vanadium 101


Vanadium is a transition metal element that is hard, silvery-grey and malleable. The elemental metal though rarely found isolated in nature, is commonly found together with Magnetite, an ore highly abundant throughout Western Australia and plentiful throughout the earth's crust. Once Vanadium is isolated artificially, the formation of an oxide layer (passivation) stabilizes the free metal against further oxidation. High purity Vanadium Pentoxide V2O5 (pictured below) is the key ingredient in a Vanadium Battery Electrolyte. 


four states


What sets Vanadium ahead of other metals for energy storage is its ability to exist in four states of charge in solution V(2+,3+,4+,5+). Because of the beautiful and brilliant colours of the four oxide states, Vanadium was named after Vanadis, the Scandinavian goddess of beauty.  

Most batteries use two chemicals that change valence (or charge or redox state) in response to electron flow that converts chemical energy to electrical energy, and vice versa. Vanadium batteries use the multiple valence states of just vanadium to store and release charges in a water-based electrolyte containing vanadium salts. Energy is stored by providing electrons making V(2+,3+), and energy is released by losing electrons to form V(4+,5+).


This means that electrons can be made to flow without requiring any other element for the electrochemical reaction. This eliminates the violent and hazardous effects of cross-contamination that is a significant risk of other flow battery types like Zinc Bromine, Sulfur Bromine and Iron Chromium which was used in the original flow battery invented by NASA in the 1970's . 

The breakthrough of using Vanadium for flow battery was made by UNSW Professor Dr Maria Skyllas-Kazacos in 1985. Like any breakthrough technology, it's taken decades for the technology to be perfected for scale and producible at a price point that is economical for the market. 


redox flow 


A Vanadium battery is different from a conventional battery in that is uses solutions to store energy. It combines reduction and oxidization reactions and it keeps the electrolyte in solution and flowing: this is know as 'redox flow'.  The architecture of a Vanadium batteries consists of two electrolyte tanks and a cell stack. When the electrolyte is pumped through the cell stack, the two solutions flow adjacent to each other past a membrane and generate a charge by moving electrons back and forth during charging and discharging. 


This simple architecture is key to the reliability and longevity of Ultra's Vanadium Batteries. It can be left completely discharged for long periods with no ill effects to the electrolyte, making maintenance simpler than other batteries.

There are many Vanadium batteries in operation throughout the world providing small-scale up to grid-scale energy storage.