Preparation method of graphite negative electrode material for lithium ion battery, lithium ion battery, energy storage device and electric equipment

Abstract

The invention relates to the technical field of energy storage, in particular to a preparation method of a graphite negative electrode material for a lithium ion battery, the lithium ion battery, an energy storage device and electric equipment. The preparation method of the graphite negative electrode material for the lithium ion battery comprises the following steps: preparing a slurry mixture containing a biomass carbon source, a nitrogen-sulfur doping agent, polyvinylpyrrolidone and a catalyst, wherein the mass ratio of the biomass carbon source to the nitrogen-sulfur doping agent to the polyvinylpyrrolidone to the catalyst is 1: (0.5-1.5): (0.05-0.1): (0.5-2.8); the slurry mixture is subjected to pre-carbonization treatment, the pre-carbonization treatment temperature ranges from 500 DEG C to 600 DEG C, and a pre-carbonization product is obtained; and carrying out graphitization treatment on the pre-carbonized product at the temperature of 1200-1400 DEG C to obtain the graphite negative electrode material. The graphite negative electrode material prepared by the preparation method disclosed by the invention is high in graphitization degree, uniform and controllable in sulfur and nitrogen element doping and excellent in electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly to a preparation method of a graphite negative electrode material for a lithium-ion battery, a lithium-ion battery, an energy storage device and an electrical equipment. Background Art

[0002] Graphitized carbon materials are widely used in fields such as batteries, supercapacitors, catalyst carriers, etc. due to their excellent electrical conductivity, chemical stability and high specific surface area. Traditional preparation methods of graphitized materials mostly use petroleum coke, pitch coke, etc. as raw materials, which have problems such as high cost and environmental pollution.

[0003] In recent years, biomass carbon sources have received attention due to their renewability and environmental friendliness, but their graphitization efficiency is relatively low, and the electrochemical performance of graphitized carbon materials needs to be further improved urgently. Summary of the Invention

[0004] The present application provides a preparation method of a graphite negative electrode material for a lithium-ion battery, a lithium-ion battery, an energy storage device and an electrical equipment, aiming to solve the technical problems mentioned in the above background art.

[0005] In a first aspect, an embodiment of the present application provides a preparation method of a graphite negative electrode material for a lithium-ion battery, including the following steps: Prepare a slurry mixture containing a biomass carbon source, a nitrogen-sulfur dopant, polyvinylpyrrolidone and a catalyst, and the mass ratio of the biomass carbon source, the nitrogen-sulfur dopant, the polyvinylpyrrolidone and the catalyst is 1:(0.5 - 1.5):(0.05 - 0.1):(0.5 - 2.8); Perform pre-carbonization treatment on the slurry mixture, and the temperature of the pre-carbonization treatment is 500°C - 600°C to obtain a pre-carbonized product; Perform graphitization treatment on the pre-carbonized product, and the temperature of the graphitization treatment is 1200°C - 1400°C to obtain a graphite negative electrode material.

[0006] In some embodiments, the nitrogen-sulfur dopant is an organometallic complex, and the central metal of the organometallic complex includes at least one of iron, cobalt and nickel.

[0007] In some embodiments, the preparation steps of the organometallic complex include: In an inert environment, use anhydrous ethanol as a solvent to prepare a mixed solution of a nitrogen-sulfur organic compound and a metal salt according to a preset molar ratio; Place the mixed solution under the conditions of 60°C - 80°C and stir and react for 5h - 8h, and the stirring rate is 200rpm / min - 400rpm / min. Purify the reaction mixture to obtain the organometallic complex.

[0008] In some embodiments, the nitrogen-sulfur organic compound includes one or more of thiourea, 2-mercaptoimidazole, cysteine, and ammonium thiocyanate; The metal salt includes one or more of iron salts, cobalt salts, and nickel salts.

[0009] In some embodiments, the slurry mixture further contains a boron dopant, and the boron dopant includes boric acid.

[0010] In some embodiments, the biomass carbon source includes one or more of glucose, lignosulfonate, malic acid, chitosan, sucrose, fructose, citric acid, oxalic acid, cellulose, lignin, and hemicellulose.

[0011] In some embodiments, the catalyst includes one or more of ferric chloride hexahydrate, cobalt chloride, nickel chloride, iron oxide, and cobalt oxide.

[0012] In some embodiments, the time of the pre-carbonization treatment is 4 h to 6 h.

[0013] In some embodiments, the time of the graphitization treatment is 6 h to 8 h.

[0014] In some embodiments, after the graphitization treatment, the preparation method further includes: soaking the graphitization treatment product in a hydrochloric acid solution, and then successively performing filtration, suction filtration washing, and drying treatment to obtain the graphite negative electrode material.

[0015] In a second aspect, an embodiment of the present application further provides a lithium-ion battery, which includes a negative electrode sheet. The negative electrode sheet includes a current collector and a graphite negative electrode material coated on the surface of the current collector. The graphite negative electrode material is prepared by the preparation method described in the first aspect.

[0016] In some embodiments, the graphite negative electrode material is doped with nitrogen and sulfur elements. The content of nitrogen element in the graphite negative electrode material is 2 wt% to 8 wt%, and the content of sulfur element in the graphite negative electrode material is 1 wt% to 5 wt%.

[0017] In some embodiments, the graphite negative electrode material is further doped with boron element. The content of boron element in the graphite negative electrode material is 3 wt% to 5 wt%.

[0018] In some embodiments, the particle size D10 of the graphite negative electrode material is 5 μm to 8 μm.

[0019] In some embodiments, the particle size D50 of the graphite negative electrode material is 5 μm to 15 μm.

[0020] In some embodiments, the tap density of the graphite negative electrode material is 1.2 g / cm 3 ~1.3 g / cm3 。

[0021] In some embodiments, the specific surface area of the graphite anode material is 1.3 m 2 / g to 1.7 m 2 / g.

[0022] In some embodiments, the intensity of the D peak in the Raman spectrum of the graphite anode material is I D , and the intensity of the G peak is I G , 0.2 ≤ I D / I G ≤ 0.5.

