Polybenzimidazole/1H-imidazole-4-sulfonic acid hybrid membranes for high-temperature proton exchange membranes fuel cells

A new sulfonated organic compound, 1H-imidazole-4-sulfonic acid (ImSA), was successfully synthesized. A series of the polybenzimidazole (PBI)/1H-imidazole-4-sulfonic acid hybrid membranes were prepared from an organosoluble, fluorine-containing PBI with ImSA to improve the conductivity of PBI membranes. The introduction of ImSA rendered the plasticizing effect of the PBI membranes with the increase of elongation at break. The conductivity of the phosphoric acid doped PBI/ImSA hybrid membranes increased with both the temperature and the ImSA content. The conductivity of acid doped PBI/ImSA could reach 7 × 10−2 (S/cm) at 160 °C. The addition of ImSA could significantly improve the conductivity, but it slightly reduces the mechanical properties of the pristine PBI membranes.