The Redox battery is an example of both a Flow Battery and a two electrolyte system. In this case, it depends on two different active aqueous electrolytes of vanadium dissolved in sulfuric acid separated by a membrane at which ionic interchange takes place. The chemical reactions take place on inert graphite electrodes stacked in a bipolar configuration. The electrolytes are stored externally from the battery and must be pumped through the cell for the chemical action to take place.
Sloping discharge characteristic with output voltage varying from 1.5 to 1.0 Volts
The name Redox is a contraction of the terms "Reduction" and "Oxidation". Although these particular batteries are named after this chemical reaction, the Redox action is common to most all Galvanic cells.
Very high power output (Tens of kiloWatts)
Fast recharge by replacing spent electrolyte
Capable of long life due to replacement of electrolyte.
Can be fully discharged
Use non toxic materials
Low energy density
Little commercial take up to date
Suitable for high power rechargeable storage systems in applications such as load levelling.
High costs since little progress from experimental systems to high volume applications.