Preparation of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 powders for cathode material in secondary battery by solid-state method

摘要

Employing Li_2CO_3, NiO, CO_3O_4, and MnCO_3 powders as starting materials,[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_2 was synthesized by solid-state reaction method. Various grinding aids were applied during milling in order to optimize the synthesis process. After successive heat treatments at 650 and 950 °C, the prepared powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy, and transmission electron microscopy. The powders prepared by adding salt (NaCl) as grinding aid exhibit a clear R 3 m layer structure. The powders by other grinding aids like heptane show some impurity peaks in the XRD pattern. The former powders show a uniform particle size distribution of less than 1 μm average size while the latter shows a wide distribution ranging from 1 to 10 μm. Energy dispersive X-ray (EDX) analysiss show that the ratio of Ni, Co, and Mn content in the powder is approximately 1/3,1/3, and 1/3, respecively, The EDX data indicate no incorporation of sodium or chlorine into the powders. Charge-discharge tests gave an initial discharge capacity of 160 mAh·g~(-1) for the powders with NaCl addition while 70 mAh·g~(-1) for the powders with heptane.