Recent Progress in Organic Redox Flow Batteries
- 2018年第24卷 
氧化还原液流电池（简称液流电池）是一种正在积极研制开发的新型大容量电化学储能装置，其活性物质是流动的电解质溶液，最显著的特点是规模化蓄电. 在广泛利用可再生能源的呼声高涨形势下，可以预见液流电池将迎来一个快速发展的时期. 氧化还原活性物质是液流电池能源转化的载体，也是液流电池中最核心的部分.传统液流电池利用无机材料作为活性物质，然而，无机材料成本高、毒性、资源有限、形成枝晶和电化学活性低等缺点限制了液流电池的大规模应用. 有机活性物质由于具有成本低、“绿色”、资源丰富、分子能级易于调节和电化学反应快等优点，引起了国内外的广泛关注. 近年来，有机液流电池的性能得到快速提升，一系列有机活性物质相继被开发出来. 本文梳理了近年来有机液流电池的研究进展. 首先简要介绍了液流电池的应用领域和技术特点；然后根据电解液种类的不同，详细讨论了有机活性物质在水系和非水系液流电池的应用情况；最后展望了有机液流电池走向实际应用所面临的挑战和潜在研究方向.Redox flow batteries (RFBs) are promising candidate for balancing instability of grids caused by integration of intermittent renewable energies such as solar energy and wind energy. Along with wide deployments in solar energy and wind energy due to abundance and declining installation cost, it can be predicted that RFBs will enter a period of rapid development. Basically,RFBs are electrochemical energy storage devices that decouple energy and power of the system by storing liquid electrolyte in tanks outside battery system itself. Such a unique framework makes RFBs flexible and fulfills the various demands of grids. During battery operation, redox-active species are energy-conversion carriers by changing molecular valence states, and thus, are critical elements for RFBs. Traditional RFBs employ inorganic materials as redox-active species, however, high cost, toxicity, resource limitation, dendrite formation and low electrochemical activity of inorganic redox-active species have hindered RFBs toward a large-scale application. Owing to advantages of low-cost, "green", abundance, molecular-energy-level (MEL) tunability and rapid redox kinetics,organic active species have drawn much attention in academic and industrial communities. In recent few years, performances of organic redox flow batteries (ORFBs) have been improved rapidly, and a series of novel organic active species have been explored and developed. This article reviews recent progresses in ORFBs. Firstly, an application field and working principle of RFBs are briefly introduced, and then technical features of vanadium redox flow battery (VRFB), zinc based flow battery (ZBFB), and hydrogen-based flow battery (HBFB) are presented with reasons for developing organic active species. Subsequently, based on a variety of support electrolyte, aqueous organic redox flow batteries (AORFBs) can be divided into acid, alkaline and neutral forms with merits and limitations of these systems are discussed. Non-aqueous organic redox flow batteries (NAORFBs) are also discussed in terms of energy density, current density, stability and bipolar molecule. Finally, the critical challenges and potential research opportunities for developing practically relevant ORFBs are prospected.