A comprehensive study on the stability and ion transport in cross-linked anion exchange membranes based on polysulfone for solid alkaline fuel cells

Abstract

Anion exchange membranes were prepared based on polysulfone and functionalized by trimethylamine and N,N,N′,N′-tetramethyl-1,6-hexanediamine using chloromethylation, amination and alkalization steps. N,N,N′,N′-tetramethyl-1,6-hexanediamine with a long alkyl chain has integrated crosslinking and amination processes into a single step and enhances psychochemical properties of the membranes. 1HNMR, FTIR, TGA and DCS analysis were done besides mechanical strength and alkaline stability studies to characterize membranes comprehensively. The prepared membranes exhibited through plane ionic conductivity of 2–42 mS/cm at 25–80 °C in different relative humidities. The ion exchange capacities, anion transport numbers and hydration numbers were within the range of 1.6–2.1 mmol/g, 0.95–0.98 and 9–16, respectively. Furthermore, the membranes showed acceptable water uptake and swelling ratio at different temperatures. A single H2/O2 fuel cell test was carried out at 60 °C which resulted in an open circuit voltage of 1.05 V and maximum power density of 110 mW/cm2 at current density of 195 mA/cm2. Based on the experiments, it can be inferred that suitable proportions of amination and crosslinking agents, could lead to the membranes with well-balanced performance between ion transport and stability. Regarding the improved electrochemical and physicochemical properties, these anion exchange membranes are proposed as a good candidate for solid alkaline fuel cells.