Silicon-carbon multi-component composite negative electrode material and preparation method thereof

Abstract

The invention relates to a carbon-carbon multi-component negative electrode material. The carbon-carbon multi-component negative electrode material is mainly composed of flexible graphite, nanometer silicon and amorphous carbon which respectively account for 30-60%, 30-50% and 10-30% based on mass percent, the amorphous carbon is obtained through high-temperature pyrolyzation of an organic carbon source, and the flexible graphite is obtained by applying pressure to expanded graphite. A preparation method of the product comprises the steps of: firstly, preparing an expanded graphite / silicon-silicon dioxide / carbon composite negative electrode material through high-temperature pyrolyzation; secondly, pouring the expanded graphite / silicon-silicon dioxide / carbon composite negative electrode material into a mould and applying pressure to obtain a flexible graphite / silicon-silicon dioxide / carbon composite negative electrode material; thirdly, processing silicon dioxide to obtain a flexible graphite / silicon / carbon composite negative electrode material through etching by a corrosive liquid; and finally, using asphalt to permeate a gap inside the flexible graphite / silicon / carbon composite negative electrode material in a protective atmosphere, and obtaining the product after high-temperature heat treatment and repetition. The carbon-carbon multi-component negative electrode material has the advantages of high capacity, high coulombic efficiency, good cycle performance, structure stability, high reversible capacity and the like.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery materials and preparation thereof, and in particular relates to a negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries are widely used in various portable electronic devices and electric vehicles due to their advantages such as large specific energy, high working voltage, low self-discharge rate, small size, and light weight. The current commercial lithium-ion battery anode material is mainly graphite, but its theoretical capacity is only 372mAh g -1 , can no longer meet the demand for high energy density power supplies in the application field of lithium-ion batteries. Therefore, there is an urgent need to develop a new type of anode material for lithium-ion batteries with high specific capacity. [0003] As an anode material for lithium-ion rechargeable batteries, silicon materials have been rece...

AI Technical Summary

Problems solved by technology

Due to the low conductivity of silicon materials and the severe volume expansion and contraction during lithium ion intercalation and deintercalation cycles, it is easy to cause damage to the material structure and mechanical crushing, which leads to the decline of electrode cycle performance and limits its commercial use. application

In order to solve these problems, the cycle performance of silicon-based negative electrode materials is mainly improved by nano-silicon particles, alloying silicon with other metals, and compounding silicon with an inert or active matrix. However, the existing silicon Similar composite anode materials still have disadvantages such as low density, low capacity, and poor cycle performance.

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