Redox Flow Batteries Applied For a Green Future-In the Perspective of Heat and Mass Transfer

The global energy crisis is making energy storage as a critical technology in the use of renewable energy sources, such as wind and solar power, which have the intermittent nature. Among emerging technologies, the redox flow battery (RFB) is a promising candidate for large-scale stationary storage applications due to its unique features, including tolerance to deep discharge without any risk of breakdown, long lifetime, independence of power and capacity, and simple structure. However, the RFB technology is still hindered by several challenging issues before its widespread commercialization. For given electrolyte and electrode materials, the performance of the RFB is basically determined by the heat, mass and charge transport characteristics on the electrolyte-electrode interface and in the porous electrode. A better understanding of these coupled characteristics thus becomes essential for improving the battery performance. Hereby, we present a mini-review to reveal the recent progresses in RFB, with an emphasis on understanding the transport characteristics as well as the effects of operating conditions. By careful arrangements of flow regime and operating temperature, the cell performance as well as system efficiency can be greatly improved. In addition, some key transport parameters can be determined via electrochemical method using a RFB structure. Finally, a better criterion for cell performance evaluation is proposed.