Pyridine‐based PBI Composite Membranes for PEMFCs

Abstract Polybenzimidazole (PBI) activated with H 3 PO 4 is one of the membranes of choice to replace Nafion® in PEMFCs in order to allow their use above 100 °C. The limits of PBI in terms of acid leaching and low conductivity below 160 °C can be overcome by a proper monomer tailoring, and by the addition of new fillers. Here, we report on new pyridine‐based PBI membranes with: (i) imidazole‐silica (SiO 2 ‐Im) and (ii) mesostructured silica (SBA‐15) fillers. Both the thermal stability and the permanent conductivity are improved by adding 5 wt.‐% of filler, but SiO 2 ‐Im gives the best results. Permanent conductivity values higher than 10 –3 S cm –1 are obtained at 120 °C and 50% R.H. Vibrational spectroscopies (FT‐IR and Raman) are used to investigate the relationships among the polymer, the filler and the activating H 3 PO 4 acid.