Negative electrode material and battery

Abstract

Provided in the present application are a negative electrode material and a battery. The negative electrode material comprises graphite and an organic polymer material located on the surface and / or inside the graphite. The negative electrode material comprises a metal element, and the metal element comprises at least one of lithium, sodium, potassium and aluminum; and on the basis of the total mass of the negative electrode material being 100%, the mass content of the metal element is 1300-4400 ppm. The negative electrode material is provided with pores, and the volume ratio of the pores having a pore diameter in the range of 5-35 nm in the total pore volume is 15-30%. The negative electrode material provided in the present application can comprehensively improve the lithium-ion transmission kinetics, the initial coulombic efficiency and the cycle performance.

Description

Anode materials and batteries

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on September 27, 2024, with application number "2024113675244" and application name "Negative Electrode Materials and Batteries", all of the contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of negative electrode materials, and in particular, to negative electrode materials and batteries. Background Art

[0004] The rapid development of lithium-ion batteries has brought about rapid changes in human life. As one of the core components of lithium-ion batteries, negative electrode materials have a significant impact on the electrochemical performance of lithium-ion batteries. Therefore, the development of cost-effective negative electrode materials is of great significance in lithium-ion battery research. Graphite materials are widely used as negative electrode materials for lithium-ion batteries, but traditional graphite materials still have problems such as many surface defects and poor electrolyte compatibility. The high specific surface area of ​​graphite materials leads to serious irreversible side reactions at the material interface during charging and discharging, resulting in low initial Coulombic efficiency and continuous decay of cycle capacity, which seriously hinders the further application of graphite negative electrode materials.

[0005] Currently, the industry primarily uses surface coating to modify graphite, reducing direct contact between the electrolyte and natural graphite and minimizing side reactions. However, conventional asphalt-coated graphite materials are difficult to precisely control the pore volume, and the lithium-ion transport capacity of the surface-coated negative electrode material decreases, resulting in a reduced initial efficiency of the graphite material. Summary of the Invention

[0006] In view of this, the present application provides a negative electrode material and a battery, wherein the negative electrode material can comprehensively improve lithium ion transfer kinetics, first coulombic efficiency and cycle performance.

[0007] In a first aspect, the present application provides a negative electrode material, the negative electrode material comprising graphite and an organic polymer material located on the surface and / or inside the graphite;

[0008] The negative electrode material comprises a metal element, wherein the metal element comprises at least one of lithium, sodium, potassium and aluminum; based on 100% of the total mass of the negative electrode material, the mass content of the metal element is 1300 ppm to 4400 ppm;

[0009] The negative electrode material has pores, wherein the volume of pores with a pore diameter ranging from 5 nm to 35 nm accounts for 15% to 30% of the total pore volume.

[0010] In some embodiments, the volume of pores with a pore diameter of less than 5 nm in the negative electrode material accounts for 2% to 10% of the total pore volume.

[0011] In some embodiments, the volume of pores with a pore diameter of 35 nm or more in the negative electrode material accounts for 60% to 83% of the total pore volume.

[0012] In some embodiments, the total pore volume of pores with a pore diameter of less than 250 nm in the negative electrode material is 0.005 cm 3 / g~0.02cm 3 / g.

[0013] In some embodiments, the organic polymer material on the surface of the graphite forms a coating layer, and the thickness of the coating layer is 20 nm to 200 nm.

[0014] In some embodiments, the graphite includes at least one of artificial graphite, natural graphite, and microcrystalline graphite.

[0015] In some embodiments, the fixed carbon content of the graphite is ≥ 98%.

[0016] In some embodiments, the negative electrode material comprises a non-metallic element, and the non-metallic element includes at least one of nitrogen, sulfur, oxygen, boron, and fluorine.

[0017] In some embodiments, the median particle size of the negative electrode material is 3 μm to 25 μm.

[0018] In some embodiments, the powder conductivity of the negative electrode material is ≤1.35*10 2 S / cm.

[0019] In some embodiments, the specific surface area of ​​the negative electrode material is 1.2 m 2 / g~3.7m 2 / g.

[0020] In some embodiments, the tap density of the negative electrode material is 1.0 g / cm 3 ~1.3g / cm 3 .

[0021] In some embodiments, in the Raman test spectrum of the negative electrode material, the negative electrode material has a Raman spectrum of 1300 cm -1 -1400cm -1 There is a D peak at 1550 cm -1 -1600cm -1 There is a G peak between them, and the Raman area ratio of the D peak to the G peak is I D / I G≤0.40.

[0022] The present application provides a battery, which includes the above-mentioned negative electrode material.

[0023] The technical solution of this application has at least the following beneficial effects:

[0024] The negative electrode material provided in the present application forms an organic polymer material on the surface and / or inside of graphite. The negative electrode material contains metal elements, and the metal elements include at least one of lithium, sodium, potassium, and aluminum. The total content of the metal elements is in the range of 1300ppm-4400ppm. The presence of the metal elements can not only enhance the conductivity within and / or between the graphite particles, promote the interface transport of lithium ions, and improve the first coulombic efficiency and cycle stability of the negative electrode material, but also some metal elements can form an inorganic-organic composite similar to a metal-organic framework material with the organic polymer material. The inorganic-organic composite can be filled in the graphite and / or attached to the surface of the graphite particles, thereby adjusting the volume proportion of pores with a pore size in the range of 5nm to 35nm in the total pore volume to 15% to 30%. The pores on the surface and / or inside of the graphite are partially filled or covered, which can effectively reduce the direct contact area between the solvated lithium ions and the graphite, reduce the irreversible side reactions between the negative electrode material and the electrolyte, enhance the stability of the solid-liquid contact interface of the negative electrode material, and improve the first coulombic efficiency of the negative electrode material. Therefore, the present application simultaneously controls the mass content of metal elements and the pore volume ratio, which can improve the lithium ion transmission kinetics and enable the negative electrode material to have both better first coulombic efficiency and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a process flow chart of a method for preparing a negative electrode material provided in this application;

[0026] FIG2 is a schematic diagram of a discharge state of a battery provided in an embodiment of the present application;

[0027] Figures 3a and 3b are electron microscope images of the negative electrode material prepared in Example 1 of the present application at different magnifications;

[0028] FIG4a is a pore size distribution diagram of the negative electrode material prepared in Example 1 of the present application in the range of 5 nm to 35 nm;

[0029] FIG4 b is a diagram showing the distribution of pore sizes below 160 nm in the negative electrode material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0030] 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.

