A passive anion-exchange membrane direct ethanol fuel cell stack and its applications

We report a passive anion-exchange membrane direct ethanol fuel cell (AEM DEFC) stack that consists of two back-to-back independent-tank single cells. This particular design not only enables a reduction in the weight and volume of the stack, but also avoids the cross reaction of the liquid alkali occurring between two single cells. Experimental results indicate that the passive dual-cell stack that uses a non-Pt anode catalyst and a non-precious metal cathode catalyst yields a peak power density of as high as 38 mW cm⁻² at room temperature, a figure which is about 22 times higher than that of the conventional proton-exchange membrane DEFC stack. The improved performance is ascribed to: i) the accelerated electrochemical kinetics for the both anode and cathode reactions, and ii) the use of the ethanol-tolerant cathode catalyst that eliminates the cathode mixed overpotential. Finally, a power pack consisting of two series-connected stacks is applied to power a toy car, which is demonstrated to continuously run for one hour at a high constant speed of 0.52 m s⁻¹ with on each fueling of a fuel tank with a volume of 4.5 mL.