Hydrogen/oxygen polymer electrolyte membrane fuel cells (PEMFCs) based on alkaline-doped polybenzimidazole (PBI)

When complexed with alkaline such as potassium hydroxide, sodium hydroxide or lithium hydroxide, films (40 mu m thick) of polybenzimidazole (PBI) show conductivity in the 5 x 10(-5)-10(-1) S/cm(-1) range, depending on the type of alkali, the time of immersion in the corresponding base bath and the temperature of immersion. It has been shown that PBI has a remarkable capacity to concentrate KOH, even in an alkaline bath of concentration 3 M. The highest conductivity of KOH-doped PBI (9 x 10(-2) S cm(-1)) at 25 degrees C obtained in this work is higher than the we had obtained previously as optimum values for H2SO4-doped PBI (5 x 10(-2) S cm(-1) at 25 degrees C) and H3PO4-doped PBI (2 x 10(-3) S cm(-1) at 25 degrees C). PEMFCs based on an alkali-doped PBI membrane were demonstrated, and their characteristics exhibited the same performance as those of PEMFCs based on Nafion(R) 117. Their development is currently under active investigation. (C) 2000 Published by Elsevier Science S.A.