Tailoring MnCO3 microspheres encapsulated by polypyrrole as cathodes for aqueous zinc-ion batteries

Constructing manganese-based cathode materials featuring high-performance and great stability during the charge or discharge process are vital for the progress of aqueous Zinc-ion batteries. In this study, MnCO3 Microspheres encapsulated by polypyrrole (MnCO3 @PPy) were successfully synthesized through a one-step hydrothermal method followed by in situ chemical oxidation polymerization. The pellicular polypyrrole (PPy) skin warped the MnCO3 microspheres uniformly making its surface smooth and orderly, which not only enhanced the electron and ion conductivity but also maintained the integrity of the cathode structure. As a result, MnCO3 @PPy cathodes displayed elevated cycling stability, reversibility and rate performance over MnCO3 cathodes. It achieved high average discharge specific capacities of 243, 151, 124, 112 and 104 mA h g(-1) when cycled at current rates of 200, 400, 600, 800 and 1000 mA g(-1), respectively, and delivered 252 mA h g(-1) after 110 cycles at the current density of 200 mA g(-1) corresponding to 94% of its maximum specific capacity (264 mA h g(-1)). The results suggest that this MnCO3 @PPy microspheres cathode is serviceable for aqueous zinc-ion batteries.