Intercalation and Interface Engineering of Layered MnO2 Cathodes toward High-Performance Aqueous Zinc-Ion Batteries

Manganese-based layered compounds offer promising cathode materials for aqueous zinc-ion batteries (AZIBs) due to their high safety, low cost, and environmental friendliness. However, their sluggish reaction kinetics, poor conductivity, and irreversible manganese dissolution result in severe capacity fading. Herein, a simple two-step method is successfully proposed to intercalate Ba2+ ions into layered manganese oxide (Ba-MnO2), which were utilized as cathode materials for AZIBs. Ba2+ ions have been innovatively introduced into the MnO2 cathode, generating abundant oxygen vacancies. Notably, the incorporated Ba2+ spontaneously forms an in situ BaSO4 layer during charging, which functions as a protective cathode electrolyte interface. These improvements promote the conductivity and ion diffusion of MnO2, enabling a reversible MnO2/Mn2+ deposition/dissolution reaction. The Zn//Ba-MnO2 full battery delivers a high capacity of 355 mA h g–1 at 0.3 C and maintains an ultrastable cycling stability of over 1200 cycles even at 3 C. This work provides an innovative strategy and a profound understanding of designing high-performance cathodes for AZIBs.