Negative electrode material and battery

Abstract

A negative electrode material and a battery. The negative electrode material comprises graphite, wherein the surface and / or the interior of the graphite has pores, and the negative electrode material has a pore volume of V cm3 / kg, a true density of D g / cm3, a specific surface area of S m2 / g, and a graphitization degree of G%, where 0.7≤V*S / D≤3.95, and 89≤G≤93. The negative electrode material and the battery can improve the rate capability and cycle performance of a graphite negative electrode material under a high-rate current.

Description

Anode materials, batteries Technical Field

[0001] The present application relates to the technical field of negative electrode materials, and in particular, to negative electrode materials and batteries. Background Art

[0002] Lithium-ion batteries, due to their excellent performance, have shown promising application prospects in portable consumer electronics, power tools, new energy vehicles, energy storage, and other fields. Since the commercialization of lithium-ion batteries, the most mature anode materials used have been graphite-based. The current development direction of lithium-ion batteries is high capacity, high rate capability, and high safety. Therefore, the development of high-performance graphite anodes is crucial for achieving high-rate performance and good cycle performance in lithium-ion batteries.

[0003] From a technical point of view, the special layered structure of graphite determines the + It can only be embedded from the end face of the material and gradually diffuse into the interior of the particles, resulting in a low diffusion rate of lithium ions and poor rate performance. At the same time, lithium embedding at a large 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, the lithium ions will be deposited in the form of metal, resulting in the inability to fully utilize the diffusion channel and electrochemical reaction area.

[0004] Therefore, at the current stage when graphite materials have developed to a very mature stage, simply improving one parameter can no longer 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 coordinated action of multiple factors and develop graphite negative electrode materials that meet market demand.

[0005] Application Contents

[0006] In view of this, the present application addresses the deficiencies of the prior art and provides a new negative electrode material and battery, which achieves precise control of the internal and / or surface pore volume, specific surface area, and true density, so that they are combined and maintained within a reasonable range, thereby achieving improvements in the capacity and rate performance of the negative electrode material.

[0007] In a first aspect, the present application provides a negative electrode material, wherein the negative electrode material comprises graphite, wherein the surface and / or interior of the graphite has pores, and the pore volume of the negative electrode material is V cm 3 / kg, true density is D g / cm 3 , the specific surface area is S m 2 / g, graphitization degree is G%, where 0.7≤V*S / D≤3.95, and 89≤G≤93;

[0008] The pore volume was measured using ASAP2460 equipment from American company Micromeritics and the BJH Desorption cumulative volume of pores model. Calculated within the pore size range.

[0009] In some embodiments, the pore volume of the negative electrode material is V cm 3 / kg, 1.812≤V≤4.987.

[0010] In some embodiments, the specific surface area of ​​the negative electrode material is S m 2 / g, 0.872≤S≤1.773.

[0011] In some embodiments, the true density of the negative electrode material is D g / cm 3 , 2.238≤D≤2.257.

[0012] In some embodiments, the pores include at least one of micropores and mesopores.

[0013] In some embodiments, the pores extend from the surface of the graphite toward the interior.

[0014] In some embodiments, the graphite is artificial graphite.

[0015] In some embodiments, the average pore size of the pores is

[0016] In some embodiments, the negative electrode material is measured by X-ray diffraction, and the interlayer spacing of the (002) plane is d 002 ,

[0017] In some embodiments, the particle size D of the negative electrode material is 50 It is 10μm~20μm.

[0018] In some embodiments, the negative electrode material further includes amorphous carbon, which exists on the surface of graphite and / or is dispersed between graphite particles.

[0019] In some embodiments, the negative electrode material further includes an amorphous carbon coating layer located on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10 nm to 500 nm.

[0020] In some embodiments, the amorphous carbon accounts for 0.1 wt % to 3 wt % of the negative electrode material.

[0021] In a second aspect, the present application provides a battery, comprising the negative electrode material according to the first aspect.

[0022] The technical solution of this application has at least the following beneficial effects:

