Microporous and low swelling branched poly(aryl piperidinium) anion exchange membranes for high-performed water electrolyzers

The Development of high-efficiency anion exchange membrane water electrolyzers (AEMWEs) depends on a well-designed anion exchange membrane (AEM) that possesses good mechanical robustness, high alkaline stability, and enhanced ionic conductivity. Herein, we use tetraphenylmethane as a branched monomer to create AEMs with branched structure based upon poly(aryl piperidinium)s. When five molar percentage of tetraphenylmethane is incorporated, the quaternized poly(p-terphenyl-tetraphenylmethane-piperidinium) membrane (QPTTP-5%) exhibits low water swelling ratio (8.53% at 80 °C) and decent mechanical strength (31.95 MPa). Meanwhile, the high microporosity and obvious microphase separation behavior of the as-developed QPTTP-5% membrane engendered by the rigid and tetrahedral tetraphenylmethane branched structure improve hydroxide conductivity, reaching 164.70 mS cm−1 at 80 °C. Moreover, the current density of the AEMWE single cell comes up to 1500 mA cm−2 at 2.2 V and 80 °C with the implementation of QPTTP-5% membrane. This study reveals that the introduction of a rigid and three-dimensional branched structure is conducive to the preparation of high-performance AEMs with microporous structure and low swelling ratio.