The effect of acid doping on the conductivity of polybenzimidazole (PBI)

Protonic conductivity of polybenzimidazole (PBI) in various electrolytes was systematically studied. Blank PBI and PBI used in a proton exchange fuel cell showed the same level of conductivity when measured in an acid electrolyte. After doping in sulphuric acid, hydrochloric acid, ammonia and phosphoric acid protonic conductivity was increased, the level depending on the type of doping acid agent and its concentration. Highest conductivity was shown for PBI doped with 16 mol/L sulphuric acid. PBI doped with 11.6 mol/L HClO{sub 4} and measured in 2 mol/L HClO{sub 4} was shown to be relatively high and of potential interest for methanol oxidation in HClO{sub 4}. Consequently, HClO{sub 4}-doped BPI is a promising candidate for methanol fuel cell applications. 29 refs., 3 tabs., 8 figs.