High-Performance Aqueous Zinc–Manganese Battery with Reversible Mn2+/Mn4+ Double Redox Achieved by Carbon Coated MnOx Nanoparticles

Abstract

Abstract There is an urgent need for low-cost, high-energy-density, environmentally friendly energy storage devices to fulfill the rapidly increasing need for electrical energy storage. Multi-electron redox is considerably crucial for the development of high-energy-density cathodes. Here we present high-performance aqueous zinc–manganese batteries with reversible Mn 2+ /Mn 4+ double redox. The active Mn 4+ is generated in situ from the Mn 2+ -containing MnO x nanoparticles and electrolyte. Benefitting from the low crystallinity of the birnessite-type MnO 2 as well as the electrolyte with Mn 2+ additive, the MnO x cathode achieves an ultrahigh energy density with a peak of 845.1 Wh kg −1 and an ultralong lifespan of 1500 cycles. The combination of electrochemical measurements and material characterization reveals the reversible Mn 2+ /Mn 4+ double redox (birnessite-type MnO 2 ↔ monoclinic MnOOH and spinel ZnMn 2 O 4 ↔ Mn 2+ ions). The reversible Mn 2+ /Mn 4+ double redox electrode reaction mechanism offers new opportunities for the design of low-cost, high-energy-density cathodes for advanced rechargeable aqueous batteries.