A novel permselective branched sulfonated polyimide membrane containing crown ether with remarkable proton conductance and selectivity for application in vanadium redox flow battery

• Published in: Journal of membrane science 2023-03, Vol.669, p.121343, Article 121343
• Main Authors: Long, Jun, Huang, Wenheng, Li, Jingfeng, Yu, Yafei, Zhang, Bo, Li, Jinchao, Zhang, Yaping, Duan, Hao
• Format: Article
• Language: English
• Subjects: Branched sulfonated polyimide; Crown ether; Membrane; Vanadium redox flow battery
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2022.121343

As a key component of vanadium redox flow battery (VRFB), the ideal membrane with high proton conductance together with high vanadium ions resistance is urgently required. In this work, a permselective monomer di(aminobenzo)-18-crown-6 with proper aperture of 0.26–0.32 nm is synthesized to prepare branched sulfonated polyimide containing crown ether (ce-bSPI-x) membranes. In virtue of the excellent balance between vanadium ions resistance and proton conductance, the ce-bSPI-60 membrane possesses the optimum physico-chemical properties among all ce-bSPI-x membranes. Subsequently, in comparison with commercial Nafion 212 membrane, the ce-bSPI-60 membrane demonstrates higher coulomb efficiencies (CEs) (96.50%–99.39%) and energy efficiencies (EEs) (69.36%–85.45%). Furthermore, the ce-bSPI-60 membrane can achieve 80% of EE at 140 mA cm−2, which is in a superior position compared with other SPI-based membranes reported in recent years. 1000-time cycles at 140 mA cm−2 without obvious structural and morphological changes proves the excellent durability of ce-bSPI-60 membrane. To sum up, the as-prepared ce-bSPI-60 membrane exhibits a great potential to match the demand of application in VRFB. [Display omitted] •A di(aminobenzo)-18-crown-6 monomer with proper aperture is self-synthesized.•The proper crown ether structure is introduced into ce-bSPI-x membranes for VRFB.•The ce-bSPI-60 membrane shows remarkable proton conductance and selectivity.•VRFB with ce-bSPI-60 membrane exhibits excellent efficiencies and long life.