Surface modification of LiNi1/3Co1/3Mn1/3O2 with Cr2O3 for lithium ion batteries

Abstract

Cr2O3-coated LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by a novel method. The structure and electrochemical properties of prepared cathode materials were measured using X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The measured results indicate that surface coating with 1.0 wt% Cr2O3 does not affect the LiNi1/3Co1/3Mn1/3O2 crystal structure (α-NaFeO2) of the cathode material compared to the pristine material, the surfaces of LiNi1/3Co1/3Mn1/3O2 samples are covered with Cr2O3 well, and the LiNi1/3Co1/3Mn1/3O2 material coated with Cr2O3 has better electrochemical performance under a high cutoff voltage of 4.5 V. Moreover, at room temperature, the initial discharging capacity of LiNi1/3Co1/3Mn1/3O2 material coated with 1.0 wt.% Cr2O3 at 0.5C reaches 169 mAh·g−1 and the capacity retention is 83.1% after 30 cycles, while that of the bare LiNi1/3Co1/3Mn1/3O2 is only 160.8 mAh·g−1 and 72.5%. Finally, the coated samples are found to display the improved electrochemical performance, which is mainly attributed to the suppression of the charge-transfer resistance at the interface between the cathode and the electrolyte.