Multilayered Membrane Electrolytes Based on Aramid Nanofibers for High-Temperature Proton Exchange Membrane Fuel Cells

The multilayered membranes based on Kevlar nanofibers, cadmium telluride (CdTe) nanocrystals, and phosphoric acid (PA) molecules were prepared with spin coating method. The accumulation of Kevlar nanofibers could support the layered (Kevlar-CdTe-PA)4 membrane. CdTe nanocrystals functioned as bridges to link PA molecules with Kevlar nanofibers besides improving the mechanical property. More PA molecules were captured with intermolecular hydrogen bonds while (Kevlar-CdTe-PA)4 membranes were immersed into PA solution. PA molecules dominated the proton conductivity of (Kevlar-CdTe-PA)4/PA membranes. The proton conductivity of (Kevlar-CdTe-PA)4/85%PA membranes reached 2.35 × 10–1 S/cm at 160 °C under anhydrous conditions. In comparison to the tensile stress value of 0.35 MPa for the (Kevlar-PA)4/85%PA membrane, the value was elevated to 2.29 MPa at room temperature (RT) for the (Kevlar-CdTe-PA)4/85%PA membrane. The layered distribution of components was considered to help reduce the resistance to proton conduction in (Kevlar-CdTe-PA)4/PA membranes.