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

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 gm 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 (Delta E/E up to +75%, Delta Y/Y up to +47%) and at 80 degrees C/70% relative humidity (Delta E/E up to +64%, Delta 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 degrees C ranges from similar to 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 degrees C. The peak power density decreases from 0.36 W cm(-2), at 80 degrees C, to 0.28 W cm(-2) at 110 degrees C, where the composite membrane performs better than the neat ionomer. (C) 2014 Elsevier B.V. All rights reserved.