A fast-charging artificial graphite negative electrode material and a preparation method thereof
By employing oxidation etching, vapor phase coating, and mechanical fusion processes, the problems of increased specific surface area and low tap density of artificial graphite anode materials have been solved, achieving high-efficiency fast-charging performance and stable battery performance, making it suitable for the preparation of anode materials for lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGDU EMINENT NEW ENERGY TECH CO LTD
- Filing Date
- 2026-03-20
- Publication Date
- 2026-06-09
Smart Images
Figure CN122177792A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery anode material preparation, and specifically relates to a fast-charging artificial graphite anode material and its preparation method. Background Technology
[0002] Since their commercialization, lithium-ion batteries have been widely used in electric vehicle power batteries and 3C digital battery fields due to their advantages such as high energy density, wide operating temperature range, and long cycle life. With the continuous development of the industry, consumers' performance requirements for lithium-ion batteries are increasing. Currently, consumers are no longer satisfied with just high energy density; they also have higher demands for fast charging capabilities. Fast charging performance has become one of the key indicators for measuring battery performance. At present, the fast charging performance of the anode material remains the main factor limiting the fast charging capability of lithium-ion batteries. During high-rate charging, traditional anode materials are prone to lithium plating, leading to battery failure and other problems, which seriously restrict the commercial application of fast charging technology.
[0003] To improve the fast-charging performance of artificial graphite anode materials, one existing technology involves surface modification of artificial graphite using oxidation etching to create numerous micropores on the graphite surface, thereby increasing the lithium-ion insertion / extraction rate and improving the battery's rate performance. However, this method also has significant drawbacks: the resulting graphite anode material has a large specific surface area, severely impacting the battery's initial efficiency and cycle performance. To compensate for this deficiency, researchers have attempted to use soft or hard carbon as auxiliary materials to modify the surface through liquid-phase or solid-phase coating to improve performance. However, technical problems such as uneven coating layers and excessively large particle growth leading to low tap density still exist, making it difficult to meet the stringent comprehensive performance requirements for commercial applications.
[0004] Therefore, developing new materials and processes that can solve the above-mentioned technical problems is of great importance to promoting the development of high-performance fast-charging lithium-ion batteries. Summary of the Invention
[0005] This invention provides a fast-charging artificial graphite anode material and its preparation method, which can solve the technical problems in the prior art that improve the fast-charging performance of artificial graphite materials by oxidation etching, resulting in increased specific surface area, reduced first-time efficiency, and low tap density caused by solid or liquid phase coating of oxidized and etched graphite.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:
[0007] In a first aspect, this application provides a method for preparing a fast-charging artificial graphite anode material, comprising the following steps:
[0008] S1. The artificial graphite raw material is subjected to oxidation etching treatment in an oxidizing gas to obtain oxidized and etched artificial graphite.
[0009] S2. The oxidized and etched artificial graphite is coated by vapor deposition using a carbon source gas to obtain a vapor-coated artificial graphite material.
[0010] S3. Under the protection of inert gas, the gas-phase coated artificial graphite material is subjected to mechanical fusion treatment;
[0011] S4. The material after mechanical fusion in step S3 is screened and demagnetized to obtain fast-charging artificial graphite anode material.
[0012] Furthermore, in step S1, the temperature of the oxidation etching process is 200~1000℃, the processing time is 0.5~8h, and the flow rate of the oxidizing gas is 50~200 mL / min.
[0013] Preferably, the oxidation etching temperature is 500~800℃, the treatment time is 2~4h, and the oxidizing gas flow rate is 80~150 mL / min.
[0014] Furthermore, step S2 includes the following steps:
[0015] Under inert gas protection, the oxidized and etched artificial graphite is heated to the target process temperature;
[0016] After reaching the target process temperature, a mixture of carbon source gas and inert gas is introduced for vapor phase deposition coating.
[0017] After the coating is completed, the gas mixture is stopped, and the mixture is cooled and discharged to obtain the gas-phase coated artificial graphite material.
[0018] Furthermore, in step S2, the target process temperature is 500~1300℃, the vapor deposition coating time is 0.5~12h, and the heating rate is 3~15℃ / min.
[0019] Preferably, in step S2, the target process temperature is 700~1200℃ and the vapor deposition coating time is 2~8h.
[0020] Furthermore, in step S2, the proportion of carbon source gas in the mixed gas is 1% to 20%, and the gas flow rate is 5 to 20 mL / min.
[0021] Preferably, in step S2, the proportion of carbon source gas in the mixed gas is 5% to 10%, and the gas flow rate is 8 to 12 mL / min.
