Long cycle lithium ion battery negative electrode material and preparation method thereof

Abstract

The application relates to the technical field of lithium ion battery materials, and particularly discloses a long-cycle lithium ion battery negative electrode material and a preparation method thereof, which comprises the following raw materials in parts by weight: 2-4 parts of modified vanadium pentoxide, 2.5-4.9 parts of lithium carbonate, 8-12 parts of modified nanometer composite silicon, 50-60 parts of deionized water and 0.04-0.06 parts of polyvinylpyrrolidone; the modified nanometer composite silicon and the lithium carbonate are used as raw materials, high-temperature calcination treatment is carried out in acetylene gas, and the lithium ion battery negative electrode material is obtained; the modified nanometer composite silicon is prepared by modifying nanometer silicon doped with nanometer nickel and nanometer bismuth by 3-aminopropyltriethoxysilane; the nanometer nickel can limit the expansion and shrinkage of the nanometer silicon, and the nanometer bismuth can relieve stress caused by volume change; the porous silicon dioxide and carbon generated after high-temperature calcination of the modified nanometer composite silicon and acetylene can prevent the agglomeration of lithium vanadate, and cooperatively improve the coulomb efficiency, specific capacity and cycle stability of the lithium ion battery negative electrode material.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery materials technology, and more specifically, to a long-cycle lithium-ion battery anode material and its preparation method. Background Technology

[0002] Lithium-ion batteries are one of the most widely used batteries today. They have advantages such as light weight, small size, high energy density, long life and low environmental pollution. Among them, the negative electrode material is one of the important factors affecting the lifespan and capacity of lithium batteries.

[0003] In existing technologies, lithium-ion battery anode materials mainly fall into two categories: carbon-based materials and silicon-based materials. While carbon-based materials offer advantages such as low cost, light weight, low potential, high conductivity, long lifespan, and good cycle performance, their theoretical specific capacity and battery stability are low, making it difficult to meet market demands. Silicon-based materials, although possessing a higher theoretical specific capacity, suffer from significant volume changes during charge and discharge, which can easily lead to electrode structure damage and decreased stability. Furthermore, silicon's inherent poor conductivity limits its performance in practical applications.

[0004] Based on the above statements, this application provides a long-cycle lithium-ion battery anode material and its preparation method. Summary of the Invention

[0005] To address the problems mentioned in the background section, this application provides a long-cycle lithium-ion battery anode material and its preparation method.

[0006] A long-cycle lithium-ion battery anode material comprises the following raw materials in parts by weight: 2-4 parts modified vanadium pentoxide, 2.5-4.9 parts lithium carbonate, 8-12 parts modified nanocomposite silicon, 50-60 parts deionized water, and 0.04-0.06 parts polyvinylpyrrolidone.

[0007] The preparation method of this long-cycle lithium-ion battery anode material includes the following steps:

[0008] Modified vanadium pentoxide, lithium carbonate, modified nanocomposite silicon, and polyvinylpyrrolidone were dissolved in deionized water, stirred evenly, and placed at 55-65℃ for 10-12 hours. Then, the mixture was placed in a CVD atmosphere sintering furnace, acetylene gas was introduced, and the temperature was raised to 730-750℃ at a heating rate of 5-10℃ / min. The reaction was held at this temperature for 4.5-5.5 hours, cooled to room temperature, and sieved to obtain a long-cycle lithium-ion battery anode material.

[0009] In the above reaction process, vanadium pentoxide and lithium carbonate generate lithium vanadate through acid-base neutralization and solid-phase reaction. At the same time, the nanocomposite silicon modified by 3-aminopropyltriethoxysilane has a flexible chain structure, which can be adsorbed on the surface of lithium vanadate particles to form a polymer protective film, so that the colloidal particles are wrapped by the flexible chain molecules of 3-aminopropyltriethoxysilane. During the sintering process, polyvinylpyrrolidone is used as a pore-forming agent, 3-aminopropyltriethoxysilane decomposes into porous nano-silica, and acetylene gas decomposes into carbon, which is deposited and coated on the surface of lithium vanadate to obtain a long-cycle lithium-ion battery anode material.