[0023] Thirdly, an energy storage device is further provided in an embodiment of the present application. The energy storage device includes a plurality of lithium-ion batteries as described in the second aspect.

[0024] Fourthly, an electrical equipment is further provided in an embodiment of the present application. The electrical equipment includes the energy storage device as described in the third aspect.

[0025] Compared with the prior art, the technical solution of the present application has at least the following technical effects: In the preparation method of the present application, the preparation raw materials further include a nitrogen-sulfur dopant and polyvinylpyrrolidone. Among them, the addition of the nitrogen-sulfur dopant can optimize the structure of the graphite anode material, enhance its graphitization degree, and can introduce nitrogen and sulfur elements into the graphite anode material, increasing the active sites on the surface of the graphite anode material. Polyvinylpyrrolidone can improve the uniformity and controllability of sulfur and nitrogen doping in the graphite anode material, and can induce the directional growth of graphite lamellae, improving the graphitization degree of the biomass carbon source; specifically, in the preparation stage of the slurry mixture, polyvinylpyrrolidone will combine with the biomass carbon source, nitrogen-sulfur dopant and catalyst to prevent the agglomeration / precipitation of biomass carbon source molecules, nitrogen-sulfur dopant molecules and catalyst molecules, so that the biomass carbon source, nitrogen-sulfur dopant and catalyst are uniformly dispersed in the solution; in the pre-carbonization treatment stage, the nitrogen-sulfur dopant and catalyst are maintained in a uniformly dispersed nanoscale structure under the wrapping of polyvinylpyrrolidone, and the biomass carbon source will form a carbon skeleton along the extension direction of the polyvinylpyrrolidone molecular chain, so that the carbon material generated by the pyrolysis of the biomass carbon source exists in a lamellar structure; in the graphitization treatment stage, polyvinylpyrrolidone releases the catalyst and nitrogen-sulfur dopant, and the catalyst catalyzes the transformation of the carbon material into graphitization. In this process, the sulfur and nitrogen elements in the dopant will jointly promote the bonding and rearrangement of carbon atoms, so that the lamellar structure grows and improves continuously, and the lamellar structure limits the growth direction of carbon atoms, making them form a graphitized material with order from micro to macro along a specific path. The graphite anode material prepared by the preparation method of the present application has a high graphitization degree, uniform and controllable doping of sulfur and nitrogen elements, and excellent electrochemical performance. Description of the Drawings

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Figure 1 It is a process flow diagram of a preparation method of a graphite negative electrode material for a lithium-ion battery in an embodiment of the present application. Specific embodiments

[0028] In the present invention, the raw materials and equipment used, unless otherwise specified, are common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0029] Unless otherwise specified, the meanings of the terms in this specification are the same as those generally understood by those skilled in the art. However, in case of conflict, the definitions in this specification shall prevail.

[0030] As used herein, the terms "comprising", "including", "containing", "having" or other variants are intended to cover non-closed inclusion, and no distinction is made between these terms. The term "including" means that other steps and components can be added without affecting the final result. The term "including" also includes the terms "consisting of" and "consisting essentially of". The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein and any additional or optional components, ingredients, steps, or limitations described herein.

[0031] All numerical values or expressions related to component amounts, process conditions, etc. used in the specification and claims should be understood to be modified by "about" in all cases. All ranges related to the same component or property include the endpoints, and these endpoints can be combined independently. Since these ranges are continuous, they include every numerical value between the minimum and maximum values. It should also be understood that any numerical range cited in the present application is expected to include all sub-ranges within that range.

[0032] It should be understood that the term "and / or" used in the present invention is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the preceding and following associated objects.

[0033] The present application provides a preparation method of a graphite negative electrode material for a lithium-ion battery.

[0034] Please refer to Figure 1 , in an embodiment of the present application, the preparation method of the graphite negative electrode material for the lithium-ion battery includes the following steps: S100. Prepare a slurry mixture containing a biomass carbon source, a nitrogen and sulfur dopant, polyvinylpyrrolidone (PVP), and a catalyst, where the mass ratio of the biomass carbon source, the nitrogen and sulfur dopant, polyvinylpyrrolidone, and the catalyst is 1:(0.5 - 1.5):(0.05 - 0.1):(0.5 - 2.8); S200. Perform pre-carbonization treatment on the slurry mixture at a temperature of 500°C - 600°C to obtain a pre-carbonized product; S300. Perform graphitization treatment on the pre-carbonized product at a temperature of 1200°C - 1400°C to obtain a graphite anode material.

[0035] In the preparation method of this application, the raw materials for preparation further include a nitrogen and sulfur dopant and polyvinylpyrrolidone. Among them, the addition of the nitrogen and sulfur dopant can optimize the structure of the graphite anode material, enhance its graphitization degree, and can introduce nitrogen and sulfur elements into the graphite anode material, increasing the active sites on the surface of the graphite anode material. Polyvinylpyrrolidone can improve the uniformity and controllability of sulfur and nitrogen doping in the graphite anode material, and can induce the directional growth of graphite sheets, improving the graphitization degree of the biomass carbon source; specifically, in the stage of preparing the slurry mixture, polyvinylpyrrolidone will combine with the biomass carbon source, the nitrogen and sulfur dopant, and the catalyst to prevent the agglomeration / precipitation of biomass carbon source molecules, nitrogen and sulfur dopant molecules, and catalyst molecules, so that the biomass carbon source, the nitrogen and sulfur dopant, and the catalyst are uniformly dispersed in the solution; in the pre-carbonization treatment stage, the nitrogen and sulfur dopant and the catalyst are maintained in a uniformly dispersed nano-scale structure under the wrapping of polyvinylpyrrolidone, and the biomass carbon source will form a carbon skeleton along the extension direction of the polyvinylpyrrolidone molecular chain, so that the carbon material generated by the pyrolysis of the biomass carbon source exists in a sheet structure; in the graphitization treatment stage, polyvinylpyrrolidone releases the catalyst and the nitrogen and sulfur dopant, and the catalyst catalyzes the transformation of the carbon material into graphitization. In this process, the sulfur and nitrogen elements in the dopant will jointly promote the bonding and rearrangement of carbon atoms, so that the sheet-like structure continuously grows and improves, and the sheet-like structure restricts the growth direction of carbon atoms, making them form a graphitized material with order from micro to macro along a specific path. The graphite anode material prepared by the preparation method of this application has a high graphitization degree, uniform and controllable doping of sulfur and nitrogen elements, and excellent electrochemical performance.

