Vanadium Redox Battery

Vanadium Redox Battery

The vanadium redox (and redox flow) battery is a type of rechargeable flow battery that employs vanadium ions in different oxidation states to store chemical potential energy. The present form (with sulfuric acid electrolytes) was patented by the University of New South Wales in Australia in 1986. An earlier German Patent on a titanium chloride flow battery was registered and granted in July 1954 to Dr. Walter Kangro, but most of the development of flow batteries was carried out by NASA researchers in the 1970s. Although the use of vanadium in batteries had been suggested earlier by Pissoort, by NASA researchers and by Pellegri and Spaziante in 1978, the first known successful demonstration and commercial development of the all-vanadium redox flow battery employing vanadium in a solution of sulfuric acid in each half was by Maria Skyllas-Kazacos and co-workers at the University of New South Wales in the 1980s.

There are currently a number of suppliers and developers of these battery systems including Ashlawn Energy in the United States, Renewable Energy Dynamics (RED-T) in Ireland, Cellstrom GmbH in Austria, Cellennium in Thailand, and Prudent Energy in China. The vanadium redox battery (VRB) is the product of over 25 years of research, development, testing and evaluation in Australia, Europe, North America and elsewhere.

The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two.

The main advantages of the vanadium redox battery are that it can offer almost unlimited capacity simply by using larger and larger storage tanks, it can be left completely discharged for long periods with no ill effects, it can be recharged simply by replacing the electrolyte if no power source is available to charge it, and if the electrolytes are accidentally mixed the battery suffers no permanent damage.

The main disadvantages with vanadium redox technology are a relatively poor energy-to-volume ratio, and the system complexity in comparison with standard storage batteries.