[0010] Preferably, the modified nanocomposite silicon is prepared by the following steps:

[0011] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 890-910℃ for 6-10 minutes to obtain expanded vermiculite. Mix the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride evenly, and under nitrogen protection, heat it to 290-300℃ for 11-13 hours. Cool it to room temperature, then place it in hydrochloric acid aqueous solution and stir for 4-6 hours. Wash it until the pH reaches 7-8, and dry it to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1-1.2:0.8:9-10:3. In the above reaction process, aluminum powder is used as a reducing agent, and anhydrous aluminum trichloride and sodium chloride are used as molten salt media. Silicon in silicates is reduced by aluminothermic reduction to obtain nano-silicon.

[0012] Step A2: Place nano-silicon in a mixture of nickel nitrate aqueous solution and bismuth nitrate aqueous solution a, stir for 0.4-0.6 h, filter and dry to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690-710℃ under H2 / Ar mixed atmosphere, and hold for 0.8-1 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.4-0.6:100-120, and the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 1-2:1. During the above reaction, the doped modified nano-silicon decomposes under high temperature calcination to produce nickel oxide and bismuth oxide. Subsequently, under H2 / Ar mixed atmosphere, it is reduced to nano-nickel and nano-bismuth at high temperature to obtain nano-composite silicon.

[0013] Step A3: Stir the nanocomposite silicon, ethanol aqueous solution and 3-aminopropyltriethoxysilane evenly, heat to 50-60℃, add sodium hydroxide aqueous solution, keep warm for 3-5 hours, centrifuge, wash and dry the precipitate, and sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, ethanol aqueous solution, 3-aminopropyltriethoxysilane and sodium hydroxide aqueous solution is 5-6:55-65:1-1.2:12-14.

[0014] Preferably, in step A1, the first heating rate is 5-7℃ / min, and the second heating rate is 2-5℃ / min.

[0015] Preferably, in step A1, the hydrochloric acid aqueous solution has a mass fraction of 6-8%.

[0016] Preferably, in step A2, H 2 / In an Ar mixed atmosphere, the volume fraction of H2 is 10-20%.

[0017] Preferably, in step A2, the mass fraction of the nickel nitrate aqueous solution is 0.4-0.6%, and the mass fraction of the bismuth nitrate aqueous solution is 0.6-0.8%.

[0018] Preferably, in step A3, the mass fraction of the ethanol aqueous solution is 45-55%.

[0019] Preferably, in step A3, the concentration of the sodium hydroxide aqueous solution is 0.4-0.6M.

[0020] Preferably, the modified vanadium pentoxide is prepared by the following steps:

[0021] Ammonium metavanadate was added to a mixture of ethylene glycol and deionized water (b) and stirred until dissolved. Polyvinylpyrrolidone was then added, and stirring continued for 1.8-2.2 hours. The mixture was heated to 175-185°C and reacted for 11-13 hours. After cooling to room temperature, it was filtered, dried, and then calcined at 395-405°C for 3-4 hours. After cooling to room temperature, modified vanadium pentoxide was obtained. The mass ratio of ammonium metavanadate, mixture b, and polyvinylpyrrolidone was 1-2:60:0.8-1.4. The mass ratio of ethylene glycol to deionized water in mixture b was... 3.5-4.5:1. In the above process, ammonium metavanadate decomposes at high temperature to produce vanadium pentoxide. In the above process, vanadium pentoxide is prepared by hydrothermal synthesis using a mixture of ethylene glycol and deionized water (b) as solvent and ammonium metavanadate as vanadium source. During the synthesis process, ethylene glycol molecules can insert into the interlayer of vanadium pentoxide. After removal by heat treatment, the interlayer spacing can be effectively enlarged and stabilized. The larger interlayer spacing provides a spacious channel for rapid ion diffusion and reduces the stress on the crystal structure caused by repeated insertion / extraction.

