Hydrophilic ePTFE-Based Composite Membranes for PEMFCs

Abstract

A hydrophilic expanded poly(tetrafluoroethylene) (ePTFE) based composite membrane was prepared and tested for proton exchange fuel cell applications. The composite membrane was prepared by impregnating hydrophilic ePTFE membrane with 5% Nafion solution (equivalent weight=1000). This new composite membrane showed higher water uptake (12.7%) than that of normal hydrophobic ePTFE based composite membrane (6.3%) and better proton conductivity. Scanning electron microscopy micrographs showed that the hydrophilic ePTFE based membrane can easily form a dense composite membrane while hydrophobic ePTFE based composite membranes tend to have micropores inside. The hydrophilic ePTFE based composite membrane showed better thermal and dimensional stability than recast Nafion membrane.