The electrochemical performance of yttrium oxide coated LiNi1/3Mn1/3Co1/3O2 as cathode material for lithium-ion batteries

The surface of LiNi_1/3Mn_1/3Co_1/3O₂ was coated with 1.0 wt.% Y₂O₃ to improve the cycling performance for lithium-ion batteries. X-ray diffraction (XRD) of the coated material indicates Y₂O₃-coating does not destroy the crystal structure of LiNi_1/3Mn_1/3Co_1/3O₂, only forming a compact coating layer on the surface of it. Differential scanning calorimetry-thermal gravimetric analyses (DSC-TGA) results show the coating layer could suppress the heating release. The Y₂O₃-coated LiNi_1/3Mn_1/3Co_1/3O₂ possesses higher discharge capacity and better cyclability than that of the bared material. The discharge capacity of coated sample is 100.7 mAh g^-1 at 2.0 C while that of bared one is only 80.0 mAh g^-1. The rate of capacity retention after 12 cycles for the coated sample is 100% at 333 K, which is much better than that of the bared one (94.9 %). The chemical diffusion coefficient of Li⁺ ion (DLi ) in the electrodes were measured by potentiostatic intermittent titration technique (PITT). The result shows that Li⁺ ion can move faster after coating.