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Vanadium is the 23rd element in the periodic table and is mainly used as a strong alloy in the tool industry.
Furthermore, it is a metal with a high electrical density for use as an electrolyte in redox flow batteries.
Vanadium is used due to its unique ability to reach four different oxidation levels – V2, V3, V4 and V5 (VO2 to VO5).
Most organic material contains a minuscule portion of vanadium; however, in the industry it is either extracted from slag in iron production or it is extracted chemically.
A VRFB is based on an old technology of principles that were invented in the 1940’s. The technology has previously not been an economically feasible solution for energy storage, however with new supporting technologies VisBlue has been able to develop a commercial VRFB for storing energy produced by PV’s (photovoltaic systems).
During the day, when the PV's produce energy, we do not necessarily consume energy, which means that we have two choices.
We can supply energy to the grid (often at a deficit), or we can find a way to store the energy.
In the evening, when the PV’s aren't producing, we need to draw energy from another source. The VRFB enables you to store energy during the day and utilise it in the evening.
The VRFB is made up of two tanks filled with a vanadium-based electrolyte-fluid and what is called a stack.
The stack is comprised of several stack cells made from a plastic frame, a graphite-polymer composite bipolar plate and a polymer membrane. The number and size of stack cells depend on the power output needed.
The size of the tanks determines the capacity of the battery. The fluid in the two tanks acts as cathode (positive electrolyte) and anode (negative electrolyte). Just like a regular battery.
The cathode and anode consist of the same vanadium-solution with high electrical storing properties. The unique ability to reach four oxidation levels is the crucial skill that enables VisBlue to have the same electrolyte in both tanks.
What separates the VRFB from other redox flow batteries is the abilities of the electrolytes. The use of vanadium instead of other types of electrolytes has enabled VisBlue to use the same solution in both tanks. This is important, because we hereby alleviate cross-contamination of the electrolytes, and therefore eliminate the problem of degrading electrolytes.
Another advantage is the independence of the capacity (amount of fluid) and power output (size/number of stacks). It is therefore possible to tailor a battery to your own needs and requirements.
The VisBlue Battery Solution consists of a vanadium-based solution, which contains water and sulphuric acid.
Most of the solution is water, which means that even in the event of short-circuiting, intense heat or high pressure, the battery is non-flammable. The battery will deduce some amount of heat, although not above a level that is safe to touch.
The vanadium redox flow battery does not contain volatile compounds of lithium, cobalt and nickel as other types of batteries do.
Additionally, the VisBlue Battery Solution does not deduce any gas. In the event of a leak, spillage will not cause toxic effect to the ambient atmosphere. However, the solution is a corrosive substance containing sulphuric acid and vanadium. It is therefore, inadvisable to get into contact with the fluid.