A high specific capacity lithium ion battery anode material and a preparation method thereof

Abstract

The application discloses a preparation method of a high-specific-capacity lithium ion battery negative electrode material, and steps of the method comprise the following steps: (1) preparing a zinc-tin composite oxide; (2) treating the zinc-tin composite oxide with a mercaptopropyl trimethoxysilane ethanol solution to obtain a primary treatment solid phase; (3) treating the primary treatment solid phase with a silver-ammonia solution to obtain a secondary treatment solid phase; and (4) treating the secondary treatment solid phase with a chloroiridic acid ethanol solution to obtain the lithium ion battery negative electrode material. The lithium ion battery negative electrode material prepared by the method has a good effect on improving the discharge capacity of a lithium ion battery, and can still maintain a large discharge specific capacity under a large-current charging and discharging condition.

Description

Technical Field

[0001] This invention relates to the field of battery anode material technology, and in particular to a high specific capacity lithium-ion battery anode material and its preparation method. Background Technology

[0002] The working principle of a lithium-ion battery is as follows: during charging, lithium ions move from the cathode to the anode, and when an external current is applied, electrical energy is converted into chemical energy. During discharge, these lithium ions return to the cathode, generating an external current to release the stored chemical energy. The reversible flow of lithium ions in the ion-conducting electrolyte between the two electrodes allows for the cyclical process of storing and releasing electrical energy from chemical energy. The basic unit of a lithium-ion battery mainly consists of a positive electrode, a negative electrode, a separator, an electrolyte, and a casing. These important components directly affect the performance of the lithium-ion battery. The selection of the negative electrode material is determined by the reversibility of lithium ion insertion and extraction, the electrochemical environment, conductivity, cycle stability, and cost. In the early stages of lithium-ion battery development, the carbon materials used were mainly graphite, soft carbon, and hard carbon. Graphite, due to its excellent electrochemical performance and long cycle life, is the most commonly used negative electrode material. While graphite offers advantages such as low cost, moderate capacity, and ease of processing, its small interlayer space results in a lower ion diffusion rate compared to amorphous carbon. Furthermore, both natural and artificial graphite lack lithium-ion intercalation sites, making their rate capability insufficient for high-rate lithium-ion battery applications. Therefore, it is necessary to composite lithium storage materials, such as tin and zinc oxides, at the negative electrode. However, tin and zinc oxides have poor conductivity and are prone to side reactions upon contact with the electrolyte, forming an SEI film on the oxide surface and reducing the performance of the negative electrode material. Therefore, current technologies typically involve coating tin and zinc oxides with a carbon layer to reduce electrolyte erosion and improve the conductivity of the material particles. However, the interface between the tin / zinc oxide and carbon layer is usually weak, easily detaching after prolonged charge / discharge, and exhibiting high contact resistance, resulting in poor negative electrode stability and difficulty in meeting high-capacity requirements. Summary of the Invention

[0003] Therefore, the present invention provides a method for preparing a high-specific-capacity lithium-ion battery anode material, the steps of which include:

[0004] (1) Zinc chloride and tin tetrachloride are added to deionized water in a reaction vessel to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath and the solution is stirred. Hydrazine hydrate is added to the solution while stirring. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for more than 8 minutes. Then the reaction vessel is sealed and heated to 180±2℃ for more than 20 hours. After the heat preservation is completed, the mixture is cooled to room temperature. The reaction vessel is opened and the solid and liquid are separated. The solid phase is washed with deionized water and dried at 60℃ for more than 2 hours to obtain zinc-tin composite oxide.

[0005] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane. Keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath. Add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane while keeping it at a constant temperature. After the addition is completed, keep it at 65±3℃ and stir for more than 3 hours. Then, cool it to room temperature and separate the solid and liquid. Wash the solid phase with ethanol and dry it at 60℃ for more than 2 hours to obtain the first-processed solid phase.

