Poly(2,5-benzimidazole)/trisilanolphenyl POSS composite membranes for intermediate temperature PEM fuel cells

Abstract

Novel organic-inorganic composites were in-situ synthesized by using TriSilanolPhenyl polyhedral oligomeric silsesquioxane (SO-POSS) as fillers and poly(2,5-benzimidazole) (ABPBI) as polymer matrix. The uniformly dispersed 3% SO-POSS particles in ABPBI matrix increased the thermal stability of the composite membranes. It was found that both the water and H3PO4 uptakes were increased significantly with the addition of SO-POSS due to the formation of hydrogen bonds between the POSS and H2O/H3PO4, which played a critical role in the improvement of the conductivity of the composite membranes at temperature over 100 °C. Proton conductivities of H3PO4 doped with 3wt% SO-POSS contained ABPBI membranes increased with the increase of H3PO4 absorbance, reaching the maximum proton conductivity of 2.55 × 10-3 S·cm-1 at 160 °C, indicating that the ABPBI/SO-POSS composite membrane could be a promising candidate for mid-temperature PEMFCs.