[0036] The preparation method of this application will be described in detail below.

[0037] S100. Prepare a slurry mixture containing a biomass carbon source, a nitrogen and sulfur dopant, polyvinylpyrrolidone, and a catalyst, where the mass ratio of the biomass carbon source, the nitrogen and sulfur dopant, polyvinylpyrrolidone, and the catalyst is 1:(0.5 - 1.5):(0.05 - 0.1):(0.5 - 2.8).

[0038] In the embodiments of the present application, the mass ratio of the biomass carbon source to the nitrogen and sulfur dopant is 1:(0.5 - 1.5), specifically it can be 1:0.5, 1:0.8, 1:1, 1:2, 1:1.5 or any ratio therebetween. The addition of the nitrogen and sulfur dopant in the raw materials can improve the graphitization degree of the pre-carbonized product, further optimize the overall structure of the finally prepared graphite anode material, and further enhance the electrochemical performance; if this ratio is too large, the performance such as the structural stability and conductivity of the graphite anode material will be reduced, thus affecting the electrochemical performance of the graphite anode material; if this ratio is too small, the electrochemical performance of the graphite anode material cannot be effectively improved.

[0039] In the embodiments of the present application, the mass ratio of the biomass carbon source to polyvinylpyrrolidone is 1:(0.05 - 0.1), specifically it can be 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.10 or any value therebetween. If this ratio is too large, that is, PVP is insufficient, PVP cannot effectively disperse the biomass carbon source, nitrogen and sulfur dopant and the catalyst, resulting in particle aggregation or precipitation; in the pre-carbonization stage, the PVP molecular chain cannot fully guide the directional extension of the biomass carbon source, and the carbon skeleton is in disordered stacking rather than a lamellar structure, which will reduce the graphitization potential and lead to the deterioration of the electrochemical performance of the graphite anode material. If this ratio is too small, that is, PVP is excessive, PVP will decompose violently during the pre-carbonization process, releasing a large amount of gas, resulting in the collapse of the internal pores of the carbon skeleton and the decrease of the specific surface area; and it will hinder the effective release of the catalyst in the graphitization stage and reduce the catalytic efficiency; in addition, PVP will form an overly thick molecular chain network, restricting the directional growth of the carbon lamellae, resulting in a dense structure of the graphitized material and uneven lamellar thickness, affecting the electrochemical performance of the graphite anode material.

[0040] In the embodiments of the present application, the mass ratio of the biomass carbon source to the catalyst is 1:(0.5 - 2.8), specifically it can be 1:0.5, 1:0.8, 1:1, 1:1.3, 1:1.5, 1:1.8, 1:2 or any value therebetween. If this ratio is too large, not only the catalytic efficiency cannot be further improved, but it will have an adverse impact on the electrochemical performance of the graphite anode material. If this ratio is too small, it will lead to ineffective catalysis of the graphitization of the pre-carbonized product, thus unable to effectively improve the electrochemical performance of the graphite anode material.

[0041] In some preferred embodiments, the mass ratio of the biomass carbon source to the catalyst is 1:(2.4 - 2.8), specifically it can be 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8 or any ratio therebetween. Within this ratio range, the catalytic efficiency of the catalyst is higher, the graphitization efficiency of the pre-carbonized product is higher, which is more conducive to improving the electrochemical performance of the finally prepared graphite anode material.

[0042] In some embodiments, the biomass carbon source includes one or more of glucose, lignosulfonate, malic acid, chitosan, sucrose, fructose, citric acid, oxalic acid, cellulose, lignin, and hemicellulose.

[0043] In some embodiments, the nitrogen-sulfur dopant is one or more of thiourea, 2-mercaptoimidazole, cysteine, and ammonium thiocyanate.

[0044] In other embodiments, the nitrogen-sulfur dopant is an organometallic complex, and the central metal of the organometallic complex includes at least one of iron, cobalt, and nickel. Compared with conventional nitrogen-sulfur dopants such as thiourea, 2-mercaptoimidazole, cysteine, and ammonium thiocyanate, the organometallic complex-based nitrogen-sulfur dopant is more conducive to improving the graphitization degree of the pre-carbonized product, so that the electrochemical performance of the finally prepared graphite anode material is more effectively improved. Specifically, the nitrogen-sulfur dopant uses metal ions such as iron, cobalt, and nickel as the central atoms and nitrogen-sulfur organic compounds as the main ligands. Among them, the metal ions have the function of catalyzing the graphitization of the pre-carbonized product. During the graphitization process of the pre-carbonized product, the nitrogen-sulfur organic compounds can adsorb the pre-carbonized product near the metal ions to promote the catalysis of the metal ions, thereby improving the graphitization degree of the pre-carbonized product. Moreover, in this process, the metal atoms can also stabilize the structure of the nitrogen-sulfur organic compounds, making the doping of nitrogen and sulfur elements in the finally prepared graphite anode material more uniform.

[0045] In some embodiments, the preparation steps of the organometallic complex include: In an inert environment, using absolute ethanol as a solvent, prepare a mixed solution of nitrogen-sulfur organic compounds and metal salts according to a preset molar ratio; Place the mixed solution under the conditions of 60°C to 80°C and stir and react for 5h to 8h, with a stirring rate of 200 rpm / min to 400 rpm / min. Purify the reaction mixture to obtain the organometallic complex.

[0046] In the above embodiments, the dosage of absolute ethanol should be such that it can completely dissolve the nitrogen-sulfur organic compounds and metal salts and ensure that the reaction system has good fluidity.

[0047] In the above embodiments, the nitrogen-sulfur organic compounds include one or more of thiourea, 2-mercaptoimidazole, cysteine, ammonium thiocyanate, etc.

