A method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers.

Abstract

A tin / vanadium oxide carbon fiber co-coated silicon lithium-ion battery composite material and its preparation method are disclosed. By controlling the precursor components and solution concentration, the uniform dispersion of silicon nanoparticles and their separation from tin / vanadium oxide are controlled, forming a uniform and dense double-layer protective layer around the silicon nanoparticles. This controls the structure and properties of the composite material, resulting in high lithium intercalation capacity, good cycle life, and excellent charge-discharge performance. Furthermore, this invention offers advantages such as simple preparation process, low cost, and high purity of reaction products. The research and application of this patented technology can further improve the energy density, cycle life, and safety performance of lithium-ion batteries, promoting the development of electric vehicles. In addition, this technology can also be applied to other fields, such as energy storage devices and mobile electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery electrode materials, specifically relating to a method for preparing a silicon lithium-ion battery composite material co-coated with tin, vanadium oxide, and carbon fiber. Background Technology

[0002] In recent years, with the widespread adoption of mobile electronic devices and the rapid development of the electric vehicle market, lithium-ion batteries have attracted considerable attention as a high-energy-density and high-performance battery system. However, lithium-ion batteries still face some challenges in terms of energy density, cycle life, and safety, such as lithium metal dendrite formation and excessive lithium-ion storage. To address these issues, researchers have begun to focus on composite materials for silicon-coated lithium-ion batteries, such as metal oxides and carbon materials.

[0003] Currently, some researchers have prepared metal oxide carbon fiber composites using the sol-gel method and studied their electrochemical properties. The results show that this composite material exhibits high silicon intercalation capacity, excellent cycle life, and good charge-discharge performance. However, this method has some drawbacks, such as complex preparation processes, high costs, and impure reaction products. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers. This method uses a simple solution electrospinning process to prepare the composite material, and controls the structure and properties of the composite material by adjusting the precursor components and solution concentration. Experiments have shown that the composite material prepared by this method exhibits high lithium intercalation capacity, good cycle life, and excellent charge-discharge performance. Furthermore, this method also has advantages such as simple preparation process, low cost, and high purity of reaction products. Through the research and application of this patented technology, the energy density, cycle life, and safety performance of lithium-ion batteries can be further improved, promoting the development of electric vehicles. In addition, this technology can also be applied to other fields, such as energy storage devices and mobile electronic devices.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers, characterized by comprising the following steps:

[0007] 1) Dissolve stannous oxalate or vanadium acetylacetonate in a mixed solution of dimethylformamide and ethanol, add 0.5~0.8 mol / L polyvinyl alcohol, stir for 1~3 hours to obtain solution A;

[0008] 2) Disperse 0.2-0.4 mol / L nano-silicon particles and 0.3-0.7 mol / L polyvinyl alcohol ultrasonically in a mixed solution of dimethylformamide and ethanol, and stir for 1-3 hours to obtain solution B;

[0009] 3) Inject solutions A and B into the cylindrical double-layered sleeve, with solution A injected into the outer layer and solution B injected into the inner layer. Set the airflow pressure to 60~80 kP and the injection speed to 0.08~0.1 mL / min, and spray it onto the aluminum foil.

[0010] 4) Collect the above products, dry them at 200~240℃ for 1~2 hours, and calcine them at 500~700℃ under argon for 1~3 hours to obtain the final product.

[0011] In step 1, the volume ratio of dimethylformamide to ethanol is 3-5:1, and the concentration of tin or vanadium ions is 0.145-0.435 mol / L.

[0012] In step 2, the volume ratio of dimethylformamide to ethanol is 3-5:1. Compared with the prior art, the present invention has the following beneficial effects:

[0013] This invention utilizes a simple solution-airflow spinning method to prepare composite materials. By controlling the precursor components and solution concentration, the uniform dispersion of silicon nanoparticles and their separation from tin / vanadium oxides are managed, forming a uniform and dense bilayer protective layer around the silicon nanoparticles, thereby controlling the structure and properties of the composite material. Experiments have demonstrated that the composite material prepared using this method exhibits high lithium intercalation capacity, good cycle life, and excellent charge-discharge performance. Furthermore, this method offers advantages such as simple preparation process, low cost, and high purity of reaction products. The research and application of this patented technology can further improve the energy density, cycle life, and safety performance of lithium-ion batteries, promoting the development of electric vehicles. In addition, this technology can also be applied to other fields, such as energy storage devices and mobile electronic devices. Attached Figure Description

[0014] Figure 1 The image shows the XRD pattern of the prepared product.

[0015] Figure 2 The image shows a scanning electron microscope (SEM) image of the prepared product.

