Negative electrode material, battery

Abstract

The application provides a negative electrode material and a battery, the negative electrode material comprising graphite, the surface and / or interior of the graphite having pores, the pore volume of the negative electrode material being V cm 3 / kg, the true density being D g / cm 3 , the specific surface area being S m 2 / g, and the graphitization degree being G%, wherein 0.7≤V*S / D≤3.95 and 89≤G≤93. The negative electrode material and the battery provided by the application can improve the rate performance and cycle performance of the graphite negative electrode material under a large rate current.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of negative electrode materials, in particular to a negative electrode material and a battery. BACKGROUND

[0002] Lithium ion batteries have shown good application prospects in the fields of portable consumer electronics, electric tools, new energy vehicles, energy storage, etc. due to their excellent performance. Since the commercialization of lithium ion batteries, the most mature negative electrode material used is graphite-based negative electrode material. The main development direction of lithium ion batteries at present is high capacity, high rate and high safety. Therefore, the development of high-performance graphite negative electrode is crucial for obtaining lithium ion batteries with high rate performance and good cycle performance.

[0003] From a technical aspect, the special layered structure of graphite determines that Li + can only be embedded from the end face of the material and gradually diffuse into the interior of the particle, resulting in a low diffusion rate of lithium ions and poor rate performance. At the same time, lithium insertion at high rate can easily cause lithium ion enrichment on the surface of the graphite negative electrode. When the lithium ion concentration at the interface reaches saturation, lithium ions will be deposited in the form of metal, resulting in insufficient utilization of diffusion channels and electrochemical reaction area.

[0004] Therefore, at the present stage when graphite materials have been developed very maturely, single improvement of a parameter cannot meet the market demand for graphite negative electrode materials with high rate performance and good cycle performance. It is necessary to explore the mechanism of the synergistic effect of multiple factors and develop graphite negative electrode materials that meet market demand. SUMMARY

[0005] In view of the above, the present application provides a new negative electrode material and a battery. The internal and / or surface pore volume, specific surface area and true density of the negative electrode material are precisely controlled, so that they are maintained within a reasonable range, thereby improving the capacity and rate performance of the negative electrode material.

[0006] In a first aspect, the present application provides a negative electrode material, which comprises graphite, the surface and / or interior of the graphite having pores, the pore volume of the negative electrode material being V cm 3 / kg, the true density being D g / cm 3 , the specific surface area being S m 2 / g, the graphitization degree being G%, wherein 0.7≤V*S / D≤3.95, and 89≤G≤93.

[0007] The pore volume is tested by using an ASAP2460 device of American Micromeritics Company, and the BJH Desorption cumulative volume of pores model is used in the range of 0.5-50 nm. The pore volume is calculated in the pore size range.

[0008] In some embodiments, the pore volume of the negative electrode material is V cm3 / g, 1.812≤V≤4.987. 3

[0009] In some embodiments, the specific surface area of the negative electrode material is S m2 / g, 0.872≤S≤1.773. 2

[0010] In some embodiments, the true density of the negative electrode material is D g / cm3, 2.238≤D≤2.257. 3

[0011] In some embodiments, the pores include at least one of micropores and mesopores.

[0012] In some embodiments, the pores extend from the surface of the graphite to the interior.

[0013] In some embodiments, the graphite is artificial graphite.

[0014] In some embodiments, the average pore size of the pores is

[0015] In some embodiments, the negative electrode material has a (002) interlayer spacing of d 002 ,

[0016] In some embodiments, the particle size D 50 of the negative electrode material is 10 μm-20 μm.

[0017] In some embodiments, the negative electrode material further includes amorphous carbon, which is present on the surface of the graphite and / or dispersed between the graphite particles.

[0018] In some embodiments, the negative electrode material further includes an amorphous carbon coating layer on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10 nm-500 nm.

[0019] In some embodiments, the mass fraction of the amorphous carbon in the negative electrode material is 0.1wt%-3wt%.

[0020] In a second aspect, the present application provides a battery, which includes the negative electrode material according to the first aspect.

[0021] The technical solution of the present application has at least the following beneficial effects:

