High-flux fast-charging artificial graphite negative electrode material and preparation method thereof

Abstract

The present application relates to a kind of high-flux fast charging type artificial graphite negative material and its preparation method, belong to lithium ion battery negative material technical field.The present application is mixed with the solution with the adhesion and the raw material powder mixed with pyrolytic ion salt uniformly after, briquetting, then graphitization, the high-flux fast charging type artificial graphite negative material of preparation is obtained.The present application can significantly improve the loading amount of graphitization by densification forming, the introduction of pyrolytic salt in the forming process is conducive to inhibiting the ordered arrangement of carbon microcrystalline in the graphitization heating process, increase defect, increase interlayer spacing, to realize the preparation of low-cost high-flux fast charging artificial graphite negative electrode.The preparation method used in the present application is simple, and the prepared fast charging artificial graphite negative electrode has excellent 3C charge-discharge performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material technology, specifically relating to a high-throughput fast-charging artificial graphite anode material and its preparation method. Background Technology

[0002] The rapid development of electronic products has placed higher demands on high-performance energy storage and conversion devices. Currently, lithium-ion batteries are an indispensable part of electronic devices. Commercially available lithium-ion anode materials are mainly made from needle coke and petroleum coke powder, which are graphitized at temperatures exceeding 3000℃ to obtain graphite carbon materials. These materials have low interlayer spacing, making it difficult to meet the rapid insertion / removal of lithium ions, thus severely limiting fast-charging performance. Currently, methods to improve the rate charge / discharge performance of artificial graphite include using alkaline or air media, and combining natural graphite, hard carbon, and artificial graphite, or blending artificial graphite powders of different particle sizes. However, alkaline etching requires specialized carbonization equipment and large amounts of water or acid to neutralize the alkali; while air oxidation introduces functional groups, which can improve high-current charging characteristics to some extent, it also increases battery leakage current and deteriorates cycle stability. Using artificial graphite in combination with natural graphite is a simple and feasible method, but it inevitably introduces the drawbacks of natural graphite into the artificial graphite system. The use of blends of different particle sizes has a limited impact on fast-charging performance. In comparison, the introduction of hard carbon into artificial graphite can effectively improve its fast-charging performance. However, the dispersion of hard carbon in graphite has become a major challenge restricting its large-scale application. In addition, the low bulk density of conventional powders leads to small capacity and high energy consumption in powder graphite charging furnaces, resulting in high production costs for artificial graphite anode materials. Summary of the Invention

[0003] To overcome the shortcomings of existing methods for preparing fast-charging artificial graphite anode materials and to alleviate the urgent need for low-cost preparation of high-performance fast-charging artificial graphite, this invention proposes a high-throughput method for preparing fast-charging artificial graphite anode materials with good cycle stability and scalable production.

[0004] The design concept of this invention is as follows: after uniformly mixing the adhesive solution with the raw material powder containing pyrolytic ionic salt, the mixture is pressed into blocks to increase the mass of the coke powder to be graphitized per unit area. Then, graphitization is carried out at 2500-2800℃ to reduce graphitization energy consumption and achieve high-throughput, low-cost preparation of fast-charging artificial graphite anode materials. Compared to current methods for preparing fast-charging artificial graphite anode materials, this method has the following characteristics: 1) The graphitization temperature is 200-500℃ lower than the graphitization temperature in current commercial artificial graphite preparation processes, which can significantly reduce energy consumption; 2) The binder component ensures the molding of the pseudo-graphitized powder raw material, thereby significantly increasing the powder bulk density and increasing the batch graphitization raw material processing capacity (i.e., graphitization loading capacity) or furnace loading; 3) After graphitization, the molded block has no high-hardness agglomerates inside and only needs simple crushing to become powder; 4) The pyrolytic ionic salt selected and used in this invention decomposes during the graphitization process, generating gas, which hinders the orderly arrangement of precursor carbon microcrystals, thereby increasing defects in graphite products and expanding interlayer spacing; 5) Due to the difference in pyrolytic characteristics between the binder and the graphite precursor, the microstructure of the pyrolytic binder-graphite interface is adjusted, thereby achieving the effect of coating graphite and using it in combination with carbon materials.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for preparing a high-throughput fast-charging artificial graphite anode material includes the following steps:

[0007] S1. Dissolve the adhesive in a solvent to obtain solution A;

[0008] S2. Mix the graphite precursor and salt in a certain proportion to obtain complex B;

[0009] S3. Mix solution A with complex B by stirring to obtain mixture C;

[0010] S4. The mixture C is pressed into blocks, dried, and graphitized to obtain a fast-charging artificial graphite anode material.

