Cho Hyeongrae, Krieg Henning M, Kerres Jochen A
Institute of Chemical Process Engineering, University of Stuttgart, 70199 Stuttgart, Germany.
Faculty of Natural Science, North-West University, Focus Area: Chemical Resource Beneficiation, Potchefstroom 2520, South Africa.
Membranes (Basel). 2018 Jun 19;8(2):33. doi: 10.3390/membranes8020033.
Both cation-exchange membranes and anion-exchange membranes are used as ion conducting membranes in vanadium redox flow batteries (VRFBs). Anion-exchange membranes (AEMs) are applied in vanadium redox flow batteries due to the high blocking property of vanadium ions via the Donnan exclusion effect. In this study, novel anion-exchange blend membranes (AEBMs) were prepared, characterized, and applied in VRFBs. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide), poly[(1-(4,4′-diphenylether)-5-oxybenzimidazole)-benzimidazole] (PBI-OO) and sulfonated polyether sulfone polymer were combined to prepare 3-component AEBMs with 1,2,4,5-tetramethylimidazole (TMIm) for quaternization. 3-component AEBMs showed significantly enhanced chemical and mechanical properties compared with those of 2-component AEBMs, resulting in an improved performance in VRFBs. The compositions of the anion-exchange polymers in 3-component AEBMs were systematically varied to optimize the AEBMs for the redox-flow battery application. While the 3-component AEBMs showed comparable efficiencies with Nafion 212 membranes, they displayed improved vanadium ions cross-over as was confirmed by open circuit voltage tests and capacity fade tests conducted in VRFBs. In addition, one of the synthesized 3-component AEBM had a superior coulombic efficiency and capacity retention in a charging⁻discharging test over 300 cycles at a current density of 40 mA/cm². It can thus be concluded that 3-component AEBMs are promising candidates for long-term operation in VRFBs.
阳离子交换膜和阴离子交换膜都被用作钒氧化还原液流电池（VRFBs）中的离子传导膜。由于通过唐南排斥效应钒离子具有高阻断性，阴离子交换膜（AEMs）被应用于钒氧化还原液流电池。在本研究中，制备、表征了新型阴离子交换共混膜（AEBMs）并将其应用于钒氧化还原液流电池。将溴甲基化聚（2,6 - 二甲基 - 1,4 - 亚苯基氧化物）、聚[（1 - （4,4′ - 二苯醚） - 5 - 氧代苯并咪唑） - 苯并咪唑]（PBI - OO）和磺化聚醚砜聚合物结合，用1,2,4,5 - 四甲基咪唑（TMIm）进行季铵化制备三元AEBMs。与二元AEBMs相比，三元AEBMs的化学和机械性能显著增强，从而在钒氧化还原液流电池中性能得到改善。系统地改变三元AEBMs中阴离子交换聚合物的组成，以优化用于氧化还原液流电池应用的AEBMs。虽然三元AEBMs与Nafion 212膜表现出相当的效率，但通过在钒氧化还原液流电池中进行的开路电压测试和容量衰减测试证实，它们的钒离子渗透有所改善。此外，在40 mA/cm²的电流密度下进行的300次充放电测试中，合成的一种三元AEBM具有优异的库仑效率和容量保持率。因此可以得出结论，三元AEBMs是钒氧化还原液流电池长期运行的有前途的候选材料。