[0022] ​​​The application provides a negative electrode material, which comprises graphite, the surface and / or interior of the graphite has pores, the pores extend from the surface of the graphite to the interior, and abundant pores are generated on the surface and near the surface of the graphite while the regular graphite layered structure of the negative electrode material is reserved. The pore volume of the negative electrode material is V cm 3 / kg, the true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G%, wherein, 0.7≤V*S / D≤3.95, and 89≤G≤93. The pore volume in the certain range is beneficial to Li +The lithium ion diffusion rate is improved from the material surface to the embedded interior of the pore structure, and the specific surface area within a certain range can ensure sufficient electrochemical reaction interface, promote the diffusion of lithium ions at the solid-liquid interface and in the solid phase, reduce the concentration difference polarization, and is beneficial to improve the capacity and rate performance of the negative electrode material. However, only to meet the appropriate pore volume and specific surface area, the rate performance of the negative electrode material still has more room for improvement, because when the lithium ion diffuses to the surface of the graphite, if the carbon atom ordering in the graphite is relatively chaotic and the ordering degree is not enough, the lithium ion entering the interior of the graphite material and the carbon atom combination electrochemical reaction is hindered. At the same time, since the graphite is polycrystalline, especially artificial graphite, there are grain boundary defects between the grains, the grain boundary defect stress is uneven, the grain boundary belongs to a kind of crystal face defects, and cracks are easy to appear. Under the condition of external force, it is easier to split along the grain boundary direction and cause intergranular fracture. Finally, the crystal plane parallel to the graphite crystal layer direction is split to form the outer surface of the graphite particle. Since these outer surfaces are perpendicular to the diffusion direction of lithium ions, they must overcome the carbon plane, making it difficult for lithium ions to enter the interior of the graphite. At the same time, lithium ions may gather on the carbon surface to form lithium clusters, thereby inhibiting the diffusion of lithium or forming lithium deposition, so that the diffusion channel and electrochemical reaction area cannot be fully utilized. Therefore, by controlling the graphitization degree and true density to provide a good diffusion path for lithium ion diffusion, and combining the design of pore structure and pore distribution to concentrate the stress in the graphite inside the pore, the stress at the grain boundary is dispersed, so that the graphite first cracks and breaks from the pore when subjected to external force. It is beneficial to form a transgranular fracture, and the pore is exposed to eventually form the outer surface of the graphite particle. Transgranular fracture is beneficial to increase the channel entrance of the graphite particle surface parallel to the lithium ion diffusion direction. In addition, the inner surface of the pore itself has a certain number of channel entrances that can diffuse lithium ions between the graphite layers. At the same time, due to the presence of many defects that can achieve edge and end lithium storage, the fracture of the particle outer surface from the pore can create more graphite microcrystal surfaces parallel to the lithium ion diffusion path. Not only does it create more lithium ion diffusion paths inside the graphite particle, but it also creates more channel entrances for lithium ions on the particle surface. At the same time, a higher graphitization degree is beneficial to the diffusion environment, reducing the hindering traps formed by lithium ion transmission due to partial crystal distortion and other defects. The degree of graphitization affects the number of graphite polycrystal grain boundaries and lattice distortion to some extent, so that the interlayer arrangement has a high and tight ordering degree, which is beneficial to improve the true density and ensure that the negative electrode material has a high specific capacity. The V*S / D of the negative electrode material is controlled within the above range, and the graphitization degree of the material is controlled, which is beneficial to the combination of lithium ions and sufficient carbon atoms under low resistance, so that the negative electrode material has sufficient deintercalation lithium reaction space, and is beneficial to obtain a negative electrode material with better rate performance and capacity. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1A scanning electron microscope picture of the graphite negative electrode material provided for Embodiment 2 of the present application.

[0024] Figure 2 Another scanning electron microscope picture of the graphite negative electrode material provided for Embodiment 2 of the present application.

[0025] Figure 3 A scanning electron microscope picture of the graphite negative electrode material provided for Embodiment 11 of the present application.

[0026] Figure 4 Another scanning electron microscope picture of the graphite negative electrode material provided for Embodiment 11 of the present application. DETAILED DESCRIPTION

[0027] In order to better illustrate the present application and facilitate the understanding of the technical solutions of the present application, the present application is further described in detail below. However, the following embodiments are only simple examples of the present application, and do not represent or limit the protection scope of the present application. The protection scope of the present application is subject to the claims.

[0028] Since the commercialization of lithium ion batteries, the most mature negative electrode material used is graphite-based negative electrode material. The special layered structure of graphite determines that Li + can only be embedded from the end face of the material and gradually diffuse into the interior of the particle, resulting in a low diffusion rate of lithium ions and poor rate performance. At the same time, lithium insertion at a large rate is easy to cause lithium ion enrichment on the surface of the graphite negative electrode. When the lithium ion concentration at the interface reaches saturation, lithium ions will be deposited in the form of metal, resulting in that the diffusion channel and the electrochemical reaction area cannot be fully utilized.

[0029] Therefore, the present application provides a negative electrode material, which comprises graphite, the surface and / or interior of the graphite has pores, the pores extend from the surface of the graphite to the interior, the pore volume of the negative electrode material is V cm 3 / kg, the true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G%, and 0.7≤V*S / D≤3.95, and 89≤G≤93.

[0030] The pore volume is tested by using the ASAP2460 equipment of American Micromeritics Company, and is calculated in the pore size range by using the BJH Desorption cumulative volume of pores model. The pore size range is 1.7-50 nm.

[0031] The negative electrode material provided in the application comprises graphite, the surface and / or interior of the graphite has pores, the pores extend from the surface of the graphite to the interior, and abundant pores are generated on the surface and near the surface of the graphite while the regular layered structure of the negative electrode material is retained. The pore volume of the negative electrode material is V cm 3 / kg, the true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G%, wherein 0.7≤V*S / D≤3.95, and 89≤G≤93. The pore volume within a certain range is beneficial to the embedding of Li + from the surface of the material to the interior along the pore structure, the diffusion rate of lithium ions is improved, the specific surface area within a certain range can ensure sufficient electrochemical reaction interface, promote the diffusion of lithium ions at the solid-liquid interface and in the solid phase, reduce the concentration difference polarization, and is beneficial to improving the capacity and rate performance of the negative electrode material. However, only by meeting the appropriate pore volume and specific surface area, the rate performance of the negative electrode material still has more room for improvement, because when the lithium ions diffuse to the surface of the graphite, if the ordering of carbon atoms in the graphite is relatively chaotic and the ordering degree is not enough, the hindrance of lithium ions to enter the interior of the graphite material and combine with carbon atoms to generate electrochemical reactions is relatively large, and meanwhile, the graphite is polycrystalline, especially artificial graphite, there are grain boundary defects between the crystal grains, the stress of the grain boundary defects is uneven, cracks are prone to occur, and the graphite is prone to split under external force. Finally, the crystal surface parallel to the layer direction of the graphite crystal is split to form the outer surface of the graphite particle. Since these outer surfaces are perpendicular to the diffusion direction of lithium ions and must climb over the carbon plane, it is difficult to enter the interior of the graphite, and lithium clusters may be formed on the carbon surface, thereby inhibiting the diffusion of lithium or forming lithium deposition, so that the diffusion channel and electrochemical reaction area cannot be fully utilized. Therefore, by controlling the graphitization degree and the true density to provide a good diffusion path for lithium ion diffusion, and combining the design of the pore structure and the distribution of the pores, the application concentrates the stress in the interior of the graphite to the pores, reduces the stress at the grain boundary, and makes the graphite first crack and break at the pores when subjected to external force, and finally forms the surface of the graphite particle. In this way, more graphite crystal surfaces parallel to the diffusion path of lithium ions can be constructed, not only more diffusion paths of lithium ions are created in the interior of the graphite particle, but also more channel entrances are created for the entry of lithium ions on the surface of the particle. Meanwhile, a higher graphitization degree is beneficial to the diffusion environment and reduces the hindering traps formed by the crystal defects to the transmission of lithium ions, so as to ensure that the negative electrode material has a higher specific capacity. The V*S / D of the negative electrode material is controlled within the above range, and the graphitization degree of the material is controlled, which is beneficial to the combination of lithium ions and sufficient carbon atoms under low resistance, so that the negative electrode material has sufficient deintercalation lithium reaction space, and a negative electrode material with better rate performance and capacity can be obtained.

