Silica negative electrode material and preparation method thereof

Abstract

The invention relates to the technical field of battery negative electrode materials, and provides a silica negative electrode material and a lithium ion battery. The silica negative electrode material has a core-shell structure and comprises an inner core, a middle layer coating the surface of the inner core and an outer shell layer coating the surface of the middle layer; the material of the inner core comprises amorphous silicon oxide and silicon microcrystals, and the sizes of the silicon microcrystals are increased in a gradient manner along the direction from the center of the inner core to the surface layer of the inner core; the middle layer is made of silicon carbide; and the outer shell layer comprises a carbon layer. The negative electrode core material with the characteristics can guide huge volume expansion stress generated in a lithium embedding process to be released outwards through silicon microcrystals which are distributed in an amorphous silicon oxide main body material and have gradually changed sizes, so that volume expansion of the silicon-based negative electrode material is inhibited, and irreversible capacity increase caused by volume expansion is reduced; therefore, the cycle life of the silicon-based negative electrode material is effectively prolonged.

Description

technical field

[0001] The application belongs to the technical field of battery anode materials, and in particular relates to a silicon-oxygen anode material and a preparation method thereof. Background technique

[0002] Lithium-ion secondary battery is the most competitive battery of the new generation, known as "green energy", and is the preferred technology to solve contemporary environmental pollution and energy problems. In recent years, lithium-ion secondary batteries have achieved great success in the field of high-energy batteries, but consumers still expect batteries with higher comprehensive performance, which depends on the research and development of new electrode materials and electrolyte systems.

[0003] The theoretical reversible capacity of the anode material silicon oxide reaches 2007mAh / g, and its cycle performance is excellent, which is the key anode material for increasing energy density. However, in the process of repeated intercalation and desorptio...

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