[0022] Furthermore, the carbon source gas is one or more of methane, ethylene, acetylene, propane, and propylene.
[0023] Furthermore, in step S3, the mechanical fusion process is carried out at a rotation speed of 800~2000 rpm, the processing time is 3~15 min, and the mechanical fusion temperature is 25~80℃.
[0024] Preferably, in step S3, the rotation speed of the mechanical fusion process is 1000~1500 rpm, the processing time is 4~8 min, and the temperature of the mechanical fusion process is 25~50℃.
[0025] Secondly, this application provides a fast-charging artificial graphite anode material, prepared by the method described in the first aspect.
[0026] Furthermore, the particle size Dv50 of the negative electrode material is 6.5~15.5μm, the specific surface area is less than 2.0 m² / g, and the tap density is greater than 1.0 g / cm³.
[0027] Thirdly, this application provides a lithium-ion battery, wherein the negative electrode of the lithium-ion battery contains the fast-charging artificial graphite negative electrode material described in the second aspect.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] 1. The fast-charging artificial graphite anode material preparation method provided by the present invention generates numerous micropores and nano-sized pores on the surface of graphite particles by oxidative etching, and uses vapor phase coating to coat a uniform and dense amorphous carbon layer on the etched graphite surface. Finally, through mechanical fusion, the loose, porous soft aggregates and sharp nano-protrusions formed by vapor phase coating are flattened or forged onto the graphite matrix by mechanical force, so that the particles are more tightly attached to the large particles, improving the tap density of the material, and enabling the anode material to maintain excellent fast-charging performance and high first efficiency while having a high tap density.
[0030] 2. The preparation method provided by this invention has a simple production process, stable product properties, and can achieve large-scale mass production;
[0031] 3. This invention constructs abundant micropores and nanochannels on the surface of graphite particles through oxidation etching, which significantly increases the lithium ion insertion / extraction channels on the graphite surface and greatly enhances the lithium ion diffusion rate, thereby improving fast charging performance.
[0032] 4. The present invention forms a dense and uniform amorphous carbon layer on the etched graphite surface through vapor phase coating treatment. This carbon layer effectively repairs the surface defects caused by oxidation etching, reduces the specific surface area of the negative electrode material, and thus significantly improves the first efficiency of the battery.
[0033] 5. The mechanical fusion process of the present invention compacts and flattens the loose agglomerates generated after gas phase coating by mechanical force, making the particles more tightly arranged and effectively improving the tap density of the negative electrode material. This not only improves the volumetric energy density of the battery and the processing performance of the material, but also enhances the stability of the electrode and improves safety. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is a SEM image of the fast-charging composite-coated artificial graphite anode material provided in an embodiment of the present invention.
[0036] Figure 2 This is a TEM image of the fast-charging composite-coated artificial graphite anode material provided in an embodiment of the present invention. Detailed Implementation
[0037] The embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0038] Example 1:
[0039] Tap density refers to the mass per unit volume of a powder material after it has been vibrated or tapped in a container. The formula is: Tap density = Mass of powder / Volume of powder after tapping. The unit is usually grams per cubic centimeter (g / cm³). Tap density measures the compactness of powder materials (such as positive or negative electrode active materials) when they are packed as tightly as possible, and is one of the key parameters for evaluating material processing performance and battery design.
[0040] Example 1:
[0041] This embodiment provides one specific implementation of a method for preparing a fast-charging artificial graphite anode material, as detailed below:
[0042] Step 1: Utilize materials with a Dv50 of 10 μm, magnetic foreign matter content <1 ppm, and a specific surface area of 1.82 m². 2 / g, tapped value is 1.29g / cm 3 Artificial graphite material was placed in a tube furnace with an air atmosphere and oxidized and etched at 700°C for 3 hours. The air flow rate into the equipment was controlled to be 100 mL / min to obtain the oxidized and etched graphite material.
[0043] Step 2: Before adding the oxidized and etched graphite, nitrogen gas is introduced into the rotary kiln to purge the oxygen content in the equipment to below 10 ppm. Then, the oxidized and etched artificial graphite obtained in the previous step is added to the rotary kiln. After the material is added, the equipment is heated to 1100 °C at a heating rate of 5 °C / min, with nitrogen gas continuously introduced for protection during the heating process. When the equipment temperature reaches 1100 °C, a mixture of methane and nitrogen is introduced for coating. The ratio of the introduced gas mixture is methane:nitrogen = 5%:95%, the flow rate of the mixed gas is 10 mL / min, and the introduction time is 6 hours. After coating is completed, the gas mixture is stopped, but nitrogen gas is continued to be introduced for cooling. The material is discharged after the temperature drops below 100 °C to obtain the gas-phase coated graphite material.
