SYNTHESIS OF LINIO2 IN AIR ATMOSPHERE - X-RAY-DIFFRACTION CHARACTERIZATION AND ELECTROCHEMICAL INVESTIGATION

The synthesis of LiNiO2 in air is studied by means of X-ray diffractio n (XRD) characterization using a new fast method based on the splittin g of the (108) and (110) peaks and the depth of the minimum between th ese peaks. From the evolution of these XRD parameters during the heat treatment of the starting mixture of LiOH and NiO the optimum synthesi s time is determined, where the separation angle has a maximum, implyi ng a good stoichiometry and low cation disorder; the minimum between t he peak is deepest, indicating a better crystallinity. Selected sample s of LiNiO2, were cycled as cathodes in laboratory-coin cells between constant charge and discharge end voltages at a constant current. It i s found that the capacity decay rate is related to the phase transitio ns occurring during cycling. This rate is dependent on the minimum lit hium content x in LixNi2-xO2 at the end of charge. As the cycling proc eeds x(min), increases despite that the end charge voltage is kept con stant, whereby the capacity decay rate diminishes.