Zirconium Phytate-Based Proton Conductors for High-Temperature Fuel Cell Applications

Abstract

Fuel cells are preferred to operate at high temperatures, i.e., more than 100°C, due to their numerous advantages, that range from improved kinetics and better water management. Unfortunately, Nafion cannot operate above 80°C as it dehydrates, so its proton conductivity decreases significantly. Therefore, in this work, a new polymer electrolyte membrane is developed. It is based on solid proton conductors-Zirconium phytate (ZrPA) and Silicotungstic acid. Ionic liquids are used as structure-directing agents. ZrPA/Silicotungstic acid/IL composite membranes were fabricated and supported on polytetrafluoroethylene (PTFE). The composite membranes were evaluated for their proton conductivity. High proton conductivity of 0.0911 S/cm was achieved at room temperature when a 7.26 wt.% ionic liquid (1-Hexyl-3- methylimidazolium tricyanomethanide) was used. The proton conductivity kept its value at 0.0066 S/cm even at a higher temperature of 150°C.