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 MmNi3.5Co0.7Al0.7Mn0.1 as the active material. The cell voltage at 20 mA/cm2 was 0.65 V (air) and 0.78 V (oxygen). Using air, 12 mW/cm2 of continuous power was delivered from the fuel cell for almost 1000 h. A maximum power output of 34 mW/cm2 (oxygen) was measured. stem acts as a fuel cell with built-in capacity because the hydrogen fuel in the anode is stored as MH. The H2-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.