CN114572978A - Preparation method of high-rate graphite negative electrode material, negative electrode material and lithium battery - Google Patents
Preparation method of high-rate graphite negative electrode material, negative electrode material and lithium battery Download PDFInfo
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- CN114572978A CN114572978A CN202210260274.9A CN202210260274A CN114572978A CN 114572978 A CN114572978 A CN 114572978A CN 202210260274 A CN202210260274 A CN 202210260274A CN 114572978 A CN114572978 A CN 114572978A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 239000010439 graphite Substances 0.000 title claims abstract description 101
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 101
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 23
- 239000007773 negative electrode material Substances 0.000 title claims description 46
- 239000000463 material Substances 0.000 claims abstract description 70
- 229920005989 resin Polymers 0.000 claims abstract description 66
- 239000011347 resin Substances 0.000 claims abstract description 66
- 238000002156 mixing Methods 0.000 claims abstract description 43
- 239000000571 coke Substances 0.000 claims abstract description 42
- 239000010406 cathode material Substances 0.000 claims abstract description 37
- 238000005087 graphitization Methods 0.000 claims abstract description 29
- 239000011163 secondary particle Substances 0.000 claims abstract description 25
- 239000003208 petroleum Substances 0.000 claims abstract description 24
- 239000002994 raw material Substances 0.000 claims abstract description 24
- 238000012216 screening Methods 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 17
- 238000005303 weighing Methods 0.000 claims abstract description 12
- IANQTJSKSUMEQM-UHFFFAOYSA-N 1-benzofuran Chemical compound C1=CC=C2OC=CC2=C1 IANQTJSKSUMEQM-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229920006026 co-polymeric resin Polymers 0.000 claims abstract description 8
- 239000012298 atmosphere Substances 0.000 claims abstract description 7
- 238000010907 mechanical stirring Methods 0.000 claims abstract description 7
- 238000012360 testing method Methods 0.000 claims description 48
- 238000010438 heat treatment Methods 0.000 claims description 40
- 239000011248 coating agent Substances 0.000 claims description 33
- 238000000576 coating method Methods 0.000 claims description 33
- 238000001069 Raman spectroscopy Methods 0.000 claims description 14
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 11
- 125000004432 carbon atom Chemical group C* 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 239000011329 calcined coke Substances 0.000 claims description 9
- 239000011331 needle coke Substances 0.000 claims description 9
- 239000010405 anode material Substances 0.000 claims description 8
- 239000002006 petroleum coke Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000007547 defect Effects 0.000 claims description 5
- 238000009396 hybridization Methods 0.000 claims description 5
- 239000006253 pitch coke Substances 0.000 claims description 5
- 239000003245 coal Substances 0.000 claims description 3
- 238000009826 distribution Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 239000013078 crystal Substances 0.000 claims description 2
- 239000010426 asphalt Substances 0.000 description 38
- 230000000052 comparative effect Effects 0.000 description 29
- 238000000113 differential scanning calorimetry Methods 0.000 description 14
- 239000006185 dispersion Substances 0.000 description 13
- 229910021385 hard carbon Inorganic materials 0.000 description 13
- 239000002131 composite material Substances 0.000 description 12
- 230000002687 intercalation Effects 0.000 description 10
- 238000009830 intercalation Methods 0.000 description 10
- 239000012300 argon atmosphere Substances 0.000 description 9
- 229910021384 soft carbon Inorganic materials 0.000 description 8
- 238000010000 carbonizing Methods 0.000 description 5
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 4
- 239000011229 interlayer Substances 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
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- 230000003179 granulation Effects 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 208000019901 Anxiety disease Diseases 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 230000036506 anxiety Effects 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-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
- C01B32/205—Preparation
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
-
- 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
-
- 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
-
- 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
Abstract
The invention discloses a preparation method of a high-rate graphite cathode material, the cathode material and a lithium battery, and the preparation method comprises the steps of weighing resin and raw coke according to a proportion, and fully and uniformly mixing to obtain a mixed raw material; the resin comprises: one or more of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated petroleum resin or coumarone resin; placing the mixed raw materials in a granulating furnace, setting a first temperature rise curve under inert atmosphere to enable the resin to be in a molten state, enabling the particles of the mixed raw materials to be mutually rubbed under mechanical stirring, enabling the molten resin to be uniformly coated on the surface of raw coke, then setting a second temperature rise curve to enable the molten resin to be coked and solidified, and removing volatile components of the raw coke to form secondary particles; placing the secondary particles in a graphitization furnace for graphitization to obtain a graphitized material; and scattering and uniformly mixing the graphitized material by using mixing equipment, and screening to obtain the high-rate graphite cathode material.
