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.