Silicon-oxygen composite negative electrode material and manufacturing method thereof

Abstract

The invention discloses a silicon-oxygen composite negative electrode material which is used for manufacturing a negative electrode of a lithium battery; the negative electrode material comprises an inner core, a coating layer and a middle layer, wherein the coating layer wraps the inner core, and the middle layer is positioned between the inner core and the coating layer, wherein the middle layercomprises non-lithium silicate, and the non-lithium silicate refers to non-lithium silicate, wherein the mass content of the non-lithium silicate in the middle layer is gradually decreased from the middle layer to the inner core. The decrementing comprises a gradient reduction from the middle layer to the inner core, and the gradient reduction refers to the fact that the mass-duty ratios on the circumference parts which have the same central distance from the inner core are the same, and when the distance from the center of the inner core is reduced, the mass-duty ratio is reduced step by step. The non-lithium silicate is generated in situ on the outer layer of the inner core, and has a non-water-soluble or non-alkaline or weakly alkaline compact structure, so that the dissolution of theinternal water-soluble lithium silicate can be effectively relieved; and the pH value of the ghost-eye composite negative electrode material can be lowered.

Description

technical field [0001] The invention relates to the technical field of secondary batteries, in particular to a silicon-oxygen composite negative electrode material and a manufacturing method thereof. Background technique [0002] Traditional graphite anode materials are widely used in commercial lithium-ion batteries, but due to their low theoretical gram specific capacity of only 372mAh / g, the long-term application of pure graphite anodes in the development of high energy density and long-cycle batteries is limited. . Therefore, people turn their attention to silicon-based and tin-based anode materials with higher capacity. Among silicon-based materials, the first lithium intercalation capacity of silicon oxide material is 2615mAh / g, which is much lower than the theoretical lithium intercalation capacity of 4200mAh / g for simple silicon, but still much higher than the traditional graphite negative electrode, which has a 300% intercalation capacity with simple silicon. Comp...

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Problems solved by technology

[0005] In view of this, the embodiment of the present invention provides a silicon-oxygen composite negative electrode material and its manufacturing method, which can effectively solve the problem of low first efficiency of the existing silicon-oxygen composite negative electrode materials

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