[0031] Based on this, in a first aspect, the present application provides a negative electrode material, the negative electrode material comprising graphite and an organic polymer material located on the surface and / or inside the graphite;

[0032] The negative electrode material contains a metal element, wherein the metal element includes at least one of lithium, sodium, potassium and aluminum; based on the total mass of the negative electrode material being 100%, the mass content of the metal element is 1300ppm to 4400ppm;

[0033] The negative electrode material has pores, wherein the volume of pores with a pore diameter ranging from 5 nm to 35 nm accounts for 15% to 30% of the total pore volume.

[0034] The negative electrode material provided in the present application forms an organic polymer material on the surface and / or inside of graphite. The negative electrode material contains metal elements, and the metal elements include at least one of lithium, sodium, potassium, and aluminum. The total content of the metal elements is in the range of 1300ppm-4400ppm. The presence of the metal elements can not only enhance the conductivity within and / or between the graphite particles, promote the interface transport of lithium ions, and improve the first coulombic efficiency and cycle stability of the negative electrode material, but also some metal elements can form an inorganic-organic composite similar to a metal-organic framework material with the organic polymer material. The inorganic-organic composite can be filled in the graphite and / or attached to the surface of the graphite particles, thereby adjusting the volume proportion of pores with a pore size in the range of 5nm to 35nm in the total pore volume to 15% to 30%. The pores on the surface and / or inside of the graphite are partially filled or covered, which can effectively reduce the direct contact area between the solvated lithium ions and the graphite, reduce the irreversible side reactions between the negative electrode material and the electrolyte, enhance the stability of the solid-liquid contact interface of the negative electrode material, and improve the first coulombic efficiency of the negative electrode material. Therefore, the present application simultaneously controls the mass content of metal elements and the pore volume ratio, which can improve the lithium ion transmission kinetics and enable the negative electrode material to have both better first coulombic efficiency and cycle performance.

[0035] In some embodiments, based on the total mass of the negative electrode material as 100%, the mass content of the metal element obtained by inductively coupled plasma testing is 1300ppm~4400ppm, specifically 1300ppm, 1341ppm, 1500ppm, 1700ppm, 1900ppm, 2000ppm, 2300ppm, 2500ppm, 2800ppm, 3000ppm, 3500ppm, 4000ppm, 4325ppm or 4400ppm, etc., of course, it can also be other values ​​within the above range, which is not limited here. When the total content of metal elements in the negative electrode material is less than 1300ppm, the interfacial lithium ion transmission of the negative electrode material is slow, which is not conducive to the performance of the capacity of the negative electrode material; at the same time, it will cause the pH value of the negative electrode material to be low, and the difficulty of electrode processing will increase; when the total content of metal elements in the negative electrode material is greater than 4400ppm, the inorganic-organic complex in the negative electrode material increases, which increases the specific surface area of ​​the negative electrode material, intensifies the side reaction between the negative electrode material and the electrolyte, and reduces the first coulombic efficiency of the negative electrode material.

[0036] In some embodiments, the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume is 15% to 30%, specifically 15%, 18%, 20%, 22%, 25%, 28% or 30%, etc., and of course it can also be other values ​​within the above range, which is not limited here. In the present application, the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume is controlled to be 15% to 30%, which can ensure that the contact area between the solvated lithium ions in the electrolyte and the negative electrode material is moderate, which is conducive to the full infiltration of the electrolyte into the negative electrode material, and is conducive to improving the lithium ion transmission efficiency and the capacity of the negative electrode material; at the same time, it can reduce the consumption of irreversible lithium ions in the first lithium insertion process and improve the first coulombic efficiency of the negative electrode material. When the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume is less than 15%, the contact area between the solvated lithium ions in the electrolyte and the negative electrode material is too small, and the electrolyte cannot fully infiltrate the negative electrode material, resulting in obstruction of lithium ion transmission and lithium ion transmission kinetics, affecting the capacity of the negative electrode material. When the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume is greater than 30%, the contact area between the solvated lithium ions in the electrolyte and the negative electrode material is too large, resulting in aggravation of the irreversible side reaction of the first lithium insertion, excessive consumption of active lithium ions, and a decrease in the first coulombic efficiency of the negative electrode material.

[0037] In some embodiments, in some embodiments, the volume proportion of pores with a pore diameter of less than 5 nm in the negative electrode material in the total pore volume is 2% to 10%, specifically 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0038] In some embodiments, the volume proportion of pores with a pore diameter of more than 35 nm in the negative electrode material in the total pore volume is 60% to 83%, specifically 60%, 60.8%, 63%, 65%, 68%, 70%, 75%, 78%, 80%, 82.9% or 83%, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0039] In some embodiments, the total pore volume of pores with a pore diameter of less than 250 nm in the negative electrode material is 0.005 cm 3 / g~0.02cm 3 / g, specifically 0.005cm 3 / g, 0.008cm 3 / g, 0.01cm 3 / g, 0.012cm 3 / g, 0.015cm 3 / g, 0.018cm 3 / g or 0.02cm 3 / g, etc., and of course, it can also be other values ​​within the above range, which is not limited here.

[0040] In some embodiments, the graphite comprises at least one of artificial graphite, natural graphite, and microcrystalline graphite. Natural graphite is flake graphite, a natural phaneritic graphite that resembles fish spores, belongs to the hexagonal crystal system, and has a layered structure. It exhibits excellent properties such as high temperature resistance, electrical and thermal conductivity, lubricity, plasticity, and acid and alkali resistance. Artificial graphite is a graphite material obtained by carbonizing organic matter and then subjecting it to high-temperature graphitization.

[0041] In some embodiments, the graphite includes spherical graphite, which is natural graphite.

[0042] In some embodiments, the fixed carbon content of the graphite is ≥ 98%, specifically 98%, 98.2%, 98.3%, 98.8%, 99%, 99.2%, or 99.5%, etc., but is not limited to the values ​​listed above, and other values ​​not listed within this range are also applicable. Preferably, the fixed carbon content of the graphite is ≥ 99%.

