CN112830482B - Graphite coating agent, coated modified graphite material, battery and preparation and application thereof - Google Patents
Graphite coating agent, coated modified graphite material, battery and preparation and application thereof Download PDFInfo
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- CN112830482B CN112830482B CN202011624865.7A CN202011624865A CN112830482B CN 112830482 B CN112830482 B CN 112830482B CN 202011624865 A CN202011624865 A CN 202011624865A CN 112830482 B CN112830482 B CN 112830482B
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 115
- 239000007770 graphite material Substances 0.000 title claims abstract description 53
- 239000011248 coating agent Substances 0.000 title claims abstract description 41
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 37
- 239000010439 graphite Substances 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 238000010438 heat treatment Methods 0.000 claims abstract description 65
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 30
- 125000003118 aryl group Chemical group 0.000 claims abstract description 25
- 239000007773 negative electrode material Substances 0.000 claims abstract description 12
- 239000012298 atmosphere Substances 0.000 claims abstract description 6
- 230000001681 protective effect Effects 0.000 claims abstract description 6
- 238000003763 carbonization Methods 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 20
- 238000000605 extraction Methods 0.000 claims description 16
- 239000012535 impurity Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 16
- 238000004523 catalytic cracking Methods 0.000 claims description 14
- 239000002002 slurry Substances 0.000 claims description 14
- 239000002904 solvent Substances 0.000 claims description 11
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical group O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 claims description 10
- 238000000576 coating method Methods 0.000 claims description 9
- 239000000084 colloidal system Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 239000011229 interlayer Substances 0.000 claims description 7
- 150000001491 aromatic compounds Chemical class 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 2
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 2
- 230000006837 decompression Effects 0.000 claims 3
- 238000004519 manufacturing process Methods 0.000 claims 2
- 238000010000 carbonizing Methods 0.000 claims 1
- 229910052757 nitrogen Inorganic materials 0.000 claims 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 9
- 239000010406 cathode material Substances 0.000 description 7
- 238000007599 discharging Methods 0.000 description 6
- 238000013461 design Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000227 grinding Methods 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000012299 nitrogen atmosphere Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000002969 artificial stone Substances 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 241000446313 Lamella Species 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 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
- 238000011161 development Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000009818 secondary granulation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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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
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention discloses a graphite coating agent, a coated modified graphite material, a battery, and preparation and application thereof. The preparation method of the graphite coating agent comprises the following steps: and (3) carrying out reduced pressure heat treatment, pressure heat treatment and crushing on the aromatic-rich fraction under a protective atmosphere. Preparing a coated modified graphite material by using the graphite coating agent; the lithium ion battery prepared by taking the coated modified graphite material as a negative electrode material has good rate capability, good quick charging performance and excellent cycle performance; when the lithium ion battery is used as a power battery in the field of passenger vehicles, the lithium ion battery can meet the requirement of quick charging.
Description
Technical Field
The invention relates to a graphite coating agent, a coated modified graphite material, a battery, and preparation and application thereof.
Background
The graphite serving as the cathode material of the conventional lithium ion battery has the advantages of low charge-discharge voltage platform, high cycle stability, low cost and the like; with the huge demand of the market on the fast-charging pure electric vehicles and the subsidy of the countries on the fast-charging electric vehicles, the electric vehicles are required to have long endurance and fast charge and discharge performance, but the interlayer spacing of the graphite material is small, the charging of high-rate current cannot be met, the lithium separation phenomenon easily occurs, and the capacity and the safety performance of the battery are seriously influenced.
The main route for improving the multiplying power performance of the graphite material comprises particle design and surface coating, wherein the particle design comprises small granulation and secondary granulation, and the quick charging performance is improved mainly by shortening a transmission path of lithium ions and increasing a transmission channel of the lithium ions; the surface coating is to form amorphous carbon on the graphite surface, so that the interlamellar spacing of carbon layers on the graphite surface is increased, the transfer resistance and the transmission channel of lithium ions on the graphite surface are reduced, and the quick charging performance is improved. However, at present, the effect of improving the quick charging performance of the lithium ion battery cathode material prepared by the particle design and surface coating method is still limited; for example, the affinity of the resin coating agent to graphite is poor, and uneven coating is likely to occur; when asphalt is used as a coating agent, the coating is carbonized to easily cause agglomeration, the rate capability of the prepared negative electrode material also has improved space, the orientation degree of a lamella is large and is generally between 10 and 15, and the demand of a fast-charging electric vehicle cannot be met.