[0032] In some embodiments, the pore volume V cm3 / g of the negative electrode material satisfies V > 0.5. 3 / kg, 1.812≤V≤4.987, specifically, 1.812, 2.016, 2.582, 2.897, 3.348, 3.476, 3.755, 3.896, 4.013, 4.167, 4.275, 4.512 or 4.987, etc., without being limited herein. When the pores are electrochemically reacted inside the electrode, the pores create more lithium ion diffusion channels and electrochemical reaction interfaces for the negative electrode material, which can promote the diffusion of lithium ions at the solid-liquid interface and in the solid phase, reduce the concentration polarization, and be beneficial to improve the rate performance of the negative electrode material.

[0033] In some embodiments, the specific surface area S m2 / g of the negative electrode material satisfies 0.872≤S≤1.773. 2 / g, 0.872≤S≤1.773; specifically, 1.773, 1.643, 1.593, 1.532, 1.498, 1.446, 1.386, 1.315, 1.267, 1.157, 1.044, 0.912 or 0.872, etc., without being limited herein. It can be understood that too large specific surface area is easy to cause excessive solid-state electrolyte film formation, consume too much irreversible lithium salt, and reduce the first efficiency of the battery.

[0034] In some embodiments, the true density D g / cm3 of the negative electrode material satisfies 2.210≤D≤2.265. 3 , 2.2385, 2.2481, 2.2440, 2.2372, 2.2476, 2.2502, 2.2514 or 2.262, etc., without being limited herein.

[0035] In some embodiments, the graphitization degree G% of the negative electrode material satisfies 89≤G≤93; specifically, 89, 90, 90.5, 91, 91.5, 92, 92.5 or 93, etc., without being limited herein.

[0036] In some embodiments, the pores include at least one of micropores and mesopores.

[0037] In some embodiments, the average pore diameter of the pores is Specifically, the average pore diameter of the pores is or , etc., without being limited herein. Controlling the average pore diameter of the pores within the above range is beneficial to Li + transport from the surface of the material along the pore structure into the graphite interior and further undergo lithium extraction and intercalation reaction. Preferably, the average pore diameter of the pores is

[0038] In some embodiments, the pores extend from the surface of the graphite to the interior.

[0039] In some embodiments, the graphite is artificial graphite.

[0040] In some embodiments, the particle size D 50 of the negative electrode material is 10-20 μm. Specifically, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 18 μm, 19 μm or 20 μm, etc., which is not limited herein. It should be noted that the particle size distribution is measured by laser diffraction method, and the volume-based cumulative particle size distribution is D 50 , which represents the particle size corresponding to 50% of the cumulative particle size distribution.

[0041] In some embodiments, the negative electrode material is determined by X-ray diffraction, and the interlayer spacing of the (002) plane is d 002 , The interlayer spacing d 002 of the (002) plane is within the above range, and the graphite crystallinity of the graphite particles is high, i.e., the graphitization degree is high, and the capacity of the product is high.

[0042] In some embodiments, the negative electrode material further comprises an amorphous carbon coating layer on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10-500 nm; specifically, it can be 10 nm, 15 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, 180 nm, 200 nm, 400 nm or 500 nm; preferably, the thickness of the amorphous carbon coating layer is 10-100 nm.

[0043] In some embodiments, the negative electrode material further comprises amorphous carbon, which exists on the surface of the graphite and / or is dispersed between the graphite particles. Specifically, the graphite particles can be embedded in the amorphous carbon material with the amorphous carbon material as the matrix, and part of the graphite particles are exposed on the surface of the amorphous carbon material.

[0044] In some embodiments, the negative electrode material further comprises amorphous carbon, and the mass fraction of the amorphous carbon in the negative electrode material is 0.1-3 wt%; specifically, it can be 0.1 wt%, 0.3 wt%, 0.5 wt%, 1 wt%, 2 wt%, 2.5 wt% or 3 wt%, etc., which is not limited herein. The presence of the amorphous carbon provides more irregular and open diffusion paths for lithium ions, which is beneficial to the improvement of the rate performance of the material.

[0045] In some embodiments, the cycle capacity retention rate of the negative electrode material is ≥90% after 500 cycles of 1C charging; specifically, it can be 91.8%, 92.3%, 90.6%, 92.4%, 93.5%, etc., which is not limited herein.

[0046] The application also provides a preparation method of a negative electrode material, comprising the following steps:

[0047] S10, mixing the softened pitch with an alkaline solution with a concentration of 0.01 mol / L-0.05 mol / L and performing ultrasonic treatment to obtain a mixture, wherein the mass content ratio of the saturated component to the aromatic component in the pitch is (5-20):(95-80).

