density and gram capacity of the whole negative electrode active material are improved, and therefore, the artificial graphite A and the artificial graphite B can fully play a synergistic effect, and the obtained negative electrode sheet has the performance advantages of the artificial graphite A and the artificial graphite B and has high gram capacity and excellent quick charge performance.
Preferably, the preparation method of the artificial graphite B comprises the following operations: s1, taking needle coke as a raw material, mixing an auxiliary material binder with the raw material, and granulating to obtain a semi-finished product; s2, graphitizing the semi-finished product to obtain graphitized particles; s3, coating and carbonizing the graphitized particles by adopting a coating agent, thereby preparing the artificial graphite B. According to the preparation method, needle coke is used as a raw material, the needle coke has the performance advantage of high gram capacity, and the dynamic performance of the artificial graphite B can be further improved on the premise of ensuring the performance advantage of the high gram capacity of the raw material by granulating, graphitizing, cladding and carbonizing the raw material.
Preferably, the auxiliary material binder comprises at least one of medium-temperature asphalt and epoxy resin.
Preferably, the graphitization treatment temperature is 2900 to 3200 ℃.
Preferably, the carbonization temperature is 900-1100 ℃.
Preferably, the particle diameter of the needle coke is less than or equal to 8um, and the tap density is more than or equal to 0.75g/cm 3 . By further limiting the particle size and tap density of the needle coke, the kinetic performance of the artificial graphite B prepared by the method can be further improved on the premise of ensuring that the raw material exerts the advantage of high gram capacity.
Preferably, in S1, the granulation temperature is 800 to 900℃and the granulation time is 6 to 8 hours.
Preferably, the mass ratio of the coating agent to the graphitized particles is 3-8:100.
Preferably, the coating agent comprises at least one of epoxy resin, phenolic resin, asphalt.
According to another aspect of the present invention, there is provided a negative electrode sheet comprising a negative electrode current collector and a negative electrode active coating layer provided on a surface of the negative electrode current collector, the negative electrode active material contained in the negative electrode active coating layer comprising the graphite-based negative electrode active material described above. The negative plate provided by the invention has excellent quick charge performance and energy density.
Preferably, the content of the graphite-based anode active material in the anode active material contained in the anode active coating layer is not less than 2.0wt%.
Preferably, the negative electrode active coating has a compacted density of 1.76g/cm or more 3 . The compaction density is beneficial to entering on the basis of ensuring good quick charging performance of the negative plateThe gram capacity and the energy density of the composite material are improved in one step.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1
The embodiment provides a lithium battery, and the preparation method thereof comprises the following steps:
1. preparation of negative electrode sheet
S1, preparation of artificial graphite A:
taking the particles with the diameter D50 of 6 mu m and the true density of 2.3g/cm 3 The petroleum coke green coke is used as a raw material, and graphitized treatment is carried out by heating the raw material to 3100 ℃ to obtain graphitized particles A; and mixing the coating agent epoxy resin with the graphitized particles A according to the mass ratio of 5:100 to coat the graphitized particles A, and then heating to 1200 ℃ to carbonize for 7h to obtain the artificial graphite A.
Wherein the artificial graphite A is primary particles, the particle diameter D50 of the artificial graphite A is 9.5 mu m, the graphitization degree is 92.0%, and the tap density is 1.03g/cm 3 。
S2, preparation of artificial graphite B:
(1) Taking the particle diameter D50 of 8 mu m and the tap density of 0.75g/cm 3 The needle coke aggregate is taken as a raw material, medium-temperature asphalt as an auxiliary material binder is mixed with the raw material according to the mass ratio of 20:100, and granulation is carried out in a granulation kettle (the granulation temperature is 950 ℃ C., the time is 7 h), so as to obtain a semi-finished product;
(2) Heating the semi-finished product to 3150 ℃ for graphitizing treatment to obtain graphitized particles B;
(3) And mixing the coating agent epoxy resin with the graphitized particles B according to the mass ratio of 4.5:100 to coat the graphitized particles B, and then heating to 1000 ℃ to carbonize for 6 hours to prepare the artificial graphite B.
