Synergistic Effects of Self-Assembled Zeolite/Nafion Nano-Composite Proton Conducting Thin-Film Membrane

Proton electrolyte membranes with high conductivity at elevated temperatures (>100^oC) and relatively low humidity (RH<80%) have been long sought for development of practical fuel cells and efficient water electrolyzers. A synergistic proton transport model is proposed here to design a thin-film composite membrane with proton-conducting polymers and zeolite nano-crystals. The self-assembled nano- composite membranes in a thin-film form are prepared by coating a porous Ni alloy sheet with Nafion polymer and small zeolite crystals. The resulting composite membrane film (<10µm thick) exhibits  exceptional proton conductivity, a few times to one order of magnitude higher than a commercial membrane sample - Nafion117 over a temperature range of 20 to 130^oC in 30% relative humidity. The synergistic effects are clearly shown. In addition to dramatic proton conductivity enhancement, the membrane material cost may be reduced by an order of magnitude using a supported thin-film membrane instead of thick self-supported sheets.