Local structure and cation ordering in O3 lithium nickel manganese oxides with stoichiometry Li[NixMn(2-x)/3Li(1-2x)/3]O-2 - NMR studies and first principles calculations

Short-range ordering in Li[NixMn(2-x)/3Li(1-2x)/3]O2 was investigated with Li-6 NMR and first principles structure computations. NMR indicates that the tendency for Ni2+ to replace Li+ in the Li+ layers decreases with decreasing nickel content. Li in the Ni/Mn layers preferentially occupies sites near Mn4+ and avoids the Ni2+ ions, leading to nonrandom configurations. Calculations indicate that the ground state of Li(Ni0.5Mn0.5)O-2 contains zigzag rows of Ni2+ and Mn4+ ions. Although a disordering temperature of approximately 1000 K is calculated, ordered fragments persist above the phase transition and these materials contain significant short-range order, even when quenched from high temperature. (C) 2004 The Electrochemical Society.