Vanadium redox flow batteries

A Redox Flow Battery (RFB) is a special type of electrochemical storage device. Electric energy is stored in electrolytes which are in the form of bulk fluids stored in two vessels. Power conversion is realized in a stack, made of electrodes, membranes, and bipolar plates. In contrast to conventional lead-acid or lithium-ion batteries, the energy conversion unit and energy storage unit are separate devices. From this point of view RFBs are more like reversible fuel cells in that the stack is the power conversion unit and it is built in a filter press design, or, compared to other storage technologies, like pumped hydro systems, where power conversion is realized by pumps and turbines, but capacity by higher and lower elevation reservoirs. This advantage leads to application where higher or various ratios of capacity to power (kilowatt hours per kilowatt) are needed or advantageous- usual are ratios from 5:1 to 10:1.