Therefore, the development of a lithium ion battery cathode material with ideal rate performance, good cycle performance and simple preparation process is urgently needed in the field.
Disclosure of Invention
The invention aims to overcome the defects that the improvement effect of the quick charging performance of a lithium ion battery cathode material prepared by a particle design and surface coating method in the prior art is still limited and cannot meet the requirements of a quick-charging electric vehicle, and provides a graphite coating agent, a coated modified graphite material, a battery, and preparation and application thereof. Preparing a coated modified graphite material by using the graphite coating agent; the lithium ion battery prepared by taking the coated modified graphite material as a negative electrode material has good rate performance, good quick charging performance and excellent cycle performance; when the lithium ion battery is used as a power battery in the field of passenger vehicles, the lithium ion battery can meet the requirement of quick charging.
The invention solves the technical problems through the following technical scheme.
The invention provides a preparation method of a graphite coating agent, which comprises the following steps: and (3) carrying out reduced pressure heat treatment, pressure heat treatment and crushing on the aromatic-rich fraction under a protective atmosphere.
In the present invention, the aromatic-rich fraction includes aromatic compounds.
Wherein, in the aromatic-rich fraction, the mass percent of the aromatic hydrocarbon compounds is more than 90%.
In the invention, the aromatic-rich fraction can further comprise colloid, asphaltene and impurities.
Wherein, the total mass percentage of the colloid and the asphaltene can be less than or equal to 3.5 percent, and is preferably 3 to 3.2 percent.
The impurities may be those conventionally produced in the preparation of the aromatic-rich fraction, and may typically be metals.
Wherein, the mass percentage of the impurities can be less than or equal to 1%, preferably 0.5-0.6%, for example 0.55%.
In the present invention, the preparation method of the aromatic-rich fraction can be conventional in the art, and generally comprises the following steps of performing multi-stage extraction on the catalytic cracking slurry oil by using a solvent.
The catalytic cracking slurry oil can be catalytic cracking slurry oil conventionally used in the field, and can be catalytic cracking slurry oil generally produced by Jinzhou petrochemical company, yida petrochemical company, daqing petrochemical company, fushun petrochemical company or Liaohe oil field company of Chinese petroleum.
Wherein, the solvent can be a solvent which is conventionally used in the operation of the type in the field, and can be furfural and/or N-methyl pyrrolidone generally.
Wherein the mass ratio of the solvent to the catalytic cracking slurry oil can be conventional in the field, and is preferably (0.5-2): 1, more preferably (1 to 2): 1.
the conditions and methods of the multistage extraction may be those conventional in such operations in the art, and may generally be carried out in an extraction column.
Wherein, the temperature of the multistage extraction can be the temperature which is conventional in the operation in the field, preferably 30-100 ℃, and more preferably 50-60 ℃.
In the present invention, the protective atmosphere may be a protective atmosphere that is not chemically reacted with the aromatic-rich fraction, and may be nitrogen gas.
In the present invention, the conditions and methods of the reduced-pressure heat treatment may be those conventional in such operations in the art, and may be generally carried out in an autoclave.
In the present invention, the reduced pressure heat treatment can be performed under stirring conditions according to the conventional operation in the field, and the stirring rotation speed can be the rotation speed of the conventional operation in the field, and is preferably 100 to 400r/min, and more preferably 100 to 350r/min.
In the present invention, the temperature of the reduced pressure heat treatment may be a temperature conventional in the art, and is preferably 370 to 420 ℃, and more preferably 370 to 390 ℃.