[0043] In some embodiments, the organic polymer material on the graphite surface forms a coating layer having a thickness of 20 nm to 200 nm. Specifically, the thickness may be 20 nm, 50 nm, 80 nm, 110 nm, 140 nm, 170 nm, or 200 nm, but is not limited to these values. Other values ​​not listed in this numerical range are also applicable. Preferably, the coating layer has a thickness of 40 nm to 100 nm.

[0044] In some embodiments, the specific surface area of ​​the negative electrode material is 1.2 m2 / g~3.7m 2 / g; specifically it can be 1.2m 2 / g, 1.5m 2 / g, 1.9m 2 / g, 2.1m 2 / g, 2.6m 2 / g, 2.9m 2 / g, 3.1m 2 / g, 3.3m 2 / g, 3.5m 2 / g or 3.7m 2 / g, of course, other numbers within the above range are also possible and are not limited here. When the specific surface area of ​​the negative electrode material is controlled within the above range, the side reactions between the negative electrode material and the electrolyte are reduced, which is conducive to improving the initial coulombic efficiency of the negative electrode material.

[0045] In some embodiments, the median particle size of the negative electrode material is 3 μm to 25 μm; more specifically, it can be 3 μm, 4 μm, 6 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 17 μm, 20 μm, 22 μm or 25 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some embodiments, the powder conductivity of the negative electrode material under a pressure of 4kN is ≤1.35*10 2 S / cm, more specifically, can be 1.35*10 2 S / cm、1.15*10 2 S / cm、0.95*10 2 S / cm、0.75*10 2 S / cm or 0.55*10 2 S / cm, etc., but are not limited to the values ​​listed here; other values ​​not listed within this range also apply. The lower the conductivity of the negative electrode material powder, the denser the coating layer and the more stable the corresponding interface layer, which is beneficial to the initial coulombic efficiency and cycling stability of the negative electrode material.

[0047] In some embodiments, in the Raman test spectrum of the negative electrode material, the negative electrode material has a wavelength of 1300 cm -1 -1400cm -1 There is a D peak at 1550 cm -1 -1600cm -1 There is a G peak between them, and the Raman area ratio of the D peak to the G peak is I D / I G ≤0.45. I D / I GSpecifically, it can be 0.45, 0.40, 0.35, 0.30, 0.27, 0.25, 0.20, 0.19, 0.15 or 0.10, etc., but it is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable. Preferably, I D / I G ≤0.35.

[0048] In some embodiments, the tap density of the negative electrode material is 1.0 g / cm 3 ~1.3g / cm 3 Specifically, the tap density can be 1.00 g / cm 3 , 1.02g / cm 3 , 1.03g / cm 3 , 1.04g / cm 3 , 1.05g / cm 3 , 1.07g / cm 3 , 1.10g / cm 3 , 1.12g / cm 3 , 1.15g / cm 3 , 1.18g / cm 3 , 1.20g / cm 3 , 1.22g / cm 3 or 1.30g / cm 3 The values ​​listed are not limited to these values; other values ​​not listed within this range also apply. A higher tap density of the negative electrode material indicates a denser coating layer and a more stable interface, which is beneficial to the initial coulombic efficiency and cycling stability of the negative electrode material.

[0049] In a second aspect, the present application provides a method for preparing a negative electrode material, as shown in FIG1 , comprising the following steps:

[0050] Step S10: mixing graphite with an organic coating solution of a coating material having active groups to obtain a mixed solution, wherein the mass ratio of graphite to the coating material is 100:(1-6).

[0051] Step S20, the mixed solution is subjected to a polymerization reaction under stirring, so that the coating material is deposited on the surface of the graphite material; a pH regulator containing metal ions is then added to adjust the pH of the mixed solution to neutral, and the stirring process is continued to obtain a negative electrode material slurry;

[0052] In step S30 , the negative electrode material slurry is subjected to solid-liquid separation and dried to obtain the negative electrode material.

[0053] In the above scheme, graphite is mixed with an organic coating solution so that part of the coating material can be polymerized and deposited on the graphite surface, and then a pH regulator containing metal ions is added to adjust the pH value of the mixed solution. At the same time, the metal ions in the pH regulator can be doped into the polymer to form an organic-inorganic composite. The inorganic-organic composite can fill the interior of the graphite and / or adhere to the surface of the graphite particles, thereby adjusting the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume in the negative electrode material. The polymer and the inorganic-organic composite jointly form a coating layer on the graphite surface, so that the pores on the surface and / or inside of the graphite are partially filled or covered, which can effectively reduce the direct contact area between the solvated lithium ions and the graphite, reduce the irreversible side reactions between the negative electrode material and the electrolyte, and have strong stability in the solid-liquid contact interface of the negative electrode material, thereby improving the first coulombic efficiency of the negative electrode material.

[0054] The following is a detailed description of the preparation method provided in this scheme:

[0055] Step S10: mixing graphite with an organic coating solution of a coating material having active groups to obtain a mixed solution, wherein the mass ratio of graphite to the coating material is 100:(1-6).

[0056] In some embodiments, the active group includes at least one of a sulfonic acid group, a carbonyl group, a carboxyl group, a hydroxyl group, a fluorine-containing group, a boron-containing group, and an amino group.

[0057] In some embodiments, the coating material having an active group includes at least one of sodium sulfamate, ammonium sulfamate, hydroxyethyl sulfonic acid, sulfamic acid, benzenesulfonic acid, aminobenzenesulfonic acid, hydroxybenzenesulfonic acid, vinylsulfonic acid, ethanesulfonic acid, hydroxyurea, hydroxythiobenzamide, hydroxybenzoic acid, aminouracil, aminofluorophenol, salicylic acid, acetylsalicylic acid, aminosalicylic acid, p-aminosalicylic acid, methylsalicylic acid, benzenesulfonamide, acetylethanolamine, ethyleneamine, benzoic acid, fluorobenzoic acid, tetrafluoroterephthalic acid, acetylbenzoic acid, vinylbenzoic acid, fluoride, boric acid, fluoroboric acid, and nitrobenzoic acid.

[0058] In some embodiments, the graphite comprises at least one of artificial graphite and natural graphite. Natural graphite is flake graphite, a natural phaneritic graphite with a fish-like shape, a hexagonal crystal system, and a layered structure. It exhibits excellent properties such as high temperature resistance, electrical and thermal conductivity, lubricity, plasticity, and acid and alkali resistance. Artificial graphite is a graphite material obtained by carbonizing organic matter and then subjecting it to a high-temperature graphitization process.

