Performance of layered Li(Ni 1/3Co 1/3Mn 1/3)O 2 as cathode for Li-ion batteries

Abstract

Layered Li(Ni 1/3Co 1/3Mn 1/3)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 Å. 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 Ni 3+ and Mn 3+ 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 ∼3.8 and ∼4.6 V are assigned to the Ni 2+/4+ and Co 3+/4+ couples, respectively.