Zirconium phosphate reinforced short side chain perflurosulfonic acid membranes for medium temperature proton exchange membrane fuel cell application

Abstract Composite membranes, made of an 830 equivalent weight short-side-chain perfluorosulfonic acid ionomer and containing up to 10 wt% zirconium phosphate (ZrP), are prepared by casting dispersions of ZrP nanoparticles in the ionomer solution. 30 μm thick composite membranes are characterized by transmission electron microscopy, X-ray diffraction, stress–strain tests, conductivity measurements, water uptake and ion-exchange capacity determinations, as well as fuel cell tests in H 2 /air. In comparison with the neat ionomer, the tensile modulus ( E ) and the yield stress ( Y ) of the composite membranes increase with the ZrP content, both at room temperature (Δ E / E up to +75%, Δ Y / Y up to +47%) and at 80 °C/70% relative humidity (Δ E / E up to +64%, Δ Y / Y up to +103%). Despite their lower hydration, the composite membranes are as conductive as the neat ionomer and the in-plane conductivity at 110 °C ranges from ∼0.005 S cm −1 at 25% RH to 0.14 S cm −1 at 90% RH. The fuel cell performance of a catalyst coated membrane loaded with 10 wt% ZrP is weakly affected by temperature in the range 80–110 °C. The peak power density decreases from 0.36 W cm −2 , at 80 °C, to 0.28 W cm −2 at 110 °C, where the composite membrane performs better than the neat ionomer.