[0048] S20, performing drying and crushing treatment on the solid product after washing the mixture to obtain powder D 50 is 10 μm-20 μm;

[0049] S30, performing carbonization treatment on the powder under an inert atmosphere at 500-1200 ℃ to obtain a precursor;

[0050] S40, performing graphitization treatment on the precursor at 2800-3200 ℃ to obtain the negative electrode material.

[0051] The preparation method of the negative electrode material provided by the application mixes the pitch with an alkaline solution with a low concentration, forms a pore structure in situ in the pitch by means of ultrasonic etching, increases the effective reaction area of the material and increases the lithium ion embedding path, then performs carbonization treatment on the powder after in-situ etching, in the carbonization process, impurities, volatile substances and unstable substances in the material are decomposed and escaped, so that the pore diameter and pore depth of the etched pores are further enlarged, performs graphitization treatment on the carbonization product, forms graphite with rich and regular pores, realizes accurate control of the pore volume of the graphite, adjusts the stress distribution in the graphite to a certain extent, finally increases the reaction area of the negative electrode active material in the electrode, and is beneficial to the improvement of the large-rate charge and discharge performance of the material. The process method is simple, the production cost is low, the prepared graphite negative electrode material has the characteristics of high specific capacity, excellent large-rate charge and discharge performance and excellent cycle performance, and can meet the needs of consumer and power users for negative electrode energy density and fast charging performance.

[0052] The technical solutions of the application are described in detail as follows:

[0053] S10, mixing the softened pitch with an alkaline solution with a concentration of 0.01 mol / L-0.05 mol / L and performing ultrasonic treatment to obtain a mixture, wherein the mass content ratio of the saturated component to the aromatic component in the pitch is (5-20):(95-80).

[0054] In some embodiments, the pitch includes coal pitch and / or petroleum pitch, and the petroleum pitch can be modified pitch and mesophase pitch.

[0055] In some embodiments, the mass content ratio of saturated components to aromatic components in the pitch is (5-20):(95-80). Specifically, it can be 5:95, 8:92, 10:90, 13:87, 15:85, 18:82, 20:80, etc., and of course can also be other values within the above range, which are not limited herein. By controlling the mass ratio of saturated components to aromatic components in the pitch, the higher the content of aromatic components, the better the flowability of the pitch, the lower the softening temperature, and the higher the volatile content. The volatile components decompose and escape during carbonization, further expanding the pore size and pore depth of the etched pores, concentrating more stress in the graphite inside the pores around the pores, reducing the stress at the grain boundaries, causing the graphite to first crack and break from the pores when subjected to external force, and ultimately building the surface of the graphite particles. This can create more graphite crystalline surfaces parallel to the lithium ion diffusion path, not only creating more lithium ion diffusion paths inside the graphite particles, but also further creating more channels for lithium ions to enter on the particle surface, which is beneficial to obtaining a negative electrode material with better rate capability and lower residual carbon content.

[0056] In some embodiments, the pitch is heated to a softening temperature of 50-80°C to form a liquid pitch. The softening temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, etc., and of course can also be other values within the above range, which are not limited herein.

[0057] In some embodiments, the alkaline solution includes at least one of a NaOH solution and a KOH solution.

[0058] In some embodiments, the concentration of the alkaline solution is 0.01-0.05 mol / L, specifically 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.045 mol / L, or 0.05 mol / L, etc., and of course can also be other values within the above range, which are not limited herein. If the concentration of the alkaline solution is too high, it will cause too many pores to be formed on the surface of the pitch during etching, which will further result in a large pore volume and a large specific surface area of the final graphite negative electrode material, making it difficult to control the V*S / D ratio within the ideal range and not conducive to improving the large-rate charge-discharge performance and cycle performance of the negative electrode material. Controlling the V*S / D ratio of the negative electrode material within the above range allows the negative electrode material to have sufficient deintercalation lithium chemical reaction space, which is conducive to obtaining a negative electrode material with better rate capability and capacity.

[0059] In some embodiments, the material ratio of the asphalt to the alkaline solution is 50 g / 100 ml to 100 g / 100 ml, and can be 50 g / 100 ml, 60 g / 100 ml, 70 g / 100 ml, 75 g / 100 ml, 80 g / 100 ml, 85 g / 100 ml, 90 g / 100 ml or 100 g / 100 ml, and the like, and can also be other values in the above range, which are not limited herein. Controlling the material ratio of the asphalt to the alkaline solution can be beneficial to the alkaline solution to fully etch the softened asphalt, so as to form a suitable number of pores on the surface of the asphalt, reduce the stress at the grain boundary of the obtained graphite after graphitization, and be beneficial to creating more lithium ion diffusion paths, and improving the specific capacity and rate performance of the negative electrode material.

[0060] In some embodiments, the ultrasonic treatment time under the heat preservation state is 5 h to 10 h, and can be 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, and the like, but is not limited to the listed values, and other unlisted values in the value range are also applicable. During the ultrasonic treatment, the alkaline solution continuously impacts and etches the asphalt, so that the pores are formed in situ in the internal small particles of the asphalt, the pore structure creates more lithium ion diffusion channels and electrochemical reaction interfaces for the negative electrode material, can promote the diffusion of lithium ions at the solid-liquid interface and in the solid phase, reduce the concentration polarization, and be beneficial to improving the rate performance of the negative electrode material.

[0061] S20, drying and crushing the solid product after washing the mixture to obtain powder D 50 is 10 μm to 20 μm.

[0062] In some embodiments, the mixture is cooled to room temperature, and repeatedly washed and filtered with distilled water until the filtrate is neutral, and the solid-liquid separation obtains a solid product.

[0063] In some embodiments, the solid-liquid separation method includes at least one of centrifugation and filtration, and the filtration can be at least one of normal pressure filtration, vacuum filtration and reduced pressure filtration.

