Advances in proton exchange membranes for wide-temperature-range fuel cellsOA

Proton exchange membranes(PEMs)play a central role in determining the efficiency,durability,and operational flexibility of PEM fuel cells(PEMFCs).However,conventional PEMs exhibit strong temperature-dependent proton-transport behavior,which limits their ability to support both rapid start-up at low temperatures and stable operation at elevated temperatures.Water-mediated PEMs show excellent conductivity under low-temperature and high-humidity conditions but suffer from dehydration and structural instability in the high-temperature regime.In contrast,water-independent PEMs,particularly phosphoric-acid-doped systems,conduct protons efficiently under anhydrous high-temperature conditions yet experience acid leaching that hampers room-temperature start-up and long-term durability.This review summarizes the fundamental proton-transport mechanisms that govern temperature-dependent performance and discusses recent advances in materials design aimed at enabling wide-temperature-range PEM operation.For water-mediated membranes,strategies such as incorporating hydrophilic fillers,constructing confined hydrophilic domains,and introducing additional proton-transfer sites have been developed to mitigate water loss and stabilize proton conduction.For water-independent membranes,approaches including strengthening polymer–acid interactions,engineering nanoscale confinement,designing multilayer architectures,and constructing multi–proton-carrier networks effectively improve acid retention and broaden operational temperature windows.Emerging fixed-carrier systems based on phosphonic-acid-grafted polymers,metal–organic frameworks,and covalent organic frameworks offer new pathways for stable anhydrous proton conduction across a wide temperature range.We conclude by outlining key challenges and future research opportunities,including reducing the dependence on volatile or leachable proton carriers,developing adaptive nanochannel architectures,improving anhydrous high-temperature conduction,and establishing scalable membrane fabrication methods.Continued innovation in these directions is expected to enable next-generation wide-temperature-range PEMs capable of flexible,high-efficiency operation from sub-zero to high-temperature conditions.