Cloisite- and bentonite-based stable nanocomposite membranes for enhancement of direct methanol fuel cell applications

Nanocomposite membranes of average thickness 100 µm were successfully fabricated using a phase inversion method which involved use of sulfonated polyether ether ketone (SPEEK) incorporated with nanoclays of cloisite 30B and bentonite. The membranes were characterized for their organic functional groups, morphological structure, thermal and physical properties under the influences of cloisite 30B and bentonite addition in SPEEK matrix. The presence of nanoclays was confirmed by the changes observed in the membrane morphology and improved glass transition temperature in pristine SPEEK membrane. The fuel cell performance of the membranes was determined by their water uptake capacity, methanol permeability and proton conductivity. The 0.5 wt% addition of cloisite and bentonite in SPEEK showed 2.1% reduction of water uptake as compared to the pristine SPEEK membrane. The cloisite-added SPEEK membrane showed the average proton conductivity of 3.05 × 10^–5 S cm⁻¹ at 80 °C. Nevertheless, cloisite- and bentonite-incorporated SPEEK nanocomposite membranes demonstrated the reduced proton conductivity of 6.14% in the methanol permeability as compared to the pristine SPEEK membrane. Hence, the modified SPEEK nanocomposite membranes with cloisite and bentonite are being suggested to be a promising proton exchange membrane for direct methanol fuel cell.