Reinforced Polyphenylene Ionomer Membranes Exhibiting High Fuel Cell Performance and Mechanical Durability

We report on thepreparation of reinforced membranes (SPP-QP-PE,where SPP stands for sulfonated polyphenylene), composed of an in-houseproton-conductive polyphenylene ionomer (SPP-QP) and a flexible porouspolyethylene (PE) mechanical support layer. By applying the push coatingmethod, dense, uniform, transparent, and thin SPP-QP-PE membraneswere obtainable. The use of SPP-QP with higher ion exchange capacityinduced very high proton conductivity of SPP-QP-PE, leading to highfuel cell performance even at low humidified conditions (e.g., at80 degrees C and 30% relative humidity), which had not been attainablewith the existing reinforced aromatic ionomer membranes. The flexibleporous PE substrate improved the mechanical toughness of the membranes;the elongation at break increased by a factor of 7.1 for SPP-QP-PEcompared to that with the bare SPP-QP membrane, leading to mechanicaldurability at least 3850 wet-dry cycles under practical fuelcell operating conditions (the United States Department of Energyprotocol). Overall, the reinforced aromatic ionomer membranes, SPP-QP-PEwith balanced proton conductivity, mechanical toughness, and gas impermeability,functioned well in fuel cells with high performance and durability.

Automated summary

Reinforced membranes composed of SPP-QP-PE showed high proton conductivity, mechanical toughness, and gas impermeability, performing well in fuel cells under high operating conditions. The use of SPP-QP with higher ion exchange capacity led to improved fuel cell performance even at low humidified conditions.