Polyarylmethylpiperidinium (PAMP) for Next Generation Anion Exchange Membranes

Abstract

Terawatt-scale hydrogen production using anion exchange membrane water electrolyzers (AEM-WEs) requires the development of facilely prepared, alkali-stable, and high-performance anion exchange membranes (AEMs). State-of-the-art polyarylpiperidinium AEMs fail to match the alkaline stability of piperidinium due to conformational deformation caused by the stiff cardo structure. Herein, polyarylmethylpiperidinium (PAMP) AEM with pendant structure is constructed by utilizing 4-formylpiperidine as a functional monomer. The inclusion of an aldehyde group in the synthesis enhances polymerization reactivity, reduces the amount of superacid required, and ensures that the piperidinium is suspended from the ether-free polymer backbone. The accelerated aging analysis demonstrates that the pendant structure of piperidinium effectively suppresses the Hofmann elimination, resulting in PAMP AEM with exceptional alkali stability, surpassing that of the commercial PiperION-A40. Most importantly, when assembled with non-noble metal OER/HER catalysts, the related AEM-WE achieves a remarkably high transient current density of 7.35 A cm−2 (@2 V, 80 °C, 1 m KOH). Moreover, the AEM-WE can operate stably at industrial current density over 1500 h (≈1.70 V at 1.0 A cm−2).