High-temperature proton-exchange membranes based on polymer-acid complexes

The published data on proton-exchange membranes designed for solid-polymer fuel cells with operating temperatures of up to 200°C are surveyed. Complexes of basic polymers with strong acids are the most attractive materials for these membranes. Particular attention is paid to complexes of polybenzimidazoles with phosphoric acid. The basic characteristics of membranes, such as proton conductivity and thermal stability, are covered in detail. The testing of the title membranes under high-temperature fuel-cell performance conditions is examined. Alterative systems containing heteropolyacids and acid-doped systems based on polybenzimidazole blends with several sulfonated polyheteroarylenes are mentioned. As an alternative for polybenzimidazoles, other aromatic condensation polymers containing basic nitrogen atoms are considered.