[0048] In the above embodiments, the metal salts include one or more of ferric chloride hexahydrate, cobalt chloride, cobalt nitrate, iron nitrate, nickel nitrate, nickel chloride, etc.

[0049] In the above embodiments, the molar ratio of the nitrogen-sulfur organic compound to the metal salt is determined according to the specific types of the nitrogen-sulfur organic compound and the metal salt, and the embodiments of the present application do not make special limitations in this regard. For example, when the nitrogen-sulfur organic compound is 2-mercaptoimidazole and the metal salt is cobalt nitrate, the molar ratio of the nitrogen-sulfur organic compound to the metal salt is 3:1.

[0050] In the above embodiments, the steps are as follows: placing the mixed solution under the conditions of 60°C to 80°C and stirring and reacting for 5 h to 8 h, with the stirring rate being 200 rpm / min to 400 rpm / min, and purifying the reaction mixture to obtain the organometallic complex. Among them, under the conditions of 60°C to 80°C, it can specifically be under the conditions of 60°C, 65°C, 70°C, 75°C, 80°C or any temperature value between them; for the stirring reaction for 5 h to 8 h, it can specifically be 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h or any duration between them; for the stirring rate of 200 rpm / min to 400 rpm / min, it can specifically be 200 rpm / min, 250 rpm / min, 300 rpm / min, 350 rpm / min, 400 rpm / min or any value between them.

[0051] In some embodiments, the step of purifying the reaction mixture includes: cooling the reaction mixture and then putting it into a centrifuge tube for centrifugation, with the centrifugation rate being 5500 rpm / min to 6500 rpm / min and the centrifugation duration being 10 min to 15 min; removing the supernatant in the centrifuge tube and washing the precipitate. Specifically: adding an appropriate amount of absolute ethanol to the centrifuge tube and performing the centrifugation operation again; repeating the washing step 2 to 3 times until no obvious impurity ions can be detected in the washed ethanol solution, and drying it under vacuum to obtain the organometallic complex.

[0052] In some embodiments, the catalyst includes one or more of ferric chloride hexahydrate, cobalt chloride, nickel chloride, iron oxide, and cobalt oxide.

[0053] In some embodiments, the catalyst is ferric chloride hexahydrate or ferric chloride, and the central metal ion in the organometallic complex is cobalt ion. During the graphitization process of the biomass carbon material, the iron ion in the catalyst and the cobalt ion in the organometallic complex can synergistically catalyze the graphitization of the pre-carbonized product.

[0054] In some embodiments, the slurry mixture further contains a boron dopant. The addition of the boron dopant in the raw materials makes the finally prepared graphite anode material doped with boron element, and the boron element, nitrogen element, and sulfur element can synergistically improve the electrochemical performance of the graphite anode material.

[0055] In the above embodiments, the boron dopant can be selected from one or more of boric acid, boron tribromide, boron oxide, boron carbide, etc.

[0056] In the above embodiments, the content of the boron dopant is 0.5% - 5%, specifically, it can be 0.5%, 1%, 2%, 3%, 4%, 5% or any value therebetween. Within this content range, the boron dopant can effectively cooperate with the nitrogen and sulfur dopants to improve the electrochemical performance of the graphite anode material.

[0057] S200. Perform pre-carbonization treatment on the slurry mixture at a temperature of 500°C - 600°C to obtain a pre-carbonized product.

[0058] In the embodiments of the present application, the temperature of the pre-carbonization treatment is 500°C - 600°C, specifically, it can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C or any value therebetween. If the pre-carbonization treatment temperature is too high, the internal pores of the carbon skeleton of the pre-carbonized product will collapse, the dopant will become ineffective, and the catalyst will be deactivated, thus affecting the electrochemical performance of the finally prepared graphite anode material. If the pre-carbonization treatment temperature is too low, the biomass carbon source will not be completely carbonized, and the nitrogen and sulfur dopants will be unevenly doped, which will increase the difficulty of graphitization of the pre-carbonized product in the subsequent process and affect the conductivity and electrochemical activity of the finally prepared graphite anode material.

[0059] In some embodiments, the time of the pre-carbonization treatment is 4h - 6h, specifically, it can be 4h, 4.5h, 5h, 5.5h, 6h or any value therebetween.

[0060] S300. Perform graphitization treatment on the pre-carbonized product at a temperature of 1200°C - 1400°C to obtain a graphite anode material.

[0061] In the embodiments of the present application, the graphitization treatment temperature is 1200°C - 1400°C, specifically, it can be 1200°C, 1250°C, 1300°C, 1350°C, 1400°C or any value therebetween. If the graphitization treatment temperature is too high, the doping of the nitrogen and sulfur dopants will become ineffective, the catalyst will be deactivated, and the formed graphite sheet layer structure will be overly stacked, resulting in the deterioration of the performance of the finally prepared graphite anode material; if the graphitization treatment temperature is too low, the degree of graphitization of the graphite anode material will be insufficient, the nitrogen and sulfur doping will be uneven, and the conductivity will be poor, so that the electrochemical performance of the graphite anode material will be greatly limited.

[0062] In some embodiments, the time of the graphitization treatment is 6h - 8h, specifically, it can be or any value therebetween.

[0063] In some embodiments, the heating rate from the pre-carbonization treatment temperature to the graphitization treatment temperature ≤ 2°C / min. Too fast heating rate may cause an increase in internal thermal stress of the material, thereby triggering cracks or structural damage.

[0064] In some embodiments, after the graphitization treatment, the graphitization treatment product obtained is cooled to room temperature at a cooling rate of ≤2 °C / min. If the cooling rate is too fast, the temperature difference between the surface and the interior of the material will increase, resulting in thermal stress concentration, which may cause the material to crack or deform.

[0065] In some embodiments, after the graphitization treatment, the preparation method further includes: soaking the graphitization treatment product cooled to room temperature in a hydrochloric acid solution to remove metal impurities in the graphitization product, and then successively performing filtration, suction filtration washing, and drying treatments to obtain a graphite negative electrode material.

[0066] In some embodiments, the concentration of the hydrochloric acid solution is , specifically, it can be , , , , , or any value between them.

