Hyperbranched Interpenetrating Hydrogen Bond Network (HIHBN) Proton Exchange Membrane for Fuel Cells Above 220 °C

High-performance proton exchange membranes (PEMs) play a vital role in the efficiency of high-temperature proton exchange membrane fuel cells. In this study, a novel PEM with a hyperbranched interpenetrating hydrogen bond network (HIHBN) is developed by incorporating hyperbranched poly(benzyl-triptycene) (PBT) and SnP2O7 hydrogen bond networks. This innovative design significantly enhances the proton conductivity. Additionally, the unique structure of the hyperbranched PBT polymer with a branching point (triptycene, a pi-conjugated aromatic ring compound with a three-cyclic configuration) contributes to an impressive glass transition temperature exceeding 400 degrees C, enabling the membrane to operate at elevated temperatures (above 220 degrees C) in fuel cell applications. This membrane shows promise as an alternative to commonly used polybenzimidazole (PBI)-based membranes, offering improved mechanical strength and a reduced swelling ratio. When applied in fuel cells, the HIHBN PEM achieves an excellent through-plane proton conductivity of 0.108 S cm(-)(1) and a peak power density of 0.75 W cm(-2) at 220 degrees C under dry H-2/O-2 conditions. Notably, it exhibited minimal degradation after approximate to 33 h under harsh operating conditions, demonstrating its stability and long-term durability. These findings highlight the potential of HIHBN PEMs for high-efficiency, durable performance in high-temperature fuel cell environments.