(Plenary) Development of PFSA Ionomers and Their Use in Fuel Cells

Perfluorosulfonic acid (PFSA) ionomers are desired to have higher proton conductivity even at elevated temperatures (95-120°C) and low relative humidity (RH) conditions so that the fuel cell systems especially in fuel cell vehicles (FCVs) can be compact, simple and lower cost through easy heat removal and humidifier less. For the ionomer in the cathode electrode, besides transporting the protons, it has to deliver high flux of oxygen to the platinum surface when operating at high current density using low platinum loading membrane electrode assembly (MEA). And for the microporous layer (MPL) on gas diffusion layer (GDL), ionomer was used as binder instead of hydrophobic resin such as polytetra-fluoroethylene (PTFE). It showed good performances in elevated temperatures and low RH conditions as well as in wet conditions through good water control. The design concepts as well as their cell performances are presented.