[0067] In some embodiments, the soaking duration of the graphitization treatment product in the hydrochloric acid solution is 20 h to 24 h, specifically, it can be 20 h, 21 h, 22 h, 23 h, 24 h or any value between them.

[0068] In some embodiments, the number of suction filtration washings is multiple times. Exemplarily, it can be 2 times or 3 times, and the washing solvent can be low melting point solvents such as methanol and ethanol.

[0069] In some embodiments, the drying temperature is 50 °C to 60 °C, specifically, it can be 50 °C, 52 °C, 54 °C, 56 °C, 58 °C, 60 °C or any value between them.

[0070] In the embodiments of the present application, the graphite negative electrode material is doped with nitrogen element and sulfur element. Among them, the content of nitrogen element in the graphite negative electrode material is 2 wt% to 8 wt%, and the content of sulfur element in the graphite negative electrode material is 1 wt% to 5 wt%.

[0071] Specifically, the content of nitrogen element in the graphite negative electrode material is 2 wt% to 8 wt%, specifically, it can be 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt% or any value between them.

[0072] The content of sulfur element in the graphite negative electrode material is 1 wt% to 5 wt%, specifically, it can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or any value between them.

[0073] In some embodiments, the graphite negative electrode material is further doped with boron element, and the content of boron element in the graphite negative electrode material is 3wt% - 5wt%, specifically it can be 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt% or any value between them.

[0074] In some embodiments, the intensity of the D peak in the Raman spectrum of the graphite negative electrode material is I D , and the intensity of the G peak is I G , 0.2 ≤ I D / I G ≤ 0.5. In a specific embodiment, in the Raman spectrum of the graphite negative electrode material, the D peak and the G peak are respectively located at and , 0.2 ≤ I D / I G ≤ 0.5, which proves indirectly that: the disordered soft carbon (i.e., the pre-carbonization product) formed by the pre-carbonization treatment has successfully completed graphitization under the continuous catalytic action of iron atoms during the graphitization treatment.

[0075] In some embodiments, the D10 particle size of the graphite negative electrode material is 5μm - 8μm, specifically it can be 5μm, 6μm, 7μm, 8μm or any value between them.

[0076] In some embodiments, the D50 particle size of the graphite negative electrode material is 5μm - 15μm, specifically it can be 5μm, 7μm, 9μm, 11μm, 13μm, 15μm or any value between them.

[0077] In some embodiments, the tap density of the graphite negative electrode material is 1.2 g / cm 3 ~ 1.3 g / cm 3 , specifically it can be 1.2 g / cm 3 , 1.22 g / cm 3 , 1.24 g / cm 3 , 1.26 g / cm 3 , 1.28 g / cm 3 , 1.3 g / cm 3 or any value between them.

[0078] In some embodiments, the specific surface area of the graphite negative electrode material is 1.3 m 2 / g ~ 1.7 m 2 / g, specifically it can be 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g or any value between them.

[0079] In a second aspect, the present application also provides a lithium-ion battery.

[0080] In an embodiment of the present application, the lithium-ion battery includes a negative electrode sheet, the negative electrode sheet includes a current collector, and a negative electrode material coating coated on the surface of the current collector. The negative electrode material coating contains a graphite negative electrode material, and the graphite negative electrode material is prepared by the preparation method described in the first aspect. For the convenience of distinction, the current collector in the negative electrode sheet is denoted as the first current collector.

[0081] In an embodiment of the present application, the first current collector can be made of copper foil or other common materials, and the present application embodiment does not make special limitations on this.

[0082] In some embodiments, the negative electrode material coating further includes a negative electrode conductive agent and a negative electrode binder, and the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder is (90-94):(2-7):(1-3).

[0083] In some embodiments, the negative electrode conductive agent is selected from at least one of Super P (SP), acetylene black, Ketjen black, conductive graphite, carbon black, etc.

[0084] In some embodiments, the negative electrode binder is selected from at least one of polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), polyacrylate binder (LA), polyacrylic acid binder (PAA), etc.

[0085] In an embodiment of the present application, the lithium-ion battery further includes a positive electrode sheet and a separator, and the separator is located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet can be assembled into a stacked structure or a wound structure, and the specific assembly method can be adjusted according to the specific type of the lithium-ion battery.

[0086] In some embodiments, the separator is a cell separator manufactured by Celgard of the United States. Of course, other commonly used cell separators in the art can also be selected.

[0087] In an embodiment of the present application, the lithium-ion battery further includes a housing, and the positive electrode sheet, the separator, and the negative electrode sheet are disposed in the housing.

[0088] In some embodiments, the housing is filled with an electrolyte, and the electrolyte includes a lithium salt and an organic solvent, and the mass ratio of the lithium salt to the organic solvent is 1:8.

[0089] In some embodiments, the lithium salt includes one or more of LiPF6, LiFSI (lithium bis(trifluoromethanesulfonyl)imide), LiBF4, LiBOB (lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), LiTFSI (lithium bis(trifluoromethylsulfonyl)imide). Of course, those skilled in the art can also select other commonly used lithium salts in the art according to the actual situation.

[0090] In some embodiments, the organic solvent includes one or more of EC (ethylene carbonate), PC (propylene carbonate), BC (butyronitrile), DEC (diethyl carbonate), DMC (dimethyl carbonate), DME (dimethoxyethane), EMC (ethyl methyl carbonate), TEP (triethyl phosphate), FEC (fluoroethylene carbonate). Of course, those skilled in the art can also select other commonly used electrolytes in the art according to the actual situation.

[0091] In the embodiments of the present application, exemplarily, the method for preparing a lithium-ion battery includes the following steps: Prepare a positive electrode sheet and a negative electrode sheet; Stack or wind the positive electrode sheet, the separator and the negative electrode sheet to obtain a pre-assembled component; Assemble the pre-assembled component with a housing to obtain a lithium-ion battery.

[0092] In some embodiments, after assembling the pre-assembled component with the housing, the method for preparing a lithium-ion battery further includes the step of injecting an electrolyte into the housing.

