CN114873589A - High-compaction-density high-rate-performance graphite negative electrode material and preparation method thereof - Google Patents
High-compaction-density high-rate-performance graphite negative electrode material and preparation method thereof Download PDFInfo
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- CN114873589A CN114873589A CN202210598186.XA CN202210598186A CN114873589A CN 114873589 A CN114873589 A CN 114873589A CN 202210598186 A CN202210598186 A CN 202210598186A CN 114873589 A CN114873589 A CN 114873589A
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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
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- 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 graphite cathode material with high compaction density and high rate performance and a preparation method thereof, wherein the preparation method mainly comprises the following steps: grinding coal-based needle coke into powder to obtain small particles, mixing the small particles with medium-temperature petroleum asphalt micro powder through a VC mixer, processing the small particles and the medium-temperature petroleum asphalt micro powder through a fusion machine to obtain fused materials, then carrying out isostatic pressing and graphitization treatment, crushing, grinding and shaping the graphitized blocks to obtain isotropic secondary graphite particles, and finally mixing and fusing the isotropic secondary graphite particles and high-softening-point asphalt and then carbonizing the isotropic secondary graphite particles to obtain the graphite cathode material. The invention improves the multiplying power performance of the battery and the cycling stability of the cathode material, and optimizes the quick charge and discharge performance of the battery.
Description
Technical Field
The invention relates to a graphite negative electrode material with high compaction density and high rate performance and a preparation method thereof, belonging to the technical field of performance optimization of negative electrode materials of lithium batteries.
Background
The current commercialized lithium ion battery negative electrode carbon material mainly comprises natural graphite and artificial graphite. The material has the characteristics of good charge and discharge capacity, good charge and discharge platform, wide raw material source and the like, so that the material is generally applied.
With the rapid development of new energy electric vehicles, the requirements on the negative electrode material of the lithium ion battery are continuously improved, the negative electrode material for preparing the new energy electric vehicle has the requirements on high multiplying power, long cycle and high safety performance, and the graphite crystal structure is microscopically anisotropic, so that the directional arrangement parallel to a current collector is easily formed, the path for the lithium ions to enter and exit from the graphite crystal is lengthened, the quick charging performance is deteriorated, and meanwhile, the volume expansion is caused to deteriorate the cycle performance in the process of repeatedly entering and exiting. Moreover, the processing performance of the powder is deteriorated, which is mainly reflected in that the compacted density of the material is low, the baking rebound after compaction is large, and the specific capacity is reduced.
In order to solve the above problems, the conventional technical method is to add small flaky particles to a binder in a granulation process, bind the small particles into secondary particles, and perform graphitization and carbonization treatment to obtain spherical-like graphite secondary particles.
Disclosure of Invention
In order to solve the technical problems, the invention adopts small-particle needle coke as a raw material and utilizes an isostatic pressing forming method to develop a high-performance negative electrode material with high isotropy, high compaction density, good rate capability and high capacity, and the specific preparation method is as follows:
step 1: mixing the pulverized coal-based needle coke with medium-temperature petroleum asphalt to obtain mixed powder, wherein the softening point of the medium-temperature petroleum asphalt in the mixed powder is 100-150 ℃;
step 2: fusing the mixed powder until the medium-temperature petroleum asphalt is wrapped on the surface of the needle coke particles to obtain a fused material;
and step 3: carrying out isostatic pressing treatment on the fused material to obtain a block material;
and 4, step 4: graphitizing the block material to obtain a graphitized block;
and 5: sequentially crushing, grinding and shaping the graphitized block to obtain isotropic graphite secondary particles;
step 6: and mixing, fusing and carbonizing the isotropic graphite secondary particles and the high-softening-point asphalt to obtain a finished product, wherein the finished product is the graphite cathode material.
And further: the specific operation steps of the step 1 are as follows: mixing the needle coke with the grain diameter of 3-5 mu m and the medium temperature petroleum asphalt with the grain diameter of 3-4 mu m for 40-60min in a VC mixer, wherein the softening point of the medium temperature petroleum asphalt is 120-160 ℃.
