Characterization of particulate sol-gel synthesis of LiNi0.8Co0.2O2 via maleic acid assistance with different solvents

Particulate sol-gel LiNi0.8Co0.2O2 has been synthesized by a maleic-acid-assisted process using de-ionized water or ethanol as the solvent. A comparison of the effect on these two different solvents was made on the basis of thermal studies, Fourier transform infrared spectroscopy, X-ray diffraction analysis, chemical diffusion coefficients measurement, and electrochemical cyclability tests. An esterification reaction occurred on the xerogel prepared with ethanol as solvent, reducing Ni and Co from their nitrate salts. LiNi0.8Co0.2O2 grew at the expense of Li2O3, NiO, and CoO during calcination. Better results of capacity and cyclability were obtained in a DI-water-solvent sample associated with a larger interslab thickness between O-Li-O and lower Ni occupancy on the Li site. The activation energy for the calcinations of DI-water-solvent sample is one-half of that of the ethanol-solvent one, which could be the reason for its better properties. Chemical diffusion coefficients of Li+ ion are of the same order 10(-10) cm(2)/s, is not affected by the solvents used and/or the temperature raise to 55 degrees C. (c) 2005 Elsevier B.V. All rights reserved.