[0044] Step 3: Add the gas-coated artificial graphite material obtained in the above steps to the fusion machine for mechanical fusion for 5 minutes, during which the fusion machine speed is controlled at 1200 rpm and the temperature is controlled at 30℃.
[0045] The material from step 3 was sieved through a 350-mesh screen and then demagnetized to obtain the fast-charging composite-coated artificial graphite anode material of Example 1. The prepared artificial graphite anode material had a particle size D50 of 10.51 μm, a magnetic foreign matter content of <1 ppm, and a specific surface area of 1.57 m². 2 / g, tapped value is 1.23 g / cm³ 3 .
[0046] The graphite anode material prepared according to the method of this embodiment is referenced. Figure 1 , Figure 2 .in, Figure 1 This is a SEM image of the fast-charging composite-coated artificial graphite anode material of the present invention. Figure 2 This is a TEM image of the fast-charging composite-coated artificial graphite anode material of the present invention.
[0047] The above preparation method involves oxidizing and etching graphite particles to generate numerous micropores and nanoscale pores on the surface. A uniform and dense amorphous carbon layer is then coated onto the etched graphite surface using vapor phase coating. Finally, a mechanical fusion method is used to flatten or forge the loose, porous soft aggregates and sharp nano-protrusions formed by the vapor phase coating onto the graphite matrix using mechanical force. This allows the particles to adhere more tightly to the larger particles, increasing the material's tap density. This enables the negative electrode material to maintain excellent fast-charging performance and high initial efficiency while also possessing a high tap density. Furthermore, the preparation method of this invention has a simple production process, stable product properties, and can achieve large-scale mass production.
[0048] Through oxidation etching, abundant micropores and nanochannels are constructed on the surface of graphite particles, significantly increasing the lithium-ion insertion / extraction channels on the graphite surface and greatly improving the lithium-ion diffusion rate, thereby enhancing fast charging performance.
[0049] This invention forms a dense and uniform amorphous carbon layer on the etched graphite surface through vapor phase coating treatment. This carbon layer effectively repairs the surface defects caused by oxidation etching, reduces the specific surface area of the negative electrode material, and thus significantly improves the first-stage efficiency of the battery.
[0050] The mechanical fusion process of this invention compacts and flattens the loose agglomerates generated after vapor phase coating using mechanical force, resulting in a tighter arrangement between particles and effectively improving the tap density of the negative electrode material. This not only increases the volumetric energy density of the battery and improves the material processing performance, but also enhances the stability of the electrode and improves safety.
[0051] Example 3:
[0052] The only difference between this embodiment and Embodiment 2 is the specifications of the artificial graphite material used: Dv50 = 7 μm, magnetic foreign matter content < 1 ppm, and specific surface area of 1.9 m². 2 / g, tapped value is 1.28 g / cm³ 3 Other conditions and parameters are the same as in Example 1.
[0053] Example 4:
[0054] The difference between this embodiment and embodiment 2 is that the mixed gas introduced in step 2 is changed to ethylene:nitrogen = 5%:95%, and the temperature is controlled at 700°C during coating. Other conditions and parameters are the same as in embodiment 2.
[0055] Example 5:
[0056] Compared with Example 2, the only difference in this embodiment is that the coating time in step 2 is reduced from 6 hours to 2 hours, while other conditions and parameters are the same as in Example 2.
[0057] Example 6:
[0058] Compared with Example 2, the only difference in this embodiment is that the mechanical fusion time in step 3 is reduced from 5 minutes to 1 minute, while other conditions and parameters are the same as in Example 2.
[0059] Example 7:
[0060] This embodiment provides a comparative example, as follows:
[0061] Comparative Example 1: Compared with Example 2, only graphite without the treatment of steps 2 and 3 was used, while other conditions and parameters were the same as in Example 2.
[0062] Comparative Example 2: Compared with Example 2, only graphite without step 3 was used, while other conditions and parameters were the same as in Example 2.
[0063] Comparative Example 3: Compared with Example 2, only the graphite that underwent steps 1 and 3, but not step 2, was treated, while other conditions and parameters were the same as in Example 2.
