Polybenzimidazole Fuel Cell Technology

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After approximately 10 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120–180°C due to the physical and chemical robustness of PBI membranes. These higher temperatures improve the electrode kinetics and conductivity of the MEAs, simplify the water and thermal management of the systems, and significantly increase their tolerance to fuel impurities. Membranes cast by a newly developed polyphosphoric acid (PPA) process possessed excellent mechanical properties, higher phosphoric acid (PA)/PBI ratios, and enhanced proton conductivities as compared to previous methods of membrane preparation. p-PBI is the most common polymer in PBI-b ...