Surface modification of LiCo_1/3Ni_1/3Mn_1/3O₂ with Y₂O₃ for lithium-ion battery

The surface of LiCo_1/3Ni_1/3Mn_1/3O₂ cathode material was coated with 1.0 wt.% Y₂O₃ via a simple method to improve the cycling performance for lithium-ion batteries. Cyclic voltammetry showed Y₂O₃-coating inhibited structural change of LiCo_1/3Ni_1/3Mn_1/3O₂ and reaction with the electrolyte on cycling. The Y₂O₃-coated material showed a higher capacity with good cyclability. The discharge capacity of coated sample was 137.5 mAh g^-1 at 2.0 mA cm^-2 while that of bared one was only 116.2 mAh g^-1. The rate of capacity decrease after 20 cycles for the coated sample was 0.7%, much smaller than that of the bared one (2.8%). X-ray photoelectron spectroscopy (XPS) data represented that the presence of two different environmental O1s ions corresponded to the surface-coated Y₂O₃ and core material. ICP-OES and EIS displayed the coating layer could protect the LiCo_1/3Ni_1/3Mn_1/3O₂ from being corroded by the electrolyte and benefit to decrease the cathode charge-transfer resistance at delithiated state.