Effect of metal oxides on electrochemical performances of La–Mg–Ni-based alloys

Metal oxides (TiO 2 , Er 2 O 3 and ZnO) were added to La–Mg–Ni-based hydrogen storage alloy electrodes and their effects on the structural and electrochemical properties were studied. The charge efficiency, especially at high charge current density was greatly ameliorated, and the high rate charge capability at 1440 mA g −1 increased from 85.1% (blank) to 94.1% (TiO 2 ), 93.3% (Er 2 O 3 ) and 90.5% (ZnO). The high temperature dischargeability was also improved in case of TiO 2 , Er 2 O 3 and ZnO additives. These additives suppressed formation of Mg(OH) 2 and La(OH) 3 during charge/discharge process and therefore the cycling stability was improved. The discharge capacity retention at the 200th cycle increased from 72.9% (blank) to 79.6% (TiO 2 ), 87.5% (Er 2 O 3 ) and 77.9% (ZnO).