[0064] In some embodiments, the drying temperature is 80°C to 120°C, and can be 80°C, 90°C, 100°C, 110°C or 120°C, and the like, but is not limited to the listed values, and other unlisted values in the value range are also applicable.

[0065] In some embodiments, the median particle size D 5010 μm to 20 μm, more specifically, can be 12 μm, 13 μm, 14 μm, 16 μm, 18 μm, 18.5 μm, 19 μm or 20 μm, etc., but not limited to the listed values, other values not listed in the range are also applicable. It is found through repeated experiments that the median particle size of the powder is controlled in the above range, which is beneficial to the processing performance, capacity and rate performance.

[0066] S30, the powder is placed under an inert atmosphere at 500-1200°C for carbonization treatment to obtain a precursor.

[0067] In some embodiments, the heating rate of the carbonization treatment process is specifically 2°C / min, 3°C / min, 5°C / min, 6°C / min, 8°C / min, 9°C / min or 10°C / min, etc. It can be understood that the heating rate of the carbonization treatment is in the above range, which is beneficial to the volatilization of volatile matter in the raw material at different rates, further expansion and / or deepening of the pore size of the pore structure, and cooperation with the heating rate of the subsequent graphitization process to obtain the negative electrode material satisfying 0.70≤V*S / D≤3.95.

[0068] In some embodiments, the carbonization treatment temperature can be specifically 500°C, 550°C, 600°C, 700°C, 750°C, 800°C, 850°C, 900°C, 1000°C or 1200°C, etc., but not limited to the listed values, other values not listed in the range are also applicable. It can be understood that the carbonization treatment temperature is in the above range, which is beneficial to the discharge of volatile matter in the powder.

[0069] In some embodiments, the holding time of the carbonization treatment is 2h-10h, which can be specifically 2h, 3h, 4h, 4.5h, 5h, 6h, 8h or 10h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0070] S40, the precursor is placed at 2800-3200°C for graphitization treatment to obtain a negative electrode material.

[0071] In some embodiments, the holding temperature of the graphitization treatment can be specifically 2800°C, 2850°C, 2900°C, 2950°C, 3000°C, 3100°C or 3200°C, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0072] In some embodiments, the holding time of the graphitization treatment is 2h-10h, which can be specifically 2h, 3h, 4h, 4.5h, 5h, 6h, 8h or 10h, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0073] In some embodiments, the heating rate of the graphitization treatment can be 2-10°C / min, specifically 2°C / min, 3°C / min, 4°C / min, 6°C / min, 8°C / min or 10°C / min, etc., but not limited to the listed values, and other values not listed in the range are also applicable. The specific heating rate is conducive to controlling the formation of internal and / or surface pores of the material graphite and the specific surface area.

[0074] In some embodiments, at least one of crushing, screening and magnetic removal is performed after the graphitization treatment. Preferably, crushing, magnetic removal and screening are sequentially performed after the graphitization treatment.

[0075] In some embodiments, the crushing method is any one of a mechanical crusher, an air flow crusher and a low-temperature crusher.

[0076] In some embodiments, the screening method is any one of a fixed screen, a drum screen, a resonance screen, a roller screen, a vibrating screen and a chain screen, and the mesh size of the screening is 100-500 mesh, specifically the mesh size of the screening can be 100 mesh, 200 mesh, 250 mesh, 325 mesh, 400 mesh, 500 mesh, etc., and the particle size of the negative electrode material is controlled within the above range, which is conducive to improving the processability of the negative electrode material.

[0077] In some embodiments, the magnetic removal device is any one of a permanent magnet cylinder magnetic separator, an electromagnetic iron remover and a pulsating high gradient magnetic separator, and the magnetic removal is to finally control the content of magnetic substances in the negative electrode material and reduce the effect of the magnetic substances on the discharge of the lithium ion battery and the safety of the battery during use.

[0078] The application also provides a battery comprising the negative electrode material.

[0079] Those skilled in the art will understand that the above-described method for preparing the battery is only an example. Other methods commonly used in the art can be used without departing from the content disclosed in the present application, and other types of batteries can also be prepared for testing, such as sodium ion batteries, potassium ion batteries, etc.

[0080] The embodiments of the present application are further described in the following examples. The embodiments of the present application are not limited to the following specific examples. Within the scope of protection, appropriate changes can be made.

[0081] Example 1

[0082] The method for preparing the negative electrode material of the present embodiment comprises the following steps:

[0083] (1) the pitch is heated to 80℃ softening, and then mixed with 0.05 mol / L KOH alkaline solution, and ultrasonic treatment is carried out at 80℃ for 10h to obtain a mixture, wherein the pitch is mainly saturated fraction and aromatic fraction, and the content ratio of the saturated fraction and the aromatic fraction is 5:95;

[0084] (2) the mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 with a particle size of 16.3μm);

[0085] (3) the powder is carbonized at 1200℃ for 10h to obtain a precursor;

[0086] (4) the precursor is high-temperature graphitized at 3000℃ for 8h to obtain a graphite negative electrode material.

[0087] Example 2

[0088] The preparation method of the negative electrode material of the present embodiment comprises the following steps:

[0089] (1) the pitch is heated to 80℃ softening, and then mixed with 0.04 mol / L KOH alkaline solution, and ultrasonic treatment is carried out at 80℃ for 10h to obtain a mixture, wherein the pitch is mainly saturated fraction and aromatic fraction, and the content ratio of the saturated fraction and the aromatic fraction is 10:90;

[0090] (2) the mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 with a particle size of 16.9μm);

[0091] (3) the powder is carbonized at 1000℃ for 10h to obtain a precursor;

[0092] (4) the precursor is high-temperature graphitized at 3000℃ for 8h to obtain a graphite negative electrode material.

