Hydrothermal Preparation and Electrochemical Properties of Co-S alloys

The Co-S alloys were prepared by a hydrothermal method and the process parameters were optimized.The surface morphology and phase structure of Co-S alloys were characterized by SEM and XRD.The electrochemical properties of Co-S alloys were investigated by galvanostatic charge and discharge tests,cyclic voltammetry and AC impedance.The results indicated that the as-prepared Co-S alloy,which was synthesized using a 70% packing volume of the reaction solution at 160℃ for 12 h,showed good crystallinity.This alloy consisted of metallic Co and Co9S8 phases with a cross-linked lamellar morphology of about 50 nm in thickness.It possessed a maximum discharge capacity of 536 mAh/g at charge and discharge current density of 150 mA/g and a good cycling stability with capacity retention rate of 77.4% after 50 cycles.The redox reactions between Co and Co(OH)2 were the main reaction during charge and discharge.Partial dissolution of Co reduced the active material and led to capacity decay.