Merit Bodner

The Effect of Platinum Electrocatalyst on Membrane Degradation in Polymer Electrolyte Fuel Cells.

Membrane degradation is a severe factor limiting the lifetime of polymer electrolyte fuel cells. Therefore, obtaining a deeper knowledge is fundamental in order to establish fuel cells as competitive product. A segmented single cell was operated under open circuit voltage with alternating relative humidity. The influence of the catalyst layer on membrane degradation was evaluated by measuring a membrane without electrodes and a membrane-electrode-assembly under identical conditions. After 100 h of accelerated stress testing the proton conductivity of membrane samples near the anode and cathode was investigated by means of ex situ electrochemical impedance spectroscopy. The membrane sample near the cathode inlet exhibited twofold lower membrane resistance and a resulting twofold higher proton conductivity than the membrane sample near the anode inlet. The results from the fluoride ion analysis have shown that the presence of platinum reduces the fluoride emission rate; which supports conclusions drawn from the literature.

Pt-Free Catalysts for Alkaline Direct Ethanol Membrane Electrode Assemblies

Efficient direct oxidation of ethanol leads to fuel cells with convenient storable fuel and to a system with high energy density and low emissions. Figure 1 shows the scheme of an Alkaline Direct Ethanol Fuel Cell (ADEFC) operated with an Anion Exchange Membrane (AEM). The operation in alkaline media opens up the opportunity to avoid platinum group metals for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) as well, but available AEMs do not show a satisfying hydroxide conductivity and exhibit high ethanol cross over. For a successful application of a DEFC, new materials are required.