Influence of Ni on Electrochemical Hydrogen Storage Property of Amorphous Co-B Alloy

A series of ternary amorphous Ni-Co-B alloys were prepared by a chemical reduction codeposition method with Ni introduction and influence of Ni on electrochemical hydrogen storage property of the amorphous Co-B alloys was investigated. Results show that at a charge/discharge rate of 650 mA/g, the amorphous Ni-Co-B alloy with Ni content of 23.8 at% has a reversible discharge capacity of about 250 mAh/g, 20 mAh/g lower than amorphous Co-B alloy does. Discharge capacity of the two samples keeps almost unchanged after 60 cycles. Nevertheless, the amorphous Ni-Co-B alloy with Ni content of 35.8 at% shows much lower discharge capacity and capacity retention during cycling than amorphous Co-B alloy does under the same condition. However, a positive effect of Ni on electrochemical hydrogen storage of Co-B alloy is also found, i.e. element Ni could suppress H-2 evolution on the surface of the amorphous Co-B alloy at a high charge rate and reduce the fluctuation of discharge potential plateau and discharge capacity during cycling. It could be attributed to that Ni decreases electrocatalytic activity for H2O dissociation on the surface and improves hydrogen diffusion rate for amorphous Co-B alloy bulk.