A proton-conducting composite membrane: Sn0.95Al0.05P2O7 and polystyrene-b-poly(ethylene/propylene)-b-polystyrene

An anhydrous proton conductor, Sn0.95Al0.05P2O7 (SAPO), composed of polystyrene-b-poly(ethylene/propylene)-b-polystyrene (SEPS), was developed and characterized using morphological, structural, and electrochemical analyses. In the composite membrane with 20 wt% SEPS, a homogeneous distribution of SAPO particles in the matrix was obtained in the thickness range of 65–90 μm, yielding a proton conductivity of 3.4 × 10−3 S cm−1 at 200 °C, tensile strength of 4.6 MPa and an elongation at break of 711.0% at room temperature. Fuel cell tests verified that the open-circuit voltage was maintained at a constant value of approximately 1 V between 100 and 250 °C. The peak power densities achieved with unhumidified H2 and air were 77.0 mW cm−2 at 100 °C, 121.0 mW cm−2 at 150 °C, and 163.1 mW cm−2 at 225 °C.