Along with the continuous optimization of the energy structure, more and more electricity come from intermittent renewable energy sources such as wind and solar energy. Redox flow batteries (RFBs) have the advantage that energy and power can be regulated independently, so they are widely used in large-scale energy storage. Redox active materials are the important components of RFBs, which determine the performance of the battery and the cost of energy storage. Some metal coordination compounds (MCCs) and their derivatives have been considered redox active materials that can replace metal-based redox flow batteries due to their properties such as tunability, high abundance and sustainability. MCCs can provide higher energy density because they are highly soluble both in the initial state and in any charged state during the battery cycling process. MCCs have also attracted a lot of attention from researchers because of their high economic value, low toxicity, and wide availability. This review provides an overview of the recent development of soluble metal coordination compounds, such as Ferrocene, and concludes with an in-depth discussion of the prospects of metal coordination compounds for application in organic redox flow batteries. Solar energy and wind energy have the advantages of abundant resources and are not limited by geographical conditions. In recent years, researchers have paid extensive attention to wind power and solar power generation. However, wind power and solar power generation have the disadvantages of discontinuity and instability, and if they are directly integrated into the power grid, it is easy to cause large-scale grid paralysis. Redox flow battery is a new type of high-capacity electrochemical energy storage device that is being actively developed. The active materials of redox flow battery is the flowing electrolyte, and the most significant feature is that it can store electricity on a large scale. However, traditional flow batteries use inorganic materials as electroactive substances, which causes high battery costs and low electrochemical activity, so researchers have turned their attention to green organic molecules. In recent years, organic redox flow batteries have developed rapidly, and most of their electroactive materials are C, H, O, N, etc., which has the advantages of low cost, environmental friendliness, abundant resources, easy adjustment of molecular energy levels and fast electrochemical reaction. Metal complexes have the advantages of good stability and high solubility, so they are widely used in various electrochemical studies. In this paper, the current research progress of metal complexes as active substances in organic redox flow batteries was summarized. Organic redox flow batteries develop rapidly, and most of their electroactive materials, especially metal complexes, have the advantages of low cost and fast electrochemical reaction. In this review, the current research progresses of metal complexes as active substances in organic redox flow batteries are summarized and discussed. image