[0093] In a third aspect, the embodiments of the present application further provide an energy storage device, which includes at least one lithium-ion battery as described in the second aspect. When the energy storage device contains multiple lithium-ion batteries, the multiple lithium-ion batteries can be connected by at least one of parallel connection and series connection.

[0094] In a fourth aspect, the embodiments of the present application further provide an electrical device, which includes the energy storage device as described in the third aspect.

[0095] It can be understood that the electrical device further includes an electrical device body, and the energy storage device is used to supply power to the electrical device body.

[0096] In the embodiments of the present application, the electrical equipment may include but is not limited to: containers, household energy storage systems, battery cars, electric vehicles, ships, spacecrafts, electric toys, electric tools, etc. Among them, the spacecrafts are, for example, airplanes, rockets, space shuttles, spaceships, etc., and the electric toys include, for example, fixed or mobile electric toys. Specifically, for example, electric vehicle toys, electric ship toys, electric airplane toys, etc. The electric tools include, for example, metal cutting electric tools, grinding electric tools, assembly electric tools, and electric tools for railways. Specifically, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers.

[0097] The present application will be further described below through specific examples and comparative examples, but the present application is not limited to this specific example.

[0098] Example 1 1. Preparation of nitrogen-sulfur dopant: In a glove box under nitrogen protection, 5.7 g of 2-mercaptoimidazole was added to a dry round-bottom flask. Then, 3.47 g of cobalt nitrate was accurately weighed according to a specific molar ratio of 2-mercaptoimidazole to cobalt nitrate of 3:1 and added to the round-bottom flask. Subsequently, 100 ml of absolute ethanol was added to the round-bottom flask as a solvent, and the round-bottom flask was taken out of the glove box and connected to a reaction device equipped with a condenser.

[0099] The magnetic stirrer was turned on, and the reaction mixture was stirred at a speed of 200 rpm / min to 400 rpm / min to fully mix 2-mercaptoimidazole, cobalt nitrate, and absolute ethanol evenly. The oil bath was turned on, and the temperature was slowly raised to 60°C to 80°C, and the reaction continued for 6 hours. After the reaction was completed, the oil bath and the magnetic stirrer were turned off, and the reaction system was allowed to cool naturally to room temperature. The cooled reaction mixture was transferred to a centrifuge tube, placed in a centrifuge, and centrifuged at a speed of 6000 rpm / min for 10 min to 15 min. Then, an appropriate amount of absolute ethanol was added to the centrifuge tube to wash the precipitate, and the centrifugation operation was performed again. The washing step was repeated 2 to 3 times until no obvious impurity ions were detected in the washed ethanol solution, and 8 g of cobalt-containing sulfur-nitrogen heterocyclic complex (i.e., nitrogen-sulfur dopant) was obtained by vacuum drying.

[0100] 2. Preparation of graphite negative electrode material (1) Weigh the raw materials: 4 g of malic acid, 3 g of chitosan, 3 g of sodium lignosulfonate, 8 g of cobalt-containing sulfur-nitrogen heterocyclic complex, 6 g of ferric chloride hexahydrate, 6 g of iron oxide, 3 g of boric acid, and 0.7 g of polyvinylpyrrolidone. All the raw materials were dissolved in 100 mL of deionized water and stirred with a magnetic stirrer for 1 h to 2 h to form a homogeneous solution. Then, it was placed in a blast dryer for drying, and the drying temperature was 100°C to 120°C to obtain a viscous paste mixture.

[0101] (2) Place the slurry mixture in a crucible, fix the crucible and place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min to 600 °C and hold for 6 h, then heat it to 1200 °C at a rate of 2 °C / min and keep it at a constant temperature for roasting for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0102] (3) Immerse the black powder material fully in hydrochloric acid solution for 24 h, then filter and wash it, and then place it in a blast drying oven at 60 °C for drying for 2 h to 3 h until it is completely dry to obtain the graphitized anode material.

[0103] Example 2 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: the contents of ferric chloride hexahydrate and iron oxide are both increased from 6 g to 12 g.

[0104] Example 3 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: the contents of ferric chloride hexahydrate and iron oxide are both increased from 6 g to 13 g.

[0105] Example 4 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: the contents of ferric chloride hexahydrate and iron oxide are both increased from 6 g to 14 g.

[0106] Example 5 The difference from Example 1 is that: There is no need to prepare the nitrogen and sulfur dopant; The preparation step (1) of the graphite anode material: replace 8 g of the cobalt-containing sulfur and nitrogen heterocyclic complex with 5.7 g of 2-mercaptoimidazole and 3.47 g of cobalt nitrate.

[0107] Example 6 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: the weighed raw materials do not contain boric acid.

[0108] Example 7 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: replace 4 g of malic acid with 4 g of glucose.

[0109] Example 8 The difference from Example 1 is that: Preparation steps of the graphite anode material (1): Replace 6 g of ferric chloride hexahydrate with 6 g of cobalt chloride, and replace 6 g of iron oxide with 6 g of cobalt oxide.

[0110] Example 9 1. Preparation of the nitrogen and sulfur dopant (cobalt-containing sulfur and nitrogen heterocyclic complex) (refer to Example 1) 2. Preparation of the graphite anode material: (1) Weigh the raw materials: 5 g of malic acid, 5 g of chitosan, 8 g of thiourea, 6 g of ferric chloride hexahydrate, 6 g of iron oxide, 3 g of boric acid, and 1 g of polyvinylpyrrolidone. Dissolve all the raw materials in 100 mL of deionized water and stir with a magnetic stirrer for 1 h to 2 h to form a homogeneous solution; then, place it in a blast dryer for drying, and the drying temperature is 100 °C to 120 °C to obtain a viscous slurry mixture.

[0111] (2) Place the slurry mixture in a crucible, fix the crucible and place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min to 550 °C and hold for 6 h, then heat it to 1300 °C at a rate of 2 °C / min and keep it at a constant temperature for roasting for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0112] (3) Immerse the black powder material in of hydrochloric acid solution for 24 h, then filter and wash it, and then place it in a blast drying oven at 60 °C for drying for 2 h to 3 h until it is completely dry to obtain the graphitized anode material.

