Performance of layered Li(Ni1/3Co1/3Mn1/3)O2 as cathode for Li-ion batteries

Layered Li(Ni1/3CO1/3Mn1/3)O-2 was prepared by mixed hydroxide method and characterised by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and charge-discharge cycling. The hexagonal lattice parameters obtained for the compound are: a = 2.864 and c = 14.233 Angstrom. XPS studies show that the predominant oxidation states of Ni, Co and Mn in the compound are 2 +, 3 + and 4 +, respectively with small content of Ni3+ and Mn3+ ions. Initial discharge capacity of 160 mAh/g was obtained in the range 2.5-4.4 V and at a specific current of 30 mA/g of which 143 mAh/g was retained at the end of 40 charge-discharge cycles. At lower current (10 mA/g) and in the voltage window 2.5-4.7 V, discharge capacity of 215 mAh/g is obtainable. From the voltage profile and cyclic voltammetry, the redox processes occurring at similar to 3.8 and similar to 4.6 V are assigned to the Ni2+/(4+) and Co3+/(4+) couples, respectively. (C) 2002 Published by Elsevier Science Ltd.