CN116588923A - Quick-charge graphite, preparation method thereof, negative plate and battery - Google Patents
Quick-charge graphite, preparation method thereof, negative plate and battery Download PDFInfo
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- CN116588923A CN116588923A CN202310235786.4A CN202310235786A CN116588923A CN 116588923 A CN116588923 A CN 116588923A CN 202310235786 A CN202310235786 A CN 202310235786A CN 116588923 A CN116588923 A CN 116588923A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 95
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 56
- 239000010439 graphite Substances 0.000 title claims abstract description 56
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 69
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 36
- 238000007600 charging Methods 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 17
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 16
- 238000001035 drying Methods 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 238000007493 shaping process Methods 0.000 claims abstract description 11
- 239000007773 negative electrode material Substances 0.000 claims abstract description 9
- 239000002612 dispersion medium Substances 0.000 claims abstract description 8
- 239000011230 binding agent Substances 0.000 claims abstract description 7
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 7
- 239000004814 polyurethane Substances 0.000 claims description 24
- 229920002635 polyurethane Polymers 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 24
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 18
- 239000003792 electrolyte Substances 0.000 claims description 14
- 239000011331 needle coke Substances 0.000 claims description 7
- 239000011347 resin Substances 0.000 claims description 7
- 229920005989 resin Polymers 0.000 claims description 7
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 6
- 239000003502 gasoline Substances 0.000 claims description 6
- 239000003350 kerosene Substances 0.000 claims description 6
- 239000005011 phenolic resin Substances 0.000 claims description 6
- 229920001568 phenolic resin Polymers 0.000 claims description 6
- 238000011049 filling Methods 0.000 claims description 5
- 239000011233 carbonaceous binding agent Substances 0.000 claims description 4
- 239000002006 petroleum coke Substances 0.000 claims description 4
- 239000006253 pitch coke Substances 0.000 claims description 3
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 claims description 2
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 claims description 2
- 239000003822 epoxy resin Substances 0.000 claims description 2
- 239000007849 furan resin Substances 0.000 claims description 2
- 229910003002 lithium salt Inorganic materials 0.000 claims description 2
- 159000000002 lithium salts Chemical class 0.000 claims description 2
- 229910021382 natural graphite Inorganic materials 0.000 claims description 2
- 229920000647 polyepoxide Polymers 0.000 claims description 2
- 159000000000 sodium salts Chemical class 0.000 claims description 2
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 claims description 2
- 238000005087 graphitization Methods 0.000 abstract description 13
- 238000005469 granulation Methods 0.000 abstract description 5
- 230000003179 granulation Effects 0.000 abstract description 5
- 239000012615 aggregate Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 14
- 239000011248 coating agent Substances 0.000 description 12
- 238000000576 coating method Methods 0.000 description 12
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- 229910052744 lithium Inorganic materials 0.000 description 8
- 238000003756 stirring Methods 0.000 description 7
- 239000010426 asphalt Substances 0.000 description 5
- 238000000498 ball milling Methods 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000008187 granular material Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012216 screening Methods 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 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
- 238000010277 constant-current charging Methods 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 229910021385 hard carbon Inorganic materials 0.000 description 2
- 150000003949 imides Chemical class 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- C01B32/21—After-treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- 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
-
- 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 discloses quick-charge graphite and a preparation method thereof, a negative plate and a battery, wherein the preparation method of the quick-charge graphite comprises the following steps: crushing and shaping carbon materials to obtain aggregate, uniformly mixing the aggregate with a carbon-containing binder and a dispersion medium, and sequentially carrying out granulation, graphitization treatment and spheroidization shaping to obtain graphitized particles; then mixing graphitized particles with a carbon source, and heating under an inert atmosphere to carbonize and coat the graphitized particles with carbon to prepare carbon-coated particles; and dispersing the carbon-coated particles in an electrolyte solution, and drying to obtain the quick-charging graphite. The quick-charge graphite prepared by the method has higher thermal stability, can improve the safety performance and the cycle stability of the battery, is applied to the negative electrode active material layer material on the negative electrode plate of the battery, and can give consideration to the normal temperature and high temperature performance of the battery.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to quick-charge graphite, a preparation method thereof, a negative plate and a battery.