[0059] Understandably, graphite forms defects during processing, such as spheroidization and purification. These defects have high reactivity due to unsaturated chemical bonds. A coating material with active groups and graphite are dispersed in a solvent to form a mixed solution. In this mixture, the highly reactive sites on the graphite surface react chemically with the active groups in the coating material. Simultaneously, polymerization occurs between the coating material molecules, forming a continuous coating layer that reduces the defect density of the graphite material.

[0060] In some embodiments, the graphite includes spherical graphite, which is natural graphite.

[0061] In some embodiments, the median particle size of the graphite is 3 μm to 25 μm, more specifically, 3 μm, 5 μm, 8 μm, 10 μm, 11 μm, 13 μm, 16 μm, 18 μm, 20 μm, 23 μm, or 25 μm, etc., but is not limited to the values ​​listed above, and other values ​​not listed within this numerical range are also applicable. Controlling the median particle size of the graphite within the above range is beneficial to reducing the specific surface area, reducing the contact between the graphite and the electrolyte, and inhibiting the occurrence of side reactions.

[0062] In some embodiments, the fixed carbon content of the graphite is ≥ 98%, specifically 98%, 98.3%, 98.5%, 98.6%, 98.8%, 99.2%, or 99.5%, etc., but is not limited to the values ​​listed above, and other values ​​not listed within this range are also applicable. Preferably, the fixed carbon content of the graphite is ≥ 99%.

[0063] In some embodiments, the organic coating solution further comprises a solvent, and the solvent includes but is not limited to at least one of water, ethanol, methanol, benzene, acetone, N-methylpyrrolidone, and NN-dimethylformamide.

[0064] In some embodiments, in the organic coating solution, the solid-liquid ratio of the coating material to the solvent is 1:(20-1000), specifically 1:20, 1:40, 1:80, 1:100, 1:200, 1:500, 1:800 or 1:1000, etc., which are not limited here. When the solid-liquid ratio of the coating material to the solvent is too high, the concentration of the coating material per unit volume of the organic coating solution is too high, and the excessive coating material is prone to agglomeration. The agglomerates are deposited on the surface of the graphite material, making it difficult to effectively fill the pores in the graphite material. An excessively thick coating layer will also aggravate the obstruction of the lithium ion transmission channel of the negative electrode material, which is not conducive to the performance of the negative electrode material. When the solid-liquid ratio of the coating material to the solvent is too low, the amount of solvent required for material preparation increases, and the production cost increases.

[0065] In some embodiments, the mass ratio of graphite to coating material is 100:(1-6), specifically 100:1, 100:2, 100:3, 100:4, 100:5 or 100:6, etc., which are not limited here. Excessive coating material leads to a thick coating layer on the surface of graphite, and the volume ratio of pores in the range of 5nm to 35nm decreases, resulting in a small direct contact area between the solvated lithium ions in the electrolyte and the graphite, and the negative electrode material Li + Poor transfer kinetics reduce the first-cycle lithium removal capacity of the negative electrode material. Too little coating material leads to a decrease in the uniformity of the coating layer on the graphite surface, an increase in the volume proportion of pores in the 5nm-35nm range, and an excessively large direct contact area between the solvated lithium ions in the electrolyte and the graphite, which aggravates the irreversible side reaction of the first lithium insertion, consumes too much active lithium ions, and reduces the first coulombic efficiency of the negative electrode material.

[0066] In step S20, the mixed solution is polymerized under stirring to deposit the coating material on the surface of the graphite material; a pH regulator containing metal ions is added to adjust the pH of the mixed solution to neutral, and the stirring process is continued to obtain a negative electrode material slurry.

[0067] In some embodiments, the polymerization reaction temperature is 40° C. to 80° C., and the holding time is 0.5 h to 6 h. Specifically, the polymerization reaction temperature is 40° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., or 80° C., and the holding time can be 0.5 h, 0.8 h, 1 h, 4 h, 5 h, or 6 h.

[0068] In some embodiments, the polymerization reaction is carried out under stirring, and the polymer formed by polymerization of the coating material having active groups is deposited and attached to the surface of the graphite.

[0069] In some embodiments, the pH value of the polymerization reaction is controlled at 6.5 to 7.5, specifically 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3 or 7.5, etc. Of course, it can also be other values ​​within the above range, which is not limited here.

[0070] In some embodiments, the pH adjuster containing metal ions includes but is not limited to at least one of sodium hydroxide, sodium carbonate, lithium hydroxide, lithium carbonate, potassium hydroxide, and aluminum oxide.

[0071] In some embodiments, the molar ratio of the metal ion-containing pH regulator to the coating material is 1:(0.8-2.2), specifically 1:0.8, 1:0.9, 1:1.1, 1:1.3, 1:1.5, 1:1.8, 1:1.9 or 1:2.2, etc. Of course, it can also be other values ​​within the above range, which is not limited here. When the addition ratio of the pH regulator containing metal ions is too low, it is difficult for the metal ions in the coating material and the coating material to form a complex similar to the metal-organic framework material, and it is difficult to accurately adjust the pore volume ratio of the negative electrode material in the range of 5nm to 35nm, resulting in an increase in the pore volume ratio of the negative electrode material in the range of 5nm to 35nm, an increase in the direct contact area between the solvated lithium ions and the graphite material, and deterioration of the electrochemical performance; when the addition ratio of the pH regulator containing metal ions is too high, the pH regulator in the mixed solution undergoes a self-deposition reaction, resulting in the appearance of inorganic agglomerates on the originally uniform coating layer, causing the specific surface area of ​​the negative electrode material to increase, and at the same time, the pore volume ratio of the negative electrode material in the range of 5nm to 35nm also increases, and the inorganic agglomerates do not have lithium storage activity, which will further lead to a decrease in the capacity of the negative electrode material.

[0072] In step S30 , the negative electrode material slurry is subjected to solid-liquid separation and dried to obtain the negative electrode material.

[0073] In some embodiments, the solid-liquid separation is at least one of stirring volatilization, spray separation, and rake stirring separation.

[0074] In some embodiments, the drying process is at least one of air drying, vacuum drying, flash drying, freeze drying, spray drying, and the like.

