Fuel cell anode structures for voltage reversal tolerance

Abstract

In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pass current during fuel starvation, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode. Such fuel cells can be made more tolerant to cell reversal by promoting water electrolysis over anode component oxidation at the anode. This can be accomplished by enhancing the presence of water in the anode catalyst layer through modifications to the anode structure or anode composition near or in the catalyst layer. For instance, water electrolysis during voltage reversal is promoted through the use of different or additional ionomer, polytetrafluoroethylene, or graphite in the anode catalyst layer, or through the use of certain sublayers between the anode catalyst layer and the anode substrate.