Membrane electrode assemblies based on sol-gel hybrid membranes - A preliminary investigation on fabrication aspects

This paper reports the preliminary results on fabrication of membrane electrode assemblies (MEA) for proton exchange membrane fuel cells (PEMFC) based on sol-gel hybrid membranes. In order to identify a suitable method, various fabrication strategies were investigated. For this purpose, hybrid membranes made from alkoxysilane-endcapped poly(ethylene glycol) (PEG) precursor consisting of monophenyl trimethoxysilane (MPh) as silica phase modifier and 4-dodecylbenzene sulfonic acid (DBSA) as proton source (PEG/SiO2/DBSA); and MPh and 12-phosphotungstic acid (PWA) (PEG/SiO2/PWA) are used as model compounds. For the better interface of MEA, impregnation solutions of similar chemical nature with hybrid membranes were examined. Polarization curves are exclusively used to evaluate the quality of MEA. A maximum current density of 80 mA cm−2, obtained with hot-pressed MEA, is the highest performance among the five different preparation methods. Good contact between the hybrid membrane as an electrolyte and the catalyst coated carbon cloth as electrodes in the MEA is achieved by coating electrodes as well as membrane with precursor sol. The flexibility of sol-gel hybrid membranes shows scope for further improvement in performance compared to hybrid membranes from solution-blending. The implications of each preparation methods are analyzed.