Crystallization kinetics and mechanism of the LixNi2-xO2 (0<x≤1) from Li2CO3 and NiO

LiNiO2 is known to be the potential material to replace expensive LiCoO2 cathode in lithium-secondary battery. Kinetics and mechanism of the LixNi2-xO2 (0 <x less than or equal to1) reacted from Li2CO3 and NiO were investigated by X-ray diffraction (XRD), SEM in this study. The formation of LixNi2-xO2 was found to be a thermally activated process, which can be represented as the Jander model [1 - (1-alpha)(1/3)](2) = kt and the reaction activation energy is estimated to be about 190 kJ/mol. The formation of LixNi2-xO2 Can be viewed as the combination of two reactions: (1) the oxidation of nickel (II) to nickel (III) accompanied by the creation of cation vacancies and followed by (2) the filling of lithium ions into the cation vacancies created. Based on the result of kinetics study in this work, the rate-determining step is considered to be the creation of nickel vacancies and can be described as 1/2O(2) ((NiO)) over right arrow V-Ni" + 2h(.) + O-0(x) (C) 2002 Elsevier Science B.V. All rights reserved.