The vanadium redox battery (VRB), also known as the vanadium flow battery (VFB) or vanadium redox flow battery (VRFB), is a type of rechargeable flow battery. It employs vanadium ions as charge carriers. The battery uses vanadium's ability to exist in a solution in four different oxidation states to make a battery with a. Pissoort mentioned the possibility of VRFBs in the 1930s. NASA researchers and Pellegri and Spaziante followed suit in the 1970s, but neither was successful. presented the first successful. ElectrodeThe electrodes in a VRB cell are carbon based. Several types of carbon electrodes used in VRB cell have been reported such as carbon felt, carbon paper, carbon cloth, and graphite felt. Carbon-based materials have the advantages of. VRBs achieve a specific energy of about 20 Wh/kg (72 kJ/kg) of electrolyte. Precipitation inhibitors can increase the density to about 35 Wh/kg (126 kJ/kg), with higher densities possible by controlling the electrolyte temperature. The Companies funding or developing vanadium redox batteries include, CellCube (Enerox), , StorEn Technologies in Australia, Largo Energy and Ashlawn Energy in the United States; H2 in Gyeryong-si,. AdvantagesVRFBs' main advantages over other types of battery: • no limit on energy capacity • can remain discharged indefinitely without damage• mixing electrolytes causes no permanent damage The reaction uses the : VO+2 + 2H + e → VO + H2O (E° = +1.00 V) V + e → V (E° = −0.26 V) Other useful properties of vanadium flow batteries are their fast response to changing loads and their overload capacities. They can. VRFBs' large potential capacity may be best-suited to buffer the irregular output of utility-scale wind and solar systems. Their reduced self-discharge makes them potentially appropriate in applications that require long-term energy storage with little maintenance—as in.