High-temperature polymer electrolyte membranes: Proton conductivity and performance of polybenzimidazole/Ti0.9Mn0.1P2O7

Abstract

Polymer electrolyte membranes have proven to be highly successful in creating efficient, emission-free fuel cells, but their low-temperature limitation restricts full potential utilization. To address this issue, in the present work, polybenzimidazole (PBI)/Ti_0.9Mn_0.1P₂O₇ (TMP) inorganic-organic composite membranes were fabricated, and their morphological and structural characterizations were performed. Before testing, all membranes were loaded with phosphoric acid. The resulting PBI/TMP composite membrane has a higher proton conductivity of 212.3 mS cm⁻¹ and activation energy ⁓ 5.49 kJ mol⁻¹ as compared to the pristine PBI membrane with protonic conductivity 102.7 mS cm⁻¹ and activation energy ⁓ 1.24 kJ mol⁻¹. The PBI/TMP membrane can function effectively up to 180 °C, achieving a maximum peak power density of 376 mW cm⁻² at the current density of 1120 mA cm⁻² with the open circuit potential ⁓0.940 V. The inclusion of TMP significantly enhances overall cell performance compared to pristine PBI, where the peak power density of 364 mW cm⁻² and current density of 958 mA cm⁻² at 180 °C were obtained with an open circuit potential of 0.819 V. This study revealed successfully the potential of PBI/TMP composite membranes for their application in high-temperature proton exchange membrane fuel cells.