Synthesis of sulfonated (ether ether ketone) based membranes containing poly(4-styrenesulfonic acid) and its excellent performance for direct methanol fuel cells

► The blend membranes based on SPEEK and PSSA are prepared. ► The max power density is 28.82 mW cm−2 at 100 mA cm−2 (2 M methanol, 80 °C). ► A moderate sulfonated PEEK can display excellent performance by doping with PSSA.