Highly reversible conversion-capacity of MnOx-loaded ordered mesoporous carbon nanorods for lithium-ion battery anodes

Abstract

An ordered mesoporous carbon (OMC) with a nanorod-shaped morphology and enhanced graphitic character was employed as an ideal support for MnO_x (major phase of Mn₃O₄ with a small portion of MnO) nanocrystals which possess a high theoretical conversion capacity as a Li-ion battery anode. The MnO_x/OMC nanocomposite was prepared by a simple wet-impregnation of Mn(NO₃)₂ aqueous solution onto OMC nanorods followed by thermal treatment at 450 °C in an Ar flow. The electrochemical properties of MnO_x/OMC were investigated in comparison to those of bare OMC and a commercial graphite as an anode for Li-ion batteries. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, N₂ adsorption–desorption analysis, X-ray photoelectron spectroscopy, and thermogravimetric analysis revealed that 3–30 nm MnO_x nanocrystals at a high loading of 68.4 wt% were formed and well dispersed in the pore structure of OMC nanorods. The MnO_x/OMC exhibited a high reversible capacity (>950 mAh g⁻¹) after 50 deep charge–discharge cycles with excellent cycling stability, Coulombic efficiency and rate capability. As an anode for Li-ion batteries, the incorporation of insulating high density MnO_x nanocrystals into OMC nanorods showed synergistic benefits of high volumetric capacity as well as specific capacity, and small redox voltage hysteresis compared to OMC nanorods.