High hydroxide conductive and alkaline stable poly(vinyl benzyl chloride) cross-linked poly(aryl piperidinium) anion exchange membrane for fuel cell applications

Fuel cells are a promising alternative for clean energy conversion, with anion exchange membrane fuel cells standing out due to their ability to employ less expensive non-platinum group metal catalysts. Although, they can outperform proton exchange membrane fuel cells, their chemical instability and poor hydroxide conductivity hinder the commercialization. Therefore, the development of anion exchange membranes with excellent hydroxide conductivity and physicochemical stability is essential. In this study, anion exchange membranes based on poly(meta/para terphenylene methyl piperidinium) cross-linked with poly(vinyl benzyl chloride) were prepared by a solution casting method. The effect of cross-linking on membrane stability and electrochemical performance was systematically investigated. Notably, the cross-linked membrane containing 20 wt% poly(vinyl benzyl chloride) exhibited the highest hydroxide ion conductivity of 152.2 mS cm⁻¹ at 90 °C, more than double that of the uncross-linked membrane. Furthermore, a hydrogen-oxygen fuel cell using this membrane achieved a peak power density of 388.9 mW cm⁻² at 60 °C. The membrane also retained 85.5 % of its conductivity after 500 h of alkaline treatment at 60 °C. These results highlight the strong potential of the cross-linked membrane for use in next-generation anion exchange membrane fuel cells.