A kind of preparation method of silicon negative electrode material containing surface modification film

Abstract

The invention discloses a method for preparing a silicon negative electrode material containing a surface modification film, which belongs to the technical field of lithium ion batteries. The method is as follows: dissolving the polymer into water, adding silicon material, stirring while heating, removing moisture in the solution, and obtaining silicon material coated with polymer film A; dissolving PAN in NMP solvent, stirring to make it Completely dissolve, add the silicon material coated with the polymer film A and the conductive agent into the PAN solution, stir while heating, remove the NMP solvent in the solution, and obtain a silicon negative electrode material containing a surface modification film. The artificially modified film of the silicon negative electrode invented can satisfy the use of ordinary SBR binders in the silicon carbon negative electrode, so that graphite and silicon negative electrodes can each generate their own SEI film without mutual influence, further improving the cycle stability of the battery . The preparation method of the silicon negative electrode artificially modified membrane described in the present invention is simple and convenient, and can meet the requirements of the conventional water system batching method for the silicon carbon negative electrode.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a method for preparing a silicon negative electrode material containing a surface modification film. Background technique [0002] Due to the advantages of high energy density, long cycle life and environmental friendliness of lithium-ion batteries, they are widely used in portable electronic products such as mobile phones and notebook computers and new energy vehicles. The density has reached the bottleneck, and the energy density is difficult to break through. [0003] In order to obtain lithium-ion batteries with higher energy density, nano-silicon, silicon oxide and silicon carbon have entered the world of lithium-ion batteries. However, the problems of swelling and pulverization of silicon negative electrodes and poor cycle performance cannot be fundamentally solved. Therefore, Nano-silicon, silicon carbon or a mixture of silicon oxide and graphite...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for preparing a silicon negative electrode material containing a surface modification film in order to solve the problem of unstable cycle performance of the high specific energy silicon-carbon negative electrode and the inapplicability of the binder. The silicon negative electrode material prepared by the present invention is Used in conjunction with graphite, they are used together as negative electrode active materials to make silicon-carbon negative deposits. The polymer forms a modified film on the surface of silicon-carbon negative deposits, which can improve the energy density and cycle performance of lithium-ion batteries using the silicon-carbon negative electrodes.

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