中性水系有机液流电池正极电解质的研究进展

Research progress on positive electrolytes for neutral aqueous organic redox flow battery

中性水系有机液流电池是一种采用在中性条件下水溶性的有机电活性材料作为电解质,通过其可逆氧化还原过程实现能量的存储和释放的电化学储能技术,具有成本低廉、性能易于调控、操作安全性高等优势,在可再生能源的规模化并网和智能化分配方面显示出巨大的应用潜力。本文结合中性水系液流电池的研究现状,对基于二茂铁衍生物与TEMPO衍生物的正极电解质的发展现状、面临的主要挑战和未来发展方向进行了详细的综述和讨论,全面总结并比较了二茂铁衍生物与TEMPO衍生物的改性策略以及作为水系有机液流电池正极电解质的发展前景。相比之下,TEMPO衍生物在电极电势、溶解度、电池容量等方面都有着显著优势,被认为更具发展前景,但其长期循环稳定性略显不足。在已提出的诸多改性措施中,增大空间位阻与静电排斥是两大典型的策略。本文通过对TEMPO衍生物降解机理的分析总结,发现其降解主要是氮氧基键受到质子攻击断裂导致,笔者认为在TEMPO环上引入保护基团有望成为进一步提高其结构稳定性的新策略。

Neutral aqueous organic redox flow batteries(AORFB)are a promising electrochemical energy storage technology owing to their low cost,easy performance regulation,and high operational safety.The technology uses water-soluble electromechanical active materials as electrolytes to store and release energy through their reversible oxidation-reduction process under neutral conditions.Their excellent properties make them highly suitable for large-scale grid connection and intelligent distribution in the renewable energy sector.Drawing on current research on neutral AORFBs,this comprehensive review summarizes the development status,main challenges,and future development direction of positive electrolytes based on ferrocene derivatives and TEMPO derivatives.The modification strategies of ferrocene derivatives and TEMPO derivatives and the development prospects as cathode electrolytes for AORFB are comprehensively summarized and compared.By contrast,TEMPO derivatives have several advantages,such as high redox electrode potential,solubility,battery capacity compared to ferrocene derivatives,and are thus considered to be more promising in practical applications However,their structural stability is still deemed insufficient for long-term operation.To this end,various modification strategies have been proposed,including the introduction of steric hindrance and electrostatic repulsion,both of which have demonstrated to be and effective.This paper presents a summary and analysis of the degradation mechanism of TEMPO derivatives,which highlights that the breakdown of nitrogen-oxygen bonds owing to proton attack is the primary cause of degradation.The authors suggest the incorporation of importing of protecting groups on the TEMPO main-ring as a potential approach to further improve the long-term structural stability.