Preparation method of composite silicon carbon negative electrode material

Abstract

The invention relates to a preparation method of a composite silicon carbon negative electrode material. The preparation method is characterized by comprising the specific steps of performing pretreatment of expanded graphite, preparing a precursor turbid liquid, preparing a precursor and preparing a silicon-rich material, and then dissolving polyacrylonitrile into an organic solution to prepare a solution with concentration of 5-20%, wherein the organic solvent is dimethyl formamide; adding a proper mass of the silicon-rich material obtained in the step four, wherein the adding amount of the silicon-rich material is determined according to different capacity requirements, and it is ensured that the theoretical silicon content is 20% or below based on the adding mass; performing complete ball milling, stirring and mixing, and preparing a silicon carbon negative electrode composite wire body by adopting an electrostatic spinning method; and performing high-temperature calcining on the silicon carbon negative electrode composite wire body under protective atmosphere at a temperature of 500-800 DEG C for 4-8h, and then performing smashing to obtain the silicon carbon composite material. By virtue of the preparation method, a buffer layer can be better provided for silicon; and finally, by matching with the electrostatic spinning method, the macromolecule organic spinning object is used as the main carbon source for compounding, so that the buffering effect to silicon can be further improved while the material cost is lowered, thereby realizing controllability of cost and performance.

Description

technical field [0001] The invention relates to a preparation method of a composite silicon-carbon negative electrode material, belonging to the technical field of lithium ion batteries. Background technique [0002] At present, as a mature energy storage unit, lithium-ion batteries have been gradually integrated into every part of life. Electrical appliances such as mobile phones and notebooks in life use lithium-ion batteries as their energy storage units. In recent years, lithium-ion batteries have been gradually used in power storage. Electric vehicles are an important application object of lithium-ion batteries. However, the current energy density of lithium-ion batteries still cannot meet the requirements for cruising range of pure electric vehicles. [0003] For a power battery, the factors that most affect its energy density should be the positive electrode material and the negative electrode material. At present, cathode materials are developing towards high capac...

AI Technical Summary

Problems solved by technology

At present, there have been many studies on silicon-carbon anode materials, such as patent application number 201210387258.2, a method for preparing silicon-carbon composite materials for lithium-ion batteries and 201210283761.3, a method for preparing anode materials for high-capacity lithium-ion batteries, both of which use silicon powder and expanded graphite Silicon-carbon anode materials are obtained by mixing treatment, but this method is limited by the size of silicon powder and the dispersion process, it is difficult to truly achieve the purpose of inserting silicon powder into the gaps of expanded graphite, and nano-scale silicon powder increases the cost of materials. In addition, all carbon in the 201210387258.2 patent All sources are made of expanded graphite, which greatly increases the cost of materials

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