The effect of surface modification of LaNi5 hydrogen storage alloy with CuCl on its electrochemical performances

•The surface of the LaNi5 hydrogen storage alloy is treated with CuCl.•The reduction of CuCl is a one-electron process, which may also bring out other effects.•It is possible that the hydrolysis and the disproportionation of CuCl can take place.•Cu2O in small amount improves electrochemical performances of the AB5 hydrogen storage alloy.

The LaNi5 hydrogen storage alloy is modified by two steps: firstly, the alloy is treated with an aqueous solution of HF and KF⋅2H2O, then the as-obtained product reacts with CuCl in aqueous media at 30 °C, 50 °C and 70 °C respectively. XRD and SEM show that the samples obtained at 50 °C and 70 °C contain Cu and Cu2O, and their particles are evenly distributed on the alloy surface. The electrochemical properties of the alloy treated with 12.5 wt.% of the alloy at 50 °C are the best, which discharge 310 mA h g–1 at a current density of 50 mA g–1, and 280 mA h g–1 at 1000 mA g–1, while the pristine alloy discharges only 290 mA h g–1 at a current density of 50 mA g–1, and 180 mA h g–1 at 1000 mA g–1.