NANO-SILICON/CARBON COMPOSITE MATERIAL AND PREPARATION METHOD THEREFOR

摘要

A lithium-ion battery-use nano-silicon/carbon composite material and a preparation method therefor, which uses as a raw material a porous electrode constituted by silicon dioxide and carbon, and forms the silicon-on-carbon nano-silicon/carbon composite material via a molten salt electrolysis method for in situ electrochemical reduction of silicon dioxide. The material is a composition of metallurgical grade, where silicon and carbon are connected therebetween via nano-silicon carbide, and improves the electrochemical cycle stability of the nano-silicon and carbon composite material. The preparation method provided in the present invention for the nano-silicon/carbon composite material is: combining a porous block body consisting of carbon and silicon dioxide powders with an electrically conductive cathode current collector to serve as a cathode; using a graphite or inert anode as an anode; arranging the cathode and the anode in CaCl2 electrolyte or a mixed molten salt electrolyte having CaCl2 to form an electrolyzer; applying an electrolytic direct current voltage between the cathode and the anode; controlling the electrolytic voltage, electrolytic current density, and electrolytic amperage; allowing electrolytic reduction of silicon dioxide within the porous block body into nano-silicon; and acquiring at the cathode the lithium-ion battery-use nano-silicon/carbon composite material.