A new type of sulfonated polyimide membrane (6f-abSPI) containing benzimidazole group and trifluoromethyl group (-CF) is synthesized by one-step copolymerization. The 6f-abSPI-60 membrane with the highest ion selectivity is selected and applied to all vanadium redox flow battery (VRFB). Compared with Nafion 212 (N212) membrane and 6f-SPI-60 membrane, the vanadium ion permeability of 6f-abSPI-60 membrane (1.78 × 10 cm min) is 1/13 lower than that of N212 membrane (2.33 × 10 cm min) and 1/2 lower than 6f-SPI-60 membrane (3.60 × 10 cm min). At the same time, the 6f-abSPI-60 membrane (2.69 × 10 S min cm) has significant selectivity, which is 5.6 times higher than N212 membrane (0.48 × 10 S min cm). In VRFB tests, the coulombic efficiency (CE) of 6f-abSPI-60 membrane (98.88 %) is significantly higher than that of N212 membrane (92.99 %) and 6f-SPI-60 membrane (97.65 %) at 100 mA cm, and the energy efficiency (EE) also reaches a higher value (77.29 %). Additionally, the VRFB equipped with the 6f-abSPI-60 membrane exhibits consistent and reliable performance throughout the 100 cycles of charging and discharging at the current densities of 100 mA cm. The good stability of 6f-abSPI membranes is explained by calculating C atoms’ natural bond orbital (NBO) charges on different polyimide (PI) rings.

中文翻译：

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钒氧化还原液流电池用低钒离子透过性含咪唑环磺化聚酰亚胺

采用一步共聚法合成了一种含有苯并咪唑基团和三氟甲基（-CF）的新型磺化聚酰亚胺膜（6f-abSPI）。选用离子选择性最高的6f-abSPI-60膜，应用于全钒氧化还原液流电池（VRFB）。与Nafion 212（N212）膜和6f-SPI-60膜相比，6f-abSPI-60膜（1.78×10 cm·min）的钒离子透过率比N212膜（2.33×10 cm·min）低1/13 ），比 6f-SPI-60 膜（3.60 × 10 cm 分钟）低 1/2。同时，6f-abSPI-60膜（2.69×10 S min cm）具有显着的选择性，比N212膜（0.48×10 S min cm）高5.6倍。在VRFB测试中，在100 mA cm下，6f-abSPI-60膜的库仑效率（CE）（98.88％）显着高于N212膜（92.99％）和6f-SPI-60膜（97.65％），并且能源效率（EE）也达到了更高的值（77.29%）。此外，配备6f-abSPI-60膜的VRFB在100 mA cm的电流密度下的100个充电和放电循环中表现出一致和可靠的性能。通过计算不同聚酰亚胺（PI）环上C原子的自然键轨道（NBO）电荷来解释6f-abSPI膜的良好稳定性。