An air–metal hydride battery using MmNi3.6Mn0.4Al0.3Co0.7 in the anode and a perovskite in the cathode

Hydrogen storage alloy MmNi3.6Mn0.4Al0.3Co0.7 (MH) was tested as anode material in a metal hydride–air cell. The cathode was a non-noble metal air electrode based on a mixture of perovskite and pyrolyzed macrocycles on carbon. Polarization and discharge capacities of the electrodes were measured and compared at 22 °C and 40 °C using air or oxygen at the cathode. Discharge capacity reaching 330 mAh/g MH with pure oxygen at 40 °C and 305 mAh/g MH with air at 22 °C were obtained. Power densities and/or energy densities were found to significantly depend on the increase of the electrode kinetics on both the ORR (oxygen reduction reaction) and HOR (hydrogen oxidation reaction). However, for air electrode, an increase of oxygen concentration by using pure oxygen gas plays a more important role than an 18 °C temperature increase.