Mn5O8 – graphene hybrid electrodes for high rate capability and large capacity aqueous rechargeable zinc ion batteries

•A novel cathode material prepared (Mn5O8/rGO) by the solution-phase method.•A H+/Zn2+ coinsertion mechanism of manganese oxide cathode was elucidated.•The addition of reduced graphene oxide enhances the cycling stability.•The Mn5O8/rGO cathode exhibits a high specific capacity with excellent rate and cyclic performance. Due to the higher requirements of energy storage equipment, aqueous rechargeable zinc ion batteries (ARZIBs) with the advantages of environmental friendliness, low cost and simple preparation have attracted wide attention. In this study, the composites of Mn5O8 uniformly deposited on the surface of graphene used as cathode of ARZIBs are synthesized. Owing to the hierarchically porous morphology, the electrode delivers a high reversible capacity of 260 mA h g−1 at a current density of 100 mA g−1 and shows excellent long-term cycling stability of up to 1000 cycles with a capacity retention of 98.8%. In addition, the energy storage mechanism of H+ and Zn2+ coinsertion was tentatively studied as well. And this study provides some inspiration of designing high-performance ARZIBs for grid-scale energy storage.