Incorporation of zirconium hydrogen phosphate into porous ionomer membranes

Abstract

Nafion membrane was cast from 5 wt % Nafion/dimethly acetamide/2-propanol solution containing a hydrophobic plasticizer, and the phase-separated low molecular weight component was leached out from the Nafion matrix by solvent extraction using diethyl ether and methanol. The resultant porous Nafion membrane was doped in situ with zirconium hydrogen phosphate (ZHP) by zirconium chloride and phosphoric acid treatment. The maximum loading of ZHP nanoparticles increased to 40 wt % because of additional precipitation in the pore structure. Field-emission scanning electron micrographs showed that the pores were completely filled with in situ doped ZHP particles. Fourier transform infrared study confirmed that more ZHP fillers improved water retention and proton conductivity of the composite ionomer membrane at high-temperature regions above 100degreesC. As a result, the power density of Nafion/ZHP membranes was much higher than that of an as-received Nafion 115 membrane at elevated temperature. (C) 2004 The Electrochemical Society.