Description
Technical Field
The invention relates to the technical field of materials, in particular to a preparation method of a high-rate graphite negative electrode material, the negative electrode material and a lithium battery.
Background
With the breakthrough development of battery technology and the improvement of battery energy density, the endurance mileage of the electric vehicle is greatly improved at present, the endurance mileage is common for five or six hundred kilometers, the anxiety of the endurance mileage of a new energy vehicle is changed into the anxiety of charging time, power battery manufacturers are developing fast-charging batteries, and a plurality of manufacturers develop battery core projects with the fast-charging time of 10-15 min.
The negative electrode material is used as a main material of the battery, the main function of the negative electrode material is lithium storage during charging, and the lithium insertion speed of the negative electrode material is one of the most important factors influencing the quick charging capability of the battery. Graphite has good chemical stability and electrical property, and is still the mainstream negative electrode material in the market at present, but because the graphite is of a lamellar structure, lithium ions can only be embedded into the end face and can not be embedded into the basal plane, and the lithium embedding speed of the conventional graphite is slow. The most common method for improving the quick charging performance of graphite is to coat a layer of soft carbon on the surface of the graphite, wherein the interlayer spacing of the soft carbon is larger than that of the graphite, the disorder degree between layers is higher, and the lithium embedding paths are more, so that lithium ions on the base surface of the graphite can be guided to the end face for embedding, and the quick charging performance of the graphite is improved. The method for providing the graphite fast-charging performance is currently activated to be hard carbon coating, wherein the interlayer spacing and the disorder degree of the hard carbon are higher than those of the soft carbon, and the fast-charging performance is better than that of the soft carbon coating.
The traditional step of preparing the negative electrode material by coating graphite with soft carbon and hard carbon comprises the steps of granulating to obtain secondary particles, graphitizing the granulated material, coating the granulated material with asphalt or resin, carbonizing, mixing, sieving and the like to obtain the negative electrode material. Although the negative electrode material obtained by coating graphite with soft carbon and hard carbon can improve the quick charging performance to a certain extent, the cost for preparing the material can be greatly increased after the soft carbon and hard carbon granules are subjected to a carbonization process, so that the energy consumption and carbon emission are increased, the requirements of the market on the production of the negative electrode material for reducing the cost are not met, and the policy of carbon neutralization is contradictory. Therefore, a simpler and more efficient preparation method is needed, which can improve the quick charging performance, reduce the energy consumption and reduce the cost.
Disclosure of Invention
The embodiment of the invention provides a preparation method, a material and an application of a high-rate graphite cathode material.
In a first aspect, an embodiment of the present invention provides a preparation method of a high-rate graphite anode material, where the preparation method includes:
weighing the resin and the raw coke in proportion, and fully and uniformly mixing to obtain a mixed raw material; the resin comprises: one or more of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated petroleum resin or coumarone resin;
placing the mixed raw materials in a granulating furnace, carrying out first temperature rise treatment under inert atmosphere to enable the resin to be in a molten state, carrying out mutual friction between particles of the mixed raw materials under mechanical stirring, uniformly coating the molten resin on the surface of raw coke, then carrying out second temperature rise treatment to enable the molten resin to be coked and solidified, and removing the volatile component of the raw coke to form secondary particles;
placing the secondary particles in a graphitization furnace for graphitization to obtain a graphitized material;
scattering and uniformly mixing the graphitized material by using mixing equipment, and screening to obtain a high-rate graphite negative electrode material;
through Raman surface scanning tests, the average value Id/Ig of the intensity ratio of a defect D peak belonging to a C atom lattice to an in-plane stretching vibration G peak belonging to C atom sp2 hybridization meets the condition that Id/Ig is more than or equal to 0.1 and less than or equal to 0.5; the absolute value of exothermic peak intensity of the high-rate graphite cathode material at 600-1000 ℃ is less than 2.0 mW/mg.