[0006] (3) Prepare silver ammonia solution; disperse the first-processed solid phase in ethanol to form a dispersion, stir the dispersion, add polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continue stirring the dispersion for more than 10 min after the addition is completed, then adjust the pH of the dispersion to 13.5 with sodium hydroxide solution; stir the dispersion for more than 10 min again, then add glucose solution to the dispersion while stirring, stir the dispersion for more than 30 min after the addition is completed, then separate the solid and liquid, wash the solid phase with deionized water, and dry it at 60℃ for more than 5 h to obtain the second-processed solid phase;

[0007] (4) Prepare an ethanol solution of chloroiridic acid, immerse the secondary treated solid phase in the ethanol solution of chloroiridic acid for 5 min, then separate the solid and liquid phases, calcine the solid phase at 110°C for 15 min, then calcine it at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it in the ethanol solution of chloroiridic acid again for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps are a whole process; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

[0008] Further, in step (1), the ratio of zinc chloride and tin tetrachloride added to deionized water is zinc chloride:tin tetrachloride:deionized water = 3-5g:2.4-4.5g:100mL; the volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is hydrazine hydrate:composite aqueous solution of zinc chloride and tin tetrachloride = 2-3:100.

[0009] Further, in step (2), the ethanol solution of mercaptopropyltrimethoxysilane contains 20% mercaptopropyltrimethoxysilane by mass, and the solvent is ethanol; the mass ratio of zinc-tin composite oxide added to the ethanol solution of mercaptopropyltrimethoxysilane is 1:50.

[0010] Further, in step (3), the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to a 0.2 mol / L silver nitrate aqueous solution until the precipitate just completely disappears, thus obtaining the silver ammonia solution; the solid-liquid mass ratio of the primary treatment solid phase dispersed in ethanol is solid / liquid = 1:80; the mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and glucose solution added to the primary treatment solid phase in the dispersion is polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treatment solid phase = 0.6~0.8:16~20:10~14:1; wherein the sodium hydroxide solution contains 5% sodium hydroxide by mass; and the glucose solution contains 0.1 g / mL glucose, with water as the solvent.

[0011] Furthermore, in step (4), the concentration of chloroiridium acid in the ethanol solution of chloroiridium acid is 10-15 g / L, and the solvent is ethanol.

[0012] A method for preparing a lithium-ion battery negative electrode includes the following steps: mixing the lithium-ion battery negative electrode material with a super-P conductive agent and a binder, adding N-methylpyrrolidone to prepare a coating solution, coating it on a copper foil, drying it at 100°C for 12 hours, and then pressing it into an electrode sheet using a roller press to obtain the lithium-ion battery negative electrode.

[0013] Furthermore, the mass ratio of the lithium-ion battery anode material, super-P conductive agent, and binder is lithium-ion battery anode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride.

[0014] Furthermore, the addition of the N-methylpyrrolidone resulted in a total mass percentage of 25% for the mixture of lithium-ion battery anode material, super-P conductive agent, and binder in the coating solution.

[0015] The beneficial effects of the present invention are as follows: the preparation of lithium-ion battery anode materials by the method described in the present invention has a good effect on improving the discharge capacity of lithium-ion batteries, and can still maintain a large discharge specific capacity under high current charging and discharging conditions. Detailed Implementation

[0016] The present invention will be further described below with reference to the embodiments.

[0017] Example 1

[0018] A method for preparing a high-specific-capacity lithium-ion battery anode material, comprising the following steps:

[0019] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 3g: 2.4g: 100mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 2:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8min. Then the reactor is sealed and heated to 180±2℃ for 20h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed 3 times with deionized water and dried at 60℃ for 2h to obtain zinc-tin composite oxide.

[0020] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0021] (3) Preparation of silver ammonia solution; the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to 0.2 mol / L silver nitrate aqueous solution until the precipitate just disappears completely, thus obtaining the silver ammonia solution; dispersing the solid phase of the first treatment in ethanol to form a dispersion, the solid-liquid mass ratio of the solid phase of the first treatment in ethanol is solid / liquid = 1:80; stirring the dispersion, adding polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continuing to stir the dispersion for 10 min after the addition is completed, and then adjusting the pH of the dispersion to 13.5 with sodium hydroxide solution; then stirring and dispersing again. The mixture was stirred for 10 minutes, and then a glucose solution was added to the dispersion under stirring. The mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and the glucose solution added to the primary treated solid phase in the dispersion was polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treated solid phase = 0.6:16:10:1. The sodium hydroxide solution contained 5% sodium hydroxide by mass. The glucose solution contained 0.1 g / mL glucose and water as the solvent. After the addition was completed, the dispersion was stirred for 30 minutes, and then the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 5 hours to obtain the secondary treated solid phase.

