Abstract A novel amphoteric membrane was prepared using imidazolium-functionalized polysulfone (ImPSf) as the base polymer and sulfonated poly (ether ether ketone) (SPEEK) as the acid polymer for vanadium flow battery applications. The introduction of the ImPSf effectively resists the migration of vanadium ions owing to the Donnan repelling effect of the imidazolium cations on the vanadium ions and the low swelling ratio of the amphoteric membranes due to the ionic cross-linked interactions between the imidazolium and sulfonic groups. The amphoteric membrane with an ImPSf mass ratio of 17% shows a vanadium permeability of 1.5 × 10−8 cm2 s−1 that is much lower than that of Nafion212 (21 × 10−8 cm2 s−1). Having a high IEC of 2.04 mmol g−1, it also exhibits a low area resistance of 0.48 Ω cm−2 that is comparable to that of Nafion212 membrane (0.41 Ω cm−2). As a result, the VFB cell with the amphoteric membrane exhibits high performances even at high current densities, i.e. at a current density of 200 mA cm−2, and the amphoteric membrane achieves a coulombic efficiency of 97.5% and an energy efficiency of 77.3%, both of which are higher than those of Nafion212 (92.4% and 73.4%). These results indicate that the ImPSf/SPEEK amphoteric membrane is promising for VFB applications.

中文翻译：

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一种用于高性能钒氧化还原液流电池的新型咪唑基两性膜

摘要 以咪唑鎓功能化聚砜（ImPSf）为基础聚合物，磺化聚醚醚酮（SPEEK）为酸性聚合物，制备了一种新型的两性膜，用于钒液流电池应用。由于咪唑鎓阳离子对钒离子的唐南排斥作用和由于咪唑鎓和磺酸基团之间的离子交联相互作用导致的两性膜的低溶胀率，ImPSf的引入有效地阻止了钒离子的迁移。ImPSf 质量比为 17% 的两性膜显示钒渗透率为 1.5 × 10−8 cm2 s−1，远低于 Nafion212（21 × 10−8 cm2 s−1）。具有 2.04 mmol g-1 的高 IEC，它还表现出 0.48 Ω cm-2 的低面积电阻，与 Nafion212 膜 (0. 41 Ω cm−2)。因此，具有两性膜的 VFB 电池即使在高电流密度下也表现出高性能，即在 200 mA cm-2 的电流密度下，两性膜实现了 97.5% 的库仑效率和 77.3% 的能量效率，两者均高于 Nafion212（92.4% 和 73.4%）。这些结果表明 ImPSf/SPEEK 两性膜有望用于 VFB 应用。