Preferably, the resin is solid at room temperature;
the raw coke comprises: one or more of petroleum coke, pitch coke, needle coke, calcined coke, coal, shot coke, metallurgical coke, graphitized resistance material or graphite crucible material; the medium particle size D50 of the raw coke is between 5 and 15 mu m;
the weight ratio of the resin to the raw coke is 10:100-50: 100.
Preferably, the volume distribution of the particle size of the high-rate graphite negative electrode material has a medium particle size D50 of 5-20 μm.
Preferably, the inert atmosphere is a nitrogen atmosphere.
Preferably, the first temperature raising process includes: heating to 50-150 ℃ higher than the softening point temperature of the resin at the heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours;
the second temperature raising process includes: continuously heating to 500-700 ℃ at the heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours.
Preferably, the graphitization furnace includes: one of an Acheson graphitization furnace, an inner-string graphitization furnace or a box furnace; the graphitization temperature is set to 2500-3000 ℃.
Preferably, the mixing device comprises a stirrer, a high-speed disperser, a ball mill or a grinder.
Preferably, the screen mesh number of the screening is 200-600 meshes.
In a second aspect, an embodiment of the present invention provides a high-rate graphite negative electrode material prepared by the preparation method described in the first aspect, where after a raman surface scan test, an average value Id/Ig of an intensity ratio between a defect D peak attributed to a C atom lattice and an in-plane stretching vibration G peak attributed to C atom sp2 hybridization satisfies 0.1 ≤ Id/Ig ≤ 0.5; the absolute value of exothermic peak intensity of the high-rate graphite cathode material at 600-1000 ℃ is less than 2.0 mW/mg.
In a third aspect, embodiments of the present invention provide a lithium battery, where the lithium battery includes the high-rate graphite negative electrode material according to the second aspect.
The invention provides a preparation method of a high-rate graphite cathode material, which comprises the steps of heating to melt resin to uniformly coat the surface of raw coke, heating to coke the resin on the surface of the raw coke to form a hard carbon layer, graphitizing, scattering and screening to obtain the hard carbon-coated high-rate graphite cathode material.
The invention utilizes the characteristic that hard carbon is difficult to graphitize, even passes the graphitization temperature of 2500-3000 ℃, the characteristics of large interlayer spacing and high disorder degree are still kept, the hard carbon coated on the surface has low crystallinity so as to provide more lithium insertion point positions, and meanwhile, the hard carbon coating ensures that the pole piece has low orientation degree, which is Li+The embedding provides convenience, and the quick charging performance of the graphite cathode material is improved.
Drawings
The technical solutions of the embodiments of the present invention are further described in detail with reference to the accompanying drawings and embodiments.
Fig. 1 is a flowchart of a method for preparing a high-rate graphite negative electrode material according to an embodiment of the present invention;
FIG. 2 is a Differential Scanning Calorimetry (DSC) comparison of the high-rate graphite negative electrode material of example 1 of the present invention with the composite material of comparative example 1;
FIG. 3 is a DSC comparison of the high-rate graphite negative electrode material of example 2 of the present invention and the composite material of comparative example 2;
FIG. 4 is a DSC comparison of the high-rate graphite negative electrode material of example 3 of the present invention and the composite material of comparative example 3;
fig. 5 is a DSC comparison graph of the high-rate graphite anode material of example 4 of the present invention and the composite material of comparative example 4.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as limiting the invention in any way, i.e., not as limiting the scope of the invention.
The embodiment of the invention provides a preparation method of a high-rate graphite negative electrode material, which comprises the following specific steps as shown in figure 1:
the resin comprises: one or more of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated petroleum resin or coumarone resin; the resin is solid at room temperature;
the raw coke comprises: one or more of petroleum coke, pitch coke, needle coke, calcined coke, coal, shot coke, metallurgical coke, graphitized resistance material or graphite crucible material; the medium particle size D50 of the raw coke is between 5 and 15 mu m;
the weight ratio of the resin to the raw coke is 10:100-50: 100.
wherein the inert atmosphere is nitrogen atmosphere;
the first temperature raising process includes: heating to 50-150 ℃ higher than the softening point temperature of the resin at the heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours;
the second temperature raising process includes: continuously heating to 500-700 ℃ at the heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours.
the graphitization furnace includes: one of an Acheson graphitization furnace, an inner-string graphitization furnace or a box furnace; the graphitization temperature is set to 2500-3000 ℃.