[0022] Compared with the prior art, this application has the following beneficial effects:

[0023] The lithium-ion battery anode material of this invention is prepared by high-temperature calcination in an acetylene atmosphere using modified nanocomposite silicon and lithium vanadate as raw materials. The modified nanocomposite silicon is prepared by modifying nano-silicon doped with nano-nickel and nano-bismuth with 3-aminopropyltriethoxysilane. The presence of nano-nickel not only forms a NiSi metal silicide alloy layer with high conductivity in situ at the silicon interface, improving the contact between silicon and the current collector and reducing the interfacial impedance, but also uses these sites as diffusion channels for lithium ions, increasing the diffusion rate of lithium ions, reducing the transport resistance of lithium ions inside the material, and improving the coulombic efficiency and specific capacity of the battery. The rigid framework effectively restricts the expansion and contraction of silicon during charging and discharging. The presence of nano-bismuth can form Bi-C covalent bonds with the carbon generated during the preparation of battery anode materials, further alleviating the stress caused by volume changes, stabilizing the electrode structure, and improving the cycle stability of lithium-ion battery anode materials. At the same time, the porous silica and carbon generated after high-temperature calcination of modified nano-composite silicon and acetylene gas can be deposited on the surface of lithium vanadate. This can not only effectively prevent the agglomeration and growth of lithium vanadate particles and improve their conductivity, but also accelerate the lithium-ion diffusion rate, further improving the coulombic efficiency, specific capacity, and cycle stability of lithium-ion battery anode materials. Detailed Implementation

[0024] To make the implementation methods of this application easier to understand, the application will be described in detail below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not limited to the application scope of this application.

[0025] Vermiculite, nickel nitrate, and bismuth nitrate were all from Aladdin Reagent Co., Ltd.; ammonium metavanadate was commercially available from Guangdong Daxiao Chemical Co., Ltd.; polyvinylpyrrolidone was commercially available from Huzhou Shenhua Polymer Materials Co., Ltd., CAS number 9003-39-8; polyethylene glycol was commercially available from Henan Juteng Chemical Products Co., Ltd., CAS number 25322-68-3; molds, separators, lithium sheets, electrolytes, etc. used in the battery assembly process were all from Duoduo Chemical Reagent Network.

[0026] Preparation Examples 1-3 and Comparative Preparation Examples 1-3 provide a modified nanocomposite silicon.

[0027] Preparation Example 1

[0028] This preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0029] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 890°C at a rate of 5°C / min. Hold the temperature for 10 min to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 500 rpm for 14 min until they are uniformly mixed. Under nitrogen protection, heat the mixture to 290°C at a rate of 2°C / min and hold the temperature for 13 h. Cool it to room temperature and then place it in an 8% hydrochloric acid aqueous solution. Stir for 4 h and wash it with deionized water until the pH reaches 7. Dry it at 50°C to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1:0.8:9:3.

[0030] Step A2: Place nano-silicon in a mixture of 0.4% (w / w) nickel nitrate aqueous solution and 0.6% (w / w) bismuth nitrate aqueous solution (a), stir at 1000 rpm for 0.4 h until homogeneous, filter, and dry at 60°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690°C under a H2 / Ar mixed atmosphere, and hold for 0.8 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.4:100, the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 1:1, and the volume fraction of H2 in the H2 / Ar mixed atmosphere is 10%.

[0031] Step A3: The nanocomposite silicon, 45% ethanol aqueous solution, and 3-aminopropyltriethoxysilane were stirred at 560 rpm for 16 min until homogeneous. The mixture was heated to 50°C, and 0.4 M sodium hydroxide aqueous solution was added. The mixture was kept at this temperature for 3 h. After centrifugation, the precipitate was washed three times each with anhydrous ethanol and deionized water. It was dried at 54°C to constant weight and passed through a 300-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, ethanol aqueous solution, 3-aminopropyltriethoxysilane, and sodium hydroxide aqueous solution was 5:55:1:12.

[0032] Preparation Example 2

[0033] This preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0034] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 900℃ at a rate of 6℃ / min, hold it at that temperature for 8 minutes to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 600 rpm for 18 minutes until they are uniformly mixed. Under nitrogen protection, heat it to 295℃ at a rate of 4℃ / min and hold it at that temperature for 12 hours. Cool it to room temperature, then place it in a 7% hydrochloric acid aqueous solution and stir for 5 hours. Wash it with deionized water until the pH reaches 7.5, and dry it at 60℃ to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1.1:0.8:9.5:3.

[0035] Step A2: Place nano-silicon in a mixture of 0.5% (w / w) nickel nitrate aqueous solution and 0.7% (w / w) bismuth nitrate aqueous solution (a), stir at 900 rpm for 0.5 h until homogeneous, filter, and dry at 60°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 700°C under a H2 / Ar mixed atmosphere, and hold for 0.9 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.5:110, the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 1.5:1, and the volume fraction of H2 in the H2 / Ar mixed atmosphere is 15%.