Background
Lithium ion batteries are increasingly becoming the preferred power supply products for electronic devices in people's lives due to their long life, high energy density, and high safety factor. Nowadays, the requirements of fast-paced life on the charging rate of a lithium ion battery are higher and higher, and a graphite negative electrode is used as a key component of the lithium ion battery, so that the charging rate is obviously improved.
The existing research can improve the graphite material from the coating and particle size to improve the charging multiplying power, and the methods of coating by resin/conductive agent, increasing the coating amount and reducing the particle size of aggregate are commonly used at present. However, these methods generally have problems of increased specific surface area and increased side reactions, and further deteriorate high temperature performance, and cannot achieve both normal temperature cycle and high temperature cycle life.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides quick-charge graphite, a preparation method thereof, a negative plate and a battery.
In a first aspect of the present invention, a method for preparing quick-charge graphite is provided, comprising the following steps:
s1, crushing and shaping a carbon material to prepare aggregate;
s2, uniformly mixing the aggregate with a carbon-containing binder and a dispersion medium, and sequentially granulating, graphitizing and spheroidizing to obtain graphitized particles;
s3, mixing the graphitized particles with a carbon source, and performing heating treatment in an inert atmosphere to carbonize and coat the graphitized particles by the carbon source to obtain carbon-coated particles;
s4, dispersing the carbon-coated particles in an electrolyte solution, and drying to obtain the quick-charging graphite.
The preparation method of the quick graphite filling provided by the embodiment of the invention has at least the following beneficial effects: in the preparation method, the carbon material is crushed and shaped to prepare aggregate, then the aggregate is uniformly mixed with a carbon-containing binder and a dispersion medium to prepare a mixture, after granulation and graphitization treatment, the mixture is further subjected to spheroidization and shaping to prepare graphitized particles, and sharp edges and corners of the particles can be removed through spheroidization and shaping after graphitization treatment, so that the particles are more round, tip side reaction active sites can be reduced, and the high-temperature performance is improved; then mixing the graphitized particles with a carbon source, and heating the mixture in an inert atmosphere until the carbon source is carbonized to coat the graphitized particles so as to modify the surfaces of the graphitized particles, thereby providing more lithium intercalation paths and improving the rate capability; and then dispersing the carbon-coated particles in an electrolyte solution, and drying to further coat the electrolyte on the surface of the carbon-coated particles, so that the thermal stability of the material surface can be improved, the safety performance and the cycle performance of the battery can be improved, and the prepared quick-charge graphite can be applied to a negative electrode active material layer material on a negative electrode plate of the battery and can give consideration to the normal temperature and high temperature performance of the battery.
In some embodiments of the present invention, in step S1, the carbonaceous material is selected from at least one of needle coke, petroleum coke, pitch coke, and natural graphite.
In some embodiments of the invention, in step S1, the aggregate has a particle size Dv50 of (5-7) ±3 μm. Step S1 may specifically include: crushing, fine grinding, ball milling and shaping the carbon material, and sieving to obtain aggregate with target particle size. By adopting the aggregate granulation with small particle size, the OI value (namely the orientation degree) can be reduced, the normal-temperature cyclic expansion can be reduced, and the battery performance can be further improved.
In step S2, the carbonaceous binder may act as a binder, and after the subsequent graphitization treatment, a carbon skeleton may be formed between the particles, firmly binding the particles together. In some embodiments of the invention, in step S2, the carbonaceous binder is selected from pitch.
In some embodiments of the present invention, in step S2, the dispersion medium is selected from at least one of gasoline, kerosene, benzene. For example, a combination of gasoline, kerosene and benzene can be used as the dispersion medium, and the mass ratio of aggregate, carbonaceous binder, gasoline, kerosene and benzene can be controlled to be (100-200): (5-15): (5-10): (1-5): (1-2); specifically, the aggregate, the carbon-containing binder and the dispersion medium are mixed, and then the temperature is increased to 150-200 ℃ and the mixture is obtained by stirring uniformly.
In some embodiments of the invention, in step S2, the graphitization temperature is 2500 to 3000 ℃. The graphitization treatment time can be controlled to be 12-60 h.
In some embodiments of the present invention, in step S3, the carbon source is selected from a resin material; preferably, the carbon source is selected from at least one of rosin, alpha-terpene resin, beta-terpene resin, phenolic resin, epoxy resin, furan resin.
