Cation order/disorder in lithium transition-metal oxides as insertion electrodes for lithium-ion batteries (original) (raw)

2000, Pure and Applied Chemistry

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 Ni 3+ and Mn 4+ 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°N i 3+ -O-Ni 3+/2+ exchange interactions, the distribution of Ni 3+ /Ni 2+ between the lithium and nickel layers in Li 1-x Ni 1+x O 2 with 0 < x < 0.4 can be determined. For layered LiNi 1-y Co y O 2 and spinel LiMn 2-x Co x O 4 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 Ni 3+ /Co 3+ and Mn 4+ /Co 3+ ordering. The results obtained are correlated with the electrochemical intercalation of lithium in these compounds. the effect of the synthesis conditions on the local cation distribution in LiNi/CoO 2 and LiMn 2-x M x O 4 (M = Co, Mg) are presented. Since magnetic properties are sensitive to the cation distribution, magnetic measurements (electron spin resonance and magnetic susceptibility measurements) were used to monitor the short-range cation ordering in these compounds, which is not possible by means of diffraction techniques.