关键词: 星形交联剂, 聚苯并咪唑微孔膜, 低面电阻, 高离子选择性, 全钒液流电池

Abstract:

All-vanadium flow batteries are essential for long-term energy storage owing to their high power density, intrinsic safety, and the decoupling of capacity and energy. However, commercial applications are hindered by issues such as low energy efficiency and poor cycle stability, which are primarily attributed to the poor ion selectivity of commonly used Nafion membrane materials. To address these limitations, this study prepared a crosslinked sulfonated polybenzimidazole microporous proton exchange membrane (tbt-SP-110) using a star crosslinker. This star crosslinker was introduced into the sulfonated polybenzimidazole membrane to construct an ion transport channel. This channel accelerated proton conduction while containing water molecules to limit the swelling of the membrane material. Combined with the inherently high ion selectivity of polybenzimidazole, this approach facilitates rapid and selective proton transport. Owing to the excellent properties of the developed membrane material, the Coulomb efficiency and energy efficiency reached 99.45% and 79.06%, respectively, at a current density of 250 mA/cm². Under a current density of 200 mA/cm², the capacity retention rate was maintained at 72% after 100 cycles. These results highlight the potential of the membrane for use in high-performance all-vanadium flow batteries.

Key words: star crosslinker, polybenzimidazole microporous film, low surface resistance, high ion selectivity, all-vanadium flow battery