Surface composition and electrochemical behavior of LiNi1/3Co1/3Mn1/3O2 cathode material with copper additive

LiNi_1/3Co_1/3Mn_1/3O₂（NCM） cathode material containing copper was prepared by co-precipitation method.The material was characterized by X-ray photoelectron spectroscopy（XPS） and galvanostatic cycling.XPS data indicate that surface compositions of the samples containing copper are different from the bare NCM.Copper on surface of particles was enriched,while nickel and lithium content was reduced.The electrochemical performance of NCM was affected by the change of surface compositions.Cycling performance charged to the cutoff voltage of 4.6 V was improved by introducing copper into the material.The effects of copper content on electrochemical behaviors of NCM at 4.5 V were discussed.