[0022] (4) Prepare an ethanol solution of chloroiridium acid, wherein the concentration of chloroiridium acid in the ethanol solution is 10 g / L and the solvent is ethanol; completely immerse the secondary treated solid phase in the ethanol solution of chloroiridium acid for 5 min, then separate the solid and liquid, calcine the solid phase at 110°C for 15 min, then calcine at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it again in the ethanol solution of chloroiridium acid for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps constitute a process group; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

[0023] A method for preparing a lithium-ion battery negative electrode includes the following steps: mixing the lithium-ion battery negative electrode material with a super-P conductive agent and a binder uniformly, wherein the mass ratio of the lithium-ion battery negative electrode material, super-P conductive agent, and binder is lithium-ion battery negative electrode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; adding N-methylpyrrolidone to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery negative electrode material, super-P conductive agent, and binder in the coating solution is 25%; coating on copper foil (20 μm thick), drying at 100°C for 12 h, and pressing the dried material into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thereby obtaining the lithium-ion battery negative electrode.

[0024] Example 2

[0025] A method for preparing a high-specific-capacity lithium-ion battery anode material, comprising the following steps:

[0026] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 4 g: 3.2 g: 100 mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 2:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8 min. Then the reactor is sealed and heated to 180±2℃ for 20 h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed three times with deionized water and dried at 60℃ for 2 h to obtain zinc-tin composite oxide.

[0027] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0028] (3) Preparation of silver ammonia solution; the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to 0.2 mol / L silver nitrate aqueous solution until the precipitate just disappears completely, thus obtaining the silver ammonia solution; dispersing the solid phase of the first treatment in ethanol to form a dispersion, the solid-liquid mass ratio of the solid phase of the first treatment in ethanol is solid / liquid = 1:80; stirring the dispersion, adding polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continuing to stir the dispersion for 10 min after the addition is completed, and then adjusting the pH of the dispersion to 13.5 with sodium hydroxide solution; then stirring and dispersing again. The mixture was stirred for 10 minutes, and then a glucose solution was added to the dispersion under stirring. The mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and the glucose solution added to the primary treated solid phase in the dispersion was polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treated solid phase = 0.7:18:12:1. The sodium hydroxide solution contained 5% sodium hydroxide by mass. The glucose solution contained 0.1 g / mL glucose and water as the solvent. After the addition was completed, the dispersion was stirred for 30 minutes, and then the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 5 hours to obtain the secondary treated solid phase.

[0029] (4) Prepare an ethanol solution of chloroiridium acid, wherein the concentration of chloroiridium acid in the ethanol solution is 10 g / L and the solvent is ethanol; completely immerse the secondary treated solid phase in the ethanol solution of chloroiridium acid for 5 min, then separate the solid and liquid, calcine the solid phase at 110°C for 15 min, then calcine at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it again in the ethanol solution of chloroiridium acid for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps constitute a process group; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

[0030] A method for preparing a lithium-ion battery negative electrode includes the following steps: mixing the lithium-ion battery negative electrode material with a super-P conductive agent and a binder uniformly, wherein the mass ratio of the lithium-ion battery negative electrode material, super-P conductive agent, and binder is lithium-ion battery negative electrode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; adding N-methylpyrrolidone to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery negative electrode material, super-P conductive agent, and binder in the coating solution is 25%; coating on copper foil (20 μm thick), drying at 100°C for 12 h, and pressing the dried material into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thereby obtaining the lithium-ion battery negative electrode.

[0031] Example 3

[0032] A method for preparing a high-specific-capacity lithium-ion battery anode material, comprising the following steps:

[0033] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 4 g: 3.8 g: 100 mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 3:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8 min. Then the reactor is sealed and heated to 180±2℃ for 20 h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed three times with deionized water and dried at 60℃ for 2 h to obtain zinc-tin composite oxide.

