A Strategy to Overcome the Trade-Off between Conductivity and Swelling Ratio in Poly(aryl piperidinium) Anion Exchange Membranes

The successful preparation of anion exchange membranes (AEMs) with outstanding hydroxide ion (OH – ) conductivity, low swelling ratio, and superior alkali stability is crucial for anion exchange membrane water electrolysis (AEMWE). Herein, a series of high-performance AEMs were favorably synthesized by introducing both hydrophobic groups and large-volume twisted binaphthyl (BN) units into the main chain of poly(aryl piperidinium) (PAP). The incorporation of hydrophobic groups significantly reduces membrane swelling. The continued introduction of BN units constructs a high-speed channel for OH – transport. Additionally, density functional theory revealed that the incorporation of BN protected piperidine cationic groups from Hoffmann elimination. The prepared QBNTP-10 AEM displayed ultrahigh OH – conductivity (190.2 mS cm – 1 at 80 °C), coupled with favorable dimensional stability (17.9% at 80 °C), tensile strength (52.18 MPa), and excellent alkaline stability (OH – conductivity retention was 93.6% at 80 °C for 1000 h in 1 M NaOH). Due to these excellent properties, QBNTP-10 AEM was assembled in an AEMWE cell, which maintained long-term stable operation for 1000 h in 1 M KOH at 80 °C. Therefore, this study provides a reference for enhancing the ion transport capacity and alkali stability of AEMs.