[0036] Step A3: The nanocomposite silicon, a 50% (w / w) aqueous ethanol solution, and 3-aminopropyltriethoxysilane were stirred at 580 rpm for 20 min until homogeneous. The mixture was then heated to 55°C, and a 0.5 M aqueous sodium hydroxide solution was added. The mixture was kept at this temperature for 4 h. After centrifugation, the precipitate was washed four times each with anhydrous ethanol and deionized water. The precipitate was dried at 58°C to constant weight and passed through a 325-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, aqueous ethanol solution, 3-aminopropyltriethoxysilane, and aqueous sodium hydroxide solution was 5.5:60:1.1:13.

[0037] Preparation Example 3

[0038] This preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0039] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 910°C at a rate of 7°C / min. Hold the temperature for 6 minutes to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 700 rpm for 22 minutes until they are uniformly mixed. Under nitrogen protection, heat the mixture to 300°C at a rate of 5°C / min and hold the temperature for 11 hours. Cool it to room temperature and then place it in a 6% hydrochloric acid aqueous solution. Maintain the stirring speed and continue stirring for 6 hours. Wash it until the pH reaches 8 and dry it at 70°C to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1.2:0.8:10:3.

[0040] Step A2: Place nano-silicon in a mixture of 0.6% (w / w) nickel nitrate aqueous solution and 0.8% (w / w) bismuth nitrate aqueous solution (a), stir at 800 rpm for 0.6 h until homogeneous, filter, and dry at 65°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 710°C under a H2 / Ar mixed atmosphere, and hold for 1 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.6:120, the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 2:1, and the volume fraction of H2 in the H2 / Ar mixed atmosphere is 20%.

[0041] Step A3: The nanocomposite silicon, a 55% (w / w) aqueous ethanol solution, and 3-aminopropyltriethoxysilane were stirred at 600 rpm for 24 min until homogeneous. The mixture was then heated to 60°C, and a 0.6 M sodium hydroxide aqueous solution was added. The mixture was kept at this temperature for 5 h, centrifuged, and the precipitate was washed five times each with anhydrous ethanol and deionized water. The precipitate was dried at 62°C to constant weight and passed through a 350-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, aqueous ethanol solution, 3-aminopropyltriethoxysilane, and aqueous sodium hydroxide solution was 6:65:1.2:14.

[0042] Comparative Preparation Example 1

[0043] This comparative preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0044] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 890°C at a rate of 5°C / min. Hold the temperature for 10 minutes to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 500 rpm for 14 minutes until they are uniformly mixed. Under nitrogen protection, heat the mixture to 290°C at a rate of 2°C / min and hold the temperature for 13 hours. Cool it to room temperature and then place it in an 8% hydrochloric acid aqueous solution. Stir for 4 hours and wash it with deionized water until the pH reaches 7. Dry it at 50°C to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1:0.8:9:3.

[0045] Step A2: Place nano-silicon in a mixture of deionized water and a 0.4% (w / w) bismuth nitrate aqueous solution (a), stir at 1000 rpm for 0.4 h until homogeneous, filter, and dry at 60°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690°C under a H2 / Ar mixed atmosphere, and maintain the temperature for 0.8 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.4:100, and the mass ratio of deionized water to bismuth nitrate aqueous solution in mixture a is 1:1. 2 / In the Ar mixed atmosphere, the volume fraction of H2 is 10%;

[0046] Step A3: The nanocomposite silicon, 45% ethanol aqueous solution, and 3-aminopropyltriethoxysilane were stirred at 560 rpm for 16 min until homogeneous. The mixture was heated to 50°C, and 0.4 M sodium hydroxide aqueous solution was added. The mixture was kept at this temperature for 3 h. After centrifugation, the precipitate was washed three times each with anhydrous ethanol and deionized water. It was dried at 54°C to constant weight and passed through a 300-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, ethanol aqueous solution, 3-aminopropyltriethoxysilane, and sodium hydroxide aqueous solution was 5:55:1:12.

