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

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° Ni 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.