The design and testing of a 20-W (average power with short pulses to 45W) prototype fuel cell is presented. This cell is intended as an auxiliary power supply for a small robotic vehicle. The energy density exceeds 300 Watt-hour/kg. This cell is essentially a dry-borohydride/injected-hydrogen-peroxide fuel cell. This enables extremely long shelf life prior to use. The anode utilizes dry NaBH4 for storage while the cathode chamber is empty during storage. The initiation of cell operation is done by injection of the oxidizer, an aqueous H2O2 solution (stored in a separate container) to the cathode side of the fuel cell. The ionic conduction required for membrane operation is initially helped by the H2O content from the H2O2 solution. Once the electrochemical reaction starts, more water is generated as the reaction product and this continues to maintain a good ionic conductance over the run time of the cell. Continued operation is done with auxiliary fuel tanks to maintain very long run time when required. Once a run is over, the cell can be drain, flushed clean and returned to storage waiting for the next mission. The experimental details of such a cell stack are described in this paper.
Extended and conditional versions of the PASTA property