[0034] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0035] (3) Preparation of silver ammonia solution; the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to 0.2 mol / L silver nitrate aqueous solution until the precipitate just disappears completely, thus obtaining the silver ammonia solution; dispersing the solid phase of the first treatment in ethanol to form a dispersion, the solid-liquid mass ratio of the solid phase of the first treatment in ethanol is solid / liquid = 1:80; stirring the dispersion, adding polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continuing to stir the dispersion for 10 min after the addition is completed, and then adjusting the pH of the dispersion to 13.5 with sodium hydroxide solution; then stirring and dispersing again. The mixture was stirred for 10 minutes, and then a glucose solution was added to the dispersion under stirring. The mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and the glucose solution added to the primary treated solid phase in the dispersion was polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treated solid phase = 0.7:18:12:1. The sodium hydroxide solution contained 5% sodium hydroxide by mass. The glucose solution contained 0.1 g / mL glucose and water as the solvent. After the addition was completed, the dispersion was stirred for 30 minutes, and then the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 5 hours to obtain the secondary treated solid phase.

[0036] (4) Prepare an ethanol solution of chloroiridium acid, wherein the concentration of chloroiridium acid in the ethanol solution is 10 g / L and the solvent is ethanol; completely immerse the secondary treated solid phase in the ethanol solution of chloroiridium acid for 5 min, then separate the solid and liquid, calcine the solid phase at 110°C for 15 min, then calcine at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it again in the ethanol solution of chloroiridium acid for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps constitute a process group; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

[0037] A method for preparing a lithium-ion battery negative electrode includes the following steps: mixing the lithium-ion battery negative electrode material with a super-P conductive agent and a binder uniformly, wherein the mass ratio of the lithium-ion battery negative electrode material, super-P conductive agent, and binder is lithium-ion battery negative electrode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; adding N-methylpyrrolidone to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery negative electrode material, super-P conductive agent, and binder in the coating solution is 25%; coating on copper foil (20 μm thick), drying at 100°C for 12 h, and pressing the dried material into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thereby obtaining the lithium-ion battery negative electrode.

[0038] Example 4

[0039] A method for preparing a high-specific-capacity lithium-ion battery anode material, comprising the following steps:

[0040] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 5 g: 4.5 g: 100 mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 3:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8 min. Then the reactor is sealed and heated to 180±2℃ for 20 h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed 3 times with deionized water and dried at 60℃ for 2 h to obtain zinc-tin composite oxide.

[0041] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0042] (3) Preparation of silver ammonia solution; the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to 0.2 mol / L silver nitrate aqueous solution until the precipitate just disappears completely, thus obtaining the silver ammonia solution; dispersing the solid phase of the first treatment in ethanol to form a dispersion, the solid-liquid mass ratio of the solid phase of the first treatment in ethanol is solid / liquid = 1:80; stirring the dispersion, adding polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continuing to stir the dispersion for 10 min after the addition is completed, and then adjusting the pH of the dispersion to 13.5 with sodium hydroxide solution; then stirring and dispersing again. The solution was stirred for 10 minutes, and then a glucose solution was added to the dispersion under stirring. The mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and the glucose solution added to the primary treated solid phase in the dispersion was polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treated solid phase = 0.8:20:14:1. The sodium hydroxide solution contained 5% sodium hydroxide by mass. The glucose solution contained 0.1 g / mL glucose and water as the solvent. After the addition was completed, the dispersion was stirred for 30 minutes, and then the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 5 hours to obtain the secondary treated solid phase.

[0043] (4) Prepare an ethanol solution of chloroiridium acid, wherein the concentration of chloroiridium acid in the ethanol solution is 10 g / L and the solvent is ethanol; completely immerse the secondary treated solid phase in the ethanol solution of chloroiridium acid for 5 min, then separate the solid and liquid, calcine the solid phase at 110°C for 15 min, then calcine at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it again in the ethanol solution of chloroiridium acid for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps constitute a process group; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

[0044] A method for preparing a lithium-ion battery negative electrode includes the following steps: mixing the lithium-ion battery negative electrode material with a super-P conductive agent and a binder uniformly, wherein the mass ratio of the lithium-ion battery negative electrode material, super-P conductive agent, and binder is lithium-ion battery negative electrode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; adding N-methylpyrrolidone to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery negative electrode material, super-P conductive agent, and binder in the coating solution is 25%; coating on copper foil (20 μm thick), drying at 100°C for 12 h, and pressing the dried material into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thereby obtaining the lithium-ion battery negative electrode.

