Preparation and Electrochemical Performances of LiNi_0.5Mn_0.5O₂ Cathode Materials for Lithium-Ion Batteries

摘要

In this work, LiNi0.5Mn0.5O2 were successfully prepared were successfully prepared by an improvedsolid-state reaction technique using the solid solution of nickel manganese oxide (Ni1.5Mn1.5O4) as theprecursor. The phase structure and surface morphologies of as-prepared LiNi0.5Mn0.5O2 were identifiedby X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM) measurements.The as-prepared LiNi0.5Mn0.5O2 presented an -NaFeO2-type (R m) layered crystalline structure, andpossessed an irregular granular appearance with a narrow size distribution and an average grain size ofca. 1.2 m. The as-prepared LiNi0.5Mn0.5O2 cathode material delivered an initial discharge capacity of-1 -1 182.4 mAh g at 0.2 C, and retained a discharge capacity of 175.4 mAh g (about 96.2% of the intial- discharge capacity) after 100 cycles. At a high rate of 4 C, a specific discharge capacity of 115 mAh g 1 (about 63% of the initial capacity at the rate of 0.2 C) was also retained. The electrochemicalmeasurements demonstrated that the as-prepared LiNi0.5Mn0.5O2 cathode material offered highlyreversible capacities, good cycling stabilities, and excellent rate capabilities. The smashingelectrochemical performance could be attributed to the as-prepared solid solution of precursorNi1.5Mn1.5O4, which resulted in a uniform distribution of nickel and manganese elements onto the ideallayer structure of as-prepared LiNi0.5Mn0.5O2.