Aromatic polyelectrolytes via polyacylation of pre-quaternized monomers for alkaline fuel cells

Abstract

To overcome alkali-resistant and synthetic hurdles to alkaline anion-exchange membranes (AAEMs) for alkaline fuel cells, the polyacylation of pre-quaternized monomers as a straightforward and versatile approach has been proposed for the first time. Via this approach, novel aromatic anion-exchange polyelectrolytes featuring a long pendent spacer (i.e., –O–(CH₂)₄–) instead of a conventional benzyl-type spacer (i.e., –CH₂–) are successfully synthesized, and exhibit not only high OH⁻ and CO₃²⁻ conductivity (91 mS cm⁻¹ and 51 mS cm⁻¹ at 60 °C, respectively) but also outstanding alkaline stability (e.g., no degradation of ammonium groups after aging in 6 mol dm⁻³ NaOH at 60 °C for 40 days). Using this kind of AAEM, a promising peak power density of 120 mW cm⁻² is obtained on a preliminary H₂/O₂ single cell at 50 °C. This powerful synthetic approach together with exceptional membrane properties should pave the way to the practical application of this kind of AAEMs in alkaline fuel cells.