[0045] Comparative Example 1

[0046] A comparative method for preparing a lithium-ion battery anode material includes the following steps: preparing a composite aqueous solution of zinc chloride and tin tetrachloride by adding zinc chloride and tin tetrachloride to deionized water in a reaction vessel, wherein the ratio of zinc chloride to tin tetrachloride in the deionized water is 4g:3.8g:100mL; maintaining the composite aqueous solution of zinc chloride and tin tetrachloride at a constant temperature of 60±3℃ in a water bath, stirring the solution, and adding hydrazine hydrate to the solution while stirring. The volume ratio of the added hydrazine to the zinc chloride and tin tetrachloride aqueous solution was 3:100. After the addition was completed, the mixture was stirred at a constant temperature of 60±3℃ for 8 minutes. Then the reactor was sealed and heated to 180±2℃ for 20 hours. After the heating was completed, the mixture was cooled to room temperature. The reactor was then opened, and the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60℃ for 2 hours to obtain a zinc-tin composite oxide, which was used as the negative electrode material of the lithium-ion battery in this comparative example.

[0047] A comparative method for preparing a lithium-ion battery anode includes the following steps: The lithium-ion battery anode material described in this comparative example is mixed uniformly with a super-P conductive agent and a binder, wherein the mass ratio of the lithium-ion battery anode material, super-P conductive agent, and binder is lithium-ion battery anode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; N-methylpyrrolidone is added to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery anode material, super-P conductive agent, and binder in the coating solution is 25%; the coating is applied to a copper foil (20 μm thick), dried at 100°C for 12 h, and then pressed into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thus obtaining the lithium-ion battery anode described in this comparative example.

[0048] Comparative Example 2

[0049] A comparative method for preparing a lithium-ion battery anode material includes the following steps:

[0050] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 4 g: 3.8 g: 100 mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 3:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8 min. Then the reactor is sealed and heated to 180±2℃ for 20 h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed three times with deionized water and dried at 60℃ for 2 h to obtain zinc-tin composite oxide.

[0051] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0052] (3) Prepare an ethanol solution of chloroiridium acid, wherein the concentration of chloroiridium acid in the ethanol solution is 10 g / L and the solvent is ethanol; completely immerse the solid phase of the first treatment in the ethanol solution of chloroiridium acid for 5 min, then separate the solid and liquid, calcine the solid phase at 110°C for 15 min, then calcine it at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it in the ethanol solution of chloroiridium acid again for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps constitute a process group; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material of this comparative example.

[0053] A comparative method for preparing a lithium-ion battery anode includes the following steps: The lithium-ion battery anode material described in this comparative example is mixed uniformly with a super-P conductive agent and a binder, wherein the mass ratio of the lithium-ion battery anode material, super-P conductive agent, and binder is lithium-ion battery anode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; N-methylpyrrolidone is added to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery anode material, super-P conductive agent, and binder in the coating solution is 25%; the coating is applied to a copper foil (20 μm thick), dried at 100°C for 12 h, and then pressed into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thus obtaining the lithium-ion battery anode described in this comparative example.

[0054] Comparative Example 3

[0055] A comparative method for preparing a lithium-ion battery anode material includes the following steps:

[0056] (1) In a reactor, zinc chloride and tin tetrachloride are added to deionized water to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The ratio of zinc chloride to tin tetrachloride added to deionized water is 4 g: 3.8 g: 100 mL. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath. The solution is stirred. Hydrazine hydrate is added to the solution while stirring. The volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is 3:100. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for 8 min. Then the reactor is sealed and heated to 180±2℃ for 20 h. After the heat preservation is completed, the mixture is cooled to room temperature. The reactor is opened and the solid and liquid are separated. The solid phase is washed three times with deionized water and dried at 60℃ for 2 h to obtain zinc-tin composite oxide.

[0057] (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane, wherein the mass percentage of mercaptopropyltrimethoxysilane in the ethanol solution is 20%, and the solvent is ethanol; keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath, and add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:50; after the addition is completed, keep the solution at 65±3℃ and stir for 3 hours, then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol 3 times, and dry it at 60℃ for 2 hours to obtain the first-processed solid phase.

