Double-layer coated silicon-based composite negative electrode material and preparation method thereof

Abstract

The invention provides a double-layer coated silicon-based composite negative electrode material and a preparation method thereof. The composite negative electrode material is formed by means of the double-layer coating of a carbon coating layer and a polymer layer; the carbon coating layer coats a silicon-based material; the polymer coating layer is arranged on the surface of the carbon coating layer; and a conductive additive is doped in the polymer coating layer. The double-layer coated silicon-based composite negative electrode material is characterized in that the polymer is a copolymer of lithium salt of unsaturated acid with carbon-carbon double bonds, unsaturated amide with carbon-carbon double bonds and fluoroalkyl ester of unsaturated acid with carbon-carbon double bonds. According to the double-layer coated silicon-based composite negative electrode material and the preparation method thereof of the invention, the surfaces of silicon-based particles are coated with a layer of carbon in advance, so that the conductivity of the silicon-based material can be greatly improved; the carbon coating layer is coated with a layer of polymer; the polymer coating layer can maintainthe integrity of the material in the lithiation and de-lithiation processes of the silicon-based material without generating a new interface in contact with an electrolyte; the continuous growth of SEI is reduced, the coulombic efficiency of the negative electrode material is improved; the cycle life of the negative electrode material is prolonged; and the negative electrode material shows excellent high-rate performance.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to a polymer-coated silicon-carbon composite negative electrode material and a preparation method thereof, as well as a battery negative electrode and a lithium-ion battery containing the polymer-coated silicon-carbon composite negative electrode material. Background technique: [0002] With the rapid development of portable electronic devices, electric vehicles, smart grids and other fields, people have higher and higher requirements for performance indicators such as energy density, power density and cycle life of energy storage devices. In order to meet the requirements of fields such as electric vehicles with higher energy density, electrode materials for lithium-ion batteries with high energy density, high power density, and long cycle life have been extensively studied. Among these materials, silicon-based materials are due to their high safety, abundant reserves...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to solve the problem of poor cycle performance and battery performance after the existing silicon-based composite material is coated, and to provide a carbon-coated and polymer-coated double-layer coated silicon-carbon composite negative electrode material and its preparation method, thereby improving the cycle life and energy density of current lithium-ion battery anode materials

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