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

Highlights: • 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. - Abstract: 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