Preparation method, product and application of silicon negative electrode material

Abstract

The invention provides a preparation method of a silicon negative electrode material, which comprises the following steps of: preparing a silicon dioxide layer containing more hydroxyl groups on the surface of a silicon material, and recording the silicon dioxide layer as Si-coated SiO2; the preparation method comprises the following steps: by taking Si-coated SiO2 as a raw material, enabling the Si-coated SiO2 to be subjected to a coupling reaction with a silane coupling agent through hydroxyl, enabling a tail amino group on the silane coupling agent to face outwards so as to obtain amino-modified Si-coated SiO2, taking aniline as a carbon source, enabling the amino group to have an electrostatic force effect on the aniline, and generating nucleation sites for oriented growth of the aniline, so that the surface of the Si-coated SiO2 is uniformly coated with polyaniline, and the surface of the Si-coated SiO2 is uniformly coated with the polyaniline. The polyaniline serving as a conductive polymer has high conductivity, and the conjugated structure of the polyaniline also has relatively high rigidity, so that the polyaniline has a very good inhibition effect on the expansion problem of the silicon material. Therefore, according to the obtained silicon negative electrode material, the reaction speed of silicon-carbon compounding is increased, the requirement for silicon particles is low, a high-quality, high-conductivity and uniformly-coated polyaniline layer can be formed, and the expansion problem of the silicon material can be effectively inhibited.

Description

technical field [0001] The invention relates to the field of secondary batteries, in particular to a preparation method, product and application of a silicon negative electrode material. Background technique [0002] The development of digital 3C, new energy vehicles and energy storage equipment puts forward higher requirements on the energy density, cycle life and safety performance of lithium-ion batteries. At present, the energy and power density of commercialized graphite anodes (specific capacity = 372mAh / g) are approaching the limit, and the development of high-capacity anode material systems is an important prerequisite for the development of high-capacity lithium-ion batteries. Silicon has the highest theoretical specific capacity (4200mAh / g) among the current negative electrode materials with lithium intercalation activity, and has a higher lithium-to-lithium potential than graphite, which can effectively avoid the safety hazard caused by high-magnification lithium ...

AI Technical Summary

Problems solved by technology

[0003] However, silicon still has the following problems as a negative electrode material: 1) It will produce huge volume expansion during the alloying process with lithium, which will lead to the fragmentation of active materials, the shedding of active materials and current collectors, and then the continuous rupture and regeneration of the SEI film. Shows extremely poor cycle stability; 2) Silicon is used as a semiconductor with an intrinsic conductivity of 2.52×10 -4 S / m, showing poor rate performance; 3) Silicon anode materials are also easily corroded by HF decomposed by the electrolyte

For the field of silicon-carbon composites, the selection of carbon sources and the combination of silicon and carbon are the research directions of most researchers, but the current silicon-carbon composite methods still have shortcomings such as slow reaction speed and poor uniformity.