[0011] Preferably, in step S1, the adhesive is a pyrolytic polymer material with a certain viscosity and residual carbon, including one or more of syrup, thermosetting resin, thermoplastic resin, and adhesive asphalt; the solvent is one or more of water, toluene, dimethylformamide, and ethanol.

[0012] Preferably, the temperature range for dissolution in step S1 is room temperature - 90°C.

[0013] Preferably, the concentration of solution A in step S1 is 2-30%.

[0014] Preferably, in step S2, the graphite precursor is one or more of needle coke, petroleum coke, raw coke or calcined coke of pitch coke, coal or coal-based semi-coke; the salt is an ionic salt of the thermal decomposition type.

[0015] Preferably, in step S2, the mass ratio of salt to graphite precursor is controlled between 0.5:1 and 10:1.

[0016] Preferably, in step S3, the mass ratio of binder to graphite precursor in mixture C is 1:100-10:100.

[0017] Preferably, in step S4, the molding pressure is 5-20 MPa; the graphitization temperature is 2500-2800℃; and the time is 0.5-8 h.

[0018] A high-throughput fast-charging artificial graphite anode material prepared by the preparation method described above.

[0019] A lithium-ion battery comprising the high-throughput fast-charging artificial graphite anode material as described above.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention can significantly increase the furnace loading of graphitization through densification molding. The introduction of pyrolytic salt during the molding process is beneficial to suppress the orderly arrangement of carbon microcrystals, increase defects, and increase the interlayer spacing during the graphitization heating process, thereby realizing the preparation of low-cost, high-throughput, fast-charging artificial graphite anode.

[0022] (2) The preparation method used in this invention is simple and easy to operate, and the fast-charging artificial graphite anode prepared has excellent 3C charge and discharge performance. Attached Figure Description

[0023] Figure 1 SEM images of the fast-charging artificial graphite anode material prepared in Example 1;

[0024] Figure 2 Cycle life curve of fast-charging artificial graphite anode material prepared in Example 1;

[0025] Figure 3 SEM images of the fast-charging artificial graphite anode material prepared in Example 2. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0027] Example 1

[0028] A method for preparing a high-throughput, fast-charging artificial graphite anode material includes the following steps: dissolving 10g of syrup in 90g of deionized water at room temperature to form a 10% homogeneous solution A; dispersing 100g of ammonium persulfate in 100g of semi-coke powder to form a mixture B; pouring solution A into solution B and stirring at room temperature for 3 hours; then placing it in a mold and molding it under a pressure of 10MPa to obtain a block; drying the obtained block and then heat-treating it in a graphitization furnace at 2500℃ for 1 hour to obtain artificial graphite.

[0029] Figure 1 The image shows a SEM image of the fast-charging artificial graphite obtained in Example 1. Its surface contains obvious porous structures, which are beneficial for electrolyte wetting and lithium-ion transport. Figure 2 Electrochemical test results show that the obtained fast-charging graphite has a specific capacity of 332 mAh / g at 0.1C and 182 mAh / g at 3C. After 700 cycles, the capacity retention rate reaches 91%.

[0030] Example 2

[0031] A method for preparing a high-throughput, fast-charging artificial graphite anode material includes the following steps: dissolving 10g of binding asphalt in toluene at 60°C to form a 20% homogeneous solution A; dispersing 100g of sodium bicarbonate in 100g of petroleum coke powder to form a mixture B; pouring solution A into solution B and stirring at 60°C for 2 hours; then placing it in a mold and molding it under a pressure of 15MPa to obtain a block; drying the obtained block and then heat-treating it in a graphitization furnace at 2700°C for 2 hours to obtain artificial graphite.

[0032] Electrochemical test results show that the obtained fast-charging graphite has a specific capacity of 326 mAh / g at 0.1C and 175 mAh / g at 3C. After 700 cycles, the capacity retention rate reaches 88%.

