Composite polymer electrolyte membrane decorated with porous titanium oxide nanotubes for fuel cell operating under low relative humidity

Abstract

A block copolymer composite membrane of sulfonated poly(arylene ether sulfone ketone) (SPESK) decorated with porous hygroscopic titanium oxide nanotubes (TNT) is designed and fabricated for low relative humidity (RH) operating polymer electrolyte fuel cells (PEFCs). The SPESK-TNT composite membrane in a PEFC operated at 100% RH, and 80 °C resulted in about 1.3 and 1.1-folds higher power density in comparison with the benchmark Nafion (NRE-212) and pristine SPESK membranes at 0.6 V. Further, operating under 30% RH and 80 °C, the SPESK-TNT composite membrane generates 3.8 and 2.8-folds improved power density in comparison with the pristine SPESK and commercial NRE-212 membranes, respectively, at 0.6 V. An outstanding improvement of PEFC performance using SPESK-TNT composite membrane also maintains relative to a SPESK-TiO2 nanoparticles composite membrane, operating under 100 and 30% RH. Moreover, the SPESK-TNT composite membrane shows a stable operating potential of more than 200 h at 30% RH and 80 °C, confirming the durable PEFC operation. The enhanced PEFC performance under dry conditions is mainly the result of improving water management by the TNT filler in the membrane and cathode catalyst utilization, yielding significantly suppressing both ohmic and mass transport overpotentials.