Diamine crosslinked anion exchange membranes based on poly(vinyl benzyl methylpyrrolidinium) for alkaline water electrolysis

Abstract New chemically crosslinked anion exchange membranes are prepared for water electrolysis based on high ion conductive poly(vinyl benzyl methylpyrrolidinium) and rigid polysulfone. Eight bifunctional tertiary amines are screened as crosslinking agents to optimize the properties of membranes. The fabricated crosslinked membranes exhibit excellent chemical resistance towards radicals, and meanwhile possess improved decreased swelling, enhanced mechanical stability, suitable conductivity and improved alkali resistance stability. As typical candidates, membranes crosslinked by N,N,N′,N′-tetramethyl-1,6-hexanediamine, 4,4′-trimethylene-bis(1-methylpiperidine) and 1,4-bis(2-methylimidazol-1-yl)butane are down-selected for water electrolysis in 1 M KOH at 80 °C, and display current densities of 500 mA cm−2, 400 mA cm−2 and 600 mA cm−2 at 1.9 V using nickel alloys as electrodes without ionomer, respectively. Furthermore, the durability profile for the cell over one week at 500 mA cm−2 illustrates the potential of membranes working in mildly alkaline conditions.