[0093] Example 3

[0094] The preparation method of the negative electrode material of the present embodiment comprises the following steps:

[0095] (1) the pitch is heated to 80℃ softening, and then mixed with 0.03 mol / L KOH alkaline solution, and ultrasonic treatment is carried out at 80℃ for 10h to obtain a mixture, wherein the pitch is mainly saturated fraction and aromatic fraction, and the content ratio of the saturated fraction and the aromatic fraction is 15:85;

[0096] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 h, and broken to obtain a powder (D 50 is 16.2 pm);

[0097] (3) The powder is carbonized at 1200℃ for 10 h to obtain a precursor;

[0098] (4) The precursor is high-temperature graphitized at 2900℃ for 8 h to obtain a graphite negative electrode material.

[0099] Example 4

[0100] The preparation method of the negative electrode material of the present example comprises the following steps:

[0101] (1) The pitch is heated to 80℃ to soften, then mixed with a 0.02 mol / L KOH alkaline solution, and ultrasonically treated at 80℃ for 10 h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0102] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 h, and broken to obtain a powder (D 50 is 15.7 pm);

[0103] (3) The powder is carbonized at 1200℃ for 10 h to obtain a precursor;

[0104] (4) The precursor is high-temperature graphitized at 2800℃ for 8 h to obtain a graphite negative electrode material.

[0105] Example 5

[0106] The preparation method of the negative electrode material of the present example comprises the following steps:

[0107] (1) The pitch is heated to 80℃ to soften, then mixed with a 0.01 mol / L KOH alkaline solution, and ultrasonically treated at 80℃ for 10 h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0108] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 h, and broken to obtain a powder (D 50 is 15.4 pm);

[0109] (3) carbonize the powder at 500℃ for 10h to obtain a precursor;

[0110] (4) high-temperature graphitize the precursor at 2800℃ for 8h to obtain the graphite negative electrode material.

[0111] Example 6

[0112] The preparation method of the negative electrode material of the present example comprises the following steps:

[0113] (1) after the pitch is heated to 80℃ and softened, it is mixed with a 0.05mol / L KOH alkaline solution, and ultrasonic treatment is performed at 70℃ for 8h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0114] (2) the mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then it is placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 16.1μm);

[0115] (3) carbonize the powder at 1200℃ for 10h to obtain a precursor;

[0116] (4) high-temperature graphitize the precursor at 3000℃ for 8h to obtain the graphite negative electrode material.

[0117] Example 7

[0118] The preparation method of the negative electrode material of the present example comprises the following steps:

[0119] (1) after the pitch is heated to 70℃ and softened, it is mixed with a 0.04mol / L KOH alkaline solution, and ultrasonic treatment is performed at 70℃ for 8h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0120] (2) the mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then it is placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 16.8μm);

[0121] (3) carbonize the powder at 1000℃ for 10h to obtain a precursor;

[0122] (4) high-temperature graphitize the precursor at 3000℃ for 8h to obtain the graphite negative electrode material.

[0123] Example 8

[0124] The preparation method of the negative electrode material of the embodiment comprises the following steps:

[0125] (1) The pitch is heated to 70℃ and then mixed with a 0.03 mol / L KOH alkaline solution, and ultrasonic treatment is performed at 70℃ for 8h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0126] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 16.7μm);

[0127] (3) The powder is carbonized at 1000℃ for 10h to obtain a precursor;

[0128] (4) The precursor is high-temperature graphitized at 2900℃ for 8h to obtain a graphite negative electrode material.

[0129] Example 9

[0130] The preparation method of the negative electrode material of the embodiment comprises the following steps:

[0131] (1) The pitch is heated to 70℃ and then mixed with a 0.02 mol / L KOH alkaline solution, and ultrasonic treatment is performed at 70℃ for 8h to obtain a mixture, wherein the pitch is mainly composed of saturates and aromatics, and the content ratio of saturates to aromatics is 20:80;

[0132] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10h, and broken to obtain a powder (D 50 16.8μm);

[0133] (3) The powder is carbonized at 800℃ for 10h to obtain a precursor;

[0134] (4) The precursor is high-temperature graphitized at 2800℃ for 8h to obtain a graphite negative electrode material.

[0135] Example 10

[0136] The preparation method of the negative electrode material of the embodiment comprises the following steps:

[0137] (1) The asphalt is heated to 70°C and then mixed with 0.01 mol / L KOH alkaline solution, and ultrasonic treatment is carried out at 70°C for 8 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80.

[0138] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 hours, and then crushed to obtain a powder (D 50 with a particle size of 15.6 μm);

[0139] (3) The powder is carbonized at 500°C for 10 hours to obtain a precursor;

[0140] (4) The precursor is high-temperature graphitized at 2800°C for 8 hours to obtain a graphite negative electrode material.

[0141] Example 11

[0142] The difference between Example 1 and Example 11 is that in step (1), the asphalt is heated to 60°C and then mixed with 0.05 mol / L NaOH alkaline solution, and ultrasonic treatment is carried out at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80.

[0143] Example 12

[0144] The difference between Example 2 and Example 12 is that in step (1), the asphalt is heated to 60°C and then mixed with 0.04 mol / L NaOH alkaline solution, and ultrasonic treatment is carried out at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80.

[0145] Example 13

[0146] The difference between Example 3 and Example 13 is that in step (1), the asphalt is heated to 60°C and then mixed with 0.03 mol / L NaOH alkaline solution, and ultrasonic treatment is carried out at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80.

[0147] Example 14

[0148] The difference between Example 4 and Example 14 is that in step (1), the asphalt is heated to 60°C and then mixed with 0.02 mol / L NaOH alkaline solution, and ultrasonic treatment is carried out at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80.

