Sulfonated Polybenzimidazole/amine functionalized titanium dioxide (sPBI/AFT) composite electrolyte membranes for high temperature proton exchange membrane fuel cells usage

Abstract The novel sulfonated polybenzimidazole (sPBI)/amine functionalized titanium dioxide (AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells (HT-PEMFCs), unlike the prior low temperature AFT endeavors. The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability. Besides, amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid (PA) doping. In addition, the appeared assembled clusters of AFT flourished a superior mechanical stability. Thus, the optimized sPBI/AFT (10 wt%) showed 65.3 MPa tensile strength; 0.084 S. cm−1 proton conductivity (at 160 °C; in anhydrous conditions), 28.6% water uptake and PA doping level of 23 mol/sPBI repeat unit. The maximum power density peak for sPBI/AFT-10 met the figure of 0.42 W.cm−2 at 160 °C (in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air. These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.