Further: the fusion treatment time in the step 2 is 20-40 min.
Further: and 3, performing isostatic pressing on the fused material, wherein the isostatic pressing is performed, the pressure is 20-200MPa, and the treatment time is 30-60 min.
Further: and (4) performing isostatic pressing treatment in the step 3, wherein the pressure is 50-180 MPa.
Further: step 4, the temperature of the graphitization treatment is 2500-.
Further: the average grain diameter of the isotropic graphite secondary particles obtained in the step 5 is 15-17 mu m.
Further: step 6, the softening point of the high-softening-point asphalt is 180 ℃ and 250 ℃, and the fusion time is 30-40 min; the temperature of the carbonization treatment is 1200-1300 ℃, and the carbonization time is 20 hours.
The invention also comprises the graphite cathode material with high compaction density and high rate capability prepared by any one of the methods.
Advantageous effects
1. The graphite secondary particles are isotropic in macroscopical view, and the prepared graphite negative electrode material is favorable for shortening the transmission path of lithium ions in graphite, improving the rate capability and improving the rapid charge and discharge performance of the lithium ions.
2. The graphite cathode material is prepared by an isostatic pressing technology, so that the graphite cathode material is compact and uniform in structure, and the compaction density is obviously improved.
3. According to the method, through a carbonization procedure, a layer of amorphous carbon is coated on the surfaces of isotropic graphite particles to form a core-shell structure, the advantage that the amorphous carbon can improve the rate capability and can also avoid collapse of the graphite structure caused by the fact that solvent molecules and lithium ions are co-embedded into a graphite layer is utilized, and the cycle stability of the cathode material is further improved.
4. According to the method, the isostatic pressing block is crushed and ground after the graphitization process, so that the integrity of the graphite crystal is ensured.
Drawings
FIG. 1 is an SEM image of an artificial graphite anode material prepared by an example of the present invention,
fig. 2 is a block flow diagram of the present invention.
Detailed Description
The present invention is further illustrated by the following figures and specific examples, which are to be understood as illustrative only and not as limiting the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalent modifications thereof which may occur to those skilled in the art upon reading the present specification.
As shown in fig. 2, the preparation method of the graphite anode material with high compaction density and high rate performance of the invention mainly comprises the following steps: grinding coal-based needle coke into powder to obtain small particles, mixing the small particles with medium-temperature petroleum asphalt micro powder through a VC mixer, processing the small particles and the medium-temperature petroleum asphalt micro powder through a fusion machine to obtain fused materials, then carrying out isostatic pressing and graphitization treatment, crushing, grinding and shaping the graphitized blocks to obtain isotropic secondary graphite particles, and finally mixing and fusing the isotropic secondary graphite particles and high-softening-point asphalt and then carbonizing the isotropic secondary graphite particles to obtain the graphite cathode material. The preparation method comprises the following steps:
step 1: mixing the pulverized coal-based needle coke with medium-temperature petroleum asphalt to obtain mixed powder, wherein the softening point of the medium-temperature petroleum asphalt in the mixed powder is 100-150 ℃;
step 2: fusing the mixed powder until the medium-temperature petroleum asphalt is wrapped on the surface of the needle coke particles to obtain a fused material;
and step 3: carrying out isostatic pressing treatment on the fused material to obtain a block material;
and 4, step 4: graphitizing the block material to obtain a graphitized block;
and 5: sequentially crushing, grinding and shaping the graphitized block to obtain isotropic graphite secondary particles;
step 6: and mixing, fusing and carbonizing the isotropic graphite secondary particles and the high-softening-point asphalt to obtain a finished product, wherein the finished product is the graphite cathode material.
Further: the specific operation steps of the step 1 are as follows: mixing the needle coke with the grain diameter of 3-5 mu m and the medium temperature petroleum asphalt with the grain diameter of 3-4 mu m for 40-60min in a VC mixer, wherein the softening point of the medium temperature petroleum asphalt is 120-160 ℃.