[0064] Electrochemical performance testing:
[0065] The fast-charging artificial graphite prepared in Examples 2-6 and Comparative Examples 1-3 was used as the negative electrode material of the battery. It was mixed with Super-P, SBR and CMC in a mass ratio of 92.5:3.5:2.2:1.8 to prepare a negative electrode active slurry. The prepared slurry was uniformly coated on copper foil and prepared into a negative electrode sheet through drying, rolling and other processes. It was then assembled with a lithium metal sheet to form a coin cell for testing.
[0066] The formula for calculating the 1C and 2C capacity retention rate of the battery is: Capacity retention rate = Battery capacity at 1C and 2C / Battery capacity at 0.05C * 100%. The test data of Examples 2-6 and Comparative Examples 1-3 are shown in Table 1.
[0067] Table 1. Experimental results and test data of fast-charging graphite anode materials
[0068]
[0069] As shown in Table 1, compared with Example 1 and Comparative Examples 1 and 3, the oxidized and etched material has a large specific surface area and a low initial efficiency. However, after vapor phase coating and mechanical fusion treatment, the specific surface area of the material is reduced, the tapping rate is high, and the initial efficiency is significantly improved, while the fast charging performance is also significantly improved.
[0070] Compared with Example 1 and Comparative Example 2, the tap density of the material that only underwent oxidation etching and vapor phase coating was significantly lower than that of the sample that underwent further mechanical fusion.
[0071] Compared to uncoated materials, vapor-phase coated materials form a continuous and dense amorphous carbon layer on the etched graphite surface. This amorphous carbon layer repairs the defects caused by oxidation etching. Furthermore, the larger interlayer spacing of this amorphous carbon layer facilitates rapid lithium-ion transport, thus improving the material's fast-charging performance. However, the tap density of the vapor-coated material is relatively low. Mechanical fusion is used to compact and flatten the amorphous carbon layer formed by vapor-phase coating, making it more dense and uniformly deposited on the graphite particle surface, thereby increasing the tap density. Therefore, the graphite anode material prepared by combining oxidation etching, vapor-phase coating, and mechanical fusion processes possesses high tap density, high initial efficiency, and excellent fast-charging performance.
[0072] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a fast-charging artificial graphite anode material, characterized in that, Includes the following steps: S1. The artificial graphite raw material is subjected to oxidation etching treatment in an oxidizing gas to obtain oxidized and etched artificial graphite. S2. The oxidized and etched artificial graphite is coated by vapor deposition using a carbon source gas to obtain a vapor-coated artificial graphite material. S3. Under the protection of inert gas, the gas-phase coated artificial graphite material is subjected to mechanical fusion treatment; S4. The material after mechanical fusion in step S3 is screened and demagnetized to obtain fast-charging artificial graphite anode material.
2. The method for preparing a fast-charging artificial graphite anode material according to claim 1, characterized in that, In step S1, the temperature of the oxidation etching process is 200~1000℃, the processing time is 0.5~8h, and the flow rate of the oxidizing gas is 50~200mL / min.
3. The method for preparing a fast-charging artificial graphite anode material according to claim 1, characterized in that, Step S2 includes the following steps: Under inert gas protection, the oxidized and etched artificial graphite is heated to the target process temperature; After reaching the target process temperature, a mixture of carbon source gas and inert gas is introduced for vapor phase deposition coating. After the coating is completed, the gas mixture is stopped, and the mixture is cooled and discharged to obtain the gas-phase coated artificial graphite material.
4. The method for preparing a fast-charging artificial graphite anode material according to claim 3, characterized in that, In step S2, the target process temperature is 500~1300℃, and the vapor deposition coating time is 0.5~12h.
5. The method for preparing a fast-charging artificial graphite anode material according to claim 3, characterized in that, In step S2, the proportion of carbon source gas in the mixed gas is 1% to 20%, and the gas flow rate is 5 to 20 mL / min.
6. The method for preparing a fast-charging artificial graphite anode material according to claim 5, characterized in that, The carbon source gas is one or more of methane, ethylene, acetylene, propane, and propylene.
7. The method for preparing a fast-charging artificial graphite anode material according to claim 1, characterized in that, In step S3, the mechanical fusion process is carried out at a rotation speed of 800~2000 rpm, the processing time is 3~15 min, and the mechanical fusion temperature is 25~80℃.
8. A fast-charging artificial graphite anode material, characterized in that, The negative electrode material is prepared by the method of any one of claims 1 to 7, wherein the particle size Dv50 is 6.5~15.5μm, the specific surface area is less than 2.0 m² / g, and the tap density is greater than 1.0 g / cm³.
9. A lithium-ion battery, characterized in that, The lithium-ion battery anode contains the fast-charging artificial graphite anode material as described in claim 8.