Silicon-based negative electrode of lithium ion battery and method for preparing silicon-based negative electrode of lithium ion battery

Abstract

The invention discloses a silicon-based negative electrode of a lithium ion battery and a method for preparing the silicon-based negative electrode of the lithium ion battery. The silicon-based negative electrode is prepared by coating a copper foil with negative electrode slurry. The negative electrode slurry is prepared from, by weight, 15.0-18.0 parts of graphite, 1.0-2.0 parts of nano silicon powder, 0.3-2.5 parts of conductive agent, 1.0-8.0 parts of binding agent, 1.0-1.5 parts of thickening agent and 70.0-80.0 parts of dispersing medium. By adoption of a polystyrene-polybutyl acrylate- polystyrene block polymer binding agent which is extremely high in silicon binding force and capable of providing high elasticity, volume variation of silicon in charging and discharging can be counteracted, and performances of a graphene-based negative electrode of the lithium ion battery are improved. The prepared high-energy-density negative electrode is 514mAh / g in energy density during 0.1C charging and discharging, and the power negative electrode is 349mAh / g in energy density in 2C charging and discharging. The silicon-based negative electrode of the lithium ion battery and the method for preparing the silicon-based negative electrode of the lithium ion battery have the advantages of easiness in raw material acquisition, technical simplicity and environment friendliness.

Description

technical field [0001] The invention relates to a silicon-based lithium ion battery, in particular to a silicon-based lithium ion battery negative electrode and a preparation method thereof. Background technique [0002] Lithium-ion batteries began to be researched and developed in the early 1980s. They were initially mainly used in portable devices. As their market continued to expand, they also played an important role in various types of electric vehicles and energy storage systems. Compared with traditional secondary batteries, lithium-ion batteries have higher volume specific energy and mass specific energy, which can make the battery smaller and lighter, and are relatively energy-saving and environmentally friendly. Its obvious advantages and broad application prospects make it It has become a research hotspot that has attracted wide attention. The active material used in the current commercial lithium-ion battery negative electrode is graphite material, and the theor...

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Problems solved by technology

Due to the existence of the polybutadiene phase in SBR, it is an adhesive with excellent viscoelasticity. Although SBR has shown excellent performance in traditional lithium-ion batteries, it still lacks performance in negative electrodes with nano-silicon materials. The main reason is that the adhesion of SBR to the silicon material is greatly affected after the SBR swells the electrolyte, and SBR as a binder cannot meet the requirements of eliminating the stress caused by the volume change of silicon when deintercalating lithium.

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