A novel side-chain-type fluorinated sulfonated polyimide (s-FSPI) membrane is synthesized for vanadium redox batteries (VRBs) by high-temperature polycondensation and grafting reactions. The s-FSPI membrane has a vanadium ion permeability that is over an order of magnitude lower and has a proton selectivity that is 6.8 times higher compared to those of the Nafion 115 membrane. The s-FSPI membrane possesses superior chemical stability compared to most of the linear sulfonated aromatic polymer membranes reported for VRBs. Also, the vanadium redox flow/static batteries (VRFB/VRSB) assembled with the s-FSPI membranes exhibit stable battery performance over 100- and 300-time charge–discharge cycling tests, respectively, with significantly higher battery efficiencies and lower self-discharge rates than those with the Nafion 115 membranes. The excellent physicochemical properties and VRB performance of the s-FSPI membrane could be attributed to the specifically designed molecular structure with the hydrophobic trifluoromethyl groups and flexible sulfoalkyl pendants being introduced on the main chains of the membrane. Moreover, the cost of the s-FSPI membrane is only one-fourth that of the commercial Nafion 115 membrane. This work opens up new possibilities for fabricating high-performance proton-conductive membranes at low costs for VRBs.

中文翻译：

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一种低成本，高性能的钒氧化还原液流/静态电池磺化聚酰亚胺质子传导膜

通过高温缩聚和接枝反应，合成了用于钒氧化还原电池（VRBs）的新型侧链式氟化磺化聚酰亚胺（s-FSPI）膜。s-FSPI膜的钒离子渗透性比Nafion 115膜低了一个数量级，质子选择性高6.8倍。与报告用于VRB的大多数线性磺化芳族聚合物膜相比，s-FSPI膜具有卓越的化学稳定性。此外，与s-FSPI膜组装的钒氧化还原液流/静态电池（VRFB / VRSB）分别在100次和300次充放电循环测试中表现出稳定的电池性能，电池效率显着提高，自放电率更低费率要高于使用Nafion 115膜的费率。s-FSPI膜的出色的理化性质和VRB性能可以归因于专门设计的分子结构，其中疏水性三氟甲基和柔性磺烷基侧基被引入到膜的主链上。而且，s-FSPI膜的成本仅为商业Nafion 115膜的四分之一。这项工作为VRB的低成本制造高性能质子传导膜开辟了新的可能性。s-FSPI膜的成本仅为商用Nafion 115膜的四分之一。这项工作为VRB的低成本制造高性能质子传导膜开辟了新的可能性。s-FSPI膜的成本仅为商用Nafion 115膜的四分之一。这项工作为VRB的低成本制造高性能质子传导膜开辟了新的可能性。