[0047] Comparative Preparation Example 2

[0048] This comparative preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0049] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 890°C at a rate of 5°C / min. Hold the temperature for 10 min to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 500 rpm for 14 min until they are uniformly mixed. Under nitrogen protection, heat the mixture to 290°C at a rate of 2°C / min and hold the temperature for 13 h. Cool it to room temperature and then place it in an 8% hydrochloric acid aqueous solution. Stir for 4 h and wash it with deionized water until the pH reaches 7. Dry it at 50°C to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1:0.8:9:3.

[0050] Step A2: Place nano-silicon in a mixture of 0.4% (w / w) nickel nitrate aqueous solution and deionized water (solution a), stir at 1000 rpm for 0.4 h until homogeneous, filter, and dry at 60°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690°C under a H2 / Ar mixed atmosphere, and hold for 0.8 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.4:100, and the mass ratio of nickel nitrate aqueous solution to deionized water in mixture a is 1:1. 2 / In the Ar mixed atmosphere, the volume fraction of H2 is 10%;

[0051] Step A3: The nanocomposite silicon, 45% ethanol aqueous solution, and 3-aminopropyltriethoxysilane were stirred at 560 rpm for 16 min until homogeneous. The mixture was heated to 50°C, and 0.4 M sodium hydroxide aqueous solution was added. The mixture was kept at this temperature for 3 h. After centrifugation, the precipitate was washed three times each with anhydrous ethanol and deionized water. It was dried at 54°C to constant weight and passed through a 300-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, ethanol aqueous solution, 3-aminopropyltriethoxysilane, and sodium hydroxide aqueous solution was 5:55:1:12.

[0052] Comparative preparation example 3

[0053] This comparative preparation example provides a modified nanocomposite silicon, which is prepared by the following steps:

[0054] Step A1: Place vermiculite in a corundum boat, then seal it in a high-temperature tube furnace, introduce nitrogen gas, and heat it to 890°C at a rate of 5°C / min. Hold the temperature for 10 min to obtain expanded vermiculite. Stir the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride at 500 rpm for 14 min until they are uniformly mixed. Under nitrogen protection, heat the mixture to 290°C at a rate of 2°C / min and hold the temperature for 13 h. Cool it to room temperature and then place it in an 8% hydrochloric acid aqueous solution. Stir for 4 h and wash it with deionized water until the pH reaches 7. Dry it at 50°C to constant weight to obtain nano-silicon. The mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1:0.8:9:3.

[0055] Step A2: Place nano-silicon in a mixture of 0.4% (w / w) nickel nitrate aqueous solution and 0.6% (w / w) bismuth nitrate aqueous solution (a), stir at 1000 rpm for 0.4 h until homogeneous, filter, and dry at 60°C to obtain doped modified nano-silicon. Transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690°C under a H2 / Ar mixed atmosphere, and hold for 0.8 h to obtain nano-composite silicon. The mass ratio of nano-silicon to mixture a is 0.4:100, and the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 1:1. 2 / In the Ar mixed atmosphere, the volume fraction of H2 is 10%;

[0056] Step A3: The nanocomposite silicon, 45% ethanol aqueous solution and polyethylene glycol are stirred at 560 rpm for 16 min until homogeneous. The temperature is raised to 50℃, and 0.4M sodium hydroxide aqueous solution is added. The reaction is kept at this temperature for 3 h. After centrifugation, the precipitate is washed three times each with anhydrous ethanol and deionized water. It is dried at 54℃ to constant weight and passed through a 300-mesh sieve to obtain modified nanocomposite silicon. The mass ratio of nanocomposite silicon, ethanol aqueous solution, polyethylene glycol and sodium hydroxide aqueous solution is 5:55:1:12.

[0057] Preparation Examples 4-6 provide a modified vanadium pentoxide.

[0058] Preparation Example 4

[0059] This preparation example provides a modified vanadium pentoxide, which is prepared by the following steps:

[0060] Ammonium metavanadate was added to a mixture of ethylene glycol and deionized water (b), and stirred at 500 rpm for 14 min until dissolved. Polyvinylpyrrolidone was then added, and the stirring was continued for 1.8 h while maintaining the stirring speed. The mixture was then heated to 175 °C and reacted for 11 h. After cooling to room temperature, the mixture was filtered, dried at 60 °C to constant weight, and then calcined at 395 °C for 3 h. After cooling to room temperature, modified vanadium pentoxide was obtained. The mass ratio of ammonium metavanadate, mixture b, and polyvinylpyrrolidone was 1:60:0.8, and the mass ratio of ethylene glycol to deionized water in mixture b was 3.5:1.

