With high scalability and independent control over energy and power, redox flow batteries (RFBs) stand out as an important large-scale energy storage system. However, the widespread application of conventional RFBs is limited by the uncompetitive performance, as well as the high cost and environmental concerns associated with the use of metal-based redox species. In consideration of advantageous features such as potentially low cost, vast molecular diversity, and highly tailorable properties, organic and organometallic molecules emerge as promising alternative electroactive species for building sustainable RFBs. This review presents a systematic molecular engineering scheme for designing these novel redox species. We provide detailed synthetic strategies for modifying the organic and organometallic redox species in terms of solubility, redox potential, and molecular size. Recent advances are then introduced covering the reaction mechanisms, specific functionalization methods, and electrochemical performances of redox species classified by their molecular structures. Finally, we conclude with an analysis of the current challenges and perspectives on future directions in this emerging research field.

中文翻译：

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用于氧化还原液流电池的有机电活性材料的分子工程

氧化还原液流电池（RFB）具有高度的可扩展性和对能量和电源的独立控制，是重要的大型能量存储系统。但是，常规RFB的广泛应用受到性能不佳以及与使用金属基氧化还原物质相关的高成本和环境问题的限制。考虑到诸如潜在的低成本，巨大的分子多样性和高度可定制的特性的有利特征，有机和有机金属分子作为用于构建可持续的RFB的有希望的替代电活性物质出现。这篇综述提出了用于设计这些新颖的氧化还原物质的系统的分子工程方案。我们提供了详细的合成策略，用于根据溶解度来修改有机和有机金属氧化还原物质，氧化还原电位和分子大小。然后介绍了最新的进展，涵盖了根据其分子结构分类的氧化还原物质的反应机理，特定的功能化方法和电化学性能。最后，我们以对这一新兴研究领域的当前挑战和对未来方向的看法的分析作为结尾。