Electrochemical characteristics of LiNi0.5Co0.5O2 synthesized at 800 °C from the different combinations of carbonates, oxides, and hydroxides

LiNi0.5Co0.5O2 cathode materials were synthesized by a solid-state reaction method at 800 °C using Li2CO3, LiOH·H2O; NiO, NiCO3; CoCO3, or Co3O4 as the sources of Li, Ni, and Co, respectively. The electrochemical properties of the synthesized samples were then investigated. The structure of the synthesized LiNi0.5Co0.5O2 was analyzed, and the microstructures of the samples were observed. The curves of voltage vs. x in LixNi0.5Co0.5O2 for first charge-discharge and intercalated and deintercalated Li quantity Δx were studied. Destruction of unstable 3b sites and phase transitions were discussed from the first and second charge-discharge curves of voltage vs. x in LixNi0.5Co0.5O2. The LiNi0.5Co0.5O2 sample synthesized from Li2CO3, NiCO3 and Co3O4 has the largest first discharge capacity (142 mAh/g). The LiNi0.5Co0.5O2 sample synthesized from Li2CO3, NiO and Co3O4 has a relatively large first discharge capacity (141 mAh/g) and the smallest capacity deterioration rate (4.6 mAh/g/cycle).