Highly Sulfonated Poly(Ether Ether Ketone) Blend with Hydrophobic Polyether Sulfone as an Alternative Electrolyte for Proton Exchange Membrane Fuel Cell

Highly sulfonated poly(ether ether ketone) (sPEEK) offers high proton conductivity but lacks in mechanical stability due to poor swelling degree. Therefore, a promising approach has been introduced in this study by incorporating the hydrophobic polyether sulfone (PES) into sPEEK matrix. The effect of incorporating PES at various composition contents (5, 10, 15 and 20 wt%) is investigated toward the membrane properties. The membranes are characterized in terms of structural, morphology, thermal, mechanical, physicochemical and electrochemical properties. It has been found that the incorporation of PES in the highly sulfonated PEEK has significantly improved the mechanical and thermal stability without sacrificing the swelling degree and hydrogen permeability. The sPEEK/PES-5 membrane shows the most promising performance among others exhibiting a comparable proton conductivity of 7.18 mS/cm to that of pristine highly sulfonated PEEK with 8.14 mS/cm. Meanwhile, the power density result of the sPEEK/PES-5 membrane shows 99.29 mW/cm 2 at par with the commercial Nafion 117 membrane of 135.75 mW/cm 2 . In conclusion, the sPEEK/PES blend membrane has shown favorable physicochemical properties and considerably high performance obtained from the blended sPEEK membrane at 5 wt% of PES loading that can be considered as a promising alternative membrane for proton exchange membrane fuel cell.