Ultrathin Zno Coating Layer to Boost the Electrochemical Reaction Kinetics of Mno Cathode for Advanced Aqueous Zinc-Ion Batteries

Abstract

Although conventional carbon-based materials and metallic oxide coating on manganese oxides (MnO) cathodes have been extensively researched, there are still some issues, including low electron conductivity, sluggish ions diffusion kinetics and inferior cycling stability, that need to be addressed through material modification. In this work, a simple atomic layer deposition strategy is proposed to fabricate ZnO-coated MnO (MnO@ZnO) as cathode for aqueous zinc-ion batteries. Benefiting from the heterogenous interface between ZnO and MnO, a strong built-in electric fields generated, as well as accelerate electron transport and ion diffusion, promoting fast reaction kinetics. Additionally, the ZnO coating layer effectively alleviate the dissolution of MnO and also boost its electrical conductivity. In contrast to the pristine MnO, MnO@ZnO exhibits enhanced specific capacity of 350 mA h g−1 at 0.1 A g−1 and excellenct longterm stability. In addition, the reaction mechanism is further comprehensively verified through various ex-situ characterization analyses. This work offers a simple coating method to boost electrochemical energy storage of MnO, which is of great significance for the design of cathodes with excellent performance.

Keywords: Atomic layer deposition, Reaction kinetics, Storage mechanism, Manganese oxides, Aqueous zinc-ion batteries