[0061] Preparation Example 5

[0062] This preparation example provides a modified vanadium pentoxide, which is prepared by the following steps:

[0063] Ammonium metavanadate was added to a mixture of ethylene glycol and deionized water (b), and stirred at 550 rpm for 18 min until dissolved. Polyvinylpyrrolidone was then added, and the stirring was continued for 2.0 h while maintaining the stirring speed. The mixture was then heated to 180 °C and reacted for 12 h. After cooling to room temperature, the mixture was filtered, dried at 65 °C to constant weight, and then calcined at 400 °C for 3.5 h. After cooling to room temperature, modified vanadium pentoxide was obtained. The mass ratio of ammonium metavanadate, mixture b, and polyvinylpyrrolidone was 1.5:60:1.1, and the mass ratio of ethylene glycol to deionized water in mixture b was 4:1.

[0064] Preparation Example 6

[0065] This preparation example provides a modified vanadium pentoxide, which is prepared by the following steps:

[0066] Ammonium metavanadate was added to a mixture of ethylene glycol and deionized water (b), and stirred at 600 rpm for 22 min until dissolved. Polyvinylpyrrolidone was then added, and stirring continued for 2.2 h. The mixture was heated to 185 °C and reacted for 13 h. After cooling to room temperature, it was filtered, dried, and then calcined at 405 °C for 4 h. After cooling to room temperature, modified vanadium pentoxide was obtained. The mass ratio of ammonium metavanadate, mixture b, and polyvinylpyrrolidone was 2:60:1.4, and the mass ratio of ethylene glycol to deionized water in mixture b was 4.5:1.

[0067] Examples 1-3 and Comparative Examples 1-4 provide a long-cycle lithium-ion battery anode material and its preparation method.

[0068] Example 1

[0069] This embodiment provides a long-cycle lithium-ion battery anode material, comprising the following raw materials in parts by weight: 2 parts of modified vanadium pentoxide prepared in Preparation Example 4, 2.5 parts of lithium carbonate, 8 parts of modified nanocomposite silicon prepared in Preparation Example 1, 50 parts of deionized water and 0.04 parts of polyvinylpyrrolidone.

[0070] The preparation method of this long-cycle lithium-ion battery anode material includes the following steps:

[0071] Modified vanadium pentoxide, lithium carbonate, modified nanocomposite silicon, and polyvinylpyrrolidone were dissolved in deionized water and stirred at 560 rpm for 12 min until homogeneous. The mixture was then placed at 55°C and allowed to stand for 10 h. It was then placed in a CVD atmosphere sintering furnace, acetylene gas was introduced, and the temperature was increased to 730°C at a rate of 5°C / min. The temperature was maintained for 5.5 h, cooled to room temperature, and passed through a 360-mesh sieve to obtain a long-cycle lithium-ion battery anode material.

[0072] Example 2

[0073] This embodiment provides a long-cycle lithium-ion battery anode material, comprising the following raw materials in parts by weight: 3 parts of modified vanadium pentoxide prepared in Preparation Example 5, 3.7 parts of lithium carbonate, 10 parts of modified nanocomposite silicon prepared in Preparation Example 2, 55 parts of deionized water and 0.05 parts of polyvinylpyrrolidone.

[0074] The preparation method of this long-cycle lithium-ion battery anode material includes the following steps:

[0075] Modified vanadium pentoxide, lithium carbonate, modified nanocomposite silicon, and polyvinylpyrrolidone were dissolved in deionized water and stirred at 600 rpm for 16 min until homogeneous. The mixture was then placed at 60°C and allowed to stand for 11 h. It was then placed in a CVD atmosphere sintering furnace, acetylene gas was introduced, and the temperature was increased to 740°C at a rate of 8°C / min. The reaction was held at this temperature for 5 h, cooled to room temperature, and passed through a 380-mesh sieve to obtain a long-cycle lithium-ion battery anode material.

[0076] Example 3

[0077] This embodiment provides a long-cycle lithium-ion battery anode material, comprising the following raw materials in parts by weight: 4 parts of modified vanadium pentoxide prepared in Preparation Example 6, 4.9 parts of lithium carbonate, 12 parts of modified nanocomposite silicon prepared in Preparation Example 3, 60 parts of deionized water and 0.06 parts of polyvinylpyrrolidone.