[0023] The negative electrode material provided in the application includes graphite, wherein the graphite has pores on its surface and / or inside. The pores extend from the surface of the graphite to the inside, while retaining the regular graphite layer structure of the negative electrode material, generating abundant pores on the surface and near the surface of the graphite. The pore volume of the negative electrode material is V cm 3 / kg, true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G%, where 0.7≤V*S / D≤3.95, and 89≤G≤93. The pore volume within a certain range is conducive to Li +The lithium ions are embedded into the material along the pore structure to increase the diffusion rate of lithium ions. 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 concentration polarization, and help improve the capacity and rate performance of the negative electrode material. However, if the appropriate pore volume and specific surface area are met alone, there is still a lot of room for improvement in the rate performance of the negative electrode material. The reason is that after the lithium ions diffuse to the graphite surface, if the arrangement of carbon atoms in the graphite is relatively chaotic and the order is insufficient, the lithium ions will enter the graphite material and combine with carbon atoms to produce electrochemical reactions. At the same time, since graphite is polycrystalline, especially artificial graphite, there are grain boundary defects between grains, and the stress of grain boundary defects is uneven. Grain boundaries are a type of crystal plane defect and are prone to cracks. When subjected to external forces, they are more likely to split along the grain boundary direction and fracture along the crystal. Finally, the crystal planes parallel to the graphite crystal plane split to form the outer surface of the graphite particles. Since these outer surfaces are perpendicular to the direction of lithium ion diffusion, they must cross the carbon plane, making it difficult for lithium ions to enter the graphite interior. At the same time, lithium ions may aggregate on the carbon surface to form lithium clusters, thereby inhibiting lithium diffusion or forming lithium deposition, and ultimately the diffusion channels and electrochemical reaction areas cannot be fully utilized. Therefore, the present application provides a good diffusion path for lithium ion diffusion by controlling the degree of graphitization and true density. At the same time, combined with the design of the pore structure and pore distribution, the stress inside the graphite is concentrated around the pores, dispersing the stress at the grain boundaries, so that when the graphite is subjected to external force, cracks first appear and break from the pores, which is conducive to the formation of transgranular fractures. After the pores are exposed, they are eventually constructed into the outer surface of the graphite particles. Transgranular fracture is conducive to increasing the channel entrances on 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 for lithium ions to diffuse into the graphite layers. At the same time, due to the presence of more defects, edge lithium storage can be achieved. Therefore, the outer surface of the particle formed by breaking from the pores can construct more graphite microcrystalline surfaces parallel to the lithium ion diffusion path, not only creating more lithium ion diffusion paths inside the graphite particles, but also creating more channel entrances on the particle surface for the entry of lithium ions. At the same time, considering that a higher degree of graphitization is beneficial to the diffusion environment, reducing the obstacles to lithium ion transmission caused by defects such as partial crystal distortion, a high degree of graphitization affects the number of polycrystalline graphite grain boundaries and lattice distortion to a certain extent, making the interlayer arrangement highly ordered and compact, which is beneficial to improving the true density and ensuring that the negative electrode material can exert a higher specific capacity. This application controls the V*S / D of the negative electrode material within the above range while controlling the degree of graphitization of the material, which is beneficial for lithium ions and sufficient carbon atoms to combine under low resistance, so that the negative electrode material has sufficient space for lithium insertion and deinsertion reactions, which is beneficial to obtaining a negative electrode material with better rate performance and capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a scanning electron microscope image of the graphite negative electrode material provided in Example 2 of the present application.

[0025] FIG2 is another scanning electron microscope image of the graphite negative electrode material provided in Example 2 of the present application.

[0026] FIG3 is a scanning electron microscope image of the graphite negative electrode material provided in Example 11 of the present application.

[0027] FIG4 is another scanning electron microscope image of the graphite negative electrode material provided in Example 11 of the present application. DETAILED DESCRIPTION

[0028] To better illustrate the present application and facilitate understanding of the technical solution of the present application, the present application is further described below. However, the following embodiments are merely simplified examples of the present application and do not represent or limit the scope of protection of the present application. The scope of protection of the present application shall be subject to the claims.

[0029] Since the commercialization of lithium-ion batteries, the most mature negative electrode materials used are graphite-based negative electrode materials. The special layered structure of graphite determines the + It can only be embedded from the end face of the material and gradually diffuse into the interior of the particles, resulting in a low diffusion rate of lithium ions and poor rate performance. At the same time, lithium embedding at a large 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, the lithium ions will be deposited in the form of metal, resulting in the inability to fully utilize the diffusion channel and electrochemical reaction area.

[0030] Therefore, the present application provides a negative electrode material, the negative electrode material includes graphite, the surface and / or interior of the graphite has pores, the pores extend from the surface of the graphite to the interior, and the pore volume of the negative electrode material is V cm 3 / kg, true density is D g / cm 3 , the specific surface area is S m 2 / g, graphitization degree is G%, where 0.7≤V*S / D≤3.95, and 89≤G≤93;

[0031] The pore volume was measured using ASAP2460 equipment from American company Micromeritics and the BJH Desorption cumulative volume of pores model. Calculated within the pore size range.

