Carbon-coated manganese dioxide nanoparticles and their enhanced electrochemical properties for zinc-ion battery applications

In this study, we report the cost-effective and simple synthesis of carbon-coated α-MnO2 nanoparticles (α-MnO2@C) for use as cathodes of aqueous zinc-ion batteries (ZIBs) for the first time. α-MnO2@C was prepared via a gel formation, using maleic acid (C4H4O4) as the carbon source, followed by annealing at low temperature of 270 °C. A uniform carbon network among the α-MnO2 nanoparticles was observed by transmission electron microscopy. When tested in a zinc cell, the α-MnO2@C exhibited a high initial discharge capacity of 272 mAh/g under 66 mA/g current density compared to 213 mAh/g, at the same current density, displayed by the pristine sample. Further, α-MnO2@C demonstrated superior cycleability compared to the pristine samples. This study may pave the way for the utilizing carbon-coated MnO2 electrodes for aqueous ZIB applications and thereby contribute to realizing high performance eco-friendly batteries.