Effects of annealing and stoichiometry to (Nd, Mg)(Ni, Al)3.5 metal hydride alloys

► The influences of stoichiometry and annealing to Nd-A2B7 alloys were studied. ► Secondary phases are critical as catalyst for hydrogen storage. ► Annealing improves capacity and high-rate dischargeability. ► Annealed AB3.5 has the best electrochemical properties.