Soluble polybenzimidazoles incorporating Troger's base for high-temperature proton exchange membrane fuel cells

In this work, a novel dicarboxylic acid (TB-COOH) containing Tro center dot ger's base (TB) was synthesized, and newly TB -based polybenzimidazole (PBI) membranes were prepared as electrolytes for high-temperature proton exchange membrane (HT-PEM) fuel cells. The TB-based PBIs, upon treatment with triethylammonium salts, showed good processability. The as-prepared TB-based PBI membranes exhibit superior tensile strength above 126.6 MPa and high decomposition temperatures at 5% weight loss ranging from 374 degrees C to 411 degrees C. The residual weights of the TB-based PBI membranes remained at above 80% in Fenton's reagent at 80 degrees C for 48 h. Notably, with extra nitrogen atoms in the TB-based PBIs, their phosphoric acid uptakes show obvious improvement over the cor-responding sulfonated polybenzimidazole (sPBI) without TB units, achieving the highest proton conductivity (93.2 mS cm-1) at 160 degrees C, 2.3 times that of 41.2 mS cm-1 from the sulfonated PBI (sPBI) membrane. The highest peak power density of the H2/air fuel cell reached 225.5 mW cm-2 under non-humidity conditions at 160 degrees C, much higher than the value of the sPBI membrane. Based on their excellent comprehensive performance, incorporating TB into chain backbones optimized the PBI electrolytes for HT-PEM applications.