Characterizations on the structural and electrochemical properties of LiNi1/3Mn1/3Co1/3O2 prepared by a wet-chemical process

LiNi1/3Mn1/3Co1/3O2 compounds were prepared at 700 (sample-A) and 900 degrees C (sample-B) by a simple wet-chemical process. X-ray diffraction showed the sample-A had a larger Li/Ni site exchange (9.9%) than that of the sample-B (4.4%). Raman scattering analysis suggests strong structural disorder within the octahedral [MO6] units due to different masses and bonding of the M-O bonds, as well as the Li/Ni site exchange in the crystals. The weakening of the E-g band was correlated with the Li/Ni site exchange. XPS analysis indicates that a lower annealing temperature than 900 'C leads to the formation of oxygen deficient LiNi1/3Mn1/3Co1/3O2-delta. The electrochemical properties of the materials were investigated by charge-discharge experiments and electrochemical impedance spectroscopy. The drastic capacity fading of the sample-A was attributed to its structural properties. The sample-B showed satisfying cycling performance. But the capacity fading in the potential region of 2.5-4.6 V was larger than that in 2.5-4.4 V, which was attributed to the large charge transfer resistance at potentials above 4.4 V. (C) 2008 Elsevier B.V. All rights reserved.