CsHSO4/TiP2O7 composite membrane for high temperature (>150 °C) proton exchange membrane fuel cells

• HT-PEMFCs present a number of potential advantages than conventional PEMFCs.
• The membrane was fabricated by impregnating CHS into porous TPP as the matrix.
• The density and strength of CHS/TiP2O7 membrane were higher than pure CHS membrane.
• The proton conductivity of CHS/TiP2O7 membrane was higher than pure TiP2O7 membrane.

Proton exchange membrane fuel cells (PEMFCs) are one of the most promising clean energy technologies converting hydrogen energy to electric power. In this study, a proton-conducting electrolyte based on a CsHSO4/TiP2O7 composite membrane and operating at > 150 °C was fabricated using the vacuum infiltration method and characterized. The electrical properties were investigated in the high temperature range of ∼ 110–190 °C, in a dry atmosphere, using an impedance analyzer. The analysis of the resultant phase relationship showed that the composite membrane exhibited the same major peaks as each individual material (TiP2O7 and CsHSO4) without any secondary phase. The relative density of the infiltrated CsHSO4/TiP2O7 composite membrane increased up to 96.76%, indicating that most of the pores present in the initial TiP2O7 supporting matrix were infiltrated with CsHSO4. It was consistent with the result of scanning electron microscopy. Moreover, the composite membranes exhibited low ionic conductivities in the low-temperature region, but at ∼ 140 °C, the ionic conductivities significantly increased because of the super-protonic phase transition of CsHSO4. The maximum conductivity (∼2.38 × 10−3 S/cm) was achieved at 190 °C under a dry Ar atmosphere.