A novel phosphotungstic acid impregnated meso-Nafion multilayer membrane for proton exchange membrane fuel cells

Abstract

A novel mesoporous Nafion (meso-Nafion) based multilayer membrane impregnated with phosphotungstic acid (HPW) is developed for the operation of proton exchange membrane fuel cells (PEMFCs) at elevated high temperature and low humidity conditions. Very different to the pristine Nafion membrane, the HPW-impregnated meso-Nafion multilayer membrane possesses a much higher conductivity under both high and low humidity conditions. For example, the proton conductivity is 0.072 S cm−1 at 80°C under 40% RH, which is ~4 times better than 0.015 S cm−1 measured on pristine Nafion 1135 membrane under identical conditions. Moreover, the new multilayer structure effectively alleviates the leaching problem of impregnated HPW. The fuel cells assembled with the multilayer membrane show good performances and much low degradation when operated at reduced humidity and elevated temperatures of 120 °C, as compared to the cells with pristine Nafion membranes. The results indicate that the multilayer membrane can significantly widen the application range of PEMFCs under low relative humidity (RH) and elevated high temperatures.