Lattice site substitution and interlayer engineering in layered manganese oxide toward durable and fast aqueous Zn-Mn batteries
Aqueous zinc ion batteries (AZIBs) are gaining considerable research attention owing to their high safety and low cost. Although MnO 2 is a promising cathode, the inevitable MnO 2 dissolution and slow kinetics still limit their application in AZIBs. Herein, we propose a Fe 3+ and K + co-doping design of MnO 2 (labeled Fe-KMnO) to improve the structural stability and kinetics. Specifically, the introduction of Fe 3+ and K + can reduce the particle size and enlarge the interlayer spacing of MnO 2 , while the lattice substitution of Fe 3+ can reduce Zn 2+ diffusion barriers inside the cathode by the density functional theory calculations, leading to the good rate stability. Meantime, the TiO 2 coated Zn foil is designed to alleviate corrosion and suppress Zn dendrites, thus reduce the interfacial resistance and improve the dynamics of Zn-MnO 2 batteries. Based on the advantages of Fe-KMnO material and the effective protection of Zn anode, Fe-KMnO electrode shows excellent performance. When it is applied to the cathode material for aqueous zinc ion battery, the reversible specific capacity of 367.4 mAh g −1 is obtained at the current density of 0.1 A g −1 , superior cycle stability (a capacity of 109.5 mAh g −1 at 1 A g −1 after 5000 cycles), making it a promising cathode for high-performance AZIBs.
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