Preparation and characterization of composite membranes based on sulfonated PEEK and AlPO4 for PEMFCs

► Composite membranes based on SPEEK and AlPO4 were prepared. ► Thermal stability of composite membranes was higher than pure SPEEK membranes. ► Proton conductivity of composite membranes was lower than pure SPEEK membranes. ► Composite membranes exhibited better swelling behavior in water.