[0032] The negative electrode material provided by the present application includes graphite, wherein the graphite has pores on its surface and / or inside. The pores extend from the surface of the graphite to the inside, while retaining the regular graphite layer structure of the negative electrode material, generating abundant pores on the surface and near the surface of the graphite. The pore volume of the negative electrode material is V cm 3 / kg, true density is D g / cm 3 , the specific surface area is S m 2 / g, the graphitization degree is G%, where 0.7≤V*S / D≤3.95, and 89≤G≤93. The pore volume within a certain range is conducive to Li + The lithium ions are embedded into the material along the pore structure to increase the diffusion rate of lithium ions. 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 concentration polarization, and help improve the capacity and rate performance of the negative electrode material. However, if the appropriate pore volume and specific surface area are met alone, there is still a lot of room for improvement in the rate performance of the negative electrode material. The reason is that after lithium ions diffuse to the graphite surface, if the arrangement of carbon atoms in the graphite is relatively chaotic and the order is insufficient, the lithium ions will be greatly hindered from entering the graphite material and combining with carbon atoms to produce electrochemical reactions. At the same time, because graphite is polycrystalline, especially artificial graphite, there are grain boundary defects between grains. The stress of grain boundary defects is uneven, cracks are prone to occur, and they are easily split when subjected to external force. Finally, the crystal plane parallel to the direction of the graphite crystal layer splits to form the outer surface of the graphite particles. Since these outer surfaces are perpendicular to the direction of lithium ion diffusion, they must cross the carbon plane, making it difficult to enter the interior of the graphite. At the same time, lithium clusters may form on the carbon surface, thereby inhibiting the diffusion of lithium or forming lithium deposition. Ultimately, the diffusion channel and the electrochemical reaction area cannot be fully utilized. Therefore, the present application provides a good diffusion path for lithium ion diffusion by controlling the degree of graphitization and true density. At the same time, the stress inside the graphite is concentrated more around the pores in combination with the design of the pore structure and the void distribution, reducing the stress at the grain boundaries. When the graphite is subjected to external force, cracks first appear and break from the pores, and finally construct the surface of the graphite particles. In this way, more graphite microcrystalline surfaces parallel to the lithium ion diffusion path can be constructed, which not only creates more lithium ion diffusion paths inside the graphite particles, but also creates more channel entrances for the entry of lithium ions on the particle surface. At the same time, considering that a higher degree of graphitization is conducive to the diffusion environment, it reduces the obstacles to lithium ion transmission formed by crystal defects, ensuring that the negative electrode material can exert a higher specific capacity. The present application controls the V*S / D of the negative electrode material within the above range while controlling the graphitization degree of the material, which is conducive to the combination of lithium ions and sufficient carbon atoms under low resistance, so that the negative electrode material has sufficient lithium insertion and deinsertion reaction space, which is conducive to obtaining a negative electrode material with better rate performance and capacity.

[0033] In some embodiments, the pore volume V cm of the negative electrode material is 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., are not limited here. When electrochemical reactions occur in the pores within 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 within the solid phase, reduce concentration polarization, and help improve the rate performance of the negative electrode material.

[0034] In some embodiments, the specific surface area of ​​the negative electrode material is S m 2 / g, 0.872≤S≤1.773; specifically, it can be 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 limitation herein. It is understandable that an excessively large specific surface area can easily lead to the formation of an excessive amount of solid electrolyte membrane, consuming excessive amounts of irreversible lithium salt, and reducing the initial efficiency of the battery.

[0035] In some embodiments, the true density of the negative electrode material is D g / cm 3 , 2.210≤D≤2.265; specifically it can be 2.2385, 2.2481, 2.2440, 2.2372, 2.2476, 2.2502, 2.2514 or 2.262, etc., which is not limited here.

[0036] In some embodiments, the graphitization degree of the negative electrode material is G%, 89≤G≤93; specifically, it can be 89, 90, 90.5, 91, 91.5, 92, 92.5 or 93, etc., which is not limited here.

[0037] In some embodiments, the pores include at least one of micropores and mesopores.

[0038] In some embodiments, the average pore size is Specifically it can be or The average pore size of the control pores is within the above range, which is beneficial to the Li + The lithium is transported from the surface of the material along the pore structure into the interior of the graphite, and further lithium insertion and extraction reactions occur. Preferably, the average pore size is

[0039] In some embodiments, the pores extend from the surface of the graphite toward the interior.

[0040] In some embodiments, the graphite is artificial graphite.

[0041] In some embodiments, the particle size D of the negative electrode material is 50 The particle size distribution of the particles is 10 μm to 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 are not limited here. It should be noted that the volume-based cumulative particle size distribution of the particle size distribution is measured by laser diffraction method, D 50 It indicates the particle size corresponding to when the cumulative particle size distribution percentage reaches 50%.

[0042] In some embodiments, the negative electrode material is measured by X-ray diffraction, and the interlayer spacing of the (002) plane is d 002 , Crystal plane interlayer spacing d 002 Within the above range, it can be seen that the graphite crystallinity of the graphite particles is high, that is, the degree of graphitization is high, and the capacity of the product is high.

[0043] In some embodiments, the negative electrode material further includes an amorphous carbon coating layer located on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10nm to 500nm; specifically, it can be 10nm, 15nm, 20nm, 30nm, 50nm, 80nm, 100nm, 150nm, 180nm, 200nm, 400nm or 500nm; preferably, the thickness of the amorphous carbon coating layer is 10nm to 100nm.

[0044] In some embodiments, the negative electrode material further comprises amorphous carbon, which is present on the surface of the graphite and / or dispersed between the graphite particles. Specifically, the graphite particles can be embedded in the amorphous carbon material with the amorphous carbon material as a matrix, with some of the graphite particles exposed on the surface of the amorphous carbon material.

[0045] In some embodiments, the negative electrode material also includes amorphous carbon, and the mass proportion of amorphous carbon in the negative electrode material is 0.1wt% to 3wt%. The mass proportion of amorphous carbon in the negative electrode material can specifically be 0.1wt%, 0.3wt%, 0.5wt%, 1wt%, 2wt%, 2.5wt% or 3wt%. The presence of amorphous carbon provides more irregular and open diffusion paths for lithium ions, which is beneficial to improving the rate performance of the material.

