Inhomogeneous distribution of chemical species in lithium nickel oxide cathode of lithium ion battery

Abstract

The spatial distribution of the oxidation state for the nickel species in the LiNiO2 cathode was analyzed by means of the in-situ XAFS imaging technique during the charging and discharging processes. The inhomogeneous reaction for the LiNiO2 cathode was observed under the operating condition. The pattern in the 2-dimensional map of the oxidation state of the active material in the discharging process was similar to that in the charging process. It means that the areas preceding the discharging reaction agree with the areas delaying the charging reaction. It was suggested that the diffusion of Li+ was restricted by the surface product of the LiNiO2 electrode, and the concentration gradient of Li+ delayed the charging reaction at the reaction channel of the discharging reaction.