[0149] Example 15

[0150] The only difference between Example 5 and Example 16 is that in step (1), the asphalt is heated to 60°C and then mixed with a 0.01 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 6 hours at 60°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0151] Example 16

[0152] The only difference between Example 1 and Example 17 is that in step (1), the asphalt is heated to 50°C and then mixed with a 0.05 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 5 hours at 50°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0153] Example 17

[0154] The only difference between Example 2 and Example 17 is that in step (1), the asphalt is heated to 50°C and then mixed with a 0.04 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 5 hours at 50°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0155] Example 18

[0156] The only difference between Example 3 and Example 17 is that in step (1), the asphalt is heated to 50°C and then mixed with a 0.03 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 5 hours at 50°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0157] Example 19

[0158] The only difference between Example 4 and Example 17 is that in step (1), the asphalt is heated to 50°C and then mixed with a 0.02 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 5 hours at 50°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0159] Example 20

[0160] The only difference between Example 5 and Example 20 is that in step (1), the asphalt is heated to 50°C and then mixed with a 0.01 mol / L NaOH alkaline solution, and the mixture is ultrasonically treated for 5 hours at 50°C. The asphalt is mainly composed of saturates and aromatics, and the ratio of the content of saturates to aromatics is 20:80.

[0161] Comparative Example 1

[0162] The preparation method of the negative electrode material of the comparative example comprises the following steps:

[0163] (1) The pitch is heated to 80℃ and then mixed with a 0.2 mol / L KOH alkaline solution, and ultrasonic treatment is performed at 80℃ for 10 hours to obtain a mixture, wherein the pitch is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 5:95;

[0164] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 hours, and then crushed to obtain a powder (D 50 with a particle size of 16.6 μm);

[0165] (3) The powder is carbonized at 1200℃ for 10 hours to obtain a precursor;

[0166] (4) The precursor is high-temperature graphitized at 3000℃ for 8 hours to obtain a graphite negative electrode material.

[0167] Comparative Example 2

[0168] The preparation method of the negative electrode material of the comparative example comprises the following steps:

[0169] (1) The pitch is heated to 70℃ and then mixed with deionized water at 70℃ for ultrasonic treatment for 8 hours to obtain a mixture, wherein the pitch is mainly composed of saturated components and aromatic components, and the content ratio of the saturated components to the aromatic components is 20:80;

[0170] (2) The mixture is cooled to room temperature, repeatedly washed and filtered with distilled water until the filtrate is neutral, the solvent is removed by suction filtration, then placed in an oven for vacuum drying for 10 hours, and then shaped to obtain a powder (D 50 with a particle size of 16.8 μm);

[0171] (3) The powder is carbonized at 1200℃ for 10 hours to obtain a precursor;

[0172] (4) The precursor is high-temperature graphitized at 3000℃ for 8 hours to obtain a graphite negative electrode material.

[0173] Test method

[0174] (1) Test method of particle size of negative electrode material:

[0175] The particle size distribution range of the composite negative electrode material is tested by a Malvern laser particle size analyzer.

[0176] (2) Test method of pore volume of negative electrode material:

[0177] The test was performed using an ASAP 2460 instrument from Micromeritics, and the pore volume V was calculated using the BJH Desorption cumulative volume of pores model in the pore size range of 1.7-3000nm

[0178] (3) Test method for specific surface area of negative electrode material:

[0179] The test was performed using a JW-DX dynamic specific surface area rapid tester from Beijing Jingwei Gaobo Science and Technology Co., Ltd., and the unit was m 2 / g.

[0180] (4) Test method for surface morphology of negative electrode material:

[0181] The surface morphology of the negative electrode material particles was observed using an S4800 scanning electron microscope from Hitachi.

[0182] (5) Test method for true density of negative electrode material:

[0183] The test was performed using a PENTAPYC 5200e true density meter from Anton Paar, which applies the Archimedes principle (density = mass / volume) and the Boyle law (PV = nRT) of an inert gas with a small diameter under certain conditions to accurately measure the true volume of the measured material, thereby obtaining its true specific gravity, with the unit being g / cm 3 .

[0184] (6) X-ray diffraction was used to characterize the interlayer spacing d 002 of the (002) plane of the material, with the unit being The crystallite size Lc in the c-axis direction and the peak intensity ratio I 004 / I 110 of the (004) plane to the (110) plane were obtained by X-ray diffraction.

[0185] (7) Test method for battery performance:

[0186] The negative electrode material, carboxymethyl cellulose, conductive carbon black, and butadiene-styrene rubber prepared in Examples 1-20 and Comparative Examples 1-2 were mixed in a mass ratio of 95:1.5:1.5:2 in deionized water under magnetic stirring for 8h to obtain a uniform mixture. The obtained slurry was coated on a copper foil, which was then vacuum dried at 60°C to obtain a working electrode. A metal lithium was used as a counter electrode and a reference electrode, a separator was Celgard 2325, and an electrolyte was 1 mol·L-1 LiPF6-EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio of 1:1:1). CR2016 button batteries were assembled in an argon-filled glove box.​

[0187] The first discharge capacity / first discharge efficiency test was performed on a LAND battery tester under the following charge / discharge conditions: rest for 2 h; discharge: 0.1 C to 0.005 V, 0.09 C, 0.08 C…0.02 C to 0.001 V; rest for 15 min; charge: 0.1 C to 1.5 V; rest for 15 min.

[0188] The rate performance test of the button half-cell was performed at 25±2℃, and the charge / discharge specific capacity and coulombic efficiency at 0.2 C, 1 C and 2 C were obtained. The charge / discharge conditions of the button rate test were as follows: ① 0.1 C to 0.01 V, constant voltage for 5 h, 0.1 C to 1.5 V; ② 0.2 C to 0.01 V, constant voltage to 0.01 C, 0.2 C to 1.5 V; ③ 0.2 C to 0.01 V, constant voltage to 0.01 C, 2 C to 1.5 V; ④ 0.2 C to 0.01 V, constant voltage to 0.01 C, 0.2 C to 1.5 V; ⑤ 1 C to 0.01 V, constant voltage to 0.01 C, 0.2 C to 1.5 V; ⑥ 2 C to 0.01 V.

