Redox flow battery (RFB) is a rechargeable electrochemical device, in which charge storage substances are dissolved in liquid electrolyte and stored in cheap storage tank, and charge discharge cycle is carried out through power conversion reactor, in which they are oxidized and reduced to alternately charge and discharge the battery. In the reactor, the two electrolytes (usually referred to as "positive electrolyte" and "negative electrolyte" according to their respective electrode potentials) are separated by a proton exchange membrane and reduced and oxidized on the surface of the porous electrode. Ions pass through the proton exchange membrane to balance the charge between the two electrolytes, so as to maintain electrical neutrality and ideally block the charge storage material. 

Like other energy storage systems, redox flow battery (RFB) requires equipment balance subsystems to support operation, including fluid, thermal and state of charge management systems.