A conductive polymer-coated silicon-based negative electrode sheet and its preparation method and application

Abstract

The invention discloses a conductive polymer-coated silicon-based negative pole piece and its preparation method and application. The silicon-based negative pole piece is used as a substrate and an ionic liquid is used as a reaction medium to make polymer monomers Electrochemical self-polymerization reaction is carried out between the voids and the surface of the substrate, and a conductive polymer film with controllable thickness is formed on the surface of the substrate to improve the interface performance and cycle stability of the silicon-based negative electrode sheet; then use the electrode sheet as the positive electrode, metal lithium The sheet is the negative electrode, and the external circuit is connected to control the current to carry out electrochemical pre-lithium to improve the first Coulombic efficiency of the matrix, and to prepare a conductive polymer-coated silicon-based negative electrode sheet. In the electrochemical polymerization process, the thickness of the conductive polymer film can be controlled by electricity, no catalyst is needed, and it can be produced on a large scale; and the reaction medium is an ionic liquid, which has almost no vapor pressure and a wide range of liquid temperatures. Compared with other organic / Inorganic solvent, more friendly to the environment, green and pollution-free.

Description

technical field [0001] The invention belongs to the technical field of negative pole pieces for lithium batteries, and in particular relates to a conductive polymer-coated silicon-based negative pole piece and a preparation method and application thereof. Background technique [0002] With the development of electric vehicles and portable appliances, the demand for lithium-ion batteries with high energy density is also increasing. The theoretical specific capacity of traditional graphite anode materials is only 372mAh / g, which is difficult to meet market demand. The first gram capacity of silicon materials is 4200mAh / g, the lithium intercalation platform is higher, the earth's crust is abundant, and it is environmentally friendly, which has gradually attracted widespread attention of researchers. [0003] However, the volume expansion of silicon is as high as 300%. During the cycle, it will not only cause silicon to separate from the surrounding conductive carbon network to...

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Problems solved by technology

JeeHoYom et al [Yom J H, Sun W H, Cho S M, et al.Improvement of irreversible behavior of SiO anodes for lithium ion batteries by a solid state reaction at high temperature[J].Journal of Power Sources,2016,311:159-166.] Through the solid-state reaction of SiO and lithium metal, carbon coating is carried out to prepare high-first-efficiency silicon-based negative electrode materials. This method improves the first-time Coulombic efficiency of the material, but the cycle performance of the material is relatively poor. Due to the use of lithium metal as the reaction The synthesis conditions are relatively harsh, and there is a safety risk, and there is a risk of gas production during the battery slurry process

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