A novel fluorinated acid-base sulfonated polyimide membrane (s-f-SPI) with trifluoromethyl (-CF₃), side-chain-type-SO₃H and benzimidazole groups was synthesized by a 2-step method for vanadium redox flow battery applications. A series of physico-chemical properties of s-f-SPI membrane were researched systematacially. The acid-base pairs between the side-chain-type -SO₃H and protonated imidazole groups provided more channels for proton-transport, enhancing the proton conductivity (0.51×10⁻¹ S cm⁻¹ at ∼25 °C), and Donnan effect of the imidazole groups impeded the penetration of vanadium-ion (3.95×10⁻⁷ cm² min⁻¹). In VRFB tests, s-f-SPI membrane exhibited a coulombic efficiency (CE) of 98.1% and an energy efficiency (EE) of 81.2% at a current density of 100 mA cm⁻², higher than those of Nafion 212 (CE: 94.1%, EE: 76.5%). Furthermore, the VRFB with s-f-SPI membrane showed a stable performance in the 500 cycles charging-discharging test at 100 mA cm⁻², and the morphology and structure remained unchanged after the cycle test. These results demonstrate that the s-f-SPI membrane has great potential for VRFB applications.

通过两步法合成了一种具有三氟甲基 (-CF ₃ )、侧链型-SO ₃ H 和苯并咪唑基团的新型氟化酸碱磺化聚酰亚胺膜 (sf-SPI)，用于钒氧化还原液流电池应用。系统地研究了sf-SPI膜的一系列理化性质。侧链型-SO ₃ H 和质子化咪唑基团之间的酸碱对为质子传输提供了更多通道，提高了质子电导率（0.51×10 ^-1 S cm ^-1在~25°C），和咪唑基团的唐南效应阻碍了钒离子的渗透（3.95×10 ^-7 cm ² min ^-1）。在 VRFB 测试中，sf-SPI 膜在 100 mA cm ^-2的电流密度下表现出 98.1% 的库仑效率 (CE) 和 81.2% 的能量效率 (EE) ，高于 Nafion 212 (CE: 94.1%) , EE: 76.5%)。此外，带有sf-SPI膜的VRFB在100 mA cm ^-2的500次循环充放电试验中表现出稳定的性能，循环试验后形貌和结构保持不变。这些结果表明 sf-SPI 膜在 VRFB 应用中具有巨大的潜力。