An Organic Coordination Manganese Complex as Cathode for High‐Voltage Aqueous Zinc‐metal Battery

Abstract

AbstractAqueous Zn−Mn battery has been considered as the most promising scalable energy‐storage system due to its intrinsic safety and especially ultralow cost. However, the traditional Zn−Mn battery mainly using manganese oxides as cathode shows low voltage and suffers from dissolution/disproportionation of the cathode during cycling. Herein, for the first time, a high‐voltage and long‐cycle Zn−Mn battery based on a highly reversible organic coordination manganese complex cathode (Manganese polyacrylate, PAL−Mn) was constructed. Benefiting from the insoluble carboxylate ligand of PAL−Mn that can suppress shuttle effect and disproportionationation reaction of Mn3+ in a mild electrolyte, Mn3+/Mn2+ reaction in coordination state is realized, which not only offers a high discharge voltage of 1.67 V but also exhibits excellent cyclability (100 % capacity retention, after 4000 cycles). High voltage reaction endows the Zn−Mn battery high specific energy (600 Wh kg−1 at 0.2 A g−1), indicating a bright application prospect. The strategy of introducing carboxylate ligands in Zn−Mn battery to harness high‐voltage reaction of Mn3+/Mn2+ well broadens the research of high‐voltage Zn−Mn batteries under mild electrolyte conditions.