A kind of hollow carbon whose inner wall is coated with silicon nano-layer material and its preparation method

Abstract

The invention belongs to the technical field of lithium-ion battery materials, and relates to a hollow carbon whose inner wall is coated with a silicon nano-layer material. The hollow carbon is partially graphitized, and the silicon nano-layer is evenly coated on the hollow carbon by high-temperature gasification of silicon. Inner wall, the high-temperature graphitization of the hollow carbon and the high-temperature gasification of silicon are carried out simultaneously; the present invention also provides its preparation method, (1) coating the outer surface of micron-sized or submicron-sized silicon particles can be converted into carbon material, high temperature treatment to form carbon coating, and then chemically etch the internal silicon particles to form a composite material of carbon coating on silicon; (2) under the condition of 2100-3200 degrees Celsius, the silicon gas coated in carbon The silicon vapor is coated on the inner wall of the hollow carbon to form a silicon nanolayer, and the coated carbon is partially graphitized simultaneously. The hollow carbon whose inner wall is coated with a silicon nano-layer material provided by the invention meets four conditions for industrial application, and has high initial discharge specific capacity, high initial coulombic efficiency, high cycle performance and low industrial cost.

Description

technical field [0001] The invention belongs to the technical field of high-capacity lithium-ion battery materials, and in particular relates to a hollow carbon whose inner wall is coated with a silicon nano-layer material and a preparation method thereof. Background technique [0002] In the research process of negative electrode materials for lithium-ion batteries, silicon-based negative electrode materials have a huge lithium storage capacity (4200mAh / g), slightly higher than the discharge platform of carbon materials, and a lower delithiation potential (0.5V) to become the next generation of lithium. Ion battery anode material. However, silicon is accompanied by a volume change of 300%-350% during the charging and discharging process of lithium ions, and its expansion coefficient is extremely high. During the charging and discharging process of lithium ions, it is easy to cause the pulverization of the electrode, and then continuously form new ESI films. Consumes the el...

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Problems solved by technology

[0004] Through in-depth research, it is found that if silicon materials are to be used as negative electrode materials for lithium-ion batteries to reduce their high expansion coefficients, the d99 particle size must be within 120nm. Through repeated practice, it is found that the high expansion coefficients above 120nm hardly change much. , the coefficient of expansion is reduced very little, but the manufacturing process of pure silicon nanoparticle materials with d50 size of 60nm and d99 size of 120nm is complicated and the manufacturing cost is too high

At present, d50 is 50nm, and d99 is 100nm. At the same time, referring to the microscopic structure, production place and brand, the price ranges from 3000-16000 yuan / kg. The high price cannot be practically applied to lithium-ion battery materials (new energy power batteries) )

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