In the present invention, the heating rate of the reduced pressure heat treatment may be a heating rate conventional in the field, and may be generally less than or equal to 3 ℃/min, preferably 1-3 ℃/min.
In the present invention, the time of the reduced pressure heat treatment may be a time conventionally used in such operations in the art, and is preferably 3 to 20 hours, more preferably 3 to 10 hours, and further more preferably 4 to 10 hours.
In the present invention, the pressure of the reduced-pressure heat treatment may be a pressure conventionally used in such operations in the art, and is preferably 0.1 to 0.3MPa, more preferably 0.2 to 0.3MPa.
In the present invention, the conditions and methods of the pressure heat treatment may be those conventional in such operations in the art, and may be generally carried out in an autoclave.
In the present invention, the pressure heat treatment may be performed under stirring conditions according to the conventional techniques in the art, and the stirring speed may be the speed conventional to such operations in the art, and is preferably 100 to 400r/min, and is more preferably 100 to 350r/min.
In the present invention, the temperature of the pressure heat treatment may be a temperature conventional in the art, and is preferably 380 to 420 ℃, and more preferably 390 to 410 ℃.
In the present invention, the heating rate of the pressure heat treatment may be a heating rate conventional in the art, and may be generally less than or equal to 3 ℃/min, preferably 1-3 ℃/min, and more preferably 2-3 ℃/min.
In the present invention, the time of the pressure heat treatment may be a time conventional in the art, and is preferably 4 to 20 hours, and more preferably 15 to 20 hours.
In the present invention, the pressure of the pressure heat treatment may be a pressure conventionally used in such operations in the art, and is preferably 2 to 3.5MPa, more preferably 2.5 to 3.5MPa.
In the present invention, the conditions and methods for the pulverization may be those conventional in such operations in the art, and may be generally carried out in a mechanical mill pulverizer, a jet mill pulverizer or a cryogenic pulverizer, preferably in a cryogenic pulverizer.
The invention also provides a graphite coating agent, which is prepared by the preparation method of the graphite coating agent.
In the present invention, the particle diameter D50 of the graphite coating agent may be generally 5 to 10 μm.
The invention also provides a preparation method of the coated modified graphite material, which comprises the following steps: the mixture of the graphite coating agent and the graphite powder is carbonized; the mass ratio of the graphite coating agent to the graphite powder is (0.05-0.12): 1.
in the invention, the graphite powder can be artificial graphite powder conventionally used for preparing lithium ion battery cathode materials in the field, and can be artificial stone toner produced by Shanghai fir technology Limited.
In the present invention, the particle size D50 of the graphite powder may be a particle size conventional to such a substance in the art, and is preferably 5 to 10 μm.
In the present invention, the preparation method of the mixture of the graphite coating agent and the graphite powder can be conventional in the art, and generally comprises the following steps: and uniformly mixing the graphite coating agent and the graphite powder.
In the present invention, the mass ratio of the graphite coating agent to the graphite powder is preferably (0.05 to 0.1): 1.
in the present invention, the carbonization treatment conditions and methods may be those conventional in the art, and may be generally carried out in a tube furnace, a box furnace, a pusher kiln or a roller kiln.
In the present invention, the temperature of the carbonization treatment may be a temperature that is conventional in the art, and is preferably 900 to 1300 ℃, more preferably 950 to 1000 ℃.
In the present invention, the carbonization time may be a time conventionally used in the art, and is preferably 2 to 6 hours, and more preferably 2 to 3 hours.
In the invention, the heating rate of the carbonization treatment can be the conventional heating rate in the field, and can be generally 3-5 ℃/min.
The invention also provides a coated modified graphite material, which is prepared by the preparation method of the coated modified graphite material.
In the present invention, the degree of orientation of the sheet layer of the coated modified graphite material may be generally 5 to 8.
In the present invention, the interlayer distance of the coated modified graphite material may be 0.34 to 0.35nm, preferably 3.5nm.
