Investigation of Factors Affecting Performance of the Iron‐Redox Battery

Abstract

The iron‐redox battery is a low power density energy storage device that may be attractive for applications such as load leveling and solar energy storage. During the charge cycle of this battery, the ferrous ion from an aqueous chloride electrolyte plates onto the negative electrode and is oxidized to ferric ion at the positive electrode. A solid graphite or titanium plate can be used for the iron electrode while a high specific area material is necessary for the redox electrode. A 100 cm 2 single cell with a microporous plastic separator has been cycled at a current density of 60 mA/cm 2 at 60°C. The cell was capable of storing and discharging energy at a round trip current efficiency of 90% and an energy efficiency of 50%, with a maximum discharge power density of 50 mW/cm 2 . The largest voltage losses occurred at the iron electrode and to a lesser extent at the redox electrode. Factors affecting voltaic and coulombic losses including electrolyte composition and temperature, cell separators, electrode materials, and electrolyte additives have been studied and the results reported.