Further: the fusion treatment time in the step 2 is 20-40 min.
Further: and 3, performing isostatic pressing on the fused material, wherein the isostatic pressing is performed, the pressure is 20-200MPa, and the treatment time is 30-60 min.
Further: and (3) performing isostatic pressing treatment under the pressure of 50-180 MPa.
Further: the graphitization treatment in the step 4 is carried out at 2500 ℃ and 3200 ℃ for 20-48 hours.
Further: the average grain diameter of the isotropic graphite secondary particles obtained in the step 5 is 15-17 mu m.
Further: step 6, the softening point of the high-softening-point asphalt is 180 ℃ and 250 ℃, and the fusion time is 30-40 min; the temperature of the carbonization treatment is 1200-1300 ℃, and the carbonization time is 20 hours.
Examples
Step 1: the needle coke with the grain size of 5 mu m after being ground and the medium-temperature petroleum asphalt (the softening point is 120 ℃) with the grain size of 3 mu m are mixed in a VC mixer for 40 min.
Step 2: and performing fusion treatment on the mixed powder for 20 min.
And step 3: performing liquid isostatic pressing treatment on the fused material at the pressure of 150 MPa; the treatment time is 30 min.
And 4, step 4: and (3) graphitizing the block after isostatic pressing at 2900 ℃ for 48 hours.
And 5: and crushing, grinding and shaping the graphitized block to obtain isotropic graphite secondary particles with the average particle size of 16 mu m.
Step 6: and mixing, fusing and carbonizing the isotropic graphite secondary particles and the high-softening-point asphalt. Wherein the high softening point asphalt is 200 ℃; the fusion time is preferably 20 min; the temperature of the carbonization treatment is as follows: 1200 ℃. The carbonization time was 15 hours. The artificial graphite cathode material can be obtained, and the SEM image of the artificial graphite cathode material is shown in figure 1.
Performance test experiment of artificial graphite cathode material in embodiment of the invention
Preparing a buckling capacitor: the artificial graphite negative electrode material prepared in the embodiment, a conductive agent, carboxymethyl cellulose and styrene butadiene rubber are mixed according to a ratio of 92:3:2:3 to prepare slurry, the slurry is coated on a copper foil and is placed in a vacuum drying oven to be dried for more than 12 hours to prepare a negative electrode sheet; and cutting the dried negative electrode plate into a circular electrode plate with the diameter of 14 mm by using a punching machine, and finally carrying out buckling assembly in a glove box. The counter electrode adopted in the experiment is a metal lithium sheet, the diaphragm is a Celgard 2300 polypropylene film, and the electrolyte is a standard electrolyte EC of the LB303 of the gorgeon state, DEC and DMC are 1:1:1LiPF61mol/L, so that the CR2016 type button cell is assembled.
And (3) performance testing: observing the appearance of the cathode material by adopting a Japanese electron (Jiejuo) Jeol Scanning Electron Microscope (SEM); adopting the compaction density of the cathode material of a compaction density instrument; and (4) analyzing and testing the initial coulombic efficiency, the initial discharge capacity, the rate capability and the cycle life of the buckling battery by adopting a blue electric testing system.
The performance parameters of the artificial graphite anode material tested in this example are shown in the following table:
the multiplying power performance data show that the graphite cathode material prepared by the graphite secondary particles is beneficial to shortening the transmission path of lithium ions in graphite, improving the multiplying power performance and improving the rapid charge and discharge performance of the lithium ions.
An SEM image of the artificial graphite negative electrode material according to the embodiment of the present invention is shown in fig. 1, which illustrates that the graphite negative electrode material according to the present invention is prepared by an isostatic pressing technique, so that the structure thereof is compact and uniform, and the compaction density is significantly increased.