140, scattering and uniformly mixing the graphitized material by using mixing equipment, and screening to obtain a high-rate graphite cathode material;
the mixing equipment comprises a stirrer, a high-speed dispersion machine, a ball mill or a grinding machine;
the mesh number of the screened screen is 200-600 meshes;
the medium particle size D50 of the particle size volume distribution of the high-magnification graphite negative electrode material is between 5 and 20 mu m;
through Raman surface scanning tests, the average value Id/Ig of the intensity ratio of a defect D peak belonging to C atom crystal lattices to an in-plane stretching vibration G peak belonging to C atom sp2 hybridization meets the condition that Id/Ig is more than or equal to 0.1 and less than or equal to 0.5; DSC test is carried out on the high-rate graphite cathode material under the argon atmosphere, and the absolute value of exothermic peak intensity between 600 ℃ and 1000 ℃ is less than 2.0 mW/mg.
The embodiment of the invention provides a lithium battery which comprises the high-rate graphite negative electrode material prepared by the preparation method.
In order to better understand the technical scheme provided by the present invention, the following specific examples are used to respectively illustrate the preparation process and characteristics of the high-rate graphite negative electrode material of the present invention.
Example 1
The embodiment provides a preparation method of a high-rate graphite negative electrode material, which comprises the following specific steps:
step 1: weighing 3 micron C5 petroleum resin and 5 micron needle coke in the weight ratio of 20:100, and mixing uniformly to obtain the mixed raw material.
And 2, step: placing the mixed raw materials in a granulating furnace, heating to 200 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere, preserving heat for 2 hours to enable the C5 petroleum resin to be molten, mechanically stirring to enable the particles of the mixed raw materials to rub with each other, uniformly coating the molten C5 petroleum resin on the surface of the needle coke, heating to 500 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours to coke and solidify the molten C5 petroleum resin, and removing volatile components of the needle coke to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an Acheson graphitizing furnace, setting the temperature to be 3000 ℃, and graphitizing the needle coke to obtain the graphitized material.
And 4, step 4: and (3) scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 500-mesh screen to obtain the high-rate graphite cathode material.
The DSC test of the high-rate graphite negative electrode material prepared in this example was performed in an argon atmosphere, and the test result is shown in fig. 2.
The high-magnification graphite cathode material prepared in this embodiment is subjected to a raman surface scanning test, and the average value of Id/Ig of the test result is shown in table 1.
Example 2
The embodiment provides a preparation method of a high-rate graphite negative electrode material, which comprises the following specific steps:
step 1: weighing 3 micron C9 petroleum resin and 8 micron calcined coke according to the weight ratio of 10:100, and uniformly mixing to obtain a mixed raw material;
and 2, step: placing the mixed raw materials in a granulating furnace, heating to 240 ℃ at a heating rate of 8 ℃/min under a nitrogen atmosphere, preserving heat for 2 hours to enable the C9 petroleum resin to be in a molten state, enabling the particles of the mixed raw materials to rub with each other under mechanical stirring, uniformly coating the molten C9 petroleum resin on the surface of calcined coke, heating to 550 ℃ at a heating rate of 5 ℃/min, preserving heat for 4 hours to coke and solidify the molten C9 petroleum resin, and removing the volatile components of the calcined coke to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an Acheson graphitization furnace, setting the temperature to be 3000 ℃, and graphitizing the calcined coke to obtain the graphitized material.
And 4, step 4: and (3) scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 325-mesh screen to obtain the high-rate graphite cathode material.
The DSC test of the high-rate graphite negative electrode material prepared in this example is performed in an argon atmosphere, and the test result is shown in fig. 3.
