One-step electrolytic preparation of Si–Fe alloys as anodes for lithium ion batteries

Abstract

One-step electrolytic formation of uniform crystalline Si–Fe alloy particles was successfully demonstrated in direct electro-reduction of solid mixed oxides of SiO2 and Fe2O3 in molten CaCl2 at 900[Formula: see text]C. Upon constant voltage electrolysis of solid mixed oxides at 2.8[Formula: see text]V between solid oxide cathode and graphite anode for 5[Formula: see text]h, electrolytic Si–Fe with the same Si/Fe stoichimetry of the precursory oxides was generated. The firstly generated Fe could function as depolarizers to enhance reduction rate of SiO2, resulting in the enhanced reduction kinetics to the electrolysis of individual SiO2. When evaluated as anode for lithium ion batteries, the prepared SiFe electrode showed a reversible lithium storage capacity as high as 470[Formula: see text]mAh g[Formula: see text] after 100 cycles at 200[Formula: see text]mA g[Formula: see text], promising application in high-performance lithium ion batteries.