Abstract:The uniform layered Li(Ni_1/3Co_1/3Mn_1/3)O₂ cathode material for lithium-ion secondary batteries were synthesized by using (Ni_1/3Co_1/3Mn_1/3)(OH)₂ synthesized by a liquid phase co-precipitated method as precursors and with NiSO₄, CoSO₄, MnSO₄ and NH₃·H₂O as raw materials. The influence of the preparation conditions such as precursors preparation, calcinations temperature and calcinations time on the structural and electrochemical properties of the Li(Ni_1/3Co_1/3Mn_1/3)O₂ were systematicelly studied. The result of XRD shows the I₀₀₃/I₁₀₄ value of the Li(Ni_1/3Co_1/3Mn_1/3)O₂ powder synthesized at 950 ℃ for 10 h is 1.26, which illustrates the well-ordered layer-structure. The average particle size of uniform Li(Ni_1/3Co_1/3Mn_1/3)O₂ powder is about 400 nm in diameter as observed by scanning electron microscopy. The first discharge capacity of Li(Ni_1/3Co1_/3Mn_1/3)O₂ electrode is 174.6 mA∙h/g at 16 mA/g between 2.8 V and 4.5 V versus Li at room temperature, and the capacity retention is 95.2% of the initial discharge capacity after 50 cycles at 32 mA/g.

Key words: Co-precipitation method; Li(Ni_1/3Co_1/3Mn_1/3)O₂; positive materials; lithium ion batteries