[0075] In some embodiments, the drying temperature is 110°C to 200°C, specifically 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, or 200°C, etc., and of course, other values ​​within the above range may also be used, which is not limited here. When the drying temperature is too low, the moisture content of the negative electrode material is too high, resulting in a decrease in the initial coulombic efficiency of the negative electrode material; when the drying temperature is too high, the coating layer itself undergoes an excessive polycondensation reaction, the pore volume proportion of the negative electrode material in the 5nm to 35nm range increases, the direct contact area between the solvated lithium ions and the graphite material increases, and the initial efficiency of the negative electrode material decreases.

[0076] The present application controls the solid-liquid ratio, time and amount of coating material added during liquid phase coating, and can promote the uniform deposition and attachment of the polymer formed by the coating agent having active groups on the surface of the graphite under stirring.

[0077] In a third aspect, an embodiment of the present invention further provides a battery. FIG2 is a schematic diagram of the discharge state of the battery provided in an embodiment of the present application. As shown in FIG2 , the battery includes a housing and an electrode assembly. The electrode assembly includes a positive electrode sheet 1, a negative electrode sheet 2, and a separator 3. The separator 3 is provided between the positive electrode sheet 1 and the negative electrode sheet 2. The electrode assembly can be a laminated structure, which is formed by alternatingly stacking the positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 in sequence. In other embodiments, the electrode assembly can also be a wound structure, which is formed by stacking the positive electrode sheet, the separator, and the negative electrode sheet in sequence and then winding them.

[0078] In some embodiments, the positive electrode sheet 1 includes a positive electrode current collector 101 and a positive electrode active layer 102 disposed on at least one surface of the positive electrode current collector 101 .

[0079] In some embodiments, the positive electrode current collector 101 may be aluminum foil or nickel foil, or any composite current collector disclosed in the prior art, such as, but not limited to, a current collector formed by combining the aforementioned conductive foil (aluminum foil or nickel foil, etc.) and a polymer substrate. The positive electrode active layer 102 includes a positive electrode active material, which includes a compound that reversibly intercalates and deintercalates metal ions.

[0080] In some embodiments, the positive electrode active material may include a lithium transition metal composite oxide, a sodium transition metal composite oxide, etc. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.

[0081] In some embodiments, the positive electrode active material may include but is not limited to lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary material (NCM), lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) or at least one of lithium iron phosphate (LiFePO4).

[0082] In some embodiments, the negative electrode sheet 2 includes a negative electrode current collector 201 and a negative electrode active material layer 202 disposed on at least one surface of the negative electrode current collector.

[0083] In some embodiments, the negative electrode current collector 201 can be made of at least one of copper foil, nickel foil, stainless steel foil, titanium foil, or a carbon-based current collector, or any composite current collector disclosed in the prior art, such as, but not limited to, a current collector formed by combining the aforementioned conductive foil and a polymer substrate. The negative electrode active material layer 202 includes a negative electrode material, which can be the negative electrode material of the first aspect described above or a negative electrode material prepared by the above-described preparation method.

[0084] The battery provided in the embodiments of the present application has the advantages of high capacity, high initial efficiency, long cycle life, excellent rate performance, and low expansion. The battery can be a lithium-ion battery, a sodium-ion battery, a solid electrolyte battery, etc., without limitation.

[0085] The embodiments of the present invention are further described below with reference to a number of embodiments.

[0086] The embodiments in this patent are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention. It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the absence of conflict, the embodiments of this application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth to facilitate a full understanding of this application. The embodiments described are only part of the embodiments of this application, not all of the embodiments. The embodiments of this application are further described below in multiple embodiments.

[0087] Example 1

[0088] (1) 3 parts of vinyl sulfonic acid and pure water were mixed at a solid-liquid ratio of 1:100 to form a uniform organic coating solution, and then 100 parts of graphite (average particle size of 17 μm) were added and mixed to form a uniform mixed solution.

[0089] (2) The mixed solution was subjected to polymerization reaction under stirring at a temperature of 60° C. for 1 hour; the pH value of the mixed solution was adjusted to 7 using a 0.5 mol / L sodium hydroxide solution (the molar ratio of vinyl sulfonic acid to sodium hydroxide was 1.0:1.05), and the mixed solution was raised to 90° C. and stirred until the solvent evaporated to form a powder state, and finally dried in a vacuum oven at 130° C. for 24 hours to obtain a negative electrode material.

[0090] Comparative Example 1

[0091] (1) 8 parts of vinyl sulfonic acid and pure water were mixed at a solid-liquid ratio of 1:40 to form a uniform organic coating solution, and 100 parts of graphite (average particle size of 17 μm) were added and mixed to form a uniform mixed solution.

[0092] (2) The mixed solution was subjected to polymerization reaction under stirring at a temperature of 60° C. for 1 hour; the pH value of the mixed solution was adjusted to 7 using a 0.5 mol / L sodium hydroxide solution (the molar ratio of vinyl sulfonic acid to sodium hydroxide was 1.0:1.05), and the mixed solution was raised to 90° C. and stirred until the solvent evaporated to form a powder state, and finally dried in a vacuum oven at 130° C. for 24 hours to obtain a negative electrode material.

[0093] Comparative Example 2

[0094] (1) 3 parts of vinyl sulfonic acid and pure water were mixed at a solid-liquid ratio of 1:100 to form a uniform organic coating solution, and then 100 parts of graphite (average particle size of 17 μm) was added to form a uniform mixed solution.

[0095] (2) The mixed solution was subjected to polymerization reaction under stirring at a temperature of 60° C. for 1 hour; the mixed solution was further heated to 90° C. and stirred until the solvent evaporated to form a powder state, and finally dried in a vacuum oven at 130° C. for 24 hours to obtain a negative electrode material.

