Structure and performance of La_1-xCa_x Ni_3.2Co_0.3Al_0.3 (0 ≤ 0.1 ≤ 0.4) low-cobalt hydrogen storage alloys

The crystal characteristics, microstructure and chemical composition of the new-type low-cobalt hydrogen storage alloys La_1-xCa_x Ni_3.2Co_0.3Al_0.3 (0 ≤ 0.1 ≤ 0.4) were analyzed by X-ray diffractometry, scanning electron microscopy and EDX, and the electrochemical properties of the alloys were investigated. The results show that the prepared alloys are basically composed of LaNi₅ as matrix phase and LaNi₃ as second phase when x ≤ 1. When 0.1 ≤ x ≤ 0.3, the second phase LaNi₃ is substituted by a new phase Al(NiCo)₃. The activity of alloys become bad with the increase of Ca content. When x = 0.2, the discharge capacity reaches the highest value of 295 mA· h/g, and the capacity of the alloys can hold 82.5% after 300 charge/discharge cycles.