[0113] Comparative Example 1 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: The raw materials weighed do not contain polyvinylpyrrolidone.

[0114] Comparative Example 2 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: The content of polyvinylpyrrolidone is increased from 0.5 g to 5 g.

[0115] Comparative Example 3 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: The contents of both ferric chloride hexahydrate and iron oxide are reduced from 6 g to 1.5 g.

[0116] Comparative Example 4 The difference from Example 1 is that: In the preparation step (1) of the graphite anode material: The contents of both ferric chloride hexahydrate and iron oxide are increased from 6 g to 15 g.

[0117] Comparative Example 5 The difference from Example 1 is as follows: Step (2) of preparing the graphite negative electrode material: Place the slurry mixture in a crucible, fix the crucible and then place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min and keep it at 400 °C for 6 h. Subsequently, heat it to 1200 °C at a rate of 2 °C / min and keep it at a constant temperature for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0118] Comparative Example 6 The difference from Example 1 is as follows: Step (2) of preparing the graphite negative electrode material: Place the slurry mixture in a crucible, fix the crucible and then place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min and keep it at 700 °C for 6 h. Subsequently, heat it to 1200 °C at a rate of 2 °C / min and keep it at a constant temperature for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0119] Comparative Example 7 The difference from Example 1 is as follows: Step (2) of preparing the graphite negative electrode material: Place the slurry mixture in a crucible, fix the crucible and then place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min and keep it at 600 °C for 6 h. Subsequently, heat it to 1000 °C at a rate of 2 °C / min and keep it at a constant temperature for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0120] Comparative Example 8 The difference from Example 1 is as follows: Step (2) of preparing the graphite negative electrode material: Place the slurry mixture in a crucible, fix the crucible and then place it in a tube resistance furnace. Under an argon atmosphere, heat it at a rate of 2 °C / min and keep it at 600 °C for 6 h. Subsequently, heat it to 1500 °C at a rate of 2 °C / min and keep it at a constant temperature for 6 h, and then cool it to room temperature at a rate of 2 °C / min to obtain black powder.

[0121] Performance test Use the graphite negative electrode materials prepared in the above Examples 1-9 and Comparative Examples 1-8 as the negative electrode materials of lithium-ion batteries to assemble CR2032 button cells to test the electrochemical performance.

[0122] Among them, the specific steps of the CR2032 button cell include: (1) The graphite anode material and the conductive agent Super are mixed and then ground until completely and evenly ground. The obtained powder mixture is fully mixed with a polyvinylidene fluoride solution (PVDF:NMP = 1:20 (mass ratio)) under stirring conditions to prepare a slurry. The mass ratio of the graphite anode material, the conductive agent Super, and polyvinylidene fluoride (PVDF) in the slurry is 91.6:6.6:1.8.

[0123] (2) The slurry is coated on a copper foil and dried under vacuum at 80 °C for 10 h to obtain a negative electrode sheet; the counter electrode is a lithium sheet.

[0124] (3) The negative electrode sheet and the lithium sheet are cut into small round pieces with a diameter of 13 mm using a cutter. In a glove box filled with argon (Ar), the positive electrode shell, shrapnel, gasket, lithium sheet, separator, negative electrode sheet, and negative electrode shell are assembled into a button cell, and the electrolyte is injected into the button cell. Among them, the separator is a separator of Celgard Company, USA, with a specification of Celgard 2400; the electrolyte composition is: 1 wt% LiPF6 + 8 wt% (EC:EMC:DMC = 3:4:3 vol%).

[0125] Testing of electrochemical performance: (1) Initial de-lithiation capacity and initial Coulombic efficiency: The button half-cell is discharged at 0.1C to 0.005V, discharged at a constant voltage of 0.005V to 0.02C, left standing for 10 min, discharged at 0.05C to 0.005V, discharged at a constant voltage of 0.005V to 0.02C, left standing for 10 min, discharged at 0.02C to 0.005V, discharged at a constant voltage of 0.005V to 0.02C, left standing for 10 min, discharged at 0.01C to 0.005V, discharged at a constant voltage of 0.005V to 0.02C, left standing for 10 min, and then charged at 0.1C to 2V to end, so as to obtain the lithium intercalation capacity and de-lithiation capacity respectively. The ratio of the initial de-lithiation capacity (charging capacity) to the initial lithium intercalation capacity is the initial Coulombic efficiency, that is, the first efficiency.

[0126] (2) Cycling performance In this paper, the LAND test system is used to test the cycling performance and rate performance of the above-assembled button cell in a constant temperature test cabinet at 25 °C. The current density for the cycling performance test is 0.3C for 10 cycles for activation and then cycles at a current density of 1C, and the voltage range is 0.01V - 3V respectively.

[0127] Table 1. Performance test results of each example and comparative example

[0128] Analysis: By comparing Examples 1-9 with Comparative Examples 1-8, it can be proved that by controlling the mass ratio of the biomass carbon source, nitrogen-sulfur dopant, polyvinyl pyrrolidone and catalyst in the slurry mixture to 1: (0.5~1.5): (0.05~0.1): (0.5~2.8), and by controlling the temperature of the pre-carbonization treatment to 500℃~600℃ and the temperature of the graphitization treatment to 1200℃~1400℃, it is more conducive to improving the degree of graphitization of the graphite negative electrode material, and making the doping of sulfur and nitrogen elements uniform and controllable, which can effectively improve the electrochemical properties of the graphite negative electrode material such as the first lithium removal capacity, the first coulomb efficiency and the cycle performance. Among them, The test results of Examples 1-4 prove that when the mass ratio of the biomass carbon source to the catalyst is 1:(2.4-2.8), the catalytic efficiency of the catalyst is higher, the graphitization efficiency of the pre-carbonized product is higher, and it is more conducive to improving the electrochemical performance of the final graphite negative electrode material.

[0129] By comparing Example 1 with Example 5 and Example 9, it can be proved that, compared with conventional nitrogen-sulfur dopants such as thiourea and 2-mercaptoimidazole, organic metal complex nitrogen-sulfur dopants are more conducive to improving the degree of graphitization of the pre-carbonized product, so that the electrochemical performance of the final graphite negative electrode material is more effectively improved.

