Inorganic manganese oxide/quinone coupling for high-capacity aqueous Zn-ion battery

Rechargeable aqueous Zinc-ion batteries belong to a hot research topic on energy storage due to its high safety and low cost. However, its practical application is still remarkably limited by the fact that cathode capacity is much lower than that of zinc anode, leading to unsatisfactory energy density far away from the commercial standard. In this context, we have proposed an inorganic oxide/organic quinone coupling strategy to prepare MnO2@PDAAQ composite cathode. Significantly enhanced performance superior to most of conventional cathode materials was identified in this MnO2@PDAAQ with an impressive high capacity of 414 mAh g−1 and energy density of 537.9 Wh kg−1. We clarified such a coupling from MnO2 and quinone results in multiple energy storage mechanisms including Zn2+/H+ co-insertion in MnO2 and two-electron dissolution/deposition mechanism of Mn4+/Mn2+ redox reaction in this composite. The proposed inorganic oxide/organic quinone coupling strategy opens up a new route for the electrode design of high-performance aqueous batteries.