[0058] (3) Preparation of silver ammonia solution; the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to 0.2 mol / L silver nitrate aqueous solution until the precipitate just completely disappears, thus obtaining the silver ammonia solution; the solid phase of the first treatment is dispersed in ethanol to form a dispersion, the solid-liquid mass ratio of the solid phase of the first treatment in ethanol is solid / liquid = 1:80; the dispersion is stirred, and polyvinylpyrrolidone and the silver ammonia solution are added to the dispersion during the stirring process. After the addition is completed, the dispersion is stirred for 10 min, and then the pH of the dispersion is adjusted to 13.5 with sodium hydroxide solution; the dispersion is stirred for another 10 min. Then, under stirring, a glucose solution is added to the dispersion. The mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and the glucose solution added to the primary treated solid phase in the dispersion is polyvinylpyrrolidone: the silver ammonia solution: the glucose solution: the primary treated solid phase = 0.7:18:12:1. The sodium hydroxide solution contains 5% sodium hydroxide by mass. The glucose solution contains 0.1 g / mL glucose and is dissolved in water. After the addition is complete, the dispersion is stirred for 30 min, and then the solid and liquid phases are separated. The solid phase is washed three times with deionized water and dried at 60°C for 5 h to obtain the lithium-ion battery anode material of this comparative example.

[0059] A comparative method for preparing a lithium-ion battery anode includes the following steps: The lithium-ion battery anode material described in this comparative example is mixed uniformly with a super-P conductive agent and a binder, wherein the mass ratio of the lithium-ion battery anode material, super-P conductive agent, and binder is lithium-ion battery anode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride; N-methylpyrrolidone is added to prepare a coating solution, wherein the total mass percentage of the mixture of lithium-ion battery anode material, super-P conductive agent, and binder in the coating solution is 25%; the coating is applied to a copper foil (20 μm thick), dried at 100°C for 12 h, and then pressed into an electrode sheet using a roller press, wherein the total thickness of the electrode sheet is 80 μm, thus obtaining the lithium-ion battery anode described in this comparative example.

[0060] Example 5

[0061] The lithium-ion battery negative electrodes obtained in the above embodiments and comparative examples were used to fabricate test batteries. The assembly process and parameters of the test batteries were completely identical. All test batteries were CR2025 button batteries, with lithium foil as the counter electrode, 1 mol / L LiPF6 solution (EC to DEC volume ratio of 1:1) as the electrolyte, and a microporous polypropylene membrane as the separator. The test batteries were tested at 5000 mA·g using an electrochemical workstation (CHI 660C). -1 The discharge specific capacity after 500 cycles under high current is shown in Table 1.

[0062] Table 1

[0063] Example 1 771.5 Example 2 784.1 Example 3 797.4 Example 4 788.0 Comparative Example 1 523.6 Comparative Example 2 657.3 Comparative Example 3 645.8

[0064] As shown in Table 1, the method described in this invention has a good effect on improving the discharge capacity of lithium-ion batteries, and can still maintain a large discharge specific capacity under high current charging and discharging conditions.

[0065] The technical solutions provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a high-specific-capacity lithium-ion battery anode material, characterized in that the steps include... include: (1) Zinc chloride and tin tetrachloride are added to deionized water in a reaction vessel to prepare a composite aqueous solution of zinc chloride and tin tetrachloride. The composite aqueous solution of zinc chloride and tin tetrachloride is kept at a constant temperature of 60±3℃ in a water bath and the solution is stirred. Hydrazine hydrate is added to the solution while stirring. After the addition is completed, the mixture is stirred at a constant temperature of 60±3℃ for more than 8 minutes. Then the reaction vessel is sealed and heated to 180±2℃ for more than 20 hours. After the heat preservation is completed, the mixture is cooled to room temperature. The reaction vessel is opened and the solid and liquid are separated. The solid phase is washed with deionized water and dried at 60℃ for more than 2 hours to obtain zinc-tin composite oxide. (2) Prepare an ethanol solution of mercaptopropyltrimethoxysilane. Keep the ethanol solution of mercaptopropyltrimethoxysilane at a constant temperature of 65±3℃ in a water bath. Add the zinc-tin composite oxide to the ethanol solution of mercaptopropyltrimethoxysilane while keeping it at a constant temperature. After the addition is completed, keep it at 65±3℃ and stir for more than 3 hours. Then, cool it to room temperature and separate the solid and liquid. Wash the solid phase with ethanol and dry it at 60℃ for more than 2 hours to obtain the first-processed solid phase. (3) Prepare silver ammonia solution; disperse the first-processed solid phase in ethanol to form a dispersion, stir the dispersion, add polyvinylpyrrolidone and the silver ammonia solution to the dispersion during stirring, continue stirring the dispersion for more than 10 min after the addition is completed, then adjust the pH of the dispersion to 13.5 with sodium hydroxide solution; stir the dispersion for more than 10 min again, then add glucose solution to the dispersion while stirring, stir the dispersion for more than 30 min after the addition is completed, then separate the solid and liquid, wash the solid phase with deionized water, and dry it at 60℃ for more than 5 h to obtain the second-processed solid phase; (4) Prepare an ethanol solution of chloroiridic acid, immerse the secondary treated solid phase in the ethanol solution of chloroiridic acid for 5 min, then separate the solid and liquid phases, calcine the solid phase at 110°C for 15 min, then calcine it at 450°C for 20 min, after calcine, air cool to room temperature, and immerse it in the ethanol solution of chloroiridic acid again for 5 min; the above immersion, solid-liquid separation, calcine at 110°C, calcine at 450°C, and air cooling steps are a whole process; repeat the above process for a total of 10 groups, the calcine time at 450°C in the last group is 1 h, and finally air cool to room temperature to obtain the lithium-ion battery anode material.

