SiOx based composite negative electrode material, preparation method and battery

Abstract

The invention relates to a high-capacity SiOx based composite negative electrode material, a preparation method and a battery, wherein the negative electrode material comprises a silicon oxide material, a carbon material and an amorphous carbon coating layer; the silicon oxide material is silicon oxide or silicon oxide material modified in a carbon coating manner; surfaces of carbon material particles are coated with the silicon oxide material. A preparation method of the high-capacity SiOx based composite negative electrode material comprises the steps of performing physical processing or carbon coating modification on a silicon oxide raw material, thus obtaining a micron-sized silicon oxide material; and then mechanically fusing, coating with a solid phase and sintering at a high temperature to obtain the high-capacity negative electrode material. Through the high-capacity SiOx based composite negative electrode material, the effect of uniform dispersing and coating of the micron-sized silicon oxide particles on the surfaces of the carbon material particles can be achieved by virtue of the combination of mechanical fusion and solid-phase coating processes. The silicon oxide particles are well dispersed on the surface of the carbon material particle; the strength of bonding between the silicon oxide particles and the carbon material particles is high; the recycling performance of the material can be greatly improved; and meanwhile, the high-capacity SiOx based composite negative electrode material is high in first efficiency (breaking through the theoretical efficiency of SiOx), low in expansion rate, long in service life, environmental-friendly, pollution-free and low in cost.

Description

technical field [0001] The invention relates to the field of negative electrode materials for lithium ion batteries, in particular, the invention relates to a novel SiOx-based composite negative electrode material, a preparation method thereof, and a lithium ion battery using the negative electrode material. Background technique [0002] Lithium-ion batteries prepared in the prior art mainly use graphite-like carbon materials as negative electrode active materials, such as: artificial graphite, natural graphite, mesophase carbon microspheres, and the like. However, after more than 20 years of material self-modification, such as multi-phase coating, doping, etc., this type of carbon negative electrode material has been optimized for battery technology, and its actual use capacity is close to the theoretical specific capacity of the material (372mAh / g). The compacted density is less than 1.8g / cm 3 , so that its volume energy density has reached a certain limit, and it is diff...

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Problems solved by technology

Although simple fusion is used in this invention, the SiO with microsphere structure x / C (D 50 =12±2μm) and graphite materials cannot form a coating structure due to point contact. The two are monodisperse, the bonding strength is low, and the material cycle performance is poor. At the same time, substances that are harmful to the body (such as pyridine, acetone, toluene, Tetrahydrofuran), etc., the environmental pollution is large, and the first Coulombic efficiency of the material is far behind that of traditional graphite, and it is difficult to be industrialized due to the limitation of the matching positive electrode material at the current stage.

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