In some embodiments of the present invention, in step S3, the heating temperature may be controlled to 250 to 300 ℃ and the heating time may be controlled to 0.5 to 5 hours.
In some embodiments of the present invention, in step S4, the components of the electrolyte solution include a polyurethane solution, an electrolyte; preferably, the electrolyte is selected from at least one of lithium salt and sodium salt. The electrolyte solution can be prepared by mixing polyurethane with a solvent to prepare a polyurethane solution and then mixing the polyurethane solution with the electrolyte. Wherein, the mass concentration of the polyurethane solution can be controlled to be 10-30%, and the mass ratio of the polyurethane solution to the electrolyte can be controlled to be 1: (0.3-1), and N, N-dimethylformamide can be used as the solvent of the polyurethane solution. The polyurethane solution and the electrolyte can be fully and uniformly stirred at 30-70 ℃. The polyurethane has better hardness, tensile property and heat resistance, and can effectively inhibit the growth of metal salt crystal branches, thereby improving the conductivity of electrolyte membranes and the thermal stability of quick graphite filling.
In a second aspect of the present invention, a quick-charge graphite is provided, which is produced by any one of the methods for producing quick-charge graphite provided in the first aspect of the present invention.
According to a third aspect of the invention, a negative electrode sheet is provided, which comprises a negative electrode current collector and a negative electrode active material layer covered on the surface of the negative electrode current collector, wherein the material of the negative electrode active material layer comprises any of the quick-charging graphite provided in the second aspect of the invention.
In a fourth aspect of the present invention, a battery is provided, which includes any one of the negative electrode sheets set forth in the first aspect of the present invention.
Detailed Description
The conception and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present invention. It is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present invention based on the embodiments of the present invention.
Example 1
The preparation method of the quick-charging graphite comprises the following steps:
s1, carrying out coarse crushing and fine grinding on needle coke, carrying out ball milling shaping treatment by using a ball mill, and screening to obtain aggregate with the Dv50 particle size of 6+/-3 mu;
s2, adding 100g of the aggregate obtained in the step S1 into an asphalt solution containing 50g of asphalt, 100g of gasoline, 5g of kerosene and 2g of industrial benzene, and then raising the temperature of the solution to 150 ℃ and continuously and uniformly stirring to obtain a mixed solution;
s3, transferring the mixed feed liquid obtained in the step S2 into a sprayer, connecting a nozzle of the sprayer with a drying tower, heating the drying tower to 200 ℃, generating powdery small particles in the drying tower by liquid sprayed by the sprayer, discharging the small particles into a mechanical fusion machine after the small particles are lowered, and granulating to obtain particles;
s4, placing the granules obtained by granulating in the step S3 into a graphitization furnace, and graphitizing at 2500 ℃ for 60 hours; transferring the particles into a ball milling shaper for spheroidizing shaping to remove sharp edges and corners of the particles, rounding the particles, and reducing tip active sites to prepare graphitized particles;
s5, mixing the graphitized particles obtained in the step S4 with phenolic resin, and heating to 250 ℃ in an inert atmosphere for 5 hours to carbonize the phenolic resin to coat the graphitized particles so as to obtain carbon-coated particles;
s6, mixing polyurethane with N, N-dimethylformamide to prepare polyurethane solution with the mass concentration of 10%, and then mixing the polyurethane solution with the mass ratio of 1:0.3, mixing the polyurethane solution with lithium bistrifluoromethylsulfonyl imide, and fully and uniformly stirring at 50 ℃ to obtain an electrolyte solution; and (3) adding the carbon-coated particles prepared in the step (S5) into an electrolyte solution, stirring and dispersing the particles uniformly by magnetic force, drying the particles, and screening the particles to obtain the quick-charging graphite with the particle size Dv50 of 8+/-3 mu m.
Example 2
This example produced a fast charge graphite, which differs from example 1 in that: in this example, step S1 was performed using petroleum coke instead of needle coke used in step S1 of example 1, and the other operations were the same as in example 1.
Example 3
This example produced a fast charge graphite, which differs from example 1 in that: in this example, pitch coke was used in step S1 instead of needle coke used in step S1 of example 1, and the other operations were the same as in example 1.
