Metal hydride fuel cell with intrinsic capacity

An alkaline metal hydride (MH) fuel cell with built-in energy storage was constructed and its performance was examined. The cell employed a bifunctional air-cathode using a La0.6Ca0.4CoO3 perovskite catalyst. The anode contained the intermetallic compound MmNi(3.5)Co(0.7)Al(0.7)Mn(0.1) as the active material. The cell voltage at 20 mA/cm(2) was 0.65 V (air) and 0.78 V (oxygen). Using air, 12 mW/cm(2) of continuous power was delivered from the fuel cell for almost 1000 h. A maximum power output of 34 mW/cm(2) (oxygen) was measured. The system acts as a fuel cell with built-in capacity because the hydrogen fuel in the anode is stored as MH. The H-2-rechargeable MH-electrode showed an attractive recharge rate suitable for practical use: 87% of the full capacity was recharged within 58 min. By using a bifunctional air-electrode the MH-electrode can also be recharged electrochemically. The fuel cell can therefore be regarded as a battery which is rechargeable like a normal secondary cell, but which has the advantage of also being rechargeable with hydrogen gas. (C) 2002 Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.