The high-magnification graphite cathode material prepared in this embodiment is subjected to a raman surface scanning test, and the average value of Id/Ig of the test result is shown in table 1.
Example 3
The embodiment provides a preparation method of a high-rate graphite negative electrode material, which comprises the following specific steps:
step 1: weighing 3 microns of C5 and C9 copolymer resin and 10 microns of petroleum coke according to the weight ratio of 30:100, and uniformly mixing to obtain the mixed raw material.
Step 2: placing the mixed raw materials in a granulating furnace, heating to 270 ℃ at a heating rate of 3 ℃/min under a nitrogen atmosphere, preserving heat for 2 hours to enable the C5 and C9 copolymer resin to be in a molten state, enabling the particles of the mixed raw materials to rub with each other under mechanical stirring, enabling the molten C5 and C9 copolymer resin to be uniformly coated on the surface of petroleum coke, then heating to 600 ℃ at a heating rate of 3 ℃/min, preserving heat for 4 hours to enable the molten C5 and C9 copolymer resin to be coked and solidified, and simultaneously removing volatile components of the petroleum coke to obtain secondary particles.
And step 3: placing the secondary particles in an Acheson graphitizing furnace, setting the temperature to be 3000 ℃, and graphitizing to obtain a graphitized material
And 4, step 4: and (3) scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 300-mesh screen to obtain the high-rate graphite cathode material.
The DSC test of the high-rate graphite negative electrode material prepared in this example was performed in an argon atmosphere, and the test result is shown in fig. 4.
The high-magnification graphite cathode material prepared in this embodiment is subjected to a raman surface scanning test, and the average value of Id/Ig of the test result is shown in table 1.
Example 4
The embodiment provides a preparation method of a high-rate graphite negative electrode material, which comprises the following specific steps:
step 1: weighing 3-micron hydrogenated petroleum resin and 15-micron asphalt coke according to the weight ratio of 15:100, and uniformly mixing to obtain a mixed raw material;
step 2: placing the mixed raw materials in a granulating furnace, heating to 200 ℃ at a heating rate of 5 ℃/min under the nitrogen atmosphere, preserving heat for 4 hours to enable the hydrogenated petroleum resin to be in a molten state, enabling the particles of the mixed raw materials to rub with each other under mechanical stirring, uniformly coating the molten hydrogenated petroleum resin on the surface of the asphalt coke, heating to 600 ℃ at a heating rate of 5 ℃/min, preserving heat for 4 hours to coke and solidify the molten hydrogenated petroleum resin, and removing the volatile components of the asphalt coke to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an inner-series graphitization furnace, setting the temperature to 2800 ℃, and graphitizing the pitch coke to obtain a graphitized material.
And 4, step 4: and (3) scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 270-mesh screen to obtain the high-magnification graphite cathode material.
The DSC test of the high-rate graphite negative electrode material prepared in this example was performed in an argon atmosphere, and the test result is shown in fig. 5.
The high-rate graphite negative electrode material prepared in this embodiment is subjected to a raman surface scanning test, and the average Id/Ig value of the test results is shown in table 1.
To better illustrate the effects of the examples of the present invention, comparative examples were compared with the above examples.
Comparative example 1
The comparative example provides a preparation method of a graphite anode material, which comprises the following specific steps:
step 1: weighing 3 microns of asphalt and 5 microns of needle coke according to the weight ratio of 11:100, and uniformly mixing to obtain a first mixed material.
Step 2: and (3) placing the first mixed material in a granulating furnace, heating to 550 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere, then preserving heat for 4 hours, and granulating to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an Acheson graphitization furnace, setting the temperature to be 3000 ℃, and graphitizing the needle coke to obtain the graphitized material. Scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 500-mesh screen to obtain the graphitized material before coating;
performing a Raman surface scanning test on the graphitized material before coating, wherein the average value of the test result Id/Ig is shown in table 1;
the graphitized material before coating is used for preparing the battery, the lithium intercalation multiplying power is tested, and the test result is shown in the table 1.
And 4, step 4: mixing the graphitized material before coating with 3-micron asphalt according to the mass ratio of 100: 3, and mixing to obtain a second mixed material.
