Self-crosslinked alkaline electrolyte membranes based on quaternary ammonium poly (ether sulfone) for high-performance alkaline fuel cells

Novel self-crosslinked alkaline electrolyte membranes with high hydroxide ion conductivity, excellent dimensional stability and extraordinary solvent resistance stability are synthesized successfully without using any catalyst or separate crosslinker. Monitored by 1H NMR analysis, the synthetic process of trimethyl poly (ether sulfone)-methylene quaternary ammonium hydroxide (TPQAOH) is found to be simple and efficient. The chemical and thermal stability of the synthetic SCL-TPQAOH-x membranes are better than other anion exchange membranes. At the same time, the hydroxide ion conductivity of SCL-TPQAOH-0.67 membrane reaches 33 mS cm−1 with an IEC value of 1.07 mmol g−1 at 80 °C, which complies with the requirements of alkaline fuel cells. This investigation also proves that self-crosslinking technology is a very simple and effective approach in improving the performance of alkaline electrolyte membranes.

► We prepared a class of CH3- substituted PES with –CH2- group in the polymer backbone. ► Self-crosslinking membranes were obtained by simple heating method. ► The resulting membranes exhibited ultra-low swelling ratio and great stability. ► The membranes showed appropriate hydroxide ion conductivity with great durability.