Vanadium is a chemical element with symbol V and atomic number 23. As a material, it is a hard, silvery grey, ductile and malleable transition metal.
The element is found only in a chemically combined form in nature, but once isolated artificially, the formation of an oxide layer stabilizes the free metal against further oxidation. Vanadium has a number of commercial applications including steel alloys, long term energy storage and as a catalyst for the manufacture of sulphuric acid.
Primarily, vanadium is used as an alloying additive for steel to give greater tensile strength and corrosion resistance.
The largest market for vanadium as an alloy additive is China, in particular, for the manufacture of reinforcement bar used in construction where there are national standards on minimum levels of vanadium content.
Vanadium is also increasingly used in high-specification metals for aerospace and transport applications as well as other minor applications.
A major new use of vanadium is now emerging as the electrolyte in Vanadium Redox Flow Batteries used for long term energy storage.
Although lithium-ion batteries are better known and are more suitable for mobile applications where weight is important, VRFBs have several advantages for fixed, high capacity and long-term storage, either as part of a grid or for isolated mini-grids.
The main advantages include minimal degradation of the contained electrolyte over time or after repeated charge and discharge cycles, vanadium electrolyte is inflammable and, therefore, does not create a fire hazard and battery capacity can be scaled independently of power by the addition of larger electrolyte tanks.
Research is ongoing into the use of vanadium in the manufacture of electric vehicle battery cathodes.