[0078] The preparation method of this long-cycle lithium-ion battery anode material includes the following steps:

[0079] Modified vanadium pentoxide, lithium carbonate, modified nanocomposite silicon, and polyvinylpyrrolidone were dissolved in deionized water and stirred at 640 rpm for 20 min until homogeneous. After standing for 12 h, the mixture was placed in a CVD atmosphere sintering furnace, acetylene gas was introduced, and the temperature was increased to 750 °C at a rate of 10 °C / min. The reaction was held at this temperature for 4.5 h, cooled to room temperature, and passed through a 400-mesh sieve to obtain a long-cycle lithium-ion battery anode material.

[0080] Comparative Example 1

[0081] Comparative Example 1 is the same as Example 1, except that the modified nanocomposite silicon in Example 1 is replaced with the modified nanocomposite silicon prepared in Comparative Preparation Example 1.

[0082] Comparative Example 2

[0083] Comparative Example 2 is the same as Example 1, except that the modified nanocomposite silicon in Example 1 is replaced with the modified nanocomposite silicon prepared in Comparative Preparation Example 2.

[0084] Comparative Example 3

[0085] Comparative Example 3 is the same as Example 1, except that the modified nanocomposite silicon in Example 1 is replaced with the modified nanocomposite silicon prepared in Comparative Preparation Example 3.

[0086] Comparative Example 4

[0087] Comparative Example 4 is the same as Example 1, except that the modified vanadium pentoxide in Example 1 is replaced with commercially available vanadium pentoxide from Xinghengtai (Wuhan) Chemical Technology Co., Ltd., CAS No. 1314-62-1.

[0088] Sample preparation for testing

[0089] The lithium-ion battery anode materials prepared in Examples 1-3 and Comparative Examples 1-4 were used as the active material of the battery anode material, acetylene black as the conductive agent, and polyvinylidene fluoride as the binder. They were mixed at a mass ratio of 8:1:1, thoroughly ground, and then an appropriate amount of N-methylpyrrolidone was added. The mixture was stirred in a magnetic stirrer for 5 hours. Copper foil (150mm*100mm*9μm) was cut as the current collector and placed on a coating machine. The slurry was evenly coated on one end of the copper foil, and the thickness was adjusted to 150μm. The current collector with the coated slurry was placed in an 80°C forced-air oven for 4 hours, and then placed in a 90°C vacuum oven for 12 hours. After removal, it was cut into 14mm diameter discs, which are the anode plates. A lithium metal sheet was used as the counter electrode, and a glass fiber membrane was used as the separator. 1M LiPF6 / EC + DMC +DEC (volume ratio 1:1:1) was used as the electrolyte. The CR2016 battery was assembled in an argon-protected glove box. The entire battery assembly process was completed in the glove box, and the atmosphere in the glove box was ensured to be Ar, with water and oxygen values ​​both less than 0.1 ppm.

[0090] Performance testing

[0091] Electrochemical performance tests were conducted on the lithium-ion battery anode materials prepared in Examples 1-3 and Comparative Examples 1-4 using CR2032 coin cells. The testing equipment was a LAND battery performance testing system. Under the conditions of 25℃, 2.5V charging voltage, and 4.2V discharging voltage, the first fully charged anode electrode expansion rate, cycle stability, and initial coulombic efficiency of the individual cells were tested. The specific test results are shown in Table 1.

[0092] Table 1 Performance tests of the lithium-ion battery anode materials prepared in Examples 1-3 and Comparative Examples 1-4

[0093]

[0094] As can be seen from Table 1, compared with Comparative Examples 1-4, the lithium-ion battery anode materials prepared in Examples 1-3 are more conducive to improving the cycle stability, capacity retention and first coulombic efficiency of lithium batteries.

