Synthesis and performance of cross-linked poly(aryl ether nitrile) anion exchange membranes with dense cations and flexible side-chain structures for water electrolysis

Abstract

Anion exchange membranes (AEMs) are the core components in anion exchange membrane water electrolysis (AEMWE), which play crucial role and affect the performance of AEMWE. In this work, a series of cross-linked poly(aryl ether nitrile) anion exchange membranes (CPAEN-dDQA-x) with dense cations and flexible side-chain structures are synthesized. By introducing multiple modification elements into the polymer structure simultaneously, the ion conductivity, dimensional stability, and alkali resistance stability of the prepared AEMs are effectively improved and balanced. The representative CPAEN-dDQA-0.25 showed water absorption of only 27.6 %, swelling rate of 11.2 %, and conductivity of 115.37 mS/cm at 80°C. The IEC and conductivity retention value of CPAEN-dDQA-0.25 after in 2 M NaOH solution at 80°C for 480 h were up to 86.2 % and 82 %, respectively. Meanwhile, the current density of the water electrolysis cell based on CPAEN-dDQA-0.25 is up to 477.0 mA/cm² in 1 M KOH and 2.2 V, and its voltage don’t has significant change after 480 h of operation at a constant current density of 500 mA/cm².