Wherein the artificial graphite B is secondary particles, the particle diameter D50 of the artificial graphite B is 12.5 mu m, the graphitization degree is 93 percent, and the tap density is 1.05g/cm 3 。
S3, preparing a cathode active main material:
and mixing the artificial graphite A and the artificial graphite B according to the mass ratio of 30:70 to obtain a graphite-based negative electrode active material, wherein the graphite-based negative electrode active material is the negative electrode active main material of the embodiment.
S4, preparation of negative plate
And (3) uniformly mixing 97.4% of a cathode active main material and 0.3% of conductive carbon black, then adding CMC glue solution (CMC content is 1.1%) into the mixture, stirring and uniformly mixing, and then adding 1.2% of SBR, stirring and uniformly mixing to obtain cathode slurry. And then coating the negative electrode slurry on a copper foil, and drying the copper foil for 12 hours in a vacuum environment at 100 ℃ to obtain a negative electrode plate.
2. Preparation of positive plate
Uniformly mixing an anode active material (lithium cobaltate), a conductive agent SP and a binder PVDF according to the mass ratio of 94:3:3, dispersing the mixture in NMP to obtain anode slurry, coating the anode slurry on an aluminum foil, and drying the aluminum foil in a vacuum environment at 85 ℃ for 24 hours to obtain the anode plate.
3. Preparation of electrolyte
Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) are mixed according to a volume ratio of 1:1:1, and then dissolving fully dried lithium salt LiPF6 in the organic solvent to prepare an electrolyte with the concentration of 1 mol/L.
4. Selection of a diaphragm
The diaphragm adopts a polyethylene film.
5. Lithium battery assembly and formation
Sequentially stacking the positive plate, the diaphragm and the negative plate, enabling the diaphragm to be positioned between the positive plate and the negative plate to play a role of isolation, and then winding to obtain a bare cell; and (3) placing the bare cell in an outer packaging shell, drying, injecting the electrolyte, vacuum packaging, standing, forming and performing constant volume working procedure to obtain the battery.
Example 2
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the negative electrode active material used in this example includes only artificial graphite a. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 3
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the mass ratio of the artificial graphite a to the artificial graphite B in the negative electrode active material used in this example was 20:80. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 4
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the mass ratio of the artificial graphite a to the artificial graphite B in the negative electrode active material used in this example was 40:60. except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 5
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the mass ratio of the artificial graphite a to the artificial graphite B in the negative electrode active material used in this example was 50:50. except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 6
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the particle diameter D50 of the artificial graphite B was 8. Mu.m. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 7
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the particle diameter D50 of the artificial graphite B was 16. Mu.m. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Example 8
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the particle diameter D50 of the artificial graphite A in the negative electrode active material used in this example was 8. Mu.m, the graphitization degree was 90%, and the tap density was 0.95g/cm 3 . Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
The preparation method of the artificial graphite A comprises the following operations: taking the particle diameter D50 of 8 mu m and the true density of 2.1g/cm 3 The raw coke of the petroleum coke is used as a raw material, and the raw material is heated to 3050 ℃ for graphitization treatment to obtain graphitized particles A; and mixing the coating agent epoxy resin with the graphitized particles A according to the mass ratio of 5:100 to coat the graphitized particles A, and then heating to 1200 ℃ to carbonize for 7h to obtain the artificial graphite A.
Example 9
This example makes a lithium battery with reference to example 1, which differs from example 1 in that: the particle diameter D50 of the artificial graphite A in the negative electrode active material used in this example was 10. Mu.m, the graphitization degree was 93%, and the tap density was 1.05g/cm 3 . Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
The preparation method of the artificial graphite A comprises the following operations: taking the particle diameter D50 of 10 mu m and the true density of 2.6g/cm 3 The petroleum coke green coke is taken as a raw material, and the raw material is heated to 3200 ℃ for graphitization treatment to obtain graphitized particles A; and mixing the coating agent epoxy resin with the graphitized particles A according to the mass ratio of 5:100 to coat the graphitized particles A, and then heating to 1200 ℃ to carbonize for 7h to obtain the artificial graphite A.
