MnCO3 Microstructures Assembled with Nanoparticles: Shape-Controlled Synthesis and Their Application for Li-Ion Batteries

MnCO3 ellipsoids and twinborn spheres have been synthesized by a hydrothermal process and a room temperature synthesis approach, respectively. The structures and morphologies of the products are investigated by X-ray powder diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). XRD patterns indicate the MnCO3 ellipsoids display higher crystallinity than twinborn spheres. SEM images show that both the MnCO3 ellipsoids and twinborn spheres have a similar size of about 1 mu m and consist of nanoscale primary particles. Brunauer-Emmett-Teller (BET) surface areas of MnCO3 ellipsoids and twinborn spheres are 33.93 and 59.35 m(2)/g, respectively. Furthermore, the lithium storage properties of these MnCO3 samples with distinct morphologies have been investigated. When used as anode materials in lithium-ion batteries, MnCO3 ellipsoids and twinborn spheres exhibit the initial discharge capacities of 1375 and 1650 mAh/g, respectively. After charged/discharged for 50 cycles at a current density of 500 mA/g, the remaining discharge capacities for MnCO3 ellipsoids and twinborn spheres are 663 and 305 mAh/g, respectively.