Silicon oxide composite negative electrode material for lithium ion battery and preparation method of silicon oxide composite negative electrode material

Abstract

The invention discloses a preparation method of a silicon oxide composite negative electrode material. The preparation method comprises the following steps: mixing silicon oxide, a reactive metal anda fused salt to obtain a mixture; carrying out a roasting reaction in a protective atmosphere, cooling and pickling to remove impurities; mixing the obtained low-oxygen value silicon oxide material and a carbon coating material or adopting gas phase coating, roasting and carbonizing, cooling, crushing and screening, thereby obtaining the silicon oxide composite negative electrode material for thelithium ion battery. Compared with the prior art, the silicon oxide composite negative electrode material disclosed by the invention is prepared by taking the silicon oxide, the reactive metal, the carbon coating material and the fused salt as raw materials, mixing, performing metal hot reduction, pickling to remove impurities and grinding, the oxygen content of the finished material is low, and the first-cycle reversible capacity and efficiency of the lithium ion battery are obviously improved. Moreover, the negative electrode material is less in impurity, high in application value and smallin silicon grain size, cycle expansion of the material is effectively improved, and the cycle life of the material is obviously prolonged.

Description

technical field [0001] The invention relates to the technical field of lithium ion secondary battery negative electrode materials, in particular to a lithium ion battery silicon oxide composite negative electrode material and a preparation method. Background technique [0002] Due to its large specific capacity, long service life, high safety, and many advantages such as portability, lithium-ion batteries have become a research hotspot in the world, and are widely used in various electronic devices, electric vehicles and portable energy storage devices. At present, lithium-ion batteries that have been commercialized on a large scale mainly use graphite-based carbon materials as negative electrode materials, but their theoretical specific capacity is only 372mAh / g, which is difficult to meet the current demand. Therefore, it is necessary to develop negative electrode materials with higher capacity density. It is an urgent problem for lithium-ion secondary batteries to be solv...

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Problems solved by technology

However, the capacity loss of the prepared material is too large, and the characteristics of the high capacity of the material cannot be fully utilized, so the practical applicability is poor.

[0006] It can be seen that the properties of the materials prepared by the above methods are poor, and there are silicate impurities that cannot be removed in the materials. At the same time, the silicon grain size of the prepared materials is relatively large, and the cyclic expansion of the materials is aggravated, which seriously affects the service life of the silicon-oxygen materials.

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