In the present invention, the degree of orientation of the sheet layer may be a ratio of thermal expansion coefficients of the coated modified graphite material in two mutually perpendicular directions, which is conventionally considered by those skilled in the art. The smaller the value of the degree of orientation of the sheet, the more excellent the isotropy.
In the present invention, the particle diameter D50 of the coated modified graphite material may be generally 7 to 16 μm, preferably 7.5 to 15.8 μm, and more preferably 13 to 15.8 μm.
The invention also provides application of the coated modified graphite material as a negative electrode material in the field of lithium ion batteries.
The invention also provides a lithium ion battery, and the cathode material of the lithium ion battery comprises the coated modified graphite material.
The invention also provides application of the lithium ion battery as a power battery in the field of passenger vehicles.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows: preparing a coated modified graphite material by using the graphite coating agent; the lithium ion battery prepared by taking the coated modified graphite material as a negative electrode material has good rate performance, good quick charging performance and excellent cycle performance; when the lithium ion battery is used as a power battery in the field of passenger vehicles, the lithium ion battery can meet the requirement of quick charging.
Drawings
FIG. 1 is a graph showing a particle size distribution of graphite powder used in examples and comparative examples;
fig. 2 is an XRD pattern of the coated modified graphite material obtained in example 1.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
The graphite powder used in the following examples and comparative examples was an artificial stone toner produced by Shanghai fir Technique GmbH, having a particle diameter D50 of 8.5 μm and a particle diameter distribution chart shown in FIG. 1.
Example 1
The preparation method of the lithium ion battery negative electrode material comprises the following steps:
(1) In an extraction tower, furfural is adopted to carry out multi-stage extraction on catalytic cracking slurry oil (the manufacturer is Jinzhou petrochemical company) to prepare aromatic-rich fraction; wherein the mass ratio of the solvent to the catalytic cracking slurry oil is 2:1, the temperature of the multi-stage extraction is 50 ℃; the aromatic-rich fraction contains 92% of aromatic compounds, 3% of colloid and asphaltene and 0.5% of impurities, wherein the impurities are metal impurities;
(2) In the nitrogen atmosphere, under the condition that the stirring speed is 100r/min, the aromatic-rich fraction prepared in the step (1) is subjected to reduced pressure heat treatment for 4 hours in an autoclave with the temperature of 390 ℃ and the pressure of 0.2MPa, and the temperature rise speed of the reduced pressure heat treatment is 1 ℃/min; performing pressure heat treatment in a 2L autoclave with a temperature of 410 deg.C and a pressure of 3.5MPa at a temperature rise rate of 2 deg.C/min for 20h; then transferring the graphite powder into a grinder for grinding to prepare a graphite coating agent with the grain diameter D50 of 10 mu m;
(3) And (3) mixing the graphite coating agent prepared in the step (2) with graphite powder according to the weight ratio of 0.1:1, adding the mixture into a tubular furnace for carbonization treatment, wherein the carbonization treatment temperature is 1000 ℃, the carbonization treatment time is 2 hours, and the temperature rise rate of the carbonization treatment is 3 ℃/min; the interlayer spacing of the coated modified graphite material is 0.34nm.
Example 2
The preparation method of the lithium ion battery negative electrode material comprises the following steps:
(1) In an extraction tower, furfural is adopted to carry out multi-stage extraction on catalytic cracking slurry oil (the manufacturer is Daqing petrochemical company) to prepare aromatic-rich fraction; wherein the mass ratio of the solvent to the catalytic cracking slurry oil is 1:1, the temperature of the multi-stage extraction is 30 ℃; the aromatic-rich fraction contains 90.8% of aromatic compounds, 3.2% of colloid and asphaltene and 0.55% of impurities, wherein the impurities are metal impurities;
(2) Carrying out reduced pressure heat treatment on the aromatic-rich fraction prepared in the step (1) in an autoclave with the temperature of 370 ℃ and the pressure of 0.1MPa for 3h in a nitrogen atmosphere at the stirring speed of 350r/min, wherein the heating speed of the reduced pressure heat treatment is 1 ℃/min; performing pressure heat treatment in a 2L autoclave with a temperature of 380 deg.C and a pressure of 2.5MPa at a temperature rise rate of 1 deg.C/min for 15 h; then transferring the graphite powder to a grinder for grinding to prepare a graphite coating agent with the particle size D50 of 5 mu m;
(3) And (3) mixing the graphite coating agent prepared in the step (2) with graphite powder according to the weight ratio of 0.05:1, adding the mixture into a tubular furnace for carbonization treatment, wherein the carbonization treatment temperature is 900 ℃, the carbonization treatment time is 3 hours, and the temperature rise rate of the carbonization treatment is 3 ℃/min; the interlayer spacing of the coated modified graphite material is 0.35nm.
