Ye Chunchun, Wang Anqi, Breakwell Charlotte, Tan Rui, Grazia Bezzu C, Hunter-Sellars Elwin, Williams Daryl R, Brandon Nigel P, Klusener Peter A A, Kucernak Anthony R, Jelfs Kim E, McKeown Neil B, Song Qilei
Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK.
EaStCHEM, School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
Nat Commun. 2022 Jun 8;13(1):3184. doi: 10.1038/s41467-022-30943-y.
Redox flow batteries using aqueous organic-based electrolytes are promising candidates for developing cost-effective grid-scale energy storage devices. However, a significant drawback of these batteries is the cross-mixing of active species through the membrane, which causes battery performance degradation. To overcome this issue, here we report size-selective ion-exchange membranes prepared by sulfonation of a spirobifluorene-based microporous polymer and demonstrate their efficient ion sieving functions in flow batteries. The spirobifluorene unit allows control over the degree of sulfonation to optimize the transport of cations, whilst the microporous structure inhibits the crossover of organic molecules via molecular sieving. Furthermore, the enhanced membrane selectivity mitigates the crossover-induced capacity decay whilst maintaining good ionic conductivity for aqueous electrolyte solution at pH 9, where the redox-active organic molecules show long-term stability. We also prove the boosting effect of the membranes on the energy efficiency and peak power density of the aqueous redox flow battery, which shows stable operation for about 120 h (i.e., 2100 charge-discharge cycles at 100 mA cm) in a laboratory-scale cell.
使用水基有机电解质的氧化还原液流电池是开发具有成本效益的电网规模储能装置的有前途的候选者。然而，这些电池的一个显著缺点是活性物质通过膜的交叉混合，这会导致电池性能下降。为克服这一问题，我们在此报告通过对基于螺二芴的微孔聚合物进行磺化制备的尺寸选择性离子交换膜，并展示其在液流电池中的高效离子筛分功能。螺二芴单元允许控制磺化程度以优化阳离子传输，而微孔结构通过分子筛作用抑制有机分子的交叉。此外，增强的膜选择性减轻了交叉引起的容量衰减，同时在pH 9的水性电解质溶液中保持良好的离子电导率，在该条件下氧化还原活性有机分子表现出长期稳定性。我们还证明了这些膜对水性氧化还原液流电池的能量效率和峰值功率密度的提升作用，该电池在实验室规模的电池中可稳定运行约120小时（即100 mA cm下2100次充放电循环）。
