Dual skeleton network in situ-construction of alkaline anion-exchange membrane for boosting water electrolysis at low concentration of alkaline solution

Abstract

As the core component of anion-exchange membrane water electrolysis (AEMWE), the search for AEM with high conductivity and good stability is particularly pursued. In this work, we report the synthesis of a series of anion-exchange membranes (PCG-GA@V-CS) with polyvinyl alcohol (PVA) and chitosan (CS) as a dual skeleton followed by the introduction of quaternary ammonium guar hydroxypropyltrimethylammonium chloride (CG) as an anion-exchange moiety. By in-situ conduction with glutaraldehyde (GA) as cross-linking agent, the PCG-GA₂@V-CS anion-exchange membrane featuring cross-transfer dual network structure was successfully established, which manifests good ionic conductivity (19.8 mS cm⁻¹), ion mobility number (0.89), dimensional stability, and mechanical property (15.99 MPa in fully hydrated). Under low concentration alkaline conditions, the PCG-GA₂@V-CS membrane displays a high current density of 550 mA cm⁻² @ 2.0 V at 80 °C in AEMWE when coupled by nickel mesh catalytic electrode. Notably, the PCG-GA₂@V-CS membrane can conduct AEMWE in 1 M KOH with a stable operation for more than fifty hours, which largely surpasses the FAB-PK-130 under the same conditions. This work provides a novel methodology for PVA-based anion-exchange membrane by coupling double skeleton regulation and in-situ cross-linking technique for boosting AEMWE at low concentration of alkaline solution.