Synthesis and characterization of anhydrous proton conducting inorganic-organic composite membranes for medium temperature proton exchange membrane fuel cells (PEMFCs)

We report on anhydrous proton conducting inorganic-organic composite membranes synthesized from tetraethoxysilane/poly(-dimethylsiloxane)/trimethylphosphate and 1-ethyl-3 methylimidazolium-bis (trifluoromethanesulfonyl) imide ionic liquid as sol-gel precursors. The Fourier transform infrared spectroscopy, 31P, 1H, and 13C Nuclear magnetic resonance, thermo gravimetric and differential thermal analysis measurements confirmed that the prepared hybrid membranes possess good chemical stability and are thermally stable up to 350 °C. Conductivity of all the fabricated hybrid membranes was measured under anhydrous conditions within the temperature range −20-150 °C, and a value of 4.87 × 10−3 S/cm at 150 °C was achieved for 40 wt% [EMI][TFSI] ionic liquid doped 72TEOS-18PDMS-10PO (OCH3)3 (mol %) hybrid membrane. For 40 wt% ionic liquid doped composite membrane, the measured hydrogen permeability value at 150 °C was 4 × 10−12 mol/cm s Pa.