Preparation method of silicon composite negative electrode material with gradient coating layer on the surface

Abstract

The invention discloses a preparation method of a silicon composite anode material provided with a gradient change coating layer on the surface, and aims to overcome conventional modification defects of a silicon anode material. According to the preparation method, a porous silicon material is prepared firstly, and on the basis, a chemical vapor deposition method is adopted to uniformly deposit a coating layer on the surface of the porous silicon material, wherein the coating layer adopts an elemental Si-SiC-C transition structure. A test is performed in a vapor deposition reacting furnace provide with segmented temperatures, independently controllable atmosphere and a plurality of furnace chambers. Compared with the prior art, a gradient change process is achieved through the surface coating layer, an obvious interface structure is not formed, the coating layer is tight, so that a volume effect and electric conductivity of the silicon-based anode material in a battery charge-discharge process are inhibited effectively, and the cycling stability of the material is improved greatly. The preparation method is simple in technology and suitable for large-scale industrial production, and has wide application prospect in the field of lithium ion batteries.

Description

technical field [0001] The invention relates to the fields of preparation of electrochemical materials and new energy sources, in particular to a method for preparing a silicon composite negative electrode material with a gradient coating layer on the surface. Background technique [0002] Traditional energy materials such as coal and petroleum are increasingly in short supply around the world, and people are looking for new renewable resources. Lithium-ion battery because of its high voltage. It is popular for its advantages of high capacity density, no memory effect, long life, green and pollution-free. With the development of green energy technology and low-carbon economy, the market has put forward higher requirements for the next generation of lithium-ion batteries: high energy density, high safety, and long cycle life. In terms of negative electrode materials, the current commercial lithium-ion batteries mainly use graphite-based carbon negative electrode materials, ...

AI Technical Summary

Problems solved by technology

In terms of negative electrode materials, the current commercial lithium-ion batteries mainly use graphite-based carbon negative electrode materials, which mainly have the following problems: the theoretical specific capacity of graphite is 372mAh / g; It is easy to precipitate "lithium dendrites" and cause safety hazards; solvent compatibility is poor, and it is easy to peel off in low-temperature electrolytes such as propylene carbonate, resulting in capacity decay

[0005] There are many studies on the modification of porous silicon, but there is no research on the use of chemical vapor deposition to deposit a tight coating layer on the surface of porous silicon with a gradient change from Si to SiC and then to C.

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