A 500-W Direct Peroxide Fuel Cell for Space Power Systems

The research on a 500-Watt direct sodium-borohydride/hydrogen-peroxide (NaBH4/H2O2) fuel cell is presented here. Aqueous solutions of NaBH4 and hydrogen peroxide are directly used at the fuel cell anode and cathode, respectively, in place of gaseous reactants. Initial results indicate: 1) conversion efficiency over 60% at a practical current density of 250 mA/cm; 2) power density over 0.5 W/cm, at 60 degree Celsius. The kiloWatt-stack consists of 24 cells, generating an OCV (open circuit voltage) of ~ 42V. The design of the reactant manifold overcomes some issues unique to an all-liquid-reactant fuel cell. One such issue is possible short-circuiting of neighboring cells from the conductivity of fuel/oxidant. Another issue is possible excessive corrosion if the manifold is not designed properly. This NaBH4/H2O2 fuel cell technology is ideal for propulsion/power for aerospace systems such as spacecraft and unmanned aerial vehicles.