Implications of reaction mechanism and kinetics on the synthesis of stoichiometric LiNiO2

The reaction mechanism and kinetics of formation of LiNiO2 using the particulate sol-gel (PSG) process derived precursors have been investigated using a combination of X-ray diffraction and thermogravimetric analysis (TGA). It has been confirmed that Li2CO3 and NiO are the intermediate products formed after decomposition of the xerogel. Subsequent heat-treatment initiates a further reaction between Li2CO3 and NiO to form LiNiO2. A single peak observed in the differential weight loss profile suggests a direct reaction between Li2CO3 and NiO with simultaneous evolution of CO2. The activation energy associated with this direct reaction is estimated as 98.5 kJ/mol using the nonisothermal Kissinger's method. The reasons for the faster reaction kinetics of the PSG derived xerogel compared to the precursors generated using the conventional solid-state process are also investigated using TGA and transmission electron microscopy. Results of the mechanism and kinetics studies have facilitated the synthesis of nearly stoichiometric LiNiO2 with <2% anti-site defects. (C) 2002 The Electrochemical Society.