High Energy Density All-Liquid Fed Fuel Cell

Power supplies for unmanned underwater vehicles (UUVs) need both a high energy density and a stable mass density. (If the system changes weight or volume during operation it can upset the buoyancy control of the UUV.) The combination of sodium borohydride (NaBH4, handled as a base stabilized aqueous solution) and hydrogen peroxide (H2O2, handled as an acid stabilized aqueous solution) offer a very high energy density, especially if they are consumed directly rather than going through intermediate species (e.g., H2 and O2). They are also storable as unpressurized liquids and produce only liquid products (also storable unpressurized) when they are reacted in a fuel cell, making them ideal for the UUV application. On a volume basis these solutions are equivalent to oxygen stored at over 3,000 psi and hydrogen stored at over 5,000 psi.. We will use these reactants in a direct fuel cell with a bipolar membrane as the electrolyte. After demonstrating the basic technology in Phase I, we will fabricate a complete standalone power supply in Phase II.