Development of a novel metal hydride air secondary battery

A laboratory metal hydride/air cell was evaluated. Charging was via a bifunctional air gas-diffusion electrode. Mixed nickel and cobalt oxides, supported on carbon black and activated carbon, were used as catalysts in this electrode. At 30 mA cm(-2) in 6 M KOH, the air electrode potentials were -0.2 V (oxygen reduction) and +0.65 V (oxygen evolution) vs Hg/HgO. The laboratory cell was cycled for 50 cycles at the C/2 rate (10 mA cm(-2)). The average discharge/charge voltages of the cell were 0.65 and 1.6 V, respectively. The initial capacity of the metal hydride electrode decreased by about 15% after 50 cycles.