And 5: and carbonizing the second mixed material to obtain the asphalt graphite composite material.
Step 6: and (3) scattering and uniformly mixing the asphalt graphite composite material by a high-speed dispersion machine, and screening by using a 500-mesh screen to obtain the graphite cathode material coated with asphalt.
The graphite cathode material prepared in the comparative example is subjected to DSC test in an argon atmosphere, and the test result is shown in FIG. 2, and compared with the high-rate graphite cathode material prepared in example 1, the absolute value of the exothermic peak intensity at 600-plus-1000 ℃ in example 1 is less than 2.0mW/mg, and the absolute value of the exothermic peak intensity at 600-plus-1000 ℃ in comparative example 1 is more than 2.0 mW/mg.
The asphalt-coated graphite negative electrode material prepared by the comparative example was used to prepare a battery, and the lithium intercalation rate was measured, and the results are shown in table 1.
Comparative example 2
The comparative example provides a preparation method of a graphite anode material, which comprises the following specific steps:
step 1: according to the weight ratio of 4: 100, weighing 3 microns of asphalt and 8 microns of calcined coke, and uniformly mixing to obtain a first mixed material.
Step 2: and (3) placing the first mixed material in a granulating furnace, heating to 550 ℃ at the heating rate of 5 ℃/min under the nitrogen atmosphere, keeping the temperature for 4 hours, and granulating to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an Acheson graphitization furnace, setting the temperature to be 3000 ℃, and graphitizing the calcined coke to obtain the graphitized material. Dispersing and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 325-mesh screen to obtain the graphitized material before coating;
performing a Raman surface scanning test on the graphitized material before coating, wherein the average value of the test result Id/Ig is shown in table 1;
the graphitized material before coating is used for preparing the battery, the lithium intercalation multiplying power is tested, and the test result is shown in table 1.
And 4, step 4: mixing the graphitized material before coating with 3-micron asphalt according to the mass ratio of 100: 3, and mixing to obtain a second mixed material.
And 5: and carbonizing the second mixed material to obtain the asphalt graphite composite material.
And 6: and (3) scattering and uniformly mixing the asphalt graphite composite material by a high-speed dispersion machine, and screening by using a 325-mesh screen to obtain the graphite cathode material coated with asphalt.
The DSC test of the graphite cathode material coated with the asphalt prepared in the comparative example is carried out in the argon atmosphere, the test result is shown in figure 3, and compared with the high-rate graphite cathode material prepared in the example 2, the absolute value of the exothermic peak intensity of the example 2 at 600-plus-1000 ℃ is less than 2.0mW/mg, and the absolute value of the exothermic peak intensity of the comparative example 2 at 600-plus-1000 ℃ is more than 2.0 mW/mg.
The asphalt-coated graphite cathode material prepared by the comparative example is used for preparing a battery, the lithium intercalation multiplying power is tested, and the test result is shown in table 1.
Comparative example 3
The comparative example provides a preparation method of a graphite anode material, which comprises the following specific steps:
step 1: according to the weight ratio of 100: 7 weighing 3 microns of asphalt and 10 microns of petroleum coke, and uniformly mixing to obtain a first mixed material;
step 2: and (3) placing the first mixed material in a granulating furnace, heating to 550 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere, then preserving heat for 4 hours, and granulating to obtain secondary particles.
And 3, step 3: and (3) placing the secondary particles in an Acheson graphitization furnace, setting the temperature to be 3000 ℃, and graphitizing the petroleum coke to obtain the graphitized material. Scattering and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 300-mesh screen to obtain the graphitized material before coating;
performing a Raman surface scanning test on the graphitized material before coating, wherein the average value of the test result Id/Ig is shown in table 1;
the graphitized material before coating is used for preparing the battery, the lithium intercalation multiplying power is tested, and the test result is shown in table 1.
And 4, step 4: mixing the graphitized material before coating with 3-micron asphalt according to the mass ratio of 100: 3, and mixing to obtain a second mixed material.
And 5: and carbonizing the second mixed material to obtain the asphalt graphite composite material.
Step 6: and (3) scattering and uniformly mixing the asphalt graphite composite material by a high-speed dispersion machine, and screening by using a 300-mesh screen to obtain the graphite cathode material coated with asphalt.