[0046] In some embodiments, the capacity retention rate of the negative electrode material after 500 cycles of 1C charging is ≥90%, which can be 91.8%, 92.3%, 90.6%, 92.4%, 93.5%, etc., which is not limited here.

[0047] The present application also provides a method for preparing a negative electrode material, comprising the following steps:

[0048] S10, mixing the softened asphalt with an alkaline solution having a concentration of 0.01 mol / L to 0.05 mol / L, and performing ultrasonic treatment to obtain a mixture, wherein the mass ratio of saturated components to aromatic components in the asphalt is (5-20):(95-80);

[0049] S20, drying and crushing the solid product after washing the mixture to obtain powder D 50 10μm~20μm;

[0050] S30, placing the powder at 500° C. to 1200° C. under an inert atmosphere for carbonization treatment to obtain a precursor;

[0051] S40, placing the precursor at 2800° C. to 3200° C. for graphitization treatment to obtain a negative electrode material.

[0052] The preparation method of the negative electrode material provided by the present application is to mix asphalt with a low concentration of alkaline solution, and to form a pore structure by in-situ etching inside the asphalt with the help of ultrasonic means, so that the effective reaction area of ​​the material is improved and the lithium ion embedding path is increased, and then the powder after in-situ etching is carbonized. During the carbonization process, impurities, volatiles and unstable substances inside the material will decompose and escape, so that the pores formed by etching are further enlarged in pore diameter and pore depth. The carbonized product is then graphitized to form graphite with rich and regular pores, so that the pore volume of the graphite is accurately controlled, the internal stress distribution of the graphite is adjusted to a certain extent, and the reactive area of ​​the negative electrode active material in the electrode is finally increased, which is beneficial to the improvement of the high-rate charge and discharge performance of the material. The process is simple and the production cost is low. The prepared graphite negative electrode material has the characteristics of high specific capacity, excellent high-rate charge and discharge performance, and excellent cycle performance, which can meet the needs of consumer and power end users for negative electrode energy density and fast charging performance.

[0053] The technical solution of this application is described in detail below:

[0054] S10, mixing the softened asphalt with an alkaline solution having a concentration of 0.01 mol / L to 0.05 mol / L, and performing ultrasonic treatment to obtain a mixture, wherein the mass content ratio of saturated components to aromatic components in the asphalt is (5-20):(95-80).

[0055] In some embodiments, the asphalt includes coal asphalt and / or petroleum asphalt, and the petroleum asphalt can be modified asphalt, mesophase asphalt, and the like.

[0056] In some embodiments, the mass ratio of saturates to aromatics in asphalt is (5-20):(95-80), and can be 5:95, 8:92, 10:90, 13:87, 15:85, 18:82, 20:80, etc., and other values ​​within the above range are also possible and are not limited here. By controlling the mass ratio of saturated components to aromatic components in asphalt, the higher the aromatic content, the better the fluidity of the asphalt and the lower the softening temperature. At the same time, the higher the volatile content, the more volatile components decompose and escape during the carbonization process, so that the pores formed by etching further expand the pore diameter and pore depth, and concentrate more stress inside the graphite around the pores, reducing the stress at the grain boundaries, so that when the graphite is subjected to external force, cracks will first appear and break from the pores, and finally construct the surface of the graphite particles. In this way, more graphite microcrystalline surfaces parallel to the lithium ion diffusion path can be constructed, which not only creates more lithium ion diffusion paths inside the graphite particles, but also creates more channel entrances for the entry of lithium ions on the particle surface, which is conducive to obtaining negative electrode materials with better rate performance and lower residual carbon content.

[0057] In some embodiments, the asphalt is heated to 50°C to 80°C to soften, thereby forming a liquid asphalt. The softening temperature may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or other values ​​within the above range.

[0058] In some embodiments, the alkaline solution includes at least one of a NaOH solution and a KOH solution.

[0059] In some embodiments, the concentration of the alkaline solution is 0.01mol / L to 0.05mol / L, specifically 0.01mol / L, 0.02mol / L, 0.03mol / L, 0.04mol / L, 0.045mol / L or 0.05mol / L, etc. Of course, it can also be other values ​​within the above range, which is not limited here. If the concentration of the alkaline solution is too high, it will cause too many pores to be formed by etching the asphalt surface, which will lead to the final graphite negative electrode material having too large a pore volume and a large specific surface area, making it difficult to control the V*S / D ratio within the ideal range, which is not conducive to improving the high-rate charge and 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 space for lithium intercalation and deintercalation chemical reactions, which is conducive to obtaining a negative electrode material with better rate performance and capacity.

