Sulfonated poly ether sulfone/heteropoly acid composite membranes as electrolytes for the improved power generation of proton exchange membrane fuel cells

The organic/inorganic hybrid membranes consisting of different concentrations of phosphotungstic acid (PWA) in sulfonated poly ether sulfone (SPES) were constructed for the usage as electrolyte in proton exchange membrane fuel cells (PEMFCs). The repulsion applied between the hydrophilic moieties of host and guest components resulted in the porosity of prepared composite membranes. The as-made membranes demonstrated the prompt thermal stability and validated its applications in elevated temperature operation of PEMFCs. When the concentration of PWA was increased to 30 wt% in sulfonated polyether sulfone, the ionic conductivity of the corresponding membrane was increased to 19 mS/cm at room temperature, presumably due to the inherent conductivity of the PWA molecules and the enhanced acidity of sulfonic acid groups in the membranes. The SPES/PWA composite membrane (IEC 1.74 meq/g) comprising 30 wt% of PWA exhibited a maximum ionic conductivity of 116 mS/cm at 90 °C under 100% relative humidity (RH). The as-made SPES/PWA-30 composite membrane exhibited the maximum PEMFC power density of 305 mW/cm², which validated its potential applications in PEMFCs.