Example 3
The preparation method of the lithium ion battery negative electrode material comprises the following steps:
(1) In an extraction tower, furfural is adopted to carry out multi-stage extraction on catalytic cracking slurry oil (the manufacturer is Liaohe oil field company in China) to prepare aromatic-rich fraction; wherein the mass ratio of the solvent to the catalytic cracking slurry oil is 0.5:1, the temperature of the multi-stage extraction is 60 ℃; the aromatic-rich fraction contains 90% of aromatic compounds, 3.5% of colloid and asphaltene and 0.6% of impurities, wherein the impurities are metal impurities;
(2) In the nitrogen atmosphere, under the condition that the stirring speed is 400r/min, the aromatic-rich fraction prepared in the step (1) is subjected to reduced pressure heat treatment for 10 hours in an autoclave with the temperature of 390 ℃ and the pressure of 0.3MPa, and the temperature rise speed of the reduced pressure heat treatment is 3 hours; performing pressure heat treatment in a 2L autoclave with a temperature of 390 ℃ and a pressure of 2MPa for 20h, wherein the temperature rise rate of the pressure heat treatment is 3 ℃/min; then transferring the graphite powder into a grinder for grinding to prepare a graphite coating agent with the grain diameter D50 of 8 mu m;
(3) And (3) mixing the graphite coating agent prepared in the step (2) with graphite powder according to the weight ratio of 0.1:1, adding the mixture into a tubular furnace for carbonization treatment, wherein the carbonization treatment temperature is 950 ℃, the carbonization treatment time is 6 hours, and the temperature rise rate of the carbonization treatment is 3 ℃/min; the interlayer spacing of the coated modified graphite material is 0.34nm.
Comparative example 1
Compared with the example 1, the difference is only that the step (2) is that the aromatic-rich fraction obtained in the step (1) is subjected to pressurized heat treatment for 3 hours in a 2L autoclave with the temperature of 390 ℃ and the pressure of 0.2MPa in a nitrogen atmosphere and the stirring speed of 350r/min, and the temperature rise speed of the pressurized heat treatment is 2 ℃/min; then transferring the graphite powder into a grinder for grinding to prepare a graphite coating agent with the grain diameter D50 of 10 mu m; other condition parameters were the same as in example 1.
Comparative example 2
The ratio of asphalt to graphite powder is 0.1:1, adding the mixture into a coating kettle for low-temperature heat treatment at the temperature of 600 ℃ for 2h, wherein the heating rate of the low-temperature heat treatment is 5 ℃/min; and then transferring the mixture to a tubular furnace for carbonization treatment, wherein the carbonization treatment temperature is 1000 ℃, and the carbonization treatment time is 2 hours.
Comparative example 3
Compared with example 1, the difference is only that in the step (3), the mass ratio of the graphite coating agent to the graphite powder is 0.03:1, other condition parameters are the same as those in example 1.
Comparative example 4
Compared with example 1, the difference is only that in the step (3), the mass ratio of the graphite coating agent to the graphite powder is 0.2:1, other condition parameters are the same as example 1.