DSC test is carried out on the graphite cathode material coated with the asphalt prepared in the comparative example under the argon atmosphere, the test result is shown in figure 4, and compared with the high-rate graphite cathode material prepared in the example 3, the absolute value of the exothermic peak intensity of the example 3 at 600-plus-1000 ℃ is less than 2.0mW/mg, and the absolute value of the exothermic peak intensity of the comparative example 2 at 600-plus-1000 ℃ is more than 2.0 mW/mg.
The asphalt-coated graphite negative electrode material prepared by the comparative example was used to prepare a battery, and the lithium intercalation rate was measured, and the results are shown in table 1.
Comparative example 4
The comparative example provides a preparation method of a graphite anode material, which comprises the following specific steps:
step 1: according to the weight ratio of 100: 9 weighing 3 micrometers of asphalt and 15 micrometers of asphalt coke, and uniformly mixing to obtain a first mixed material.
Step 2: and (3) placing the first mixed material in a granulating furnace, heating to 550 ℃ at the heating rate of 5 ℃/min in the nitrogen atmosphere, then preserving heat for 4 hours, and granulating to obtain secondary particles.
And step 3: and (3) placing the secondary particles in an Acheson graphitization furnace, setting the temperature to be 3000 ℃, and graphitizing the pitch coke to obtain the graphitized material. Dispersing and uniformly mixing the graphitized material by a high-speed dispersion machine, and screening by using a 270-mesh screen to obtain the graphitized material before coating;
performing a Raman surface scanning test on the graphitized material before coating, wherein the average value of the test result Id/Ig is shown in table 1;
the graphitized material before coating is used for preparing the battery, the lithium intercalation multiplying power is tested, and the test result is shown in table 1.
And 4, step 4: the graphitized material before coating and 3-micron asphalt are mixed according to the mass ratio of 100: 3, and mixing to obtain a second mixed material.
And 5: and carbonizing the second mixed material to obtain the asphalt graphite composite material.
Step 6: and (3) scattering and uniformly mixing the asphalt graphite composite material by a high-speed dispersion machine, and screening by using a 270-mesh screen to obtain the graphite cathode material coated with asphalt.
DSC (differential scanning calorimetry) test is carried out on the graphite negative electrode material coated with the asphalt prepared in the comparative example under the argon atmosphere, the test result is shown in figure 5, and compared with the high-rate graphite negative electrode material prepared in the example 4, the absolute value of the exothermic peak intensity at 600-plus-1000 ℃ of the example 4 is less than 2.0mW/mg, and the absolute value of the exothermic peak intensity at 600-plus-1000 ℃ of the comparative example 4 is more than 2.0 mW/mg.
The asphalt-coated graphite cathode material prepared by the comparative example is used for preparing a battery, the lithium intercalation multiplying power is tested, and the test result is shown in table 1.
TABLE 1
The high-rate graphite negative electrode material prepared in the embodiment of the invention, the graphitized material before coating prepared in the comparative example and the graphite negative electrode material after coating with asphalt are respectively subjected to Raman surface scanning test, and the battery prepared from the materials is subjected to lithium intercalation rate test, and the test results are shown in Table 1.
According to the test results, the average Id/Ig value of the high-magnification graphite negative electrode material prepared in the embodiment is larger than that of the graphitized material before coating of the comparative example by one order of magnitude, and is similar to that of the graphite negative electrode material coated with the asphalt.
The lithium intercalation rate of the battery prepared by the high-rate graphite cathode material in the embodiment is larger than that of the battery prepared by the graphitized material before coating in the comparative example, and is similar to that of the battery prepared by the graphite cathode material coated by asphalt.
The reason is that the granulation effect of the resin adopted by the invention is better than that of the asphalt, and the invention adopts two temperature rising curves, so that the resin is firstly melted under the first temperature rising curve and uniformly coated on the surface of the raw coke, then is coked and solidified under the second temperature rising curve, and is coated on the surface of the raw coke as hard carbon, namely the resin is used as a granulation binder and can be uniformly coated on the surface of the raw coke, and after the resin is granulated, the characteristics of large interlayer spacing and high disorder degree are still kept by utilizing the characteristic that the hard carbon is difficult to graphitize even at the graphitization temperature of 2500-+The embedding provides convenience, and the quick charging performance of the graphite cathode material is improved. In the comparative example, asphalt is used as a granulation binder, after high-temperature graphitization, the surface of the graphite material has high crystallinity, small carbon layer spacing and poor rate capability, and the rate capability can be improved only after a certain amount of asphalt is mixed for low-temperature carbonization coating.
