Cross-linked anion exchange membranes for alkaline fuel cells synthesized using a solvent free strategy

This article describes the preparation of cross-linked anion exchange membranes (AEMs) using a solvent free strategy. A novel casting solution is formed by dissolving cardo polyetherketone (PEK-C) as an essential polymer intensifier in a mixture of vinylbenzyl chloride (VBC) and divinylbenzene (DVB) monomers without any organic solvent. Tetraethylenepentamine (TEPA) is added to act as a cross-linker between VBC and PKE-C. Polymerization and quaternization are successively implemented to obtain the cross-linked AEMs, whose properties are found to compare well to many referenced AEMs. Apart from improving the compatibility of PEK-C with poly(VBC-co-DVB), TEPA also effectively enhances the charge density, ionic conductivity and alkaline stabilities of the resulting AEMs, whilst simultaneously inhibiting the swelling ratio. The optimal membrane shows an ionic conductivity of 76 mS cm−1 at 70 °C and 100% relative humidity and can remain stable after immersing in 2 mol dm−3 KOH solution for 168 h. A power density of 6 mW cm−2 is achieved in a H2/O2 fuel cell test at 50 °C with an optimal AEM but a non-optimized membrane electrode fabrication process. Generally, the novel method herein highlights an environmentally friendly and economically attractive method for the preparation of AEMs used in alkaline fuel cells.

► Cross-linked AEMs were synthesized using a solvent free strategy. ► Such method is of environment and economic benefits. ► TEPA as a cross-linker greatly improves the membrane properties. ► AEMs herein are suitable for the AEMFCs application.