2. The method for preparing a high-specific-capacity lithium-ion battery anode material according to claim 1, characterized in that, In step (1), the ratio of zinc chloride and tin tetrachloride added to deionized water is zinc chloride:tin tetrachloride:deionized water = 3-5g:2.4-4.5g:100mL; the volume ratio of the added hydrazine hydrate to the volume of the composite aqueous solution of zinc chloride and tin tetrachloride is hydrazine hydrate:zinc chloride and tin tetrachloride composite aqueous solution = 2-3:

100.

3. The method for preparing a high-specific-capacity lithium-ion battery anode material according to claim 1, characterized in that, In step (2), the ethanol solution of mercaptopropyltrimethoxysilane contains 20% mercaptopropyltrimethoxysilane by mass and ethanol by solvent; the zinc-tin composite oxide is added to the ethanol solution of mercaptopropyltrimethoxysilane at a mass ratio of zinc-tin composite oxide to ethanol solution of mercaptopropyltrimethoxysilane = 1:

50.

4. The method for preparing a high-specific-capacity lithium-ion battery anode material according to claim 1, characterized in that, In step (3), the silver ammonia solution is prepared by adding 1 mol / L ammonia solution to a 0.2 mol / L silver nitrate aqueous solution until the precipitate just disappears completely, thus obtaining the silver ammonia solution; the solid-liquid mass ratio of the primary treatment solid phase dispersed in ethanol is solid / liquid = 1:80; the mass ratio of polyvinylpyrrolidone, the silver ammonia solution, and glucose solution added to the primary treatment solid phase in the dispersion is polyvinylpyrrolidone: silver ammonia solution: glucose solution: primary treatment solid phase = 0.6~0.8:16~20:10~14:1; the mass percentage of sodium hydroxide in the sodium hydroxide solution is 5%; the concentration of glucose in the glucose solution is 0.1 g / mL, and the solvent is water.

5. The method for preparing a high-specific-capacity lithium-ion battery anode material according to claim 1, characterized in that, In step (4), the concentration of chloroiridium acid in the ethanol solution is 10-15 g / L, and the solvent is ethanol.

6. A method for preparing a lithium-ion battery negative electrode, characterized in that, The steps are as follows: the lithium-ion battery negative electrode material as described in any one of claims 1 to 5 is mixed evenly with super-P conductive agent and binder, N-methylpyrrolidone is added to prepare a coating solution, which is then coated on copper foil and dried at 100°C for 12 hours. After drying, the material is pressed into an electrode sheet using a roller press to obtain the lithium-ion battery negative electrode.

7. The method for preparing a lithium-ion battery negative electrode according to claim 6, characterized in that, The mass ratio of the lithium-ion battery anode material, super-P conductive agent, and binder is lithium-ion battery anode material: super-P conductive agent: binder = 7:2:1; the binder is polyvinylidene fluoride.

8. The method for preparing a lithium-ion battery negative electrode according to claim 6, characterized in that, The addition of the N-methylpyrrolidone resulted in a total mass percentage of 25% for the mixture of lithium-ion battery anode material, super-P conductive agent, and binder in the coating solution.