Preparation of LiCoO2 concaved cuboctahedra and their electrochemical behavior in lithium-ion battery.

LiCoO(2) concaved cuboctahedra with a size of about 1.0 μm were hydrothermally prepared from CoCO(3) and LiOH·H(2)O at 150 °C. Field-emitting scanning electron microscope (FESEM) images show that the cuboctahedra consisted of four hexagonal plates, with angles of 70.5° in neighboring plates. Electron diffraction (ED) patterns of the hexagonal plates show 1  0  0 diffraction of LiCoO(2) in rhombohedral phase and 2 2 0 diffraction in spinel phase, which means LiCoO(2) concaved cuboctahedra are comprised of two intergrown phases. The electrochemical performance of these concaved cuboctahedra of LiCoO(2) at a rate of 0.5 C demonstrated first run charge/discharge capacities of 155 and 141 mAh g(-1) and a stable discharge capacity of 114 mAh g(-1) after 100 cycles. After that, FESEM images show the LiCoO(2) concaved cuboctahedra have undergone no significant change. At a temperature of 120 °C and under the same conditions, only a small amount of LiCoO(2) concaved cuboctahedron appeared. As the temperature rose to 180 °C, flower-like LiCoO(2) microstructures with a size of about 1.0 μm were formed, constructed of irregular plates. The electrochemical performance of the products prepared at 120 °C and 180 °C indicates lower stability than that of LiCoO(2) concaved cuboctahedra.