Structural and electrochemical properties of Li-Ni-Co oxides synthesized by wet chemistry via a succinic-acid-assisted technique

Lithiated metal oxides LiCo1-xNiyO2 were synthesized by a sol-gel method us ing succinic acid as chelating agent. Microcrystalline materials were forme d by calcination in oxygen at 800 degreesC. The physicochemical properties of the powders (crystallinity, lattice constants, size grain) has been inve stigated in the compositional range 0 less than or equal to y less than or equal to 1. Structural studies show that a layered single phase was obtaine d. The local cationic environment has been studied by Raman and FTIR spectr oscopy. The changes in the vibrational spectra are well related to those ob served by X-ray diffraction. It is shown that the lithium predominant layer s are preserved in the entire range of substitution. Pelletized LiCo1-yNiyO 2 powders (0.2 less than or equal to y less than or equal to 1.0) were test ed in Li//LiCo1-yNiyO2 cells by galvanostatic titration. These cells have a n initial capacity of 140 mAh/g in the voltage range 2.8-4.2 V and show att ractive charge-discharge profiles upon cycling. (C) 2001 Elsevier Science L td. All rights reserved.