Comparative example 1
This comparative example a lithium battery was prepared with reference to example 1, and this comparative example was different from example 1 in that: the particle diameter D50 of the artificial graphite A was 7. Mu.m. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Comparative example 2
This comparative example a lithium battery was prepared with reference to example 1, and this comparative example was different from example 1 in that: the particle diameter D50 of the artificial graphite A was 12. Mu.m. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Comparative example 3
This comparative example a lithium battery was prepared with reference to example 1, and this comparative example was different from example 1 in that: the graphitization degree of the artificial graphite A was 88.5%. Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Comparative example 4
This comparative example a lithium battery was prepared with reference to example 1, and this comparative example was different from example 1 in that: the tap density of the artificial graphite A is 0.9g/cm 3 . Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Comparative example 5
This comparative example a lithium battery was prepared with reference to example 1, and this comparative example was different from example 1 in that: the tap density of the artificial graphite A is 1.1g/cm 3 . Except for the above differences, the materials used in this example and the process operations were exactly the same as in example 1.
Test example 1
1. Test object:
examples 1 to 9 and comparative examples 1 to 5 were the test subjects of this test example.
2. Test items:
(1) Fast charge performance (3C charge cross current ratio): and 3C direct charging test is carried out on the battery by adopting a Xinwei test cabinet, the cut-off voltage is 4.48V, the cut-off current is 0.025C, and the ratio of the 3C direct charging capacity to the total charging capacity acquired by the test cabinet is checked to be the 3C charging cross current ratio.
(2) Gram volume: and carrying out discharge capacity test on the cathode active main material by adopting a half-cell test, wherein the charge-discharge system is as follows: DC:0.6mA to 5.0mV,0.06mA to 5.0mV,CC:0.6mA to 2.0V.
3. Test results:
table 1 relevant parameters of lithium batteries of examples 1 to 9 and comparative examples 1 to 5
Table 1 results of performance tests of lithium batteries of examples 1 to 9 and comparative examples 1 to 5
The test results are shown in Table 1. The performance test results corresponding to comparative examples 1 to 5 were compared with example 1. As is clear from Table 1, under the same conditions of other materials and operations for preparing a battery, the battery obtained in example 1 has excellent quick-charge performance and gram capacity, while the particle diameter D50 of the artificial graphite A used in comparative example 1 is less than 8 μm, the particle diameter of the artificial graphite A used in comparative example 2 is greater than 10 μm, the graphitization degree of the artificial graphite A used in comparative example 3 is less than 90%, and the tap density of the artificial graphite A used in comparative example 4 is less than 0.95g/cm 3 The tap density of the artificial graphite A used in comparative example 5 was > 1.05g/cm 3 The fast charge performance of the battery thus obtained was significantly lower than that of example 1. From this, it is demonstrated that the battery provided in example 1 employs a specific graphite-based negative electrode active material as a negative electrode active material, which enables rapid intercalation and deintercalation of lithium ions into and from the surface of the graphite-based negative electrode active material by simultaneously controlling the particle diameter, graphitization degree and tap density of the artificial graphite a, thereby improving the lithium ion transport kinetics and rapid charging performance of the battery, relative to comparative examples 1 to 5.
The performance test results of example 1 and example 2 were compared. As can be seen from table 1, the graphite-based negative electrode active material used in example 2 does not include artificial graphite B under the same conditions as other materials and operations for preparing a battery, and thus the gram capacity of the negative electrode active material obtained is lower than that of example 1. It is thus demonstrated that the battery provided in example 1, compared to example 2, has an advantage of higher compacted density by using a graphite-based anode active material including a specific artificial graphite B as an anode active material, and is advantageous in that artificial graphite a is filled in the voids of artificial graphite B, increasing the compacted density of the anode active material, thereby increasing its gram capacity.
