Mara , Muhammad Ikhsan Yang, Chaeyeon Ghotia, Kamal Egert, Franz Ansar, Syed-Asif Żurowska, Olga Rózga,, Maria Michalak, Artur Kraglund, Mikkel Rykær Aili, David Park, Hyun S. Razmjooei, Fatemeh Henkensmeier, Dirk 2025-10-16T11:00:19Z 2025-10-16T11:00:19Z 2025-10-13 2025-11 2058-7546 https://pubs.kist.re.kr/handle/201004/153338 Ion solvating membranes based on polybenzimidazole (PBI) are alternatives to diaphragms in alkaline water electrolysers but can typically only operate with electrolyte concentrations of 15-30 wt% KOH. Sulfonation of the membrane broadens the operational range to 0.1 wt%-30 wt%; however, the swelling of sulfonated para-PBI means that crosslinkers are needed, complicating membrane fabrication and decreasing alkaline stability. Here we report a non-crosslinked PBI membrane with a 50% degree of sulfonation that shows a high room temperature conductivity in 1 M KOH of 135 mS cm-1. We did not observe degradation in a 6-month alkaline stability test at 80 °C. Using this membrane in an anion-exchange membrane water electrolyser, we report a current density of 4.8 A cm-2 at 2 V (3 M KOH at 80 °C; Pt and NiFe electrode catalysts); the H2 crossover to the O2 side remained <2%. Using non-platinum group metal electrodes and a polyphenylene sulfide-reinforced membrane, a cell operated for >1,000 h without failure. 1Center for English NATURE PUBLISHING GROUP Sulfonated polybenzimidazole for low-alkalinity ion solvating membrane water electrolysis Article 10.1038/s41560-025-01876-9 1 Nature Energy, v.10, no.11, pp.1347 - 1359 Nature Energy 10 11 1347 1359 N scie scopus 001591751900001 Energy & Fuels Materials Science, Multidisciplinary Energy & Fuels Materials Science Article CONDUCTIVITY ELECTRODES SEPARATOR