Preparation method of composite negative electrode material for lithium ion battery

Abstract

The invention discloses a preparation method of a composite negative electrode material for a lithium ion battery. The method is characterized in that the m-Si@G composite negative electrode material is prepared through the combination of a surface modification method and a hydrothermal reduction method. The method specifically includes the following steps of firstly, conducting surface modification on nanometer silicon, adding the nanometer silicon together with a reducing agent to dispersion liquid of graphite oxide, conducting hydrothermal reaction after dispersion is uniform, shifting into a water solution to conduct ion exchange after suction filtration is conducted, and obtaining the composite negative electrode material after suction filtration and freeze drying are conducted. The prepared m-Si@G composite negative electrode material is stable in structure and excellent in circulating performance and rate capability.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials and preparation methods thereof, and relates to a lithium ion battery m -The preparation method of SiG composite anode material. Background technique [0002] Silicon anode has the highest theoretical specific capacity (4 200 mAh g -1 ), low lithium extraction potential (0.02~0.6 V vs. Li + / Li), has received extensive attention from scholars at home and abroad; however, the huge volume change (~300%) of the material itself during the delithiation / intercalation process will cause the electrode material to gradually pulverize and break, making the silicon particles and their contact with each other The electrical contact between the current collectors becomes poor, causing the specific capacity of the material to decay rapidly, and the poor rate performance accompanied by the lower electronic conductivity further hinders the practical application of silicon as a negative electrode mat...

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Problems solved by technology

[0002]Si anode has the highest theoretical specific capacity (4 200 mAh·g-1), low lithium extraction potential (0.02~0.6 V vs. Li+ / Li), has received extensive attention from scholars at home and abroad; however, the huge volume change (~300%) of the material itself during the delithiation / intercalation process will cause the electrode material to gradually powder. The electrical contact between the silicon particles and the current collector is deteriorated, causing the specific capacity of the material to decay rapidly, and the poor rate performance accompanied by the lower electronic conductivity further hinders the use of silicon as a material. The practical application of lithium-ion battery negative electrode materials; and graphene because of its excellent physical and chemical properties, such as excellent electronic conductivity and high specific surface area, and its structural flexibility can help buffer other materials when intercalating / extracting Li There is a large volume change in the process, and more importantly, the precursors for the preparation of graphene, such as graphene oxide, have a large number of oxygen-containing functional groups on the surface, which can effectively combine other ions or functional groups. Shows great potential in the field of lithium-ion batteries

[0003]Currently reported silicon and graphene composite materials are mainly prepared by mechanical mixing, suction filtration, freeze-drying and other methods, silicon particles are dispersed between graphene sheets , showing a two-dimensional sandwich structure, but the overall bonding strength is poor, the structure is unstable, and it is easy to separate during the charging and discharging process; in order to improve the electrochemical performance of the silicon negative electrode, a structurally stable m-SiG composite anode material is of great significance

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