One‐Step Crosslinking and Quaternization toward Polystyrene AEMs With Balanced Water Uptake and Swelling for Alkaline Water Electrolysis

ABSTRACT Anion exchange membrane water electrolysis (AEMWE) has great potential for hydrogen production from electrolytic water. However, the low chemical stability and ionic conductivity of the membrane limit its development. In this study, a series of crosslinked AEMs CMPS‐DO‐x were prepared using a simple preparation: quaternization and crosslinking during the membrane formation process. The crosslinked membranes exhibited superior stability and ionic conductivity due to the crosslinked structure restricting the SR as well as the special conformation of quaternization reagent with cage‐like structures, compared with the uncrosslinked membrane quaternized by trimethylamine. All crosslinked membranes showed superior performance, especially CMPS‐DO‐40 showed the optimal comprehensive properties: at 80°C, it had low swelling ratio of 19.4%, moderate water uptake of 61.6%, and high ionic conductivity of 137.6 mS cm ^{− 1} . In addition, it also exhibited strong alkaline stability with a conductivity retention rate of 87.7% after 1128 h in 1 M KOH at 60°C. The AEMWE assembled with this membrane exhibits excellent performance of 2V@5.46 A cm ^{− 2} at 80°C. In addition, the membrane CMPS‐DO‐40 was subjected to AEMWE durability tests at 0.5 A cm ⁻² for 180 h, showing considerable durability and verifying its potential for AEMWE application.