A Method to Inhibit Disproportionation of Mn3+ for Low-Cost Mn–Fe All-Flow Battery

Among battery technologies considered for large-scale energy storage, manganese-based redox flow batteries have been extremely attractive due to the low cost of materials. Impeding its industrial adoption is the precipitation of MnO2 due to disproportionation of Mn3+. In this work, we overcome the formation of MnO2 precipitates through complexation of Mn3+ with Cl– ions. By virtue of the stable [MnCl4(H2O)2]− complex, an inexpensive and scalable Fe–Mn flow battery was demonstrated using Mn3+/Mn2+ and Fe3+/Fe2+ redox couples as catholyte and anolyte, respectively. The flow battery achieved an output voltage of 0.7 V and current density of up to 160 mA cm–2.