Local Structure and Cation Ordering in O3 Lithium Nickel Manganese Oxides with Stoichiometry Li [ Ni x Mn ( 2 − x ) / 3Li ( 1 − 2x ) / 3 ] O 2 NMR Studies and First Principles Calculations

Short-range ordering in Li[Ni x Mn ( 2 - x ) / 3 Li ( 1 - 2 x ) / 3 ]O 2 was investigated with 6 Li NMR and first principles structure computations. NMR indicates that the tendency