[0033] Example 3

[0034] A method for preparing a high-throughput fast-charging artificial graphite anode material includes the following steps: dissolving 5g of polyacrylonitrile in dimethylformamide at 60℃ to form an 8% homogeneous solution A; dispersing 100g of sodium bicarbonate in 100g of coal powder to form a mixture B; pouring solution A into solution B and stirring at 60℃ for 2h; then placing it in a mold and molding it under a pressure of 10MPa to obtain a block; drying the obtained block and then heat-treating it in a graphitization furnace at 2700℃ for 2h to obtain artificial graphite.

[0035] Electrochemical test results show that the obtained fast-charging graphite has a specific capacity of 324 mAh / g at 0.1C and 155 mAh / g at 3C. After 700 cycles, the capacity retention rate reaches 85%.

[0036] Example 4

[0037] A method for preparing a high-throughput, fast-charging artificial graphite anode material includes the following steps: dissolving 7g of thermosetting phenolic resin in ethanol at room temperature to form a 10% homogeneous solution A; dispersing 300g of sodium hypophosphite in 100g of pitch coke to form a mixture B; pouring solution A into solution B and stirring at room temperature for 5 hours; then placing it in a mold and molding it under a pressure of 10MPa to obtain a block; drying the obtained block and then heat-treating it in a graphitization furnace at 2700℃ for 3 hours to obtain artificial graphite.

[0038] Electrochemical test results show that the obtained fast-charging graphite has a specific capacity of 346 mAh / g at 0.1C and 188 mAh / g at 3C. After 700 cycles, the capacity retention rate reaches 93%.

[0039] Example 5

[0040] A method for preparing a high-throughput, fast-charging artificial graphite anode material includes the following steps: dissolving 7g of thermoplastic phenolic resin in ethanol at room temperature to form a 10% homogeneous solution A; dispersing 200g of ammonium persulfate in 100g of needle coke to form a mixture B; pouring solution A into solution B and stirring at room temperature for 5 hours. Then, placing the mixture in a mold and molding it under a pressure of 12MPa to obtain a block; drying the obtained block and then heat-treating it at 2800℃ for 2 hours in a graphitization furnace to obtain artificial graphite.

[0041] Electrochemical test results show that the obtained fast-charging graphite has a specific capacity of 361 mAh / g at 0.1C and 192 mAh / g at 3C. After 700 cycles, the capacity retention rate reaches 86%.

[0042] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a high-throughput fast-charging artificial graphite anode material, characterized in that, Includes the following steps: S1. Dissolve the adhesive in a solvent to obtain solution A; S2. Mix the graphite precursor and the salt in a certain proportion to obtain complex B, where the salt is an ionic salt that decomposes upon heating. S3. Mix solution A with complex B by stirring to obtain mixture C; S4. The mixture C is pressed into blocks, dried, and graphitized to obtain a fast-charging artificial graphite anode material.

2. The preparation method of a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S1, the adhesive is one or more of syrup, thermosetting resin, thermoplastic resin, and adhesive asphalt; the solvent is one or more of water, toluene, dimethylformamide, and ethanol.

3. The preparation method of a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, The temperature range for dissolution in step S1 is room temperature - 90°C.

4. The preparation method of a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S1, the concentration of solution A is 2-30%.

5. The preparation method of a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S2, the graphite precursor is one or more of the following: needle coke, petroleum coke, raw coke of pitch coke, calcined coke, coal, and coal-based semi-coke.

6. The method for preparing a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S2, the mass ratio of salt to graphite precursor is controlled between 0.5:1 and 10:

1.

7. The method for preparing a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S3, the mass ratio of binder to graphite precursor in mixture C is 1:100-10:

100.

8. The preparation method of a high-throughput fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step S4, the molding pressure is 5-20 MPa; the graphitization temperature is 2500-2800℃; and the time is 0.5-8 h.

9. A high-throughput fast-charging artificial graphite anode material prepared by the preparation method according to any one of claims 1 to 8.

10. A lithium-ion battery, characterized in that, Including the high-throughput fast-charging artificial graphite anode material as described in claim 9.

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