Polymer Electrolyte Fuel Cells Based on Phosphoric Acid-Impregnated Poly(2,5-benzimidazole) Membranes

Preparation and characterization of membranes of poly(2,5-benzimidazole) (ABPBI) (as thin as 20 Mm) for polymer electrolyte
\nmembrane fuel cells are reported. These membranes were prepared by solution casting and then impregnated in phosphoric acid
\nbaths. Their characterization included thermogravimetric analyses, conductivity measurements, Fourier transform infrared spectroscopy,
\nX-ray diffraction, and scanning electron microscopy. These membranes have high thermal stability and good proton
\nconductivity at temperatures up to 200°C (6.2 3 1022 S cm21 at 150°C and 30% relative humidity!, similar to the well-known
\ncommercial polybenzimidazole (PBI). ABPBI membrane-electrode assemblies (MEAs) using commercially available E-TEK Pt/C
\nelectrodes were tested in H2 /O2 cells, obtaining power densities similar to those of PBI MEAs studied here as reference at
\ntemperatures of up to 180°C, humidifying the reactants at room temperature