[0060] In some embodiments, the material ratio of asphalt to alkaline solution is 50g / 100ml to 100g / 100ml, and specifically can be 50g / 100ml, 60g / 100ml, 70g / 100ml, 75g / 100ml, 80g / 100ml, 85g / 100ml, 90g / 100ml, or 100g / 100ml, etc., and of course other values ​​within the above range are also possible, and are not limited here. Controlling the material ratio of asphalt to alkaline solution can facilitate the alkaline solution to fully etch the softened asphalt, thereby etching an appropriate number of pores on the asphalt surface, reducing stress at the grain boundaries of the graphite obtained after graphitization, and facilitating the creation of more lithium ion diffusion paths, thereby improving the specific capacity and rate performance of the negative electrode material.

[0061] In some embodiments, the ultrasonic treatment time under heat preservation is 5 to 10 hours, specifically 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours, but is not limited to the listed values. Other values ​​not listed within this range are also applicable. During ultrasonic treatment, the alkaline solution continuously impacts and etches the asphalt, causing in-situ etching within the small asphalt particles to form a pore structure. The pore structure creates 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 within the solid phase, reduce concentration polarization, and help improve the rate performance of the negative electrode material.

[0062] S20, drying and crushing the solid product after washing the mixture to obtain powder D 50 It is 10μm~20μm.

[0063] In some embodiments, the mixture is cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate is neutral, and solid-liquid separation is performed to obtain a solid product.

[0064] 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.

[0065] In some embodiments, the drying temperature is 80°C to 120°C, specifically 80°C, 90°C, 100°C, 110°C and 120°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] In some embodiments, the median particle size D of the crushed powder is 50The median particle size of the powder is 10 μm to 20 μm, more specifically, 12 μm, 13 μm, 14 μm, 16 μm, 18 μm, 18.5 μm, 19 μm or 20 μm, etc., but is not limited to the values ​​listed above. Other values ​​not listed in this numerical range are also applicable. After multiple tests, it was found that controlling the median particle size of the powder within the above range is beneficial to taking into account processing performance, capacity and rate performance.

[0067] S30, placing the powder at 500° C. to 1200° C. under an inert atmosphere for carbonization treatment to obtain a precursor.

[0068] In some embodiments, the heating rate of the carbonization 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. It can be understood that the heating rate of the carbonization process within the above range is conducive to the escape of volatiles in the raw materials at different rates, further expanding and / or deepening the pore size of the pore structure, and coordinating with the heating rate of the subsequent graphitization process to obtain a negative electrode material that meets 0.70≤V*S / D≤3.95.

[0069] In some embodiments, the carbonization temperature can be 500°C, 550°C, 600°C, 700°C, 750°C, 800°C, 850°C, 900°C, 1000°C, or 1200°C, but is not limited to the listed values. Other values ​​not listed within this range are also applicable. It can be understood that a carbonization temperature within the above range is conducive to the discharge of volatile substances and other substances in the powder.

[0070] In some embodiments, the holding time of the carbonization treatment is 2h to 10h, specifically 2h, 3h, 4h, 4.5h, 5h, 6h, 8h or 10h, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0071] S40, placing the precursor at 2800° C. to 3200° C. for graphitization treatment to obtain a negative electrode material.

[0072] 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 is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0073] In some embodiments, the holding time of the graphitization treatment is 2 hours to 10 hours, specifically 2 hours, 3 hours, 4 hours, 4.5 hours, 5 hours, 6 hours, 8 hours or 10 hours, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] In some embodiments, the graphitization heating rate may be 2°C / min to 10°C / min, specifically 2°C / min, 3°C / min, 4°C / min, 6°C / min, 8°C / min, or 10°C / min, but is not limited to the listed values. Other values ​​not listed within this range are also applicable. A specific heating rate is beneficial for controlling the formation of pores inside and / or on the surface of the graphite material and the specific surface area.

[0075] In some embodiments, after the graphitization treatment, at least one of pulverization, screening, and demagnetization is further performed. Preferably, after the graphitization treatment, pulverization, demagnetization, and screening are performed in sequence.

[0076] In some embodiments, the pulverization method is any one of a mechanical pulverizer, a jet mill, and a low-temperature pulverizer.

[0077] 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 screening mesh number is 100 to 500 meshes. Specifically, the screening mesh number can be 100 mesh, 200 mesh, 250 mesh, 325 mesh, 400 mesh, 500 mesh, etc. The particle size of the negative electrode material is controlled within the above range, which is beneficial to improving the processing performance of the negative electrode material.

[0078] In some embodiments, the demagnetization equipment is any one of a permanent magnetic drum magnetic separator, an electromagnetic iron remover, and a pulsating high gradient magnetic separator. The purpose of demagnetization is to ultimately control the magnetic material content of the negative electrode material, reduce the discharge effect of the magnetic material on the lithium-ion battery, and ensure the safety of the battery during use.

[0079] The present application also provides a battery comprising the above-mentioned negative electrode material.

[0080] Those skilled in the art will appreciate that the battery preparation method described above is merely an example. Without departing from the disclosure of this application, other methods commonly used in the art may be employed, and other types of batteries may be prepared for testing, such as sodium-ion batteries, potassium-ion batteries, and the like.