[0189] Full cell test: the negative electrode material prepared in each example was used as the negative electrode active material, and the mass percentage of the negative electrode active material, conductive agent, binder and dispersing agent was 95.2:1.5:2:1.3, which was dissolved in deionized water and mixed to control the solid content to 50wt%, and then coated on an 8μm thick copper foil current collector, vacuum dried to prepare a negative electrode sheet; lithium iron phosphate, polyvinylidene fluoride and conductive carbon black were mixed in a mass ratio of 95:2:3 with a solvent NMP (N-methyl pyrrolidone) and then coated on a 16μm thick aluminum foil, vacuum dried to prepare a positive electrode sheet; the coated positive and negative electrode sheets were subjected to sheet making, winding, drying, liquid injection, sealing and formation, and were then subjected to other processes to prepare a 554065 type soft package lithium ion battery.

[0190] The obtained soft package battery was subjected to charge / discharge test on a LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd. under normal temperature conditions, 1C / 1C current charge / discharge, charge / discharge voltage limit of 3.0V-4.35V, first efficiency and 500 cycle capacity retention rate test (the negative electrode sheet compaction density was 1.60g / cm 3 ).

[0191] The performance test results of the negative electrode material prepared in the above examples are shown in Table 1, and the battery performance test results of the negative electrode material are shown in Table 2.

[0192] Table 1. Comparison results of negative electrode material performance

[0193]

[0194]

[0195] Table 2. Battery performance comparison results table

[0196]

[0197]

[0198] According to the test data of examples 1-20, the pores are formed in the interior and / or surface of the graphite prepared by the examples, which improves the large rate charge performance of the material. This is because, the parameter of the negative electrode material is controlled to 0.7≤V*S / D≤3.95, and 89≤G≤93 at the same time, which is beneficial to the combination of lithium ions and sufficient carbon atoms under low resistance, the rapid diffusion of lithium ions in the solid-liquid interface and the solid phase, the inhibition of the formation of lithium deposition, the reduction of concentration polarization, the full use of the lithium ion diffusion channel of the negative electrode material, the sufficient reaction space of the negative electrode material for lithium extraction, and the obtaining of the negative electrode material with better rate performance and capacity.

[0199] The negative electrode material prepared by Comparative Example 1 uses an alkali solution with too large concentration, the etching produces pores with too large volume and specific surface area, V*S / D deviates from the above range, and the inter-particle pores of the negative electrode material are infiltrated, then the solid electrolyte film is formed on the surface of the negative electrode material particles and the surface lithium storage is formed, the electrolyte lithium ions are gathered on the surface of the graphite particles, the concentration polarization occurs, the lithium deposition is formed, and then the diffusion of lithium ions is inhibited, so that the particle surface cannot occur electrochemical reaction, the "effective electrochemical reaction space" of the negative electrode material decreases, and the cycle performance of the material is poor.

[0200] The negative electrode material prepared by Comparative Example 2 is not treated by in-situ etching with an alkali solution during the preparation process, but is directly graphitized, the pores of the graphite are not rich enough, the pore volume V is too small, the specific surface area is also decreased, V*S / D deviates from the above range, the lithium ions do not have sufficient diffusion channels, and the rate performance of the material is poor.

[0201] Although the above is disclosed with preferred embodiments, it is not intended to limit the claims, any person skilled in the art can make several possible changes and modifications without departing from the concept of the present application, therefore the protection scope of the present application should be limited by the scope defined by the claims of the present application.

Claims

1. A negative electrode material, characterized by, The negative electrode material includes graphite, the surface and / or interior of the graphite has a hole, the hole extends from the surface of the graphite to the interior, the hole volume of the negative electrode material is V cm 3 / kg, the true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G %, wherein, 0.7≤V S / D≤3.95, and simultaneously 1.812≤V≤4.987, 0.872≤S≤1.773, 2.238≤D≤2.257, and 89≤G≤93. The pore volume is tested by using an ASAP 2460 device of Micromeritics, and is calculated by using a BJH Desorption cumulative volume of pores model in a pore diameter range of 17 Å~3000 Å; The true density is tested by using a PENTAPYC 5200e true density meter of Anton Paar; The specific surface area is tested by using a dynamic specific surface area rapid tester JW-DX of Beijing Jingmi Gaobote Science and Technology Co., Ltd.

2. The negative electrode material according to claim 1, characterized in that, The negative electrode material satisfies at least one of the following characteristics: (1) The pores include at least one of micropores and mesopores; (2) The graphite is artificial graphite.

3. The negative electrode material according to claim 2, characterized in that, The average pore diameter of the pores is 50 Å~200 Å.

4. The negative electrode material of claim 1, wherein, The negative electrode material has a (002) plane interlayer spacing of d 002 , 3.356 Å ≤ d 002 ≤ 3.364 Å.

5. The negative electrode material of claim 1, wherein, The particle size D of the negative electrode material 50 The size ranges from 10μm to 20μm.

6. The negative electrode material of claim 1, wherein, The negative electrode material further includes amorphous carbon, and the amorphous carbon exists on the surface of the graphite and / or is dispersed between the graphite particles.

7. The negative electrode material of claim 1, wherein, The negative electrode material further includes an amorphous carbon coating layer on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10 nm~500 nm.

8. The negative electrode material according to claim 6 or 7, characterized in that, The mass ratio of the amorphous carbon in the negative electrode material is 0.1wt%~3wt%.

9. A battery, characterized by The battery includes the negative electrode material according to any one of claims 1 to 8.

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