A novel tool for detecting Li diffusion in solids containing magnetic ions; μ+SR study on LixCoO2

Abstract

The diffusion coefficient of Li+ ions (DLi) in the battery material LixCoO2 has been investigated by means of muon-spin relaxation (μ+SR), because DLi for positive electrode materials has not been determined correctly so far. Based on performing the experiments in zero-field and weak longitudinal-fields at temperatures up to 400 K, we determined the fluctuation rate (v) of the fields on the muons due to their interaction with the nuclear moments. Combined with susceptibility data and electrostatic potential calculations, clear Li + ion diffusion was detected above ∼ 150 K. The DLi estimated from v was in very good agreement with predictions from first-principles calculations, and we present the μ+SR technique as a novel and optimal probe to detect DLi of unique usefulness for materials containing magnetic ions. © 2010 IOP Publishing Ltd.