Proton Conductor Confinement Strategy for Polymer Electrolyte Membrane Assists Fuel Cell Operation in Wide-Range Temperature

摘要

Acid loss and plasticization of phosphoric acid (PA)-doped polymer electrolytemembranes are critical hampers for its actual application especially duringstartup/shutdown stages due to the produced water and thermal stress. Toconquer these barriers, a proton conductor confinement strategy is introduced,which may trap PA molecules in the side-chain acidophilic microphaseand weaken plasticizing effect caused by PA toward the polymer backboneto remain membrane tensile stress. The grafted polyphenylene oxide (PPO)is synthesized as model polymers, both molecular electrostatic potential andmolecular dynamics reveal the retention mechanism between PA and sidechainof PPO as well as the aggregation state of PA. Through precisely regulatingpolymer side-chain structure and defined plasticization quantitativeindicator, significant refinements in membrane’s conductivity, durability, andsingle-cell performance are achieved successfully. The designed PPO membranesexhibit ultra-fast and stable proton conducting even at low protoncarrier concentrations and under wide-range working temperature between80 ℃–180 ℃ as well as satisfied resistance to harsh accelerated aging test.These insights will shed light on holistic understanding of PA interactionsand retention from molecular level, and provide radical approaches towardhigh-performance PA/PEMs design.