Example 4
This example produced a fast charge graphite, which differs from example 1 in that: in this embodiment, the mass ratio of the polyurethane solution to lithium bistrifluoromethylsulfonylimide in the electrolyte solution preparation process in step S6 was adjusted from 1:0.3 to 1:0.5 in example 1, and the other operations were the same as in example 1.
Example 5
This example produced a fast charge graphite, which differs from example 1 in that: in this embodiment, the mass ratio of the polyurethane solution to lithium bistrifluoromethylsulfonylimide in the electrolyte solution preparation process in step S6 was adjusted from 1:0.3 to 1:0.8 in example 1, and the other operations were the same as in example 1.
Example 6
This example produced a fast charge graphite, which differs from example 1 in that: in this embodiment, the mass concentration of the polyurethane solution prepared in step S6 was adjusted from 10% to 20% in example 1, and the other operations were the same as in example 1.
Example 7
This example produced a fast charge graphite, which differs from example 1 in that: in this embodiment, the mass concentration of the polyurethane solution prepared in step S6 was adjusted from 10% to 30% in example 1, and the other operations were the same as in example 1.
Comparative example 1
This comparative example, which differs from example 1 in that a quick charge graphite was prepared: in this comparative example, the electrolyte coating operation in step S6 of example 1 was omitted, and specifically, after carbon-coated pellets were produced by the operations in steps S1 to S5 of example 1, they were directly sieved to obtain quick-charging graphite having a particle diameter Dv50 of 8±3 μm.
Comparative example 2
This comparative example, which differs from example 1 in that a quick charge graphite was prepared: in this comparative example, the operation sequence of graphitization treatment and hard carbon coating was adjusted, specifically, the hard carbon coating operation was performed first after the completion of granulation, followed by graphitization treatment. The preparation method of the fast-charging graphite of the comparative example comprises the following steps:
s1, carrying out coarse crushing and fine grinding on needle coke, carrying out ball milling shaping treatment by using a ball mill, and screening to obtain aggregate with the Dv50 particle size of 6+/-3 mu;
s2, adding 100g of the aggregate obtained in the step S1 into an asphalt solution containing 50g of asphalt, 100g of gasoline, 5g of kerosene and 2g of industrial benzene, and then raising the temperature of the solution to 150 ℃ and continuously and uniformly stirring to obtain a mixed solution;
s3, transferring the mixed feed liquid obtained in the step S2 into a sprayer, connecting a nozzle of the sprayer with a drying tower, heating the drying tower to 200 ℃, generating powdery small particles in the drying tower by liquid sprayed by the sprayer, discharging the small particles into a mechanical fusion machine after the small particles are lowered, and granulating to obtain particles;
s4, mixing the particles obtained by granulating in the step S3 with phenolic resin, and heating to 250 ℃ in an inert atmosphere for 5 hours to carbonize and coat the phenolic resin to obtain carbon-coated particles;
s5, placing the carbon-coated particles prepared in the step S4 into a graphitization furnace, and graphitizing at 2500 ℃ for 60 hours; transferring the particles into a ball milling shaper for spheroidizing shaping to remove sharp edges and corners of the particles, rounding the particles, and reducing tip active sites to prepare graphitized particles;
s6, mixing polyurethane with N, N-dimethylformamide to prepare polyurethane solution with the mass concentration of 10%, wherein the mass ratio is 1:0.3, mixing the polyurethane solution with lithium bistrifluoromethylsulfonyl imide, and fully and uniformly stirring at 50 ℃ to obtain an electrolyte solution; and (3) adding the graphitized particles prepared in the step (S5) into an electrolyte solution, stirring and dispersing the graphitized particles uniformly by magnetic force, drying the graphitized particles, and screening the graphitized particles to obtain the quick-charging graphite with the particle size D50 of 8+/-3 mu m.
