Lithium ion battery negative electrode material

Abstract

The invention provides a lithium ion battery negative electrode material. The negative electrode material includes a silicon nitride structure taking beta phase silicon nitride as a main body, and thesilicon nitride includes more than 50 wt% of the beta phase silicon nitride; the beta phase silicon nitride is a layered hexagonal system structure; the easy embedding and embedded of lithium ions can be achieved because of layered characteristics, so that a lithium dendrites structure generated by the unfavorable embedded of the lithium ions can be reduced, and as the size of the structure is stable during charging and discharging, the recession of electric capacity caused by the breaking and disintegrating of the material can be greatly reduced, so that the cycle life of the negative electrode material can be enhanced. The chemical formula of the disclosed beta phase silicon nitride is beta-Si3Nx, wherein 1 <= x <= 4; and the beta phase silicon nitride (beta-Si3Nx) can have unstable dangling bonds, unsaturated bonds and other unpaired bonds due to low nitrogen atom weight percentage, so that the activity and electric capacity of the negative electrode material can be enhanced.

Description

Technical field [0001] The present invention provides a lithium ion battery negative electrode material, in particular to a β-phase silicon nitride lithium ion battery negative electrode material including unsaturated bonds. Background technique [0002] Lithium-ion batteries have been widely used in electronic products, but with the development of science and technology, they have been unable to meet the needs of high-capacity batteries. Silicon-based anode materials have high capacitance characteristics, up to 4200mAh / g, and are the anode materials with the highest capacitance today. However, there are shortcomings of disintegration and pulverization of the anode material after the insertion and insertion of lithium ions. In order to solve the above problems, many studies have modified and modified silicon-based materials in terms of composition and structure. Among them, the modification in composition is that silicon and one or more non-silicon atoms are physically mixed and ...

AI Technical Summary

Problems solved by technology

In the above patents, silicon nitride is mainly used as an auxiliary and buffering material for negative electrodes, and cannot increase the capacity of lithium-ion batteries, and its effect on improving the cycle life of lithium-ion batteries is limited.

[0004] From the change in the appearance of silicon nitride, the molding technology can be used to make silicon nitride in a columnar or hollow nanotube structure, and the surrounding space is reserved, which can make the volume expansion of lithium ion intercalation and intercalation easy, and achieve stability. cycle life[8-10], but it still has structural strength defects. Under the lithium ion intercalation and intercalation reactions, the volume expansion and contraction will concentrate on the contact surface of the negative electrode material and the current collector due to stress, and the negative electrode material At the top position, there are problems such as cracking and pulverization, which will reduce the capacitance and cycle life of the negative electrode material.

[0005] Although it is mentioned in the existing literature that the crystal phase structure of silicon nitride is used as the negative electrode material [11-12], there is no specific mention of the crystal structure and composition of the silicon nitride, and its proportion range, α-phase silicon nitride It is a trigonal crystal structure, and the steric barrier of its crystal lattice is larger than that of the layered structure of β-phase silicon nitride, which affects the intercalation and intercalation of lithium ions, and is not conducive to the capacitance and cycle life of negative electrode materials.

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