Synergistic Hydrogen‐Bonding and Covalent Crosslinking in Polybenzimidazole Membranes for Wide‐Temperature Anhydrous Fuel Cells

ABSTRACT Expanding the operational temperature range and reducing the humidity dependence of proton exchange membrane fuel cells (PEMFCs) remain critical challenges. To address these issues, we developed a dual‐network architecture that integrates a thermally reinforced hydrogen‐bonding matrix with an amine‐anhydride covalent crosslinking framework within Tröger's Base (TB)‐functionalized polybenzimidazole membranes. The covalently crosslinked TBAm‐PBI‐TB membrane with dual‐network architecture exhibited a high phosphoric acid uptake of 469.5% with negligible leaching and achieved proton conductivities of 255.5 mS cm ^{− 1} at 90°C and 20% relative humidity (RH) and 264.7 mS cm ^{− 1} at 160°C under anhydrous conditions. It also demonstrated excellent oxidative and mechanical stability. A membrane electrode assembly (MEA) based on the TBAm‐PBI‐TB membrane delivered peak power densities ranging from 108.6 to 446.2 mW cm ^{− 2} between 30 and 160°C under anhydrous H ₂ /air conditions. This maximum power density exceeds that of a Nafion 211‐based MEA, which reached 367.8 mW cm ^{− 2} at 30°C under 40%–50% RH. The MEA also showed outstanding operational durability. This work presents a strategy for developing wide‐temperature proton‐conducting membranes for anhydrous fuel cells.