Preparation method of high-capacity silicon-carbon composite negative electrode material with core-shell structure for lithium-ion battery

Abstract

The invention discloses a preparation method of a high-capacity silicon-carbon composite negative electrode material with a core-shell structure for a lithium-ion battery. The high-capacity silicon-carbon composite negative electrode material with the core-shell structure contains a silicon substance and a carbon substance, and the molar ratio of Si to C is 0.003-0.316. According to the invention,the problems in the prior art are solved, and the negative electrode material not only improves the structural stability of the core material silicon but also can effectively reduce the volume changeand particle fragmentation of an electrode in the lithium intercalation and deintercalation process. Meanwhile, the capacity bottleneck of a shell material carbon is solved, a difference between theresistance and the discharge potential of the core material and the shell material is reduced such that the core material and the shell material can reach a relatively consistent level in the aspect of lithium ion de-intercalation, and the advantage complementation between the core material silicon and the shell material carbon is realized. The coating effect is fully exerted, the structure of thesubstance is stabilized, and the safety stability and the electrochemical performance of the material are improved.

Description

technical field [0001] The invention relates to the fields of power and energy storage materials and electrochemistry, in particular to a method for preparing a core-shell structure high-capacity silicon-carbon composite negative electrode material for lithium-ion batteries. Background technique [0002] In today's society, with the rapid development of economy, the energy crisis and environmental problems are becoming more and more serious. Because of its high energy density, high power density, long cycle life, no memory effect, low self-discharge rate, wide operating temperature range, safety and reliability, and environmental friendliness, lithium-ion batteries have been used in portable consumer electronics, power tools, medical Electronics and other fields have been widely used. At the same time, it also shows good application prospects in the fields of pure electric vehicles, hybrid vehicles, and energy storage. [0003] However, in recent years, the demand for batt...

AI Technical Summary

Problems solved by technology

[0005] ①The silicon material repeatedly expands and shrinks during the process of deintercalating lithium, causing the negative electrode material to pulverize and fall off, and eventually cause the negative electrode material to lose electrical contact and completely fail the battery

[0006] ②The continuous growth of the SEI film on the surface of the silicon material will always irreversibly consume the limited electrolyte in the battery and lithium from the positive electrode, eventually leading to a rapid decline in battery capacity

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