Synthesis of Mo2C@MWCNTs and its application in improving the electrochemical hydrogen storage properties of Co0.9Cu0.1Si alloy

The current hydrogen storage alloys used for Ni-MH battery negative electrode are difficult to guarantee excellent performance in terms of discharge capacity and cycle stability. Co 0.9 Cu 0.1 Si alloy has been widely investigated as a negative electrode material for nickel hydrogen battery, but its capacity and cycle stability need to be improved for commercial applications. In this work, Co 0.9 Cu 0.1 Si alloy was prepared by mechanical alloying. Molybdenum carbide (Mo 2 C) was loaded on multi-walled carbon nanotubes (MWCNTs) by in-situ carburizing . In order to improve the electrochemical hydrogen storage performance of Co 0.9 Cu 0.1 Si alloy, 5 wt% MWCNTs, Mo 2 C and molybdenum carbide modified multi-walled carbon nanotubes (Mo 2 C@MWCNTs) were added to Co 0.9 Cu 0.1 Si alloy via mechanical alloying method. The structure and morphology of the composites were characterized by XRD and SEM. The discharge capacity, cyclic stability and high rate discharge performance of the composites were tested, the electrochemical performance of the composites was investigated by three-electrode battery system. The composite materials have better discharge capacity, cycle stability and electrochemical performance compared with the pristine alloy. The Co 0.9 Cu 0.1 Si alloy doped with 5 wt% Mo 2 C@MWCNTs-2 has the best electrochemical hydrogen storage performance among all the composite materials. Its optimal discharge capacity is 609.9 mAh/g and its maximum capacity retention rate is 64.7 %. The enhancement of the electrochemical hydrogen storage performances of the composites are due to the high conductivity and high specific surface area of MWCNTs and the high catalytic activity of Mo 2 C. The synergistic effect of MWCNTs and Mo 2 C can improve the electrochemical hydrogen storage performances of the composites.