Return of the Iron Age

In this issue of Joule , Liu and coworkers present the use of the well-known ferrocyanide complex as an active electrode material for an aqueous organic/organometallic redox flow battery. The ammonium cation was used as counter cation in place of the former-utilized sodium and potassium ions. Interestingly, by this simple cation exchange, remarkable capacity and cycle stability were achieved. A battery system is presented comprising ammonium ferrous hexacyanide and an organo-functionalized viologen compound.