[0096] According to the preparation steps of Example 1, Examples 2 to 18 (abbreviated as S1 to S18) and Comparative Examples (abbreviated as D1 to D4) were prepared. The process parameters of each Example and Comparative Example are shown in Table 1:

[0097] Table 1. Preparation process parameters of negative electrode materials

[0098] Test Method

[0099] (1) Test method for non-carbon elements and their content in negative electrode materials:

[0100] The lithium, sodium, potassium, and aluminum content of the negative electrode material is tested using an inductively coupled plasma optical emission spectrometer (ICP). The sample is atomized and introduced into the plasma. The elements are excited at high temperatures and emit characteristic spectra. The relationship between the spectral intensity and elemental concentration is analyzed using a spectrometer and detector. The procedure is as follows: Weigh approximately 0.5g of sample, add 9ml of hydrochloric acid and 3ml of nitric acid, and heat to a gentle boil on a hot plate for approximately 30 minutes to completely dissolve the elements to be tested. After filtering and constant volume, the sample is analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES).

[0101] Ion chromatography was used to test the fluorine content in the negative electrode material. Fluorine was separated based on the reversible exchange between dissociable ions on the ion exchange resin and solute ions of the same charge in the mobile phase, and the difference in affinity between the analyte and the exchanger. The steps were as follows: 1 g of sample was weighed to the nearest 0.0001 g in a 50 mL beaker, 40 mL of pure water was added to the sample beaker, and ultrasonic treatment was performed for 3 minutes. The sample was then filtered and diluted to a 100 mL volumetric flask. A DIONEX ICS-3000 ion chromatograph was used for testing. The instrument settings were as follows: eluent concentration: 4.5 mmol / L Na2CO3-1.4 mmol / L NaHCO3; eluent flow rate: 1.2 mL / min; column temperature: 30°C; detection cell temperature: 35°C; chromatographic column: anion exchange column (4 x 250 mm).

[0102] The nitrogen and oxygen elements in the negative electrode material are tested using the German Airt ONH-2000 nitrogen and oxygen analyzer. The sample and flux are added to a graphite crucible and heated to a maximum of 3000°C after power is applied to melt, releasing CO (oxidized to CO2) and N2 or H2. CO2 is measured by an infrared detection cell, and N2 and H2 are measured by a thermal conductivity cell.

[0103] An infrared carbon-sulfur analyzer is used to test the sulfur content of the negative electrode material. The sulfur in the solid sample is subjected to high-frequency heating in oxygen-rich conditions, oxidizing it to gases such as SO2. This purified gas is then introduced into sulfur and carbon detection cells. The strongest infrared absorption signal of SO2 at 7.35μm is converted by the detector into an electrical signal, which is then processed by a computer and output. The procedure is as follows: Ensure that the carrier gas (oxygen: ≥99.9990%) and the power gas (nitrogen: ≥99.99%, free of water or oil) are turned on. The nitrogen operating pressure is 0.5-0.6MPa, and the oxygen operating pressure is 0.2-0.3MPa. Using a 1 / 10,000th balance, accurately weigh the sample and evenly distribute it in a ceramic crucible. The weight should be less than 0.50g. Approximately 1.5g of flux (composition: tungsten:tin = 5:1) is added, and the analyzer is turned on for testing.

[0104] (2) Test method for particle size distribution of negative electrode materials: The particle size volume distribution range of negative electrode materials was tested using a Malvern 3000 laser particle size analyzer. Dispersant (ethanol, pure water, and low-foaming surfactant) and the test sample were placed in a 50 mL beaker. A certain amount of pure water was added and stirred thoroughly with a glass rod to ensure uniform dispersion of the sample. The equipment pump speed was set to 2400 r / min to 2500 r / min and the frequency was 19.5 Hz for particle size testing.

[0105] (3) Test method for the tap density of negative electrode materials: Use a Micrometer tap density tester to test the specific surface area of ​​the material. Place the negative electrode material in the sample chamber of the tap density tester, vibrate it 1000 times, and record the sample volume at this time. The tap density can be calculated based on the mass-to-volume ratio.

[0106] (4) Test method for specific surface area, pore size distribution and pore volume of negative electrode materials: Use a Microbead tester to test the specific surface area of ​​the material. Place the sample in a sample tube, use an isothermal jacket on the sample tube, place the filling rod in the bubble tube, install the retaining ring and O-ring on the bubble tube, and then place the assembled sample bubble tube into the corresponding analysis station for testing. Under constant temperature and low temperature, after measuring the amount of gas adsorbed on the solid surface at different relative pressures, the sample monolayer adsorption amount is calculated based on the Brownauer-Ettel-Taylor adsorption theory and its formula (BET formula), thereby calculating the specific surface area, pore volume and pore size distribution of the material.

[0107] (5) Test method for the conductivity of negative electrode material powder: Use the Japanese Mitsubishi Chemical MCP-PD51 powder resistivity test system to test the conductivity of graphite material. First, use a balance to weigh 2.5010~2.5099g of sample, concentrate the sample on the center of the weighing paper, pinch the edge of the paper that does not cover the sample, roll it into a cone shape, and carefully pour it into the mold cavity tower (a combination of the mold cavity and the electrode body). Connect the mold to the tester and turn on the machine to test the powder conductivity under different pressures.

[0108] (6) Test method for the surface morphology and coating layer of negative electrode material particles: Use a HITACHI-S4800 scanning electron microscope to observe the microscopic morphology of the surface of the negative electrode material. The steps are as follows: stick the conductive glue on the sample cup, evenly apply the sample on the conductive glue, use an ear bulb to blow away the sample that is not firmly fixed, and place it in the scanning electron microscope room for testing. The test steps for the cross section and coating layer are as follows: First, use a HITACHI-E3500 ion milling machine to polish the graphite particles, apply a small amount of carbon conductive glue on the edge of the sample table, and evenly sprinkle the graphite sample, press lightly with a glass sheet, wait for 2 minutes for the conductive glue to dry, and blow away the excess sample with an ear bulb. Place the sample table on the sample holder, adjust the sample position, and after completion, adjust the airflow to the maximum ion beam current, set the polishing time for sample processing. After completion, use a HITACHI-S4800 scanning electron microscope to observe the cross section and coating layer of the negative electrode material surface.

[0109] (7) Raman test method for negative electrode materials: The Raman scattering spectrum was tested using a HORIBA-XPLORA laser confocal Raman spectrometer with a laser wavelength of 532 nm. 30 points were randomly selected on the surface of the negative electrode material particles for data collection. The scattering spectrum obtained at each point was then peak fitted to obtain the peak at 1300 cm -1 -1400cm -1 The peak area of ​​the characteristic peak D in the range of 1550 cm -1 ~1600cm -1 The intensity ratio of the G characteristic peak in the range is I D / I G .

