Enhanced electrochemical properties of Y2O3-coated-(lithium-manganese)-rich layered oxides as cathode materials for use in lithium-ion batteries.

In this study, a 5–10-nm-thick Y 2 O 3 layer is employed as a surface-coating layer on (lithium-manganese)-rich Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO) cathode materials for the first time. The results indicate that the bulk structure of LMNCO is unchanged with the additional Y 2 O 3 coating, and the electrochemical properties, including initial coulombic efficiency, cycle stability and rate performance, are greatly enhanced in these coated materials. In particular, the 2.0 wt% Y 2 O 3 -coated LMNCO expresses an initial discharge capacity of 280.3 mAhg −1 with capacity retention of 89.1% at a 0.5 C rate after 200 cycles, which is much better than that of 76.3% of the pristine sample. Furthermore, electrochemical impedance spectroscopy demonstrates that the Y 2 O 3 -coating layer can protect the LMNCO from being impaired by the electrolyte and can make contributions to reduce the cathode charge-transfer resistance at the delithiated condition. These findings offer new research directions for solving serious defects, such as a large proportion of initial nonreversible capacity loss and poor cycling stability, in lithium-rich cathode materials used for lithium-ion batteries. [ABSTRACT FROM AUTHOR]