Preparation method of flexible self-supporting silicon/graphene cathode material of lithium ion battery

Abstract

The invention discloses a preparation method of a flexible self-supporting silicon / graphene cathode material of a lithium ion battery. The method comprises the following steps: I, dispersing nano silicon particles in a mixed solution to be heated and cleaned and centrifugalized; II, dispersing the centrifugalized precipitate in a polydiene dimethyl ammonium chloride solution to obtain the nano silicon particles with positive charges; III, dropwise adding the nano silicon particles into a graphene oxide solution and carrying out suction filtration to obtain a silicon / graphene oxide composite film; and IV, thermally treating the silicon / graphene oxide composite film at a high temperature to obtain the flexible self-supporting silicon / graphene cathode material. The nano silicon particles withpositive charges and the graphene oxide with negative charges are self-assembled statically to botain the flexible self-supporting silicon / graphene cathode material which is excellent in mechanical flexibility. An electrode of the lithium ion battery can be directly prepared without adding a binder and conducting carbon black, so that the problem that the electrochemical property is reduced by adding the binder is solved, and the service life of the lithium ion battery is prolonged while the high capacity of the lithium ion battery is ensured.

Description

technical field [0001] The invention belongs to the technical field of preparation of negative electrode materials of lithium ion batteries, and in particular relates to a preparation method of flexible self-supporting silicon / graphene negative electrode materials of lithium ion batteries. Background technique [0002] With the earth's energy crisis and the deteriorating environment, research on efficient, clean, and sustainable energy development has become the focus of energy development, and the development of flexible lithium-ion batteries has attracted great attention. However, the theoretical capacity (372mAh / g) of graphite anodes in commercial lithium-ion batteries is greatly limited and cannot meet the needs of applications in high-power devices. [0003] Silicon (Si) is considered as a promising anode material for lithium-ion batteries due to its highest theoretical capacity (4200mAh / g). Due to the huge volume expansion (>300%) of silicon in the charging and dis...

AI Technical Summary

Problems solved by technology

Due to the huge volume expansion (>300%) of silicon in the charging and discharging process of lithium-ion batteries, the pulverization and fragmentation of silicon itself occurs, and the continuous formation of SEI film on the surface of silicon is exposed to the electrolyte, resulting in rapid decline in capacity and severe limitations. The commercial application of silicon-based anode

In many reports of negative electrode materials for lithium-ion batteries, binders are usually added to keep the composite material tightly adhered to the current collector, but this greatly hinders ion transport and reduces electrochemical performance.

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