[0081] The following further illustrates the embodiments of the present invention in multiple embodiments. The embodiments of the present invention are not limited to the following specific embodiments. Within the scope of protection, appropriate changes can be made to the implementation.

[0082] Example 1

[0083] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0084] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.05 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 5:95;

[0085] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.3 μm);

[0086] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0087] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0088] Example 2

[0089] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0090] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.04 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 10:90;

[0091] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.9 μm);

[0092] (3) carbonizing the powder at 1000°C for 10 h to obtain a precursor;

[0093] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0094] Example 3

[0095] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0096] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.03 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 15:85;

[0097] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.2 μm);

[0098] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0099] (4) The precursor was graphitized at 2900°C for 8 h to obtain a graphite negative electrode material.

[0100] Example 4

[0101] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0102] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.02 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0103] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 15.7 μm);

[0104] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0105] (4) The precursor is graphitized at 2800°C for 8 hours to obtain a graphite negative electrode material.

[0106] Example 5

[0107] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0108] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.01 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0109] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 15.4 μm);

[0110] (3) carbonizing the powder at 500°C for 10 h to obtain a precursor;

[0111] (4) The precursor is graphitized at 2800°C for 8 hours to obtain a graphite negative electrode material.

[0112] Example 6

[0113] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0114] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.05 mol / L KOH alkaline solution and ultrasonically treated at 70°C for 8 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80.

[0115] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.1 μm);

[0116] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0117] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0118] Example 7

[0119] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0120] (1) After the asphalt is heated to 70°C and softened, it is mixed with a 0.04 mol / L KOH alkaline solution and ultrasonically treated at 70°C for 8 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0121] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.8 μm);

[0122] (3) carbonizing the powder at 1000°C for 10 h to obtain a precursor;

[0123] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0124] Example 8

[0125] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0126] (1) After the asphalt is heated to 70°C and softened, it is mixed with a 0.03 mol / L KOH alkaline solution and ultrasonically treated at 70°C for 8 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0127] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.7 μm);

[0128] (3) carbonizing the powder at 1000°C for 10 h to obtain a precursor;

[0129] (4) The precursor was graphitized at 2900°C for 8 h to obtain a graphite negative electrode material.

[0130] Example 9

[0131] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0132] (1) After the asphalt is heated to 70°C and softened, it is mixed with a 0.02 mol / L KOH alkaline solution and ultrasonically treated at 70°C for 8 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0133] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.8 μm);

[0134] (3) carbonizing the powder at 800°C for 10 h to obtain a precursor;

[0135] (4) The precursor is graphitized at 2800°C for 8 hours to obtain a graphite negative electrode material.

[0136] Example 10

[0137] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0138] (1) After the asphalt is heated to 70°C and softened, it is mixed with a 0.01 mol / L KOH alkaline solution and ultrasonically treated at 70°C for 8 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 20:80;

[0139] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 15.6 μm);

[0140] (3) carbonizing the powder at 500°C for 10 h to obtain a precursor;

[0141] (4) The precursor is graphitized at 2800°C for 8 hours to obtain a graphite negative electrode material.

[0142] Example 11

[0143] The only difference from Example 1 is that in step (1), the asphalt is heated to 60°C to soften it, then mixed with a 0.05 mol / L NaOH alkaline solution, and ultrasonically treated at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0144] Example 12

[0145] The only difference from Example 2 is that in step (1), the asphalt is heated to 60°C to soften it, mixed with a 0.04 mol / L NaOH alkaline solution, and ultrasonically treated at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0146] Example 13

[0147] The only difference from Example 3 is that in step (1), the asphalt is heated to 60°C to soften it, mixed with a 0.03 mol / L NaOH alkaline solution, and ultrasonically treated at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0148] Example 14

[0149] The only difference from Example 4 is that in step (1), the asphalt is heated to 60°C to soften it, mixed with a 0.02 mol / L NaOH alkaline solution, and ultrasonically treated at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0150] Example 15

[0151] The only difference from Example 5 is that in step (1), the asphalt is heated to 60°C to soften it, mixed with a 0.01 mol / L NaOH alkaline solution, and ultrasonically treated at 60°C for 6 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0152] Example 16

[0153] The only difference from Example 1 is that in step (1), the asphalt is heated to 50°C to soften it, mixed with a 0.05 mol / L NaOH alkaline solution, and ultrasonically treated at 50°C for 5 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0154] Example 17

[0155] The only difference from Example 2 is that in step (1), the asphalt is heated to 50°C to soften it, mixed with a 0.04 mol / L NaOH alkaline solution, and ultrasonically treated at 50°C for 5 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0156] Example 18

[0157] The only difference from Example 3 is that in step (1), the asphalt is heated to 50°C to soften it, mixed with a 0.03 mol / L NaOH alkaline solution, and ultrasonically treated at 50°C for 5 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0158] Example 19

[0159] The only difference from Example 4 is that in step (1), the asphalt is heated to 50°C to soften it, mixed with a 0.02 mol / L NaOH alkaline solution, and ultrasonically treated at 50°C for 5 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0160] Example 20

[0161] The only difference from Example 5 is that in step (1), the asphalt is heated to 50°C to soften it, mixed with a 0.01 mol / L NaOH alkaline solution, and ultrasonically treated at 50°C for 5 hours to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80.

