Redox flow batteries (RFBs) have attracted researchers due to their decoupled nature of energy and power modulations, suitability for large-scale stationary energy storage, and integration of renewable intermittent energy sources such as solar and wind power. Water’s narrow electrochemical stability window limits the energy density of aqueous redox flow batteries. Thus, a shift to non-aqueous organic redox flow batteries (NAORFBs) is necessary to achieve high energy density while benefiting from organic solvents’ expansive electrochemical stability windows. Nonetheless, the degradation and crossover of organic electroactive materials cause rapid capacity loss in NAORFBs. To improve the cycling stability of NAORFBs, molecular engineering is required to enhance the stability of redox-active species, particularly charged species, and the solubility of redox-active species. An appropriate ion-selective membrane that mitigates crossover by selectively allowing the passage of ions of supporting salts needs to be developed. This review discusses molecular design strategies that may improve radical ion stability, increase the solubility of redox-active species, and reduce redox-active species crossover and the selection of appropriate supporting electrolytes and separators/membranes for the overall enhancement of the cycle life and performance.

中文翻译：

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分子工程、支持电解质和膜选择增强非水性有机氧化还原液流电池循环稳定性：综述


氧化还原液流电池 （RFB） 因其能量和功率调制的解耦性质、适用于大规模固定储能以及太阳能和风能等可再生间歇性能源的集成而吸引了研究人员。水的电化学稳定性窗口狭窄，限制了水性氧化还原液流电池的能量密度。因此，必须转向非水性有机氧化还原液流电池 （NAORFB） 以实现高能量密度，同时受益于有机溶剂广泛的电化学稳定性窗口。尽管如此，有机电活性材料的降解和交叉会导致 NAORFBs 的快速容量损失。为了提高 NAORFB 的循环稳定性，需要分子工程来增强氧化还原活性物质（尤其是带电物质）的稳定性以及氧化还原活性物质的溶解度。需要开发一种合适的离子选择性膜，通过选择性地允许支持盐的离子通过来减轻交叉。本文讨论了可能提高自由基离子稳定性、增加氧化还原活性物质溶解度、减少氧化还原活性物质交叉的分子设计策略，以及选择合适的支持电解质和隔膜/膜，以全面提高循环寿命和性能。