Synthesis and electrochemical characteristics of LiNi_(0.5)Co_(0.5)O_2 from different combinations of carbonates and oxides

摘要

Cathode materials with a composition of LiNi_(0.5)Co_(0.5)O_2 were synthesized by a solid-state reaction method at 850℃ using Li_2CO_3, NiO or NiCO_3, and COCO_3 or Co_3O_4, as the sources of Li, Ni, and Co, respectively. Electrochemical properties, structure, and microstructure of the synthesized LiNi_(0.5)Co_(0.5)O_2 samples were analyzed. The curves of voltage vs. x in LiJNTio.5Coo.5O2 for the first charge-discharge and the intercalated and deintercalated Li quantity Ax were studied. The destruction of unstable 3b sites and phase transitions are discussed from the first and second charge-discharge curves of voltage vs. x in Li_xNi_(0.5)Co_(0.5)O_2. The LiNio.5Coo.5O2 sample synthesized from Li_2CO_3, NiO, and Co_3O_4 has the largest first discharge capacity (159 mAh/g), with a discharge capacity deterioration rate of 5.8 mAh/g/cycle.