[0016] Figure 3 Charge-discharge cycle diagram of the prepared product. Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings: Example

[0018] A method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers, characterized by comprising the following steps:

[0019] 1) Dissolve stannous oxalate (tin ion concentration of 0.145 mol / L) in a mixed solution of dimethylformamide and ethanol, with a volume ratio of dimethylformamide to ethanol of 4:1. Add 0.7 mol / L polyvinyl alcohol and stir for 2 hours to obtain solution A.

[0020] 2) 0.3 mol / L nano-silicon particles and 0.5 mol / L polyvinyl alcohol were ultrasonically dispersed in a mixed solution of dimethylformamide and ethanol, with a volume ratio of dimethylformamide to ethanol of 4:1. After stirring for 2 hours, solution B was obtained.

[0021] 3) Inject solutions A and B into the cylindrical double-layered sleeve, with solution A injected into the outer layer and solution B injected into the inner layer. Set the airflow pressure to 70 kP and the injection speed to 0.1 mL / min, and spray it onto the aluminum foil.

[0022] 4) Collect the above products, dry them at 240℃ for 1 hour, and calcine them at 600℃ under argon for 2 hours to obtain the final product. Example

[0023] 1) Vanadium acetylacetonate (vanadium ion concentration of 0.435 mol / L) was dissolved in a mixed solution of dimethylformamide and ethanol at a volume ratio of 5:1. 0.8 mol / L polyvinyl alcohol was added and stirred for 2 hours to obtain solution A.

[0024] 2) 0.4 mol / L nano-silicon particles and 0.7 mol / L polyvinyl alcohol were ultrasonically dispersed in a mixed solution of dimethylformamide and ethanol, with a volume ratio of dimethylformamide to ethanol of 5:1. After stirring for 2 hours, solution B was obtained.

[0025] 3) Inject solutions A and B into the cylindrical double-layered sleeve, with solution A injected into the outer layer and solution B injected into the inner layer. Set the airflow pressure to 80 kP and the injection speed to 0.1 mL / min, and spray it onto the aluminum foil.

[0026] 4) Collect the above products, dry them at 240℃ for 2 hours, and calcine them at 700℃ under argon for 3 hours to obtain the final product.

[0027] Based on the two products mentioned above:

[0028] See Figure 1 , Figure 1 Here is the XRD pattern of this product, from Figure 1 a can determine that the phase composition of the composite material is Si, SnO, and C, from... Figure 1b can determine that the phase composition of the composite material is Si, V0, and C, among which the peak around 23° is an amorphous C peak.

[0029] See Figure 2 , Figure 2 This is a scanning electron microscope image of the product, showing Si@SnO / C composite nanofibers. Figure 2 a) has a diameter of approximately 200 nm, which is smaller than that of Si@VO / C composite nanofibers ( Figure 2 b) Diameter of 200~400nm. In addition, Si, SnO, and VO nanoparticles are uniformly dispersed in the one-dimensional carbon material.

[0030] See Figure 3 , Figure 3 The graph shows the electrochemical performance of this product. As anode materials for lithium-ion batteries, Si@SnO / C and Si@VO / C have initial discharge specific capacities of 1274 and 1561 mAh g, respectively. -1 The initial coulombic efficiencies were 76% and 82%, respectively, and after 100 charge-discharge cycles, the discharge specific capacities were 654 and 841 mAh g, respectively. -1 .

Claims

1. A method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers, characterized in that, Includes the following steps: 1) Dissolve stannous oxalate or vanadium acetylacetonate in a mixed solution of dimethylformamide and ethanol, add 0.5~0.8 mol / L polyvinyl alcohol, stir for 1~3 hours to obtain solution A; 2) Disperse 0.2-0.4 mol / L nano-silicon particles and 0.3-0.7 mol / L polyvinyl alcohol ultrasonically in a mixed solution of dimethylformamide and ethanol, and stir for 1-3 hours to obtain solution B; 3) Inject solutions A and B into the cylindrical double-layered sleeve, with solution A injected into the outer layer and solution B injected into the inner layer. Set the airflow pressure to 60~80 kP and the injection speed to 0.08~0.1 mL / min, and spray it onto the aluminum foil. 4) Collect the above products, dry them at 200~240℃ for 1~2 hours, and calcine them at 500~700℃ under argon for 1~3 hours to obtain the final product.

2. The method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers according to claim 1, characterized in that, In step 1, the volume ratio of dimethylformamide to ethanol is 3-5:1, and the concentration of tin or vanadium ions is 0.145-0.435 mol / L.

3. The method for preparing a silicon lithium-ion battery composite material co-coated with tin and vanadium oxide carbon fibers according to claim 1, characterized in that, In step 2, the volume ratio of dimethylformamide to ethanol is 3~5:1.

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