Performance of H2/O2 fuel cell using membrane electrolyte of phosphotungstic acid-modified 3-glycidoxypropyl-trimethoxysilanes

Proton-conducting membranes based on phosphotungstic acid (PWA) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) was investigated as the electrolyte for low temperature H₂/O₂ fuel cell. Parameters determining the conductivity and elastic modulus of the membranes were characterized by thermogravimetry/differential thermal analysis and infrared spectroscopic measurements. The composite containing 5% of PWA exhibited an elastic modulus below 100 MPa at room temperature and a high proton conductivity of 1.0 × 10⁻² S/cm at 80 °C and 100% RH. Low elastic modulus of the membrane was found to be useful for both the reduction of the membrane thickness and the better contact with the electrodes. The performance of the membrane electrode assemblies (MEA) was systematically studied as an effect of preparation conditions. A maximum power density of 45 mW/cm² and the current density of 175 mA/cm² at 0.2 V were achieved at 90 °C and 100% RH for the membrane of 5PWA·95GPTMS composition and 0.2 mm thickness.