Synthesis, structural and electrochemical properties of LiNi0.79Co0.1Mn0.1Cr0.01O2 via fast co-precipitation

A novel layered material of LiNi0.79Co0.1Mn0.1Cr0.01O2 is synthesized by fast co-precipitation method. Transmission electron microscope (TEM) and energy dispersive analysis of X-rays (EDAX) exhibit that Cr is successfully incorporating into LiNi0.8Co0.1Mn0.1O2. X-ray diffraction (XRD) and Rietveld refinement show that cation mixing is reduced by Cr substitution. Cyclic voltammerty (CV) indicates that the Cr substitution could decrease Jahn-Teller distortion, and improve reversibility of Li+ ions during intercalating/deintercalating. Electrochemical impedance spectroscopy (EIS) reveals that Cr substitution has an effect on restraining the charge transfer impedance of cathode. Electrochemical studies confirm that Cr substitution for LiNi0.8Co0.1Mn0.2O2 also results in improved discharge capacity, initial coulombic efficiency, rate ability and cycling property of cathode. The capacity retention of LiNi0.8Co0.1Mn0.1O2 after 50 cycles at 5C is only 76.1%, however, that of the LiNi0.79Co0.1Mn0.1Cr0.01O2 is improved to 89.02%. It is noted that the discharge capacity of LiNi0.79Co0.1Mn0.1Cr0.01O2 is 209.9, 183, 171.4, 164.2 and 152.8 mAhg(-1) at 0.1, 1, 3, 5 and 10C, respectively, in the cut-off voltage of 2.7-4.3 V. (C) 2010 Elsevier B.V. All rights reserved.