The Effect of Nafion Content on DMFC Electrode Characteristics

In this work the influence of the ionomer content in the electrodes on DMFC operation is studied. Nafion content in the anode can be used to control permeation of methanol and water, but has an influence on cell voltage as well. An optimum was found at intermediate Nafion content, where permeation was already reduced without a significant influence on cell voltage. Nafion content in the cathode can be used to improve tolerance towards low air stoichiometry and operation with humidified air. While a Nafion-to-carbon ratio around 0.8 is the optimum for operation with dry air, a significantly lower Nafion-to-carbon ratio of 0.4 should be used for operation with humidified air. On the cathode it was shown that the catalyst layer with the lowest Nafion content had the finest nanopores. For higher Nafion-contents the pore-size maximum was shifted to larger pores and the total nanopore volume was reduced