Recent research progress of redox flow batteries based on deep eutectic solvents (DESs)
Yannan Ji, Haotian Zhou, Peizhuo Sun, Junfeng Liu, Qing Li, Ping Lü, Qian Xu
Abstract
As a potential energy storage technology, redox flow batteries (RFBs) have been developed rapidly in recent years. However, designing systems with low cost and high energy density remains a major challenge for the development of RFBs. Redox active substances are the carriers of energy conversion and the core components of RFBs, increasing their concentration in the electrolyte can effectively improve the energy density. As a new type of green solvent, deep eutectic solvents (DESs) have inherent characteristics, such as low cost, easy synthesis, and environmental friendliness. Meanwhile, this solvent can effectively increase the concentration of redox active substances, showing a good prospect in RFBs. This paper reviews the recent research progress of RFBs based on DESs, with focuses on the metal-based DESs and metal-free DESs (the choice of materials, the state-of-the-art cell performance) and outlines the challenges and potential research directions for realizing large-scale applications, aiming to provide guidance for the development of higher energy density and more efficient flow batteries.