Combustion-synthesized LiNi_0.6Mn_0.2Co _0.2O₂ as cathode material for lithium ion batteries

A nitrate/urea mixture was used as fuel to simply combustion-synthesize LiNi_0.6Co_0.2Mn_0.2O₂ as a high-capacity cathode material for lithium ion batteries. The reaction formulas and physical properties of the resultant cathode materials sintered at various temperatures were examined using thermogravimetric analysis/simultaneous differential thermal analysis, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrometry, and inductively coupled plasma/atomic emission spectrometry. The influence of sintering temperature on the electrochemical performance was evaluated by analyzing the charge/discharge profiles and cycling and rate-capability performances. The LiNi _0.6Co_0.2Mn_0.2O₂ cathode sintered at 800 °C exhibited a discharge capacity of 170 mA h g^-1 measured at a constant 20 mA g^-1, 98.2% capacity retention after 30 cycles, and better rate capability than the cathodes sintered at 700, 900, and 1000 °C. The experimental results suggest that the enhanced electrochemical performance of the LiNi_0.6Co_0.2Mn_0.2O₂ cathode sintered at 800 °C is attributable to the pure, well-organized layered structure containing few mixed cations and to the shorter diffusion path resulting from the uniformly distributed nanoparticles.