Surface modification of spinel LiMn ₂O ₄ with Y ₂O ₃ for lithium-ion battery

Spinel LiMn ₂O ₄ was modified with Y ₂O ₃ coating by a chemical process. The crystal structures of the as-prepared samples were investigated by X-ray diffraction (XRD). The charge/discharge characteristics of the modified samples were evaluated at different rates between 3.0 and 4.4V. The discharge capacities of 2.0 wt.% Y ₂O ₃-coated LiMn ₂O ₄ are 116 mAh·g ^-1, 99.7mAh·g ^-1, 93.3mAh·g ^-1 and 82.9mAh·g ^-1 at 0.1C, 0.5C, 1C and 2C rates (at 20°C). The cycle abilities improvement of the spinel LiMn ₂O ₄ coated with Y ₂O ₃ are demonstrated at elevated temperature (55°C) and high rates (2C). From the analysis of electrochemical impedance spectroscopy (EIS), the improvement of cycle ability may be attributed to the suppression on the formation of the passivating films and the reduction of Mn dissolution, which result from the surface modification with Y ₂O ₃.