Application example
The quick-charge graphite prepared in each of the examples and comparative examples can be further used for preparing a negative plate, and then assembled into a battery. The preparation method of the electrode slice and the battery comprises the following steps: mixing 97wt% of quick-charge graphite with 1.5wt% of conductive carbon black and 1.5wt% of polyvinylidene fluoride, adding a proper amount of N-methyl pyrrolidone to prepare negative electrode active material slurry, coating the negative electrode active material slurry on a copper foil current collector, putting the coated sample into a vacuum oven at 80 ℃ for drying for 12 hours, and forming a negative electrode active material layer on the surface of the copper foil current collector to prepare a negative electrode plate. Then with 1mol/L LiPF 6 As the electrode liquid, ethylene Carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) are adopted as the solvent in a volume ratio of 1:1:1; and the metal lithium sheet is used as a counter electrode, and the PP/PE composite film is used as a diaphragm, so that the battery is assembled.
The negative electrode sheets were prepared by using the quick-charge graphites prepared in examples 1 to 7 and comparative examples 1 to 2, respectively, according to the above method, and then assembled into batteries, which were designated as batteries c#1 to c#9, respectively. In order to examine the performance of each quick-charge graphite, the performance of each prepared battery is further tested, and the specific test method is as follows:
(1) First discharge capacity and first efficiency: the test conditions for the first discharge capacity were that discharge was carried out at 0.05C to 0.005V at normal temperature (25 ℃); the test conditions for the first charge capacity were that discharge was carried out at 0.1C to 2V at normal temperature (25 ℃); calculating the first efficiency according to the first efficiency = first discharge capacity/first charge capacity;
(2) Expansion rate after normal temperature cycle of 500 weeks: charging the battery to 2V at constant current and constant voltage at a multiplying power of 5C at normal temperature (25 ℃), cutting off current of 0.05C, discharging to 0.005V at a multiplying power of 0.1C, and performing 500-week circulation; then, the expansion ratio at room temperature after 500 cycles was calculated as the thickness expansion ratio (%) = (the thickness after 500 cycles-the initial thickness before cycles)/the initial thickness before cycles x 100%;
(3) 5C multiplying power constant current charging ratio: discharging the battery, charging the battery to 1V at constant current and constant voltage of 5C multiplying power at normal temperature (25 ℃), and taking the capacity of a charging constant current section/the capacity of a constant current constant voltage section;
(4) Thermal shock resistance: placing the fully charged battery into an incubator, raising the temperature of the incubator at a heating rate of 5 ℃/min, and detecting at what temperature the battery can explode;
(5) Capacity retention rate at 45 ℃ for 500 weeks: charging the battery to 1V at a constant current and constant voltage of multiplying power of 5C at 45 ℃, cutting off current of 0.05C, discharging to 0.005V at multiplying power of 0.1C, and performing 500-week circulation; then, the 500-cycle capacity retention rate at 45 ℃ was calculated as 500-cycle capacity retention rate (%) = (500-cycle discharge capacity/first-cycle discharge capacity) ×100%.
Batteries prepared using the fast-charge graphite of each example and comparative example were tested according to the above methods, and the results are shown in tables 1 and 2.
TABLE 1
| Battery cell | Quick-charging graphite | First discharge capacity | First time efficiency | Expansion rate of 500 weeks in normal temperature cycle | 5C multiplying power constant current charging ratio |
| Battery C#1 | Example 1 | 356 | 94.5 | 6.0％ | 85.0％ |
| Battery C#2 | Example 2 | 352 | 93.0 | 7.3％ | 80.3％ |
| Battery C#3 | Example 3 | 349 | 91.3 | 8.7％ | 78.5％ |
| Battery C#9 | Comparative example 2 | 356 | 94.2 | 7.5％ | 83.1％ |
TABLE 2
According to table 1, comparing the batteries c#1 to c#3 prepared by using the fast-charging graphite of examples 1 to 3, it can be seen that the fast-charging graphene is prepared by using the needle coke as a raw material, and the prepared battery has higher first discharge capacity and first efficiency, and has better charging capability, compared with the batteries prepared by using petroleum coke and asphalt coke as raw materials. Comparing the battery C#1 with the battery C#9, wherein the battery C#1 adopts the quick-charge graphite prepared in the embodiment 1, particles are subjected to graphitization treatment and then carbon coating after granulation in the preparation process of the quick-charge graphite in the embodiment 1, a carbon-containing binder among particles can be converted into a graphite structure in the graphitization treatment process, the structure is stable, the circulation process can not be dispersed, and then the carbon coating treatment is performed to modify the carbon coating layer on the surface of the graphitized particles, so that more lithium intercalation paths can be provided, and the quick-charge rate performance is improved; and the battery C#9 adopts the quick graphite filling prepared in the comparative example 2, after the granules are prepared in the preparation process of the quick graphite filling in the comparative example 2, the granules are coated with carbon, and then graphitized, wherein the carbon coating on the surfaces of the granules is graphitized together in the graphitization process, so that the ordered structure of the graphite layers is changed, and further, the deintercalated lithium can only enter from the end face of the graphite, so that the charging capability is greatly reduced.
