Organic Redox Flow Battery

Redox flow batteries are stationary batteries in which the energy is located in the electrolyte, outside of the cell itself, as in a fuel cell. They are often marketed with the prefix “eco” since they open the possibility of storing excess energy from, for example, the Sun and wind. It appears that they can be recharged an unlimited number of times; however, redox flow batteries often contain vanadium, a scarce and expensive metal. The electrolyte in which energy is stored in a redox flow battery can be water-based, which makes the battery safe to use but results in a lower energy density.