Durable Proton Exchange Membrane Based on Polymers of Intrinsic Microporosity for Fuel Cells

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) is regarded as a promising energy conversion system owing to simplified water management and enhanced tolerance to fuel impurities. However, phosphoric acid (PA) leaching remains a critical issue, diminishing energy density and durability, posing a significant obstacle to the commercial development of HT-PEMFCs. To address this, we designed composite membranes incorporating the carboxylic acid-modified polymer of intrinsic microporosity (cPIM-1) as framework polymer, blended with polyvinylpyrrolidone (PVP) for HT-PEMFCs. The Lewis acid-base interactions between cPIM-1 and PVP created an extensive hydrogen-bonding network, improving membrane compatibility. The optimized microporous structure and multiple anchoring sites gave rise to 'domain-limited' PA clusters, enhancing the capillary effect on PA. Simultaneously, improved hydrophobicity synergistically optimises the catalytic interface, promoting continuous and stable proton transfer. The MEA based on PVP/cPIM-1 composite membrane achieved a peak power density of 1090.0 mW cm-2 at 160 °C, representing a 152% improvement compared to PVP/PES membrane. Additionally, it demonstrated excellent durability, with a voltage decay of 0.058 mV h-1 over 210 hours of accelerated stress testing (AST) corresponds to more than 5000 hours of constant current density durability test. This study presents a promising strategy for the development of high-performance and durable novel composite membranes in various energy conversion systems.