A lithium battery silicon-carbon composite material and preparation method thereof

Abstract

The invention discloses a method for preparing a silicon-carbon composite material for a lithium battery, which comprises the following steps: using an inert gas to send coarse silicon powder through a first powder feeder into a plasma spraying system to be evaporated into silicon vapor, and using an inert gas to pass the graphite through The second powder feeder is sent into the cooling tank, and the silicon vapor enters the cooling tank to condense or deposit on the graphite to form a mixture of nano-silicon powder and graphite; then, the mixture of nano-silicon powder and graphite is input into the CVD furnace for vapor deposition carbon coating, Then it is sent to a fusion machine for fusion with a binder, and then it is carbonized at a high temperature in a roller kiln to obtain a silicon-carbon composite material product. The invention adopts the plasma spraying system to nanometerize the silicon, effectively suppresses the expansion characteristic of the material, and improves the cycle performance of the material. CVD is used to coat the surface of nano-silicon and graphite to form a conductive carbon layer. After mechanical fusion with the binder and high-temperature carbonization in the later stage, the first-time efficiency and cycle performance of the product are improved.

Description

technical field [0001] The invention relates to the technology in the field of composite materials, in particular to a silicon-carbon composite material for lithium batteries and a preparation method thereof. Background technique [0002] With the rapid development of the needs of the times, the energy density of lithium-ion batteries is increasing at a rate of 7%-10% per year. In 2016, my country released the hard indicators of power battery energy density. According to the "Technical Roadmap for Energy Saving and New Energy Vehicles", the energy density target of pure electric vehicle power batteries in 2020 is 350W·h / kg. At present, the commercial lithium-ion batteries mainly use graphite as the negative electrode material, but the theoretical specific capacity of graphite is only 372mAh / g, which limits the further improvement of the specific energy of lithium-ion batteries. / g theoretical lithium storage capacity, so silicon anode materials have been attracting attentio...

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Problems solved by technology

[0003] In view of this, the present invention aims at the deficiencies in the prior art, and its main purpose is to provide a silicon-carbon composite material for lithium batteries and its preparation method, which can effectively solve the problem of obvious volume effect and cycle stability of existing silicon negative electrode materials. poor defect

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