The results of the performance tests of example 1 and examples 3 to 5 were compared. As can be seen from table 1, the mass of the artificial graphite a in the negative electrode active material used in example 3 was as follows: the mass of the artificial graphite B is less than 30-40:60-70, and the quick charge performance of the obtained battery is slightly lower than that of the battery in the embodiment 1; mass of artificial graphite a in the negative electrode active material used in example 5: the mass of the artificial graphite B is more than 30-40:60-70, and the gram capacity of the negative electrode active material obtained by the method is slightly lower than that of the example 1. From this, it is demonstrated that, compared to examples 3 and 5, the batteries provided in examples 1 and 4 have improved the gram capacity of the negative electrode active material and the quick charge performance of the battery by properly setting the mass ratio of the artificial graphite a and the artificial graphite B in the negative electrode active material, so that the smooth artificial graphite a is sufficiently dispersed between the gaps of the artificial graphite B, the compaction density of the negative electrode active material is improved, and further, the artificial graphite a and the artificial graphite B exert the synergistic advantages of both.
The results of the performance tests of example 1 and examples 6 to 7 were compared. As is clear from Table 1, the particle size of the artificial graphite B used in example 6 was < 11 μm, the particle size of the artificial graphite B used in example 7 was > 14 μm, and the gram capacity of the negative electrode active material obtained therefrom was slightly lower than that of example 1, and the quick-charge performance of the battery obtained therefrom was slightly lower than that of example 1, under the same conditions as other materials and operations for preparing a battery. From this, it is demonstrated that, compared to examples 6 to 7, the battery provided in example 1 is advantageous in that smooth artificial graphite a is filled between gaps of artificial graphite B by using artificial graphite B having a suitable particle diameter as a component of the negative electrode active material, the compacted density of the graphite-based negative electrode active material is improved, and at the same time, the synergistic advantages of both artificial graphite a and artificial graphite B are sufficiently exerted, thereby improving the gram capacity of the negative electrode active material and the quick charge performance of the battery.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention, but these modifications or substitutions are all within the scope of the present invention.
Claims (10)
1. The graphite-based negative electrode active material is characterized by comprising artificial graphite A, wherein the artificial graphite A is primary particles, the particle size D50 of the artificial graphite A is 8-10 mu m, the graphitization degree of the artificial graphite A is 90-93%, and the tap density of the artificial graphite A is 0.95-1.05 g/cm 3 。
2. The graphite-based anode active material according to claim 1, wherein the method for preparing artificial graphite a comprises the following operations: and taking raw coke as a raw material, carrying out graphitization treatment on the raw material to obtain graphitized particles A, and coating and carbonizing the graphitized particles A by adopting a coating agent to obtain the artificial graphite A.
3. The graphite-based anode active material according to claim 2, wherein the true density of the green coke is > 2.1g/cm 3 。
4. The graphite-based negative electrode active material according to claim 1, further comprising artificial graphite B, wherein the artificial graphite B is a secondary particle, the particle diameter D50 of the artificial graphite B is 11 to 14 μm, and the graphitization degree of the artificial graphite B is 93 to 94%;
the mass ratio of the artificial graphite A to the artificial graphite B is 30-40: 60 to 70.
5. The graphite-based anode active material according to claim 4, wherein the method for preparing the artificial graphite B comprises the following operations:
s1, taking needle coke as a raw material, mixing an auxiliary material binder with the raw material, and granulating to obtain a semi-finished product;
s2, graphitizing the semi-finished product to obtain graphitized particles;
s3, coating and carbonizing the graphitized particles by adopting a coating agent, thereby preparing the artificial graphite B.
6. The graphite-based anode active material according to claim 5, wherein the particle diameter of the needle coke is not more than 8 μm and the tap density is not less than 0.75g/cm 3 。
7. The graphite-based anode active material according to claim 5, wherein in S1, the granulating temperature is 800 to 900 ℃ and the granulating time is 6 to 8 hours.
8. The graphite-based anode active material of claim 5, wherein the mass ratio of said coating agent to said graphitized particles is 3 to 8:100.
9. A negative electrode sheet comprising a negative electrode current collector and a negative electrode active coating layer provided on a surface of the negative electrode current collector, wherein the negative electrode active material contained in the negative electrode active coating layer comprises the graphite-based negative electrode active material according to any one of claims 1 to 8.
10. The negative electrode sheet according to claim 9, wherein the negative electrode active coating has a compacted density of 1.76g/cm or more 3 。
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