Effects of the embodiment
The particle size and specific surface area of the negative electrode materials of the lithium ion batteries prepared in the above examples 1 to 3 and comparative examples 1 to 4 were measured, and the results are shown in table 1; the first discharge capacity, the first charge-discharge efficiency, the rate capability and the cycle performance of the lithium ion battery cathode materials prepared in the examples 1-3 and the comparative examples 1-4 are measured by adopting a half-cell test method, and the results are shown in table 1; XRD analysis of the coated modified graphite material obtained in example 1 showed that the coated modified graphite material obtained in the present invention had a low degree of orientation of the sheet layer and good isotropy, as shown in FIG. 2.
The particle size testing equipment is a laser particle size distribution instrument MS2000; the specific surface area testing equipment is a specific surface area tester NOVATouch2000.
The half cell test method comprises the following steps:
the negative electrode materials of the batteries prepared in examples 1 to 3 and comparative examples 1 to 4, the conductive agents SP, CMC and SBR were uniformly mixed in water according to a ratio of 95.5 6 The button cell is assembled by using a mixed solution of Ethylene Carbonate (EC) and dimethyl carbonate (DMC) in a mass ratio of 1:1 and a PE/PP/PE composite membrane as a diaphragm. The test conditions were: the charge and discharge were carried out at a current density of 0.1C, and the charge voltage was limited to 0.005 to 2V.
And (3) rate performance test: discharging to 5mV with a constant current of 0.6mA in the first period, then discharging at a constant voltage, stopping discharging with a current of 0.06mA, and charging to 2V with a constant current of 0.1C; discharging to 5mV at constant current of 0.1C, then discharging at constant voltage, stopping current of 0.06mA, charging to 2V at constant current of 0.2C, and then discharging at multiplying power at 0.2C,0.5C,1C,2C,3C; after 3C, the current returns to 0.2C, and the rate charging current is 0.1C.
TABLE 1
As can be seen from the table, the lithium ion negative electrode battery prepared by the invention has ideal rate performance and cycle performance and high isotropy.
Claims (19)
1. The preparation method of the coated modified graphite material is characterized by comprising the following steps: carbonizing the mixture of the graphite coating agent and the graphite powder; the mass ratio of the graphite coating agent to the graphite powder is (0.05-0.12): 1; the preparation method of the graphite coating agent comprises the following steps: carrying out reduced pressure heat treatment, pressurized heat treatment and crushing on the aromatic fraction under the protective atmosphere to obtain the aromatic extract; the aromatic-rich fraction includes aromatic compounds.
2. The method for producing a coated modified graphite material according to claim 1, wherein the aromatic hydrocarbon compound is contained in the aromatic-rich fraction in an amount of 90% by mass or more;
and/or the preparation method of the aromatic fraction comprises the following steps of carrying out multi-stage extraction on the catalytic cracking slurry oil by adopting a solvent;
and/or the protective atmosphere is nitrogen;
and/or the reduced pressure heat treatment is carried out under the condition of stirring, and the rotating speed of the stirring is 100-400 r/min;
and/or the temperature of the reduced pressure heat treatment is 370-420 ℃;
and/or the temperature rise speed of the reduced pressure heat treatment is less than or equal to 3 ℃/min;
and/or the time of the decompression heat treatment is 3-20 h;
and/or the pressure of the reduced pressure heat treatment is 0.1-0.3 MPa;
and/or the pressure heat treatment is carried out under the condition of stirring, and the rotating speed of the stirring is 100-400 r/min;
and/or the temperature of the pressure heat treatment is 380-420 ℃;
and/or the heating speed of the pressure heat treatment is less than or equal to 3 ℃/min;
and/or the time of the pressure heat treatment is 4-20 h;
and/or the pressure of the pressure heat treatment is 2-3.5 MPa.
