Synthesis of Nano-Structured Li[Ni1/3Co1/3Mn1/3]O2 Via a Modified Carbonate Process

초록

There is great deal of interest in using lithium transition-metal oxides, Li[Ni1/3Co1/3Mn1/3]O2, as the positive electrode material for high energy and high power lithium-ion rechargeable Li-ion secondary batteries. One of the drawbacks of Li[Ni1/3Co1/3Mn1/3]O2 is that the synthesis of Li[Ni1/3Co1/3Mn1/3]O2 is not easy. An appropriate synthesis method needs to be employed, otherwise the transition metal component often saturates, resulting in oxide impurities such as NiO, Co3O4, Mn2O3 or MnO2. Therefore, selection of appropriate preparation method is critical to attain a final product with high purity. Here, we report electrochemical properties of nanostructured Li[Ni1/3Co1/3Mn1/3]O2 powder synthesized via a newly modified carbonate process, utilizing a chelating agent. With this new method, nanostructured Li[Ni1/3Co1/3Mn1/3]O2 powder with improved uniformity and superior rate capability can be synthesized. Electrochemical properties of the synthesized powders were satisfactory and final product were broad with regular particle shapes. Therefore, selection of appropriate preparation method is critical to attain a final product with high purity. Powder X-ray diffraction(Rigaku, Rint-2000) employing Cu Ka radiation was used to identify the crystalline phase of the prepared powders at each stage. The prepared powders were also observed using scanning electron microscopy (TEM, JEM2010, JEOL). Chemical compositions of the resulting powders were analyzed with an atomic absorption spectroscopy (Vario 6, Analyticjena). Charge-discharge tests were performed with a coin type cell (CR2032) with a current density of 20mAg-1 at 30℃.