From table 2, it is known that, when comparing the battery c#1, the battery c#4, and the battery c#5 prepared by using the quick-charge graphites of examples 1, 4, and 5, respectively, the increase of the proportion of the electrolyte in the electrolyte solution for the electrolyte coating during the preparation of the quick-charge graphites can improve the charging ability of the quick-charge graphites, but can result in a decrease of the high temperature performance to some extent, and, in combination, the battery C4# prepared by using the quick-charge graphites of example 4 has a higher combination of the high temperature safety performance and the charging ability. Comparing the battery C#1, the battery C#6 and the battery C#7 prepared by respectively adopting the quick-charging graphite of the embodiments 1, 6 and 7, specifically, comparing the battery C#1 and the battery C#6, it can be known that the concentration of the polyurethane solution for preparing the electrolyte solution is improved from 10% to 20%, the high-temperature safety performance of the battery is improved, the high-temperature cycle performance is also improved, but the constant current ratio is reduced; further comparing the battery C#6 and the battery C#7, it is known that the concentration of the polyurethane solution is increased from 20% to 30%, the safety performance of the battery is not increased any more, the high-temperature cycle performance is not obviously increased, and further, the mass concentration of the polyurethane solution can be controlled to 10-30% by comprehensively considering. Compared with the battery C#1 and the battery C#8, compared with the battery C#8 adopting the comparative example 1 to rapidly charge graphite (without electrolyte coating), the battery C#1 adopting the example 1 to rapidly charge graphite has obviously improved thermal shock resistance and high-temperature cycle performance, and the charging capacity is reduced to a certain extent, but in actual preparation, the charging capacity of the rapidly-charged graphite can be compensated by increasing the proportion of electrolyte in electrolyte solution, so that the charging rate level is further improved.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (10)
1. The preparation method of the quick-filling graphite is characterized by comprising the following steps of:
s1, crushing and shaping a carbon material to prepare aggregate;
s2, uniformly mixing the aggregate with a carbon-containing binder and a dispersion medium, and sequentially granulating, graphitizing and spheroidizing to obtain graphitized particles;
s3, mixing the graphitized particles with a carbon source, and performing heating treatment in an inert atmosphere to carbonize and coat the graphitized particles with the carbon source to obtain carbon-coated particles;
s4, dispersing the carbon-coated particles in an electrolyte solution, and drying to obtain the quick-charging graphite.
2. The method for preparing quick charge graphite as set forth in claim 1, wherein in step S1, the carbonaceous material is at least one selected from needle coke, petroleum coke, pitch coke, and natural graphite.
3. The method of producing quick graphite according to claim 1, wherein in step S1, the aggregate has a particle diameter Dv50 of (5 to 7) ± 3 μm.
4. The method of claim 1, wherein in step S2, the carbonaceous binder is selected from pitch.
5. The method for preparing quick charge graphite as set forth in claim 1, wherein in step S2, the dispersion medium is at least one selected from the group consisting of gasoline, kerosene, and benzene.
6. The method of preparing quick charge graphite according to claim 1, wherein in step S3, the carbon source is selected from the group consisting of resin materials; preferably, the carbon source is selected from at least one of rosin, alpha-terpene resin, beta-terpene resin, phenolic resin, epoxy resin, furan resin.
7. The method of preparing quick graphite according to any one of claims 1 to 6, wherein in step S4, the components of the electrolyte solution include a polyurethane solution, an electrolyte; preferably, the electrolyte is selected from at least one of lithium salt and sodium salt.
8. A quick charge graphite produced by the method of producing a quick charge graphite as claimed in any one of claims 1 to 7.
9. A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector, wherein the material of the negative electrode active material layer comprises the quick-charging graphite as claimed in claim 8.
10. A battery comprising the negative electrode sheet according to claim 9.
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