[0162] Comparative Example 1

[0163] The preparation method of the negative electrode material of the comparative example comprises the following steps:

[0164] (1) After the asphalt is heated to 80°C and softened, it is mixed with a 0.2 mol / L KOH alkaline solution and ultrasonically treated at 80°C for 10 h to obtain a mixture in which the asphalt is mainly composed of saturated components and aromatic components, with the ratio of saturated components to aromatic components being 5:95;

[0165] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and crushed to obtain a powder (D 50 16.6 μm);

[0166] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0167] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0168] Comparative Example 2

[0169] The preparation method of the negative electrode material of this comparative example comprises the following steps:

[0170] (1) After the asphalt is heated to 70°C and softened, deionized water is added and ultrasonically treated for 8 hours while maintaining the temperature at 70°C to obtain a mixture, wherein the asphalt is mainly composed of saturated components and aromatic components, and the ratio of saturated components to aromatic components is 20:80;

[0171] (2) The mixture was cooled to room temperature, washed and filtered repeatedly with distilled water until the filtrate was neutral, the solvent was removed by suction filtration, and then placed in an oven for vacuum drying for 10 hours and shaped to obtain a powder (D 50 16.8 μm);

[0172] (3) carbonizing the powder at 1200°C for 10 h to obtain a precursor;

[0173] (4) The precursor is graphitized at 3000°C for 8 hours to obtain a graphite negative electrode material.

[0174] Test Method

[0175] (1) Test method for particle size of negative electrode material:

[0176] The particle size distribution range of the composite negative electrode material was tested by Malvern laser particle size analyzer.

[0177] (2) Testing method of pore volume of negative electrode material:

[0178] The test was carried out using the ASAP2460 equipment from American Micromeritics. The pore volume V was calculated using the BJH Desorption cumulative volume of pores model. Calculated within the pore size range

[0179] (3) Testing method for specific surface area of ​​negative electrode material:

[0180] The dynamic specific surface area rapid tester JW-DX of Beijing Jingwei Gaobo Science and Technology Co., Ltd. was used for testing. The unit is m 2 / g.

[0181] (4) Testing method of surface morphology of negative electrode materials:

[0182] The surface morphology of the negative electrode material particles was observed using a Hitachi S4800 scanning electron microscope.

[0183] (5) Test method for true density of negative electrode material:

[0184] The Anton Paconta PENTAPYC 5200e true density meter is used for testing. The Archimedean principle of gas displacement (density = mass / volume) and the Bohr law (PV = nRT) of inert gases with small molecular diameters under certain conditions are used to accurately measure the true volume of the material being tested, thereby obtaining its true specific gravity in g / cm 3 .

[0185] (6) X-ray diffraction characterization of the interlayer spacing d of the (002) plane of the material 002 , the unit is The crystallite size Lc in the c-axis direction and the peak intensity ratio I of the (004) plane to the (110) plane obtained by X-ray diffraction 004 / I 110 .

[0186] (7) Battery performance test method:

[0187] The negative electrode materials, carboxymethyl cellulose, conductive carbon black, and styrene-butadiene rubber prepared in Examples 1 to 20 and Comparative Examples 1 to 2 were magnetically stirred in deionized water at a mass ratio of 95:1.5:1.5:2 for 8 hours to mix them evenly. The mixed slurry was coated on copper foil and dried in vacuo at 60°C as a working electrode. Metallic lithium was used as the counter electrode and reference electrode, the diaphragm was Celgard 2325, and the electrolyte was 1 mol·L-1 LiPF6-EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio of 1:1:1). The CR2016 button cell was assembled in a glove box filled with high-purity argon.

[0188] The first discharge capacity / first discharge efficiency test was performed on a LAND battery tester with the following charge and discharge conditions: 2 h rest; discharge: 0.1C to 0.005V, 0.09C, 0.08C…0.02C to 0.001V; 15 min rest; charge: 0.1C to 1.5V; 15 min rest.

[0189] The coin cell half-cell was subjected to rate performance testing at 25±2°C, and the charge-discharge specific capacity and coulombic efficiency at 0.2C, 1C, and 2C were obtained. The charge-discharge conditions for the coin cell rate test were as follows: ① 0.1C discharge to 0.01V, constant voltage for 5h, 0.1C charge to 1.5V; ② 0.2C discharge to 0.01V, constant voltage to 0.01C, 0.2C charge to 1.5V; ③ 0.2C discharge to 0.01V, constant voltage to 0.01C, 2C charge to 1.5V; ④ 0.2C discharge to 0.01V, constant voltage to 0.01C, 0.2C charge to 1.5V; ⑤ 1C discharge to 0.01V, constant voltage to 0.01C; 0.2C charge to 1.5V; ⑥ 2C discharge to 0.01V.

