Multilayer silicon/graphene composite lithium battery positive electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of energy materials, provides a multilayer silicon/graphene composite lithium battery positive electrode material and a preparation method thereof, and aims to overcome the defects that a silicon cathode has an intense volume effect in the electrochemical lithium storage process, a stable surface solid electrolyte membrane is hard to form and the electric circulation performance is poor as the intrinsic conductivity of the silicon cathode self is low. The multilayer silicon/graphene composite lithium battery positive electrode material provided by the invention comprises foamed nickel, graphene layers and silicon layers, wherein the graphene layers and the silicon layers are arranged on the foamed nickel alternatively; the most top layer is a graphene layer. As a multilayer 'graphene/silicon/graphene'sandwich structure is formed, and silicon powder is wrapped in a layer manner by virtue of high mechanical properties and high conductivity of the graphene, great volume change of the silicon powder in the charge/discharge process can be effectively inhibited, a stable SEI (Solid Electrolyte Interface) membrane can be formed, and the multiplying power property and the circulation stability are improved on premise that a high specific capacity of silicon is maintained; meanwhile, the preparation method of the material is simple in process, low in cost and good in repeatability.

Description

technical field [0001] The invention belongs to the technical field of energy materials, and relates to a lithium battery negative electrode material and a preparation method thereof, in particular to a nickel foam collector multilayer silicon / graphene composite lithium battery negative electrode material and a preparation method thereof. Background technique [0002] The development of green energy technology and low-carbon economy has put forward higher and higher requirements for the next generation of high-performance lithium-ion batteries. In terms of anode materials, the current commercial lithium-ion batteries mainly use graphite-based carbon anode materials; however, graphite The theoretical specific capacity is only 372mAh g -1 , and the potential platform of lithium intercalation is close to metal lithium, and the phenomenon of "lithium separation" is prone to occur during fast charging or low-temperature charging, causing potential safety hazards; materials to re...

AI Technical Summary

Problems solved by technology

[0002] The development of green energy technology and low-carbon economy has put forward higher and higher requirements for the next generation of high-performance lithium-ion batteries. In terms of anode materials, the current commercial lithium-ion batteries mainly use graphite-based carbon anode materials; however, graphite The theoretical specific capacity is only 372mAh g -1 , and the potential platform of lithium intercalation is close to metal lithium, and the phenomenon of "lithium separation" is prone to occur during fast charging or low-temperature charging, causing potential safety hazards; materials to replace graphite-like carbon anodes

[0003] Among various anode materials, silicon has attracted the attention of more and more researchers with its obvious advantages and potential. The theoretical lithium storage capacity of silicon is as high as 4200mAh g -1 , more than 10 times the capacity of graphite, and has the highest capacity among elements that can be alloyed to store lithium; the voltage platform of silicon is slightly higher than that of graphite, and it is difficult to cause the phenomenon of "lithium precipitation" on the surface during charging, and its safety performance is better than that of graphite negative electrode material; in addition, silicon is one of the most abundant elements in the earth’s crust, with a wide range of sources, low price, and suitable for industrial production; however, t

Images