Solid polymer electrolyte based on sulfonated polysulfone membranes and acidic silica for direct methanol fuel cells

► Composite membranes based on acidic silica and sulfonated polysulfone (SPSf). ► The acidic silica SPSf membrane has lower methanol crossover than bare SPSf. ► The maximum DMFC power density is achieved with the acidic silica SPSf membrane. ► The DMFC performance is mainly influenced by methanol crossover.