Nanoflaky MnO2 grown in situ on carbon microbeads as an anode material for high-performance lithium-ion batteries

Abstract

A flower-like MnO₂ encapsulated carbon microbead (MnO₂@CMB) nanocomposite is firstly synthesized via in situ nucleation and growth of birnessite-type MnO₂ on the surface of monodisperse carbon microbeads. The structure, morphology and performance of the samples are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and galvanostatic charge/discharge. The results reveal that the flower textured MnO₂@CMB nanocomposite is composed of a CMB core and a MnO₂ nanosheet shell. As the anode material for lithium-ion batteries, the MnO₂@CMB nanocomposite exhibits excellent electrochemical performance. It shows a good rate capability of 230 mA h g⁻¹ at a current density of 1500 mA g⁻¹ and a large reversible capacity of 620 mA h g⁻¹ without capacity fading for the 80^th cycle at 100 mA g⁻¹, which is much better than those of pure MnO₂ and graphite. The superior electrochemical performance can be attributed to the unique hierarchical architecture and the combinative effects of the MnO₂ nanosheet and carbon matrices.