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.