A kind of silicon-oxygen composite negative electrode material and its preparation method

Abstract

A silicon-oxygen composite negative electrode material, used to make the negative electrode of electric vehicles, smart cars or terminal lithium batteries, the negative electrode material includes an inner core, a cladding layer coated outside the inner core, and a coating located on the inner core and the An intermediate layer between cladding layers, wherein the intermediate layer includes the non-lithium silicate, the non-lithium silicate refers to the non-lithium silicate, and the non-lithium silicate is in the intermediate layer The mass content in the distribution decreases from the middle layer to the inner core. The decrement includes a gradient decrease from the middle layer to the inner core, and the gradient decrease means that the proportion of mass on a circle with the same distance from the center of the inner core is the same, and as the distance from the center of the inner core decreases And the mass proportion decreases step by step. The non-lithium silicate is generated in situ on the outer layer of the inner core, and has a dense structure that is non-water-soluble or non-alkaline or weakly alkaline, which can effectively alleviate the dissolution of the internal water-soluble lithium silicate and reduce the silicon-oxygen recombination. The pH value of the negative electrode material.

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 their theoretical gram specific capacity is only 372mAh / g, which limits the long-term application of pure graphite anodes in the development of high energy density and long cycle batteries. . Therefore, people turn their attention to silicon-based and tin-based anode materials with higher capacity. Among the silicon-based materials, the initial lithium intercalation capacity of silicon oxide material is 2615mAh / g, although it is much lower than the theoretical lithium intercalation capacity of elemental silicon, which is 4200mAh / g, but it is still much higher than that of traditional graphite anode. Compared with the volume expansion of lithium / delithiati...

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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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