The VRB is a reduction / oxidation (redox) flow battery that employs an electrolyte solution where energy is stored and a cell stack where the energy conversion occurs.

The VRB essentially comprises three basic components:

1. a negative electrolyte tank with a pump,
2. a positive electrolyte tank with a pump
3. a series of membranes or electrochemical cells (“the cell stack”) through which the vanadium electrolyte flows (or is pumped).

Each cell in the cell stack is an electrically conductive carbon impregnated polymer sheet to which graphite felt is heat bonded. The electrodes are inert and unlike conventional lead acid batteries do not participate in the electro-chemical reactions.

Vanadium, an abundant and stable metal, is held in two ionic forms in a diluted sulphuric acid electrolyte solution. It is the Vanadium pentoxide resulting from this process that effectively stores the energy.

The two electrolyte solutions circulate from the storage tanks, through the cell stack and back to the tanks. Energy is released when charged electrolyte flows through the cell stack causing electron transfer between the different forms of vanadium ions across the separating membrane to flow into an external load.

Running current into the cell stack reverses the process and recharges the electrolyte solution, which can be reused to release energy at any time. Charging the battery or storing energy is possible from a number of different sources such as wind, solar, hydro, excess power generation or mains electricity.