Structural and Thermal Analysis and Membrane Characteristics of Phosphoric Acid-doped Polybenzimidazole/Strontium Titanate Composite Membranes for HT-PEMFC Applications

A series of novel PBI/SrTiO 3 nanocomposite membranes composed of polybenzimidazole (PBI) and strontium titanate (SrTiO 3 ) with a perovskite structure were fabricated with various concentrations of SrTiO 3 through a solution casting method. Various characterization techniques such as proton nuclear magnetic resonance, thermogravimetric analysis, atomic force microscopy (AFM) and AC impedance spectroscopy were used to investigate the chemical structure, thermal, phosphate absorption and morphological properties, and proton conductivity of the fabricated nanocomposite membranes. The optimized PBI/SrTiO 3 -8 polymer nanocomposite membrane containing 8wt% of SrTiO 3 showed a higher proton conductivity of 7.95 × 10 -2 S/cm at 160℃ compared to other nanocomposite membranes. The PBI/SrTiO 3 -8 composite membrane also showed higher thermal stability compared to pristine PBI. In addition, the roughness change of the polymer composite membrane was also investigated by AFM. Based on these results, nanocomposite membranes based on perovskite structures are expected to be considered as potential candidates for high-temperature PEM fuel cell applications.