Pure and Applied Chemistry

Abstract: Results on the local cation ordering in layered lithium-nickel/cobalt oxides and metal-substituted lithium-manganese spinels are presented. It is shown that electron spin resonance of Ni³⁺ and Mn⁴⁺ and magnetic susceptibility measurements are powerful tools to monitor the short-range cation ordering in these compounds, which is not accessible by diffraction techniques. Thus, owing to the different strength of the 90° and 180° Ni³⁺–O–Ni^3+/2+ exchange interactions, the distribution of Ni³⁺/Ni²⁺ between the lithium and nickel layers in Li_1–xNi_1+xO₂ with 0 < x < 0.4 can be determined. For layered LiNi_1–yCo_yO₂ and spinel LiMn_2–xCo_xO₄ solid solutions, analysis of the temperature-independent EPR line width in terms of dipole–dipole and exchange interactions has been used to examine the local Ni³⁺/Co³⁺ and Mn⁴⁺/Co³⁺ ordering. The results obtained are correlated with the electrochemical intercalation of lithium in these compounds.