Vanadium: effective, but big
The vanadium redox battery, also known as the vanadium flow battery, is a rechargeable battery that employs vanadium ions in different oxidation states to store chemical potential energy.
Because they are usually pretty bulky, vanadium batteries tend to be used for grid energy storage, and are attached to power plants and electrical grids.
It’s thought by Bushveld Minerals (LON:BMN), a producer of vanadium, and others, that 90% of the demand for storage to absorb renewable energy and balance the power system will be for long-duration, typically greater than four hours, and mostly for six to 10 hours. Vanadium batteries meet this need since they become relatively cheaper for long-duration applications and their water-based chemistry is inherently fire-safe.
They also offer other benefits including long lifespans of 20 or more years with minimal degradation, easy recoverability of vanadium from the electrolyte at the end of battery life; and up to 30% lower carbon dioxide intensity compared with other battery technologies.
Using a vanadium battery can help stabilise a power grid that uses large amounts of variable renewable energy sources and smooth a power system’s load distribution by shifting power demand. Excess power generated during off-peak periods can also be stored.
Lithium: more mobile, and more variable in efficiency and safety
Lithium-ion batteries can be far smaller than vanadium batteries, of a size that allows their use in portable electronics and electric vehicles. They are also increasingly being used in military and aerospace applications.
These batteries use an intercalated lithium compound as the material at the positive electrode and typically graphite at the negative electrode. They also often contain a significant quantity of nickel, depending on the precise type of battery. Other metals used in lithium-ion batteries include manganese and cobalt.
Lithium-ion batteries have a high energy density. In certain circumstances they can be a safety hazard since they contain flammable electrolytes. If damaged or incorrectly charged they can cause explosions and fires.
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