Preparing method of lithium ion battery silicon carbon negative electrode material

Abstract

The invention discloses a preparing method of a lithium ion battery silicon carbon negative electrode material. A compound containing amidogens or ammonium ions is adopted for modifying nanometre silicon, so that the nanometre silicon carries positive charges, a scheme of modifying negative ions or oxidizing the negative ions is adopted, so that a carbon skeleton carries negative charges, in a solvent, the silicon and the carbon skeleton which carry the opposite charges are self-assembled to a composite material, and then the surface of the composite material is coated with pyrolytic carbon. Compared with existing methods for preparing silicon/carbon composite materials, the adopted self-assembly method is mild in condition and simple in step, complicated and expensive equipment is not needed, and large-scale popularization is facilitated; meanwhile, after the prepared silicon/carbon composite material is subjected to charge-discharge cycles 200 times, the discharge specific capacity is still larger than 500 mAh.g<-1>, and the electrochemical performance of the lithium ion battery silicon carbon negative electrode material is obviously improved compared with silicon/carbon composite materials which are prepared through simple mixing.

Description

technical field [0001] The invention relates to the field of preparation of negative electrode materials for lithium ion batteries, more specifically, especially the preparation of silicon carbon negative electrode materials for lithium ion batteries. Background technique [0002] With the increasing pressure of energy shortage and environmental protection, lithium-ion batteries are considered as the most potential energy storage system. In recent years, due to its advantages of high energy density, small self-discharge, and no memory effect, it has been widely used in portable electronic equipment, electric vehicles, large power supplies and other fields. The current commercial lithium ion negative electrode material is carbon material, but its theoretical specific capacity is only 372mAh g -1 , can no longer meet the huge market demand for high specific capacity lithium ion batteries, so it is urgent to develop new lithium ion battery negative electrode materials with hig...

AI Technical Summary

Problems solved by technology

At present, the preparation methods of silicon / carbon composite materials mainly include CVD method, magnesia thermal reduction method, etching method and template method, but most of these methods require expensive equipment or templates, highly toxic reactants or solvents (such as silane, tetrahydrofuran , hydrogen fluoride), complex reaction process, harsh reaction conditions (such as high temperature, high pressure), thus hindering the industrial production of silicon / carbon composites

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