Conductive polymer-coated silicon-based negative electrode sheet, and preparation method and application thereof

Abstract

The invention discloses a conductive polymer-coated silicon-based negative electrode sheet, and a preparation method and an application thereof. The silicon-based negative electrode sheet is used as amatrix, ionic liquid is used as a reaction medium, a polymer monomer generates an electrochemical self-polymerization reaction in a gap and on the surface of a matrix through an electrochemical polymerization reaction, and a conductive polymer film with a controlled thickness is formed on the surface of the matrix to improve the interfacial properties and the cycling stability of the silicon-based negative electrode sheet; and then the electrode sheet is used as a positive electrode, a metal lithium sheet is used as a negative electrode, an external circuit is connected to control the currentto perform electrochemical pre-lithium, so as to improve the first-time coulombic efficiency of the matrix, and the conductive polymer-coated silicon-based negative electrode sheet is prepared. During the electrochemical polymerization reaction, the thickness of the conductive polymer film can be controlled by electric quantity, no catalyst is needed, and mass production can be realized; and thereaction medium is the ionic liquid, which has almost no vapor pressure and a wide liquid temperature range, so compared with other organic / inorganic solvents, it is more environmentally friendly, 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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