| Abstract
| - The state-of-the-art of polymer electrolyte membrane fuel cell (PEMFC) technology is basedon perfluorosulfonic acid (PFSA) polymer membranes operating at a typical temperature of80 °C. Some of the key issues and shortcomings of the PFSA-based PEMFC technology arebriefly discussed. These include water management, CO poisoning, hydrogen, reformate andmethanol as fuels, cooling, and heat recovery. As a means to solve these shortcomings, high-temperature polymer electrolyte membranes for operation above 100 °C are under activedevelopment. This treatise is devoted to a review of the area encompassing modified PFSAmembranes, alternative sulfonated polymer and their composite membranes, and acid−base complex membranes. PFSA membranes have been modified by swelling with nonvolatilesolvents and preparing composites with hydrophilic oxides and solid proton conductors.DMFC and H2/O2(air) cells based on modified PFSA membranes have been successfullyoperated at temperatures up to 120 °C under ambient pressure and up to 150 °C under 3−5atm. Alternative polymers are selected from silicon- and fluorine-containing inorganicpolymers or aromatic hydrocarbon polymers and functionalized by sulfonation. The sulfonatedhydrocarbons and their inorganic composites are potentially promising for high-temperatureoperation. High conductivities have been obtained at temperatures up to 180 °C. Acid−basecomplex membranes constitute another class of electrolyte membranes. A high-temperaturePEMFC based on H3PO4-doped PBI has been demonstrated for operation at temperaturesup to 200 °C under ambient pressure. The advanced features include high CO tolerance,simple thermal and water management, and possible integration with the fuel processingunit.
- The newest development in the field of polymer electrolyte membrane fuel cells is thermally resistant membranes for operation above 100 °C. This review is devoted to the area encompassing modified PFSA membranes, alternative sulfonated polymers and their composite membranes, and acid−base complex membranes.
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