An investigation on the effect of Li+/Ni2+ cation mixing on electrochemical performances and analysis of the electron conductivity properties of LiCo0.33Mn0.33Ni0.33O2

Two alternative synthesis procedures, i.e. co-precipitation and sol gel, have been used to prepare LiCo0.33Mn0.33Ni0.33O2 samples. Inductive coupled plasma optical emission spectroscopy (ICP-OES), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) have been used in order to determine the stoichiometry, the structural characteristic and the morphology of the materials. The results show that these samples obtained by sol gel have a high level of crystal defectivity, particularly in terms of Ni2+/Li+ cation mixing. We show that the defectivity reflects directly on electrochemical performances since lithium diffusion is hindered by nickel cations in the 3a sites as well as by a distorted structure. Then, co-precipitation samples have been selected as the most promising for battery application. The results confirm that this sample may be effectively used as cathode in advanced lithium ion polymer batteries formed by a Li4Ti5O12 anode and a PVdF LiPF6 EC:PC gel polymer electrolyte.