Novel silica/poly(2,6-dimethyl-1,4-phenylene oxide) hybrid anion-exchange membranes for alkaline fuel cells: Effect of silica content and the single cell performance

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based organic-inorganic hybrid alkaline membranes with enhanced hydroxyl (OH⁻) conductivity are prepared in response to the relatively low conductivity of previously reported PPO-based systems. The membranes also exhibit higher swelling-resistant properties and the hydroxyl (OH⁻) conductivity values are comparable to previously reported fluoropolymer-containing membranes: 0.012-0.035 S cm⁻¹ in the temperature range 30-90 °C. Other favorable properties for fuel cell application include high tensile strengths up to 25 MPa and large ion-exchange capacities in the range 2.01-2.27 mmol g⁻¹. Beginning-of-life fuel cell testing of a membrane with a thickness of 140 μm yielded an acceptable H₂/O₂ peak power density of 32 mW cm⁻² when incorporated into an alkaline membrane electrode assembly. Therefore, this class of hybrid membrane is suitable for application in alkaline membrane fuel cells.