[0110] (8) Electrochemical performance test method: The negative electrode materials prepared in the examples and comparative examples were dissolved in deionized water at a mass ratio of 96.5:1.5:1 for the negative electrode material, carboxymethyl cellulose, and styrene-butadiene rubber, respectively, with the solid content controlled to 50%. The negative electrode sheets were coated on copper foil current collectors and vacuum dried to obtain negative electrode sheets. A metal lithium sheet was used as the counter electrode and assembled into button-type batteries in an argon-filled glove box. Charge and discharge tests were performed at a current density of 0.1C with a charge and discharge range of 0.01-1.5V. The first reversible specific capacity, first cycle charge capacity, and first cycle discharge capacity were obtained by cyclic charge and discharge. First coulombic efficiency = first cycle discharge capacity / first cycle charge capacity.

[0111] Table 2. Summary of performance test results of negative electrode materials

[0112] Table 3. Summary of battery performance test results

[0113] As shown in Figure 3a, the surface morphology of the negative electrode material prepared in Example 1 is smooth, indicating that the coating layer is evenly distributed on the surface of the graphite material. As shown in Figure 3b, under low-power field of view, the negative electrode material presents a spherical particle distribution, and there are no coating agglomerates, indicating that the coating in the negative electrode material is difficult to nucleate alone, and there is almost no coating particle agglomeration phenomenon. Figure 4a shows the pore size distribution diagram of the negative electrode material in the range of 5nm to 35nm in Example 1, and Figure 4b is the total pore size distribution diagram. The pore volume of the material in Example 1 in the range of 5nm to 35nm accounts for 22.1%. It can be seen that the direct contact area between the negative electrode material and the solvated lithium ions in the electrolyte is small, the irreversible reaction of the first lithium insertion is weak, the interface stability of the negative electrode material is high, and the first coulombic efficiency and capacity of the negative electrode material are relatively excellent.

[0114] According to the test data of Examples 1 to 18, the total content of metal elements in the negative electrode material is in the range of 1300ppm-4400ppm. The presence of metal elements can enhance the conductivity within and / or between graphite particles, promote lithium ion interface transmission, and improve the first coulombic efficiency and cycle stability of the negative electrode material. At the same time, some metal elements can also form a composite material similar to a metal-organic framework material with organic polymer materials. The inorganic-organic composite material can be filled in the graphite and / or attached to the surface of the graphite particles, and can adjust the volume proportion of pores with a pore size in the range of 5nm to 35nm in the total pore volume to 15% to 30%, which can effectively reduce the direct contact area between the solvated lithium ions and the graphite, reduce the irreversible side reaction between the negative electrode material and the electrolyte, and the solid-liquid contact interface of the negative electrode material is strong, thereby improving the first-cycle lithium removal capacity and the first coulombic efficiency of the negative electrode material.

[0115] As shown in the data of Tables 1 to 3, according to the test data of Examples 1 to 5, in the process of mixing the coating agent, graphite and solvent to form a uniform organic coating solution, by adjusting the solid-liquid ratio, the pore volume proportion of the negative electrode material in the range of 5nm to 35nm can be effectively controlled. As the solid-liquid ratio decreases, the content of the coating material per unit volume decreases, the deposition reaction on the surface of the graphite material becomes more uniform, the pore volume proportion in the range of 5nm to 35nm gradually decreases, and the graphite and the solvated Li + The direct contact area is reduced and the first coulombic efficiency of the negative electrode material is also improved.

[0116] According to the test data of Examples 1, 6 and 7, as the mass ratio of the coating material to graphite increases, the thickness of the coating layer on the surface of the graphite material increases, the proportion of pore volume in the range of 5nm to 35nm decreases, the specific surface area of ​​the negative electrode material also decreases, the first coulombic efficiency of the negative electrode material increases, but the capacity decreases.

[0117] According to the test data of Examples 1, 8 to 10, it can be seen that under the same process, changing the type of coating agent has no significant effect on the pore size distribution characteristics, specific surface area, first coulombic efficiency and other properties of the negative electrode material, indicating that the negative electrode materials prepared using the coating materials selected in this application can improve the specific surface area of ​​the negative electrode material and improve the first coulombic efficiency of the negative electrode material.

[0118] According to the test data of Examples 1 and 11-12, during the stirring reaction, solid-liquid separation and drying treatment, under the same process, changing the solvent type has no significant effect on the pore size distribution, specific surface area and first coulombic efficiency of the negative electrode material.

[0119] According to the test data of Example 1 and Examples 13 to 16, during the stirring reaction, solid-liquid separation and drying process, as the drying temperature increases, the specific surface area of ​​the negative electrode material gradually increases, the pore volume ratio in the 5nm to 35nm range shows a trend of first decreasing and then increasing, and the first coulombic efficiency shows a trend of first increasing and then decreasing. This is because the decrease in the pore volume ratio will cause the solvated Li in the electrolyte to + The direct contact area with graphite is reduced, the irreversible reaction of the first lithium insertion is weak, and the first coulombic efficiency of the negative electrode material is improved. Properly increasing the drying temperature can improve the first coulombic efficiency of the negative electrode material; however, when the drying temperature is too high, due to excessive condensation of the coating layer on the surface of the graphite material, the pore volume ratio in the range of 5nm to 35nm increases, and the solvated Li in the electrolyte + The direct contact area with graphite increases, the irreversible reaction of the first lithium insertion intensifies, and the initial efficiency of the negative electrode material decreases.

[0120] According to the test data of Example 1 and Examples 17 to 18, under the same process, by changing the graphite type to microcrystalline graphite and artificial graphite, and selecting pH regulators of other metal ions, as long as the total metal element content of the negative electrode material is controlled in the range of 1300ppm-4400ppm, and the volume proportion of pores with a pore diameter in the range of 5nm to 35nm in the total pore volume is in the range of 15% to 30%, the capacity and first efficiency of the negative electrode material can still be improved. It can be seen that the preparation method of the present application can be applied to different types of graphite negative electrode materials.

