Fast Bulky Anion Conduction Enabled by Free Shuttling Phosphonium Cations

• Published in: Research (Washington) 2021, Vol.2021, p.9762709-9762709
• Main Authors: Ge, Xiaolin, He, Yubin, Zhang, Kaiyu, Liang, Xian, Wei, Chengpeng, Shehzad, Muhammad A., Song, Wanjie, Ge, Zijuan, Li, Geng, Yu, Weisheng, Wu, Liang, Xu, Tongwen
• Format: Article
• Language: English
• ISSN: 2639-5274; 2639-5274
• DOI: 10.34133/2021/9762709

Highly conductive anion-exchange membranes (AEMs) are desirable for applications in various energy storage and conversion technologies. However, conventional AEMs with bulky HCO 3 - or Br - as counterion generally exhibit low conductivity because the covalent bonding restrains the tethered cationic group’s mobility and rotation. Here, we report an alternative polyrotaxane AEM with nontethered and free-shuttling phosphonium cation. As proved by temperature-dependent NMR, solid-state NMR, and molecular dynamics simulation, the phosphonium cation possesses a thermally trigged shuttling behavior, broader extension range, and greater mobility, thus accelerating the diffusion conduction of bulky anions. Owing to this striking feature, high HCO 3 - conductivity of 105 mS cm -1 at 90°C was obtained at a relatively lower ion-exchange capacity of 1.17 mmol g -1 . This study provides a new concept for developing highly conductive anion-exchange membranes and will catalyze the exploration of new applications for polyrotaxanes in ion conduction processes.