Thin and methanol-resistant reinforced composite membrane based on semi-crystalline poly (ether ether ketone) for fuel cell applications

Nowadays, demands for the utilization of thin membranes in the next generation of direct methanol fuel cells become urgent to acquire the high power density. However, the fuel crossover coefficient is inversely proportional to the thickness of membranes which easily causes the reduction of the energy density. Hence, we propose a thin reinforced pore-filling composite membrane that is fabricated from a highly sulfonated poly (ether ether ketone) electrolyte and a high mechanical strength semi-crystalline poly (ether ether ketone) porous matrix. The semi-crystalline poly (ether ether ketone) derived from a soluble precursor of PEEK-1,3-dioxolane is first reported to be used for preparing the porous membrane. Uniform pore structures of the porous matrix are obtained by a water induced phase inversion method. As-prepared porous PEEK shows high toughness with an elongation at break of 8.2%. The reinforced composite membrane (only 20 tun) demonstrates superior methanol tolerance (3.2 x 10(-7) cm(2) s(-1),S) and good proton conductivity due to the packed-acid structure. In addition, the membrane electrode assembly indicates a preferable behavior in single cell performance, with an open circuit voltage of 0.53 V and a peak power density of 34.6 mW/cm(2).