Vanadium Redox Flow Batteries: Electrochemical Engineering

The importance of reliable energy storage system in large scale is increasing to replace fossil fuel power and nuclear power with renewable energy completely because of the fluctuation nature of renewable energy generation. The vanadium redox flow battery (VRFB) is one promising candidate in large-scale stationary energy storage system, which stores electric energy by changing the oxidation numbers of anolyte and catholyte through redox reaction. This chapter covers the basic principles of vanadium redox flow batteries, component technologies, flow configurations, operation strategies, and cost analysis. The thermodynamic analysis of the electrochemical reactions and the electrode reaction mechanisms in VRFB systems have been explained, and the analysis of VRFB performance according to the flow field and flow rate has been described. It is shown that the limiting current density of "flow-by" design is more than two times greater than that of "flow-through" design. In the cost analysis of 10 kW/120 kWh VRFB system, stack and electrolyte account for 40 and 32% of total cost, respectively.