[0130] By comparing Example 1 with Examples 6-8, it can be proved that: boron, nitrogen and sulfur can synergistically improve the electrochemical properties of graphite negative electrode materials; malic acid is a more excellent carbon source due to the high reactivity of its carboxylic acid group, strong interaction with the catalyst / dopant and controllable pyrolysis behavior; the iron ions in the catalyst and the cobalt ions in the organometallic complex can synergistically catalyze the biomass carbon material to improve the electrochemical properties of the material.

[0131] By comparing Example 1 with Comparative Examples 1-2, it can be proved that polyvinyl pyrrolidone can improve the uniformity and controllability of sulfur and nitrogen doping in graphite negative electrode materials, and can induce directional growth of graphite sheets, improve the degree of graphitization of biomass carbon sources to improve the electrochemical properties of materials, and the mass ratio of biomass carbon source to polyvinyl pyrrolidone is too large to effectively disperse the biomass carbon source, nitrogen and sulfur dopants and catalysts to produce particle agglomeration or precipitation; in the pre-carbonization stage, the PVP molecular chain cannot fully guide the directional extension of the biomass carbon source, and the carbon skeleton is disorderedly stacked rather than a lamellar structure, which reduces the graphitization potential and leads to degradation of the electrochemical performance.

[0132] By comparing Example 1 with Comparative Examples 3-4, it can be proved that for the mass ratio of the biomass carbon source to the catalyst, if the ratio is too large, it cannot further improve the catalytic efficiency, but will adversely affect the electrochemical performance of the graphite anode material. If the ratio is too small, it will lead to ineffective catalysis of the graphitization of the pre-carbonized product, thus unable to effectively improve the electrochemical performance of the graphite anode material.

[0133] By comparing Example 1 with Comparative Examples 5-8, it can be proved that too low or too high pre-carbonization and graphitization temperatures will limit the electrochemical performance of the material.

[0134] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A preparation method of a graphite anode material for a lithium-ion battery, characterized in that, It includes the following steps: Prepare a slurry mixture containing a biomass carbon source, a nitrogen and sulfur dopant, polyvinylpyrrolidone, and a catalyst, where the mass ratio of the biomass carbon source, the nitrogen and sulfur dopant, the polyvinylpyrrolidone, and the catalyst is 1:(0.5 - 1.5):(0.05 - 0.1):(0.5 - 2.8); Perform pre-carbonization treatment on the slurry mixture at a temperature of 500°C - 600°C to obtain a pre-carbonized product; Perform graphitization treatment on the pre-carbonized product at a temperature of 1200°C - 1400°C to obtain a graphite anode material.

2. The preparation method according to claim 1, characterized in that, The nitrogen and sulfur dopant is an organometallic complex, and the central metal of the organometallic complex includes at least one of iron, cobalt, and nickel.

3. The preparation method according to claim 2, characterized in that, The preparation steps of the organometallic complex include: In an inert environment, use absolute ethanol as a solvent to prepare a mixed solution of a nitrogen and sulfur organic compound and a metal salt according to a preset molar ratio; Place the mixed solution under stirring reaction at 60°C - 80°C for 5h - 8h, with a stirring rate of 200 rpm / min - 400 rpm / min, and purify the reaction mixture to obtain the organometallic complex.

4. The preparation method according to claim 3, characterized in that, The nitrogen and sulfur organic compound includes one or more of thiourea, 2-mercaptoimidazole, cysteine, and ammonium thiocyanate; The metal salt includes one or more of iron salts, cobalt salts, and nickel salts.

5. The preparation method according to claim 1, characterized in that, The slurry mixture further contains a boron dopant, and the boron dopant includes boric acid.

6. The preparation method according to any one of claims 1-5, characterized in that, It also includes at least one of the following features (1)-(5): (1) The biomass carbon source includes one or more of glucose, lignosulfonate, malic acid, chitosan, sucrose, fructose, citric acid, oxalic acid, cellulose, lignin, and hemicellulose; (2) The catalyst includes one or more of ferric chloride hexahydrate, cobalt chloride, nickel chloride, iron oxide, and cobalt oxide; (3) The time of the pre-carbonization treatment is 4h - 6h; (4) The time of the graphitization treatment is 6h - 8h; (5) After the graphitization treatment, the preparation method further includes: soaking the graphitization treatment product in a hydrochloric acid solution, and then performing filtration, suction filtration and washing, and drying treatment in sequence to obtain the graphite anode material.

7. A lithium-ion battery, characterized in that, It includes a negative electrode sheet, the negative electrode sheet includes a current collector and a graphite anode material coated on the surface of the current collector, and the graphite anode material is prepared by the preparation method described in any one of claims 1 - 6.

8. The lithium ion battery according to claim 7, characterized in that, The graphite anode material is doped with nitrogen and sulfur elements, the content of nitrogen element in the graphite anode material is 2wt% - 8wt%, and the content of sulfur element in the graphite anode material is 1wt% - 5wt%.

9. The lithium ion battery according to claim 8, characterized in that, The graphite anode material is further doped with boron element, and the content of boron element in the graphite anode material is 3wt% - 5wt%.

10. The lithium-ion battery according to claim 7, wherein, It also includes at least one of the following features (1)-(5): (1) The particle size D10 of the graphite anode material is 5μm - 8μm; (2) The particle size D50 of the graphite anode material is 5μm - 15μm; (3) The tap density of the graphite anode material is 1.2 g / cm 3 ~1.3 g / cm 3 ; (4) The specific surface area of the graphite anode material is 1.3 m 2 / g to 1.7 m 2 / g; The intensity of the D peak in the Raman spectrum of the graphite negative electrode material is I D , and the intensity of the G peak is I G , 0.2 ≤ I D / I G ≤ 0.

5.

11. A energy storage device, characterized in that, It includes a plurality of lithium-ion batteries described in any one of claims 7 - 10.

12. An electrical device, characterized in that, It includes an energy storage device described in claim 11.

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