3. The method for preparing the coated modified graphite material according to claim 2, wherein the aromatic hydrocarbon compound is contained in the aromatic-rich fraction in an amount of 90 to 92% by mass;
and/or the solvent is furfural and/or methyl pyrrolidone;
and/or the reduced pressure heat treatment is carried out under the condition of stirring, and the rotating speed of the stirring is 100-350 r/min;
and/or the temperature of the reduced pressure heat treatment is 370-390 ℃;
and/or the temperature rise speed of the reduced pressure heat treatment is 1-3 ℃/min;
and/or the time of the decompression heat treatment is 3-10 h;
and/or the pressure of the reduced pressure heat treatment is 0.2-0.3 MPa;
and/or the pressure heat treatment is carried out under the condition of stirring, and the rotating speed of the stirring is 100-350 r/min;
and/or the temperature of the pressure heat treatment is 390 to 410 ℃;
and/or the heating rate of the pressure heat treatment is 1-3 ℃/min;
and/or the time of the pressure heat treatment is 15-20 h;
and/or the pressure of the pressure heat treatment is 2.5-3.5 MPa.
4. The method of preparing a coated modified graphite material of claim 3, wherein the aromatic-rich fraction further comprises colloids, asphaltenes and impurities;
and/or the mass ratio of the solvent to the catalytic cracking slurry oil is (0.5-2): 1
And/or the time of the decompression heat treatment is 4-10 h;
and/or the heating rate of the pressure heat treatment is 2-3 ℃/min.
5. The method of preparing a coated modified graphite material according to claim 4, wherein the total mass percentage of the colloid and the asphaltene is less than or equal to 3.5%;
and/or the mass ratio of the solvent to the catalytic cracking slurry oil is (1-2): 1.
6. the method of preparing the coated modified graphite material according to claim 5, wherein the total mass percentage of the colloid and the asphaltene is 3% to 3.2%;
and/or the temperature of the multi-stage extraction is 30-100 ℃.
7. The method of preparing a coated modified graphite material according to claim 6, wherein the impurity is a metal;
and/or the temperature of the multistage extraction is 50-60 ℃.
8. The method of preparing a coated modified graphite material according to claim 7, wherein the impurity is 1% by mass or less.
9. The method for preparing the coated modified graphite material according to claim 8, wherein the impurity is 0.5 to 0.6% by mass.
10. The method of preparing the coated modified graphite material according to claim 1, wherein the particle size D50 of the graphite coating agent is 5 to 10 μm.
11. The method for preparing the coated modified graphite material according to claim 1, wherein the graphite powder is an artificial graphite powder;
and/or the particle size D50 of the graphite powder is 5-10 mu m;
and/or the mass ratio of the graphite coating agent to the graphite powder is (0.05-0.1): 1;
and/or the temperature of the carbonization treatment is 900-1300 ℃;
and/or the carbonization treatment time is 2-6 h;
and/or the temperature rise speed of the carbonization treatment is 3-5 ℃/min.
12. The method for preparing the coated modified graphite material according to claim 11, wherein the temperature of the carbonization treatment is 950 to 1000 ℃;
and/or the carbonization treatment time is 2-3 h.
13. A coated modified graphite material, which is produced by the production method of the coated modified graphite material according to any one of claims 1 to 12.
14. The coated modified graphite material according to claim 13, wherein the coated modified graphite material has a degree of sheet orientation of 5 to 8;
and/or the interlayer spacing of the coated modified graphite material is 0.34-0.35 nm;
and/or the particle size D50 of the coating modified graphite material is 7-16 mu m.
15. The coated modified graphite material of claim 14, wherein the coated modified graphite material has an interlayer spacing of 0.35nm;
and/or the particle size D50 of the coating modified graphite material is 7.5-15.8 μm.
16. The coated modified graphite material according to claim 15, wherein the particle size D50 of the coated modified graphite material is 13 to 15.8 μm.
17. Use of the coated modified graphite material according to any one of claims 13 to 16 as a negative electrode material in the field of lithium ion batteries.
18. A lithium ion battery, characterized in that its negative electrode material comprises the coated modified graphite material according to any one of claims 13 to 16.
19. Use of the lithium ion battery according to claim 18 as a power battery in the field of passenger vehicles.
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| CN111834634A (en) * | 2020-07-07 | 2020-10-27 | 鞍钢化学科技有限公司 | High-performance artificial graphite negative electrode material and production process thereof |
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