In conclusion, the preparation method adopts resin as a granulating binder, the resin is coated on the surface of the raw coke through two temperature rise curves, the hard carbon-coated high-rate graphite cathode material can be obtained after the raw coke is graphitized, and compared with the soft carbon-coated graphite cathode material, the rate performance is similar.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A preparation method of a high-rate graphite negative electrode material is characterized by comprising the following steps:
weighing the resin and the raw coke in proportion, and fully and uniformly mixing to obtain a mixed raw material; the resin comprises: one or more of C5 petroleum resin, C9 petroleum resin, C5 and C9 copolymer resin, hydrogenated petroleum resin or coumarone resin;
placing the mixed raw materials in a granulating furnace, carrying out first temperature rise treatment under inert atmosphere to enable the resin to be in a molten state, carrying out mutual friction between particles of the mixed raw materials under mechanical stirring, uniformly coating the molten resin on the surface of raw coke, then carrying out second temperature rise treatment to enable the molten resin to be coked and solidified, and removing the volatile component of the raw coke to form secondary particles;
placing the secondary particles in a graphitization furnace for graphitization to obtain a graphitized material;
scattering and uniformly mixing the graphitized material by using mixing equipment, and screening to obtain a high-rate graphite negative electrode material;
through Raman surface scanning tests, the average value Id/Ig of the intensity ratio of a defect D peak belonging to a C atom lattice to an in-plane stretching vibration G peak belonging to C atom sp2 hybridization meets the condition that Id/Ig is more than or equal to 0.1 and less than or equal to 0.5; the absolute value of exothermic peak intensity of the high-rate graphite cathode material at 600-1000 ℃ is less than 2.0 mW/mg.
2. The production method according to claim 1, wherein the resin is in a solid state at room temperature;
the raw coke comprises: one or more of petroleum coke, pitch coke, needle coke, calcined coke, coal, shot coke, metallurgical coke, graphitized resistance material or graphite crucible material; the medium particle size D50 of the raw coke is between 5 and 15 mu m;
the weight ratio of the resin to the raw coke is 10:100-50: 100.
3. The preparation method according to claim 1, wherein the volume distribution of the particle size of the high-rate graphite anode material has a medium particle size D50 of 5-20 μm.
4. The production method according to claim 1, wherein the inert atmosphere is a nitrogen atmosphere.
5. The production method according to claim 1, wherein the first temperature-raising treatment includes: heating to 50-150 ℃ higher than the softening point temperature of the resin at a heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours;
the second temperature raising process includes: continuously heating to 500-700 ℃ at the heating rate of 1-8 ℃/min, and keeping the temperature for 2-6 hours.
6. The production method according to claim 1, wherein the graphitization furnace includes: one of an Acheson graphitization furnace, an inner-string graphitization furnace or a box furnace; the graphitization temperature is set to 2500-3000 ℃.
7. A production method according to claim 1, wherein the mixing apparatus comprises a stirrer, a high-speed disperser, a ball mill or a grinder.
8. The method of claim 1, wherein the sieve has a mesh size of 200 to 600 mesh.
9. The high-rate graphite anode material prepared by the preparation method of claims 1-8 is characterized in that the intensity ratio average value Id/Ig of a defect D peak attributed to a C atom crystal lattice and an in-plane stretching vibration G peak attributed to a C atom sp2 hybridization meets the requirement that Id/Ig is more than or equal to 0.1 and less than or equal to 0.5 through a Raman surface scan test; the high-rate graphite cathode material is at 600 DEG C
The absolute value of exothermic peak intensity between-1000 ℃ is less than 2.0 mW/mg.
10. A lithium battery comprising the high-rate graphite negative electrode material according to claim 9.
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