[0190] Full battery test: The negative electrode material prepared in each embodiment was used as the negative electrode active material, and the mass percentage of the negative electrode active material, conductive agent, binder, and dispersant was 95.2:1.5:2:1.3. It was dissolved in deionized water and mixed to control the solid content to 50wt%. The mixture was coated on an 8μm thick copper foil current collector and vacuum dried to prepare a negative electrode sheet; lithium iron phosphate, polyvinylidene fluoride, and conductive agent carbon black were mixed in a mass ratio of 95:2:3 with solvent NMP (N-methylpyrrolidone), coated on a 16μm thick aluminum foil, and vacuum dried to prepare a positive electrode sheet; the coated positive and negative electrode sheets were subjected to sheeting, winding, drying, liquid injection, sealing, formation, and volume separation processes to make a 554065 soft-pack lithium-ion battery.

[0191] The obtained soft pack battery was charged and discharged on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd. At room temperature, 1C / 1C current was charged and discharged, and the charge and discharge voltage was limited to 3.0V~4.35V. The first efficiency and 500-week capacity retention rate tests were performed (the compaction density of the negative electrode sheet was 1.60g / cm 3 ).

[0192] The results of the performance test of the negative electrode material obtained in the above embodiment are shown in Table 1 below, and the results of the performance test of the battery made of the negative electrode material are shown in Table 2 below:

[0193] Table 1. Comparison of negative electrode material performance

[0194] Table 2. Battery performance comparison results

[0195] According to the test data of Examples 1 to 20, the graphite prepared in the present application has pores formed inside and / or on its surface, which improves the high-rate charging performance of the material. This is because the parameters of the negative electrode material are controlled to be 0.7≤V*S / D≤3.95, and 89≤G≤93, which is conducive to the combination of lithium ions and sufficient carbon atoms under low resistance. Lithium ions diffuse rapidly at the solid-liquid interface and in the solid phase, inhibiting the formation of lithium deposits, reducing concentration polarization, and making full use of the lithium ion diffusion channels of the negative electrode material. This allows the negative electrode material to have sufficient space for lithium insertion and extraction reactions, which is conducive to obtaining a negative electrode material with better rate performance and capacity.

[0196] In the negative electrode material prepared in Comparative Example 1, the concentration of the alkaline solution used is too high, the pore volume generated by etching is too large, the specific surface area is too large, and the V*S / D deviates from the above range. After the pores between the negative electrode material particles are infiltrated, a solid electrolyte membrane will be formed on the surface of the negative electrode material particles, and surface lithium storage will be formed at the same time. The electrolyte lithium ions that gather more on the surface of the graphite particles will undergo concentration polarization, forming lithium deposition, thereby inhibiting the diffusion of lithium ions. As a result, no electrochemical reaction can occur on the surface of the particles, and the "effective electrochemical reaction space" of the negative electrode material decreases, resulting in poor cycle performance of the material.

[0197] In the negative electrode material prepared in Comparative Example 2, no alkaline solution was added for in-situ etching during the preparation process, but graphitization was performed directly. The graphite pores were not rich enough, the pore volume V was too small, the specific surface area was also reduced, and V*S / D was out of the above range. There was no sufficient diffusion channel for lithium ions, resulting in poor rate performance of the material.

[0198] Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the claims. Any person skilled in the art may make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

Claims

1. A negative electrode material, characterized in that: The negative electrode material comprises graphite, the surface and / or interior of the graphite has pores, and the pore volume of the negative electrode material is V cm 3 / kg, 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 is tested by using the ASAP2460 equipment of Mack Company of the United States, and the BJH Desorption cumulative volume of pores model is used. Calculated within the aperture range.

2. The negative electrode material according to claim 1, characterized in that The negative electrode material meets at least one of the following characteristics: (1) The pore volume of the negative electrode material is V cm 3 / kg, 1.812≤V≤4.987; (2) The specific surface area of ​​the negative electrode material is S m 2 / g, 0.872≤S≤1.773; (3) The true density of the negative electrode material is D g / cm 3 , 2.238≤D≤2.

257.

3. The negative electrode material according to claim 1 or 2, characterized in that: The negative electrode material meets at least one of the following characteristics: (1) The pores include at least one of micropores and mesopores; (2) The pores extend from the surface of the graphite toward the inside; (3) The graphite is artificial graphite.

4. The negative electrode material according to claim 3, characterized in that The average pore size of the pores is 5. The negative electrode material according to claim 1 or 2, characterized in that: The negative electrode material is measured by X-ray diffraction, and the interlayer spacing of the (002) plane is d 002 , 6. The negative electrode material according to claim 1 or 2, characterized in that: The particle size D of the negative electrode material 50 It is 10μm~20μm.

7. The negative electrode material according to claim 1, characterized in that The negative electrode material further includes amorphous carbon, which exists on the graphite surface and / or is dispersed between graphite particles.

8. The negative electrode material according to claim 1, characterized in that The negative electrode material further comprises an amorphous carbon coating layer located on the surface of the graphite, and the thickness of the amorphous carbon coating layer is 10nm to 500nm.

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

10. A battery, characterized in that: The battery comprises the negative electrode material according to any one of claims 1 to 9.

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