[0095] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A long-cycle lithium-ion battery anode material, characterized in that, The raw materials include the following parts by weight: 2-4 parts modified vanadium pentoxide, 2.5-4.9 parts lithium carbonate, 8-12 parts modified nanocomposite silicon, 50-60 parts deionized water and 0.04-0.06 parts polyvinylpyrrolidone; The modified vanadium pentoxide is prepared by hydrothermal synthesis of ammonium metavanadate in a mixture of ethylene glycol and deionized water (b). The modified nanocomposite silicon is first prepared by aluminothermic reduction of vermiculite, aluminum powder, anhydrous aluminum trichloride and sodium chloride to obtain nano-silicon, and then further calcined at high temperature in a mixture of nickel nitrate aqueous solution and bismuth nitrate aqueous solution to obtain doped modified nano-silicon, which is then placed in a H2 / Ar mixed atmosphere and reduced to obtain nanocomposite silicon, and finally modified by 3-aminopropyltriethoxysilane to obtain modified nanocomposite silicon.

2. The long-cycle lithium-ion battery anode material according to claim 1, characterized in that, The modified nanocomposite silicon is prepared by the following steps: Step A1: Place vermiculite in a high-temperature tube furnace and heat it to 890-910℃ under nitrogen protection. Hold the temperature for 6-10 minutes to obtain expanded vermiculite. Mix the expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride evenly. Heat the mixture to 290-300℃ under nitrogen protection and hold the temperature for 11-13 hours. Cool it to room temperature and then place it in hydrochloric acid aqueous solution. Stir for 4-6 hours and wash until the pH reaches 7-8. Dry the mixture to obtain nano-silicon. Step A2: Place nano-silicon in a mixture of nickel nitrate aqueous solution and bismuth nitrate aqueous solution a, stir for 0.4-0.6 h, filter and dry to obtain doped modified nano-silicon, transfer the doped modified nano-silicon to an atmosphere furnace, heat to 690-710℃ under H2 / Ar mixed atmosphere, and hold for 0.8-1 h to obtain nano-composite silicon; Step A3: Stir the nanocomposite silicon, ethanol aqueous solution and 3-aminopropyltriethoxysilane evenly, heat to 50-60℃, add sodium hydroxide aqueous solution, keep warm for 3-5 hours, centrifuge, wash and dry the precipitate, and sieve to obtain modified nanocomposite silicon.

3. The long-cycle lithium-ion battery anode material according to claim 2, characterized in that, In step A1, the mass ratio of expanded vermiculite, aluminum powder, anhydrous aluminum trichloride, and sodium chloride is 1-1.2:0.8:9-10:

3.

4. The long-cycle lithium-ion battery anode material according to claim 2, characterized in that, In step A2, the mass ratio of nano-silicon to mixture a is 0.4-0.6:100-120, and the mass ratio of nickel nitrate aqueous solution to bismuth nitrate aqueous solution in mixture a is 1-2:

1.

5. The long-cycle lithium-ion battery anode material according to claim 2, characterized in that, In step A3, the mass ratio of nanocomposite silicon, aqueous ethanol solution, 3-aminopropyltriethoxysilane and aqueous sodium hydroxide solution is 5-6:55-65:1-1.2:12-14.

6. The long-cycle lithium-ion battery anode material according to claim 1, characterized in that, The modified vanadium pentoxide is prepared by the following steps: Ammonium metavanadate was added to a mixture of ethylene glycol and deionized water (b) and stirred until dissolved. Polyvinylpyrrolidone was then added, and stirring continued for 1.8-2.2 hours. The temperature was raised to 175-185°C, and the reaction was carried out for 11-13 hours. The mixture was then cooled to room temperature, filtered, dried, and calcined at 395-405°C for 3-4 hours. After cooling to room temperature, modified vanadium pentoxide was obtained.

7. The long-cycle lithium-ion battery anode material according to claim 6, characterized in that, The mass ratio of ammonium metavanadate, mixture b, and polyvinylpyrrolidone is 1-2:60:0.8-1.4, and the mass ratio of ethylene glycol to deionized water in mixture b is 3.5-4.5:

1.

8. A method for preparing a long-cycle lithium-ion battery anode material as described in any one of claims 1-7, characterized in that, Includes the following steps: Modified vanadium pentoxide, lithium carbonate, modified nanocomposite silicon, and polyvinylpyrrolidone were dissolved in deionized water, stirred evenly, and placed at 55-65℃ for 10-12 hours. Then, the mixture was placed in a CVD atmosphere sintering furnace, acetylene gas was introduced, and the temperature was raised to 730-750℃ at a heating rate of 5-10℃ / min. The reaction was held at this temperature for 4.5-5.5 hours, cooled to room temperature, and sieved to obtain a long-cycle lithium-ion battery anode material.

Images