Preparation and electrochemical characterization of LiNi0.8Co0.2O2 cathode material by a modified sol-gel method

LiNi0.8Co0.2O2 cathode powders for lithium-ion batteries were prepared by a modified sol-gel method with citric acid as chelating agent and a small amount of hydroxypropyl cellulose as dispersant agent. The structure and morphology of LiNi0.8Co0.2O2 powders calcined at various temperatures for 4 h in air were characterized by means of powder X-ray diffraction analyzer, scanning electron microscope, thermogravimetric analyzer and differential thermal analyzer, and Brunauer-Emmett-Teller specific surface area analyzer. The results show that LiNi0.8Co0.2O2 powders calcined at 800 A degrees C exhibit the best layered structure ordering and appear to have monodispersed particulates surface. In addition, the electrochemical properties of LiNi0.8Co0.2O2 powders as cathode material were investigated by the charge-discharge and cyclic voltammetry studies in a three-electrode test cell. The initial charge-discharge studies indicate that LiNi0.8Co0.2O2 cathode material obtained from the powders calcined at 800 A degrees C shows the largest charge capacity of 231 mAh g(-1) and the largest discharge capacity of 191 mAh g(-1). And, the cyclic voltammetry studies indicate that Li+ insertion and extraction in LiNi0.8Co0.2O2 powders is reversible except for the first cycle.