Phase Control of Co-Sn Alloys through Direct Electro-Deoxidation of Co3O4/SnO2 in LiCl-KCl Molten Salt

Co can form a series of intermetallic compounds with Sn which usually exhibit unique physical and chemical properties. However, it is a challenge to control the phase composition of Co-Sn alloys. Here, we attempted to prepare Co3Sn2, CoSn and CoSn2 from the mixture of Co3O4/SnO2 using electro-deoxidation. We investigated the effects of sintering temperature for the mixed oxide plate and electrolysis conditions, such as voltage, electrolysis time, and molten salt temperature on the electro-deoxidation process of Co3O4/SnO2. The electrochemical deoxidation mechanisms of Co3O4, SnO2, and Co3O4/SnO2 composites were also explored by cyclic voltammetry using metallic cavity electrode. The Co-Sn alloys with different phase compositions, such as Co3Sn2, CoSn, and CoSn2, were obtained through controlling the molar ratio between Co and Sn in the initial Co3O4/SnO2 plate and the molten salt temperature. The obtained Co-Sn alloys were used as anode materials for lithium-ion batteries which showed 123.0, 246.5, and 323.4 mAh g(-1) for Co3Sn2, CoSn, and CoSn2, respectively.