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

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 degrees C; in anhydrous conditions), 28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit. The maximum power density peak for sPBI/AFT-10 met the figure of 0.42 W . cm(-2) at 160 degrees C (in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H-2/air. These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.