Mechanically robust and chemically stable poly(aryl piperidinium)-SBS copolymer anion exchange membranes for 3000-h durable alkaline water electrolyzers

Abstract

Anion exchange membrane (AEM) is a core component of potentially more efficient and cost-effective anion exchange membrane water electrolyzers (AEMWEs), which combine the advantages of traditional alkaline water electrolyzers (AWEs) and proton exchange membrane water electrolyzers (PEMWEs). Despite extensive research efforts in recent years, AEMs still face significant challenges, particularly insufficient alkaline stability and limited dimensional/mechanical stability. In this work, we enhanced the mechanical and alkaline stability of AEMs by incorporating the thermoplastic elastomer polystyrene-block-polybutadiene-block-polystyrene (SBS) into the poly (terphenyl piperidinium) (PTP) matrix. The optimal PTP-SBS-2.5 ​% membrane exhibits outstanding dimensional stability (9.4 ​% swelling at 20 ​°C), robust mechanical properties (tensile strength of 51.5 ​MPa and elongation of 63.1 ​% at break in wet state), low alkali absorption (0.875 ​%) and exceptional alkaline stability (92.4 ​% conductivity retention after 1500 ​h). Notably, the membrane demonstrates stable operation in AEMWE for over 3000 ​h with a low voltage decay rate of 41.1 ​μV ​h⁻¹. These results highlight the significance of SBS in enhancing both the alkaline stability and mechanical performance of PTP-based AEMs.