As can be seen from the fact that the capacity retention rate is not lower than 90% after 2000 cycles, the method enables the surfaces of isotropic graphite particles to be coated with a layer of amorphous carbon to form a core-shell structure through a carbonization procedure, so that the rate capability is improved, the advantage that the graphite structure collapses due to the fact that solvent molecules and lithium ions are co-embedded into a graphite layer is avoided, and the cycle stability of the negative electrode material is further improved.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (9)
1. A preparation method of a graphite cathode material with high compaction density and high rate capability is characterized by comprising the following steps:
step 1: mixing the pulverized coal-based needle coke with medium-temperature petroleum asphalt to obtain mixed powder, wherein the softening point of the medium-temperature petroleum asphalt in the mixed powder is 100-150 ℃;
step 2: fusing the mixed powder until the medium-temperature petroleum asphalt is wrapped on the surface of the needle coke particles to obtain a fused material;
and step 3: carrying out isostatic pressing treatment on the fused material to obtain a block material;
and 4, step 4: graphitizing the block material to obtain a graphitized block;
and 5: sequentially crushing, grinding and shaping the graphitized block to obtain isotropic graphite secondary particles;
step 6: and mixing, fusing and carbonizing the isotropic graphite secondary particles and the high-softening-point asphalt to obtain a finished product, wherein the finished product is the graphite cathode material.
2. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: the specific operation steps of the step 1 are as follows: mixing the needle coke with the grain diameter of 3-5 mu m and the medium temperature petroleum asphalt with the grain diameter of 3-4 mu m for 40-60min in a VC mixer, wherein the softening point of the medium temperature petroleum asphalt is 120-160 ℃.
3. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: the fusion treatment time in the step 2 is 20-40 min.
4. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: and 3, performing isostatic pressing on the fused material, wherein the isostatic pressing is performed, the pressure is 20-200MPa, and the treatment time is 30-60 min.
5. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 4, wherein the method comprises the following steps: and (3) performing isostatic pressing treatment under the pressure of 50-180 MPa.
6. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: the graphitization treatment in the step 4 is carried out at 2500 ℃ and 3200 ℃ for 20-48 hours.
7. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: the average grain diameter of the isotropic graphite secondary particles obtained in the step 5 is 15-17 mu m.
8. The method for preparing the high-compaction-density high-rate-performance graphite negative electrode material according to claim 1, characterized in that: the softening point of the pitch with the high softening point in the step 6 is 180-250 ℃, and the fusion time is 30-40 min; the temperature of the carbonization treatment is 1200-1300 ℃, and the carbonization time is 20 hours.
9. A high compaction density and high rate capability graphite cathode material is characterized in that: is prepared by any one of the methods.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116443869A (en) * | 2023-03-17 | 2023-07-18 | 乌海宝杰新能源材料有限公司 | Quick graphite charging negative electrode material for starting and stopping power supply and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102931381A (en) * | 2011-08-12 | 2013-02-13 | 宁波杉杉新材料科技有限公司 | Isotropous graphite secondary particle, and preparation method and use thereof |
| CN106532053A (en) * | 2016-12-22 | 2017-03-22 | 上海杉杉科技有限公司 | Graphite anode material for lithium ion batteries and preparation method thereof |
| CN110642247A (en) * | 2019-09-30 | 2020-01-03 | 广东凯金新能源科技股份有限公司 | Artificial graphite negative electrode material, preparation method thereof and lithium ion battery |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102931381A (en) * | 2011-08-12 | 2013-02-13 | 宁波杉杉新材料科技有限公司 | Isotropous graphite secondary particle, and preparation method and use thereof |
| CN106532053A (en) * | 2016-12-22 | 2017-03-22 | 上海杉杉科技有限公司 | Graphite anode material for lithium ion batteries and preparation method thereof |
| CN110642247A (en) * | 2019-09-30 | 2020-01-03 | 广东凯金新能源科技股份有限公司 | Artificial graphite negative electrode material, preparation method thereof and lithium ion battery |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116443869A (en) * | 2023-03-17 | 2023-07-18 | 乌海宝杰新能源材料有限公司 | Quick graphite charging negative electrode material for starting and stopping power supply and preparation method thereof |
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