On the LiCo2/3Ni1/6Mn1/6O2 positive electrode material

LiCo2/3Ni1/6Mn1/6O2 layered oxide was synthesized by the combustion method that led to a crystalline phase with good homogeneity and low particles size. The structural properties of the prepared positive electrode material were investigated by performing XRD Rietveld refinement. Practically no Li/Ni mixing was detected evidencing that the studied compound adopts almost an ideal alpha-NaFeO2 type structure. The Li parallel to LiCo2/3Ni1/6Mn1/6O2 cell showed a discharge capacity of 199 mAh g(-1) when cycled in the 2.7-4.6V potential range while the best cycling performances were recorded when the upper cut off is fixed at 4.5 V. Structural changes in LixCo2/3Ni1/6Mn1/6O2 with lithium electrochemical de-intercalation were studied using X-ray diffraction. This study clearly shows the existence of a solid solution domain in the 0.1 < x < 1.0 composition range while for x = 0.1, a new phase appears explaining the decrease of the electrochemical performance when the cell is cycled at high upper cut off voltage. (C) 2011 Elsevier Ltd. All rights reserved.