Hybrid membranes for formic acid fuel cells

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The earliest market for fuel cells is seen in the portable sector because small fuel cells have an inherent higher energy density than batteries. Tekion is engaged in the commercialization of an energy system for portable power applications. However, improvement of their micro fuel cell is crucial to maintain their competitive edge. It is the aim of this project to improve the Tekion FormiraTM fuel cell which relies on a formic acid fuel cell. To achieve this objective, acid formic permeation through the membrane has to be reduced by at least 20%. This project addresses for the first time the improvement of Nafion membranes for formic acid fuel cells and the development of Nafion hybrid membranes is proposed. Our strategy rely on mixing the Nafion ionomer with inorganic bi-functional fillers (both hygroscopic and proton conductors) that will prevent or diminish formic acid cross-over without hampering the ionic conductivity. Two types of bi-functional fillers will be used: hydrous ruthenium oxide, RuO2.xH2O, a mixed electronic-protonic conductor with four times lower activation energy for proton transport than Nafion, and modified Faujasite zeolites, a high surface area molecular sieve, that will be acid stabilised (dealuminated) and functionalised with organic moieties containing sulfonic acid groups to improve their proton conductivity. Different configurations of mixed Nafion / RuO2.xH2O and Nafion / modified Faujasite zeolites will be prepared by solvent casting. The preparation procedure will be optimized to lower formic acid cross-over while maintaining without unduly affecting the membrane resistance.