[0121] According to the test data of Comparative Example 1, the ratio of coating material to graphite material in the preparation process of Comparative Example 1 is 8:100. Due to the increase in the amount of coating material added, the coating layer on the surface of the negative electrode material is too thick, and the pore volume of the negative electrode material with a pore diameter in the range of 5nm to 35nm accounts for only 12.6%, which is too low. Since the amount of pH regulator added also increased year-on-year, the metal element content in the negative electrode material is as high as 5320ppm, and the inorganic-organic complex on the surface of the graphite material increases, which increases the specific surface area of ​​the negative electrode material, intensifies the side reaction between the negative electrode material and the electrolyte, and reduces the first coulombic efficiency of the negative electrode material. At the same time, the pore volume ratio in the range of 5nm to 35nm decreases, the direct contact area between the solvated lithium ions and the graphite in the electrolyte is too small, and the electrolyte is difficult to fully infiltrate the negative electrode material, resulting in obstruction of lithium ion transmission and obstruction of lithium ion transmission kinetics, affecting the capacity of the negative electrode material. According to the data in Table 4, compared with Example 3, the first-cycle lithium delithiation capacity of the negative electrode material in Comparative Example 1 is only 341 mAh / g, which is lower than the normal requirement of 355 mAh / g for graphite-based negative electrode materials, and the practicality of the negative electrode material is reduced.

[0122] Compared with Example 1, Comparative Example 2 did not add a pH regulator containing metal ions during the preparation process, resulting in a significant decrease in the mass content of metal elements in the negative electrode material, which is only 875 ppm. Although the volume proportion (21%) of pores with a pore diameter in the range of 5 nm to 35 nm in the negative electrode material in the total pore volume is in the range of 15% to 30%, the lithium ion transmission efficiency of the coating layer is greatly reduced, and the negative electrode material has processing performance problems in the process of preparing the electrode sheet, making it difficult to achieve mass production application.

[0123] Compared with Example 1, the drying temperature of Comparative Example 3 is higher during the preparation process, resulting in excessive condensation of the coating layer on the surface of the negative electrode material, and the specific surface area of ​​the negative electrode material increases. Although the mass content of the metal element of the negative electrode material (2060ppm) is in the range of 1300ppm to 4400ppm, and since the polymer coating layer has a higher crystallinity with the increase of the drying temperature, the powder conductivity of the negative electrode material is slightly increased compared with Example 1; however, the coating layer after excessive condensation causes part of the pores to be re-exposed on the surface of the negative electrode material, and the pore volume proportion of the negative electrode material with a pore diameter in the range of 5nm to 35nm is relatively high (31.5%), and the contact area between the solvated lithium ions in the electrolyte and the negative electrode material is too large, resulting in the aggravation of the irreversible side reaction of the first lithium insertion, excessive consumption of active lithium ions, and a decrease in the capacity and the first coulombic efficiency of the negative electrode material.

[0124] Compared with Example 1, Comparative Example 4 did not use a suitable coating material during the preparation process, resulting in difficulty in forming a uniform coating layer on the surface of the graphite material. The mass content of the metal element in the negative electrode material reached 2061 ppm. Under the action of a large amount of exposed graphite material and an appropriate amount of metal elements, the powder conductivity of the negative electrode material was relatively high. However, the exposed graphite material has a large number of pores, and its pore volume in the range of 5nm to 35nm accounts for a relatively high proportion (37.2%). The contact area between the solvated lithium ions in the electrolyte and the negative electrode material is too large, resulting in an aggravation of the irreversible side reaction of the first lithium insertion, excessive consumption of active lithium ions, and a decrease in the capacity and first coulombic efficiency of the negative electrode material.

[0125] 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 includes graphite and an organic polymer material located on the surface and / or inside of the graphite; The negative electrode material comprises a metal element, wherein the metal element comprises at least one of lithium, sodium, potassium and aluminum; based on 100% of the total mass of the negative electrode material, the mass content of the metal element is 1300 ppm to 4400 ppm; The negative electrode material has pores, wherein the volume of pores with a pore diameter ranging from 5 nm to 35 nm accounts for 15% to 30% of the total pore volume.

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 volume of pores with a pore diameter of less than 5 nm in the negative electrode material accounts for 2% to 10% of the total pore volume; (2) In the negative electrode material, the volume of pores with a pore diameter of 35 nm or more accounts for 60% to 83% of the total pore volume.

3. The negative electrode material according to claim 1, characterized in that The total pore volume of the pores with a pore diameter of less than 250 nm in the negative electrode material is 0.005 cm 3 / g~0.02cm 3 / g.

4. The negative electrode material according to claim 1, characterized in that The organic polymer material located on the surface of the graphite forms a coating layer, and the thickness of the coating layer is 20nm to 200nm.

5. The negative electrode material according to claim 1, characterized in that The thickness of the coating layer is 40nm to 100nm.

6. 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 graphite includes at least one of artificial graphite, natural graphite and microcrystalline graphite; (2) The fixed carbon content of the graphite is ≥98%.

7. 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 negative electrode material contains a non-metallic element, and the non-metallic element includes at least one of nitrogen, sulfur, oxygen, boron and fluorine; (2) The fixed carbon content of the graphite is ≥90%.

8. The negative electrode material according to claim 1, characterized in that The median particle size of the negative electrode material is 3 μm to 25 μm.

9. The negative electrode material according to any one of claims 1 to 8, characterized in that The powder conductivity of the negative electrode material is ≤1.35*10 under a pressure of 4kN 2 S / cm.

10. The negative electrode material according to claim 9, characterized in that The powder conductivity of the negative electrode material is 1.04*10 2 ~1.35*10 2 S / cm.

11. The negative electrode material according to any one of claims 1 to 8, characterized in that The specific surface area of ​​the negative electrode material is 1.2 m 2 / g~3.7m 2 / g.

12. The negative electrode material according to any one of claims 1 to 8, characterized in that The tap density of the negative electrode material is 1.0 g / cm 3 ~1.3g / cm 3 .

13. The negative electrode material according to any one of claims 1 to 8, characterized in that In the Raman test spectrum of the negative electrode material, the negative electrode material has a wavelength of 1300 cm -1 -1400cm -1 There is a D peak at 1550 cm -1 -1600cm -1 There is a G peak between them, and the Raman area ratio of the D peak to the G peak is I D / I G ≤0.

45.

14. The negative electrode material according to claim 13, characterized in that I D / I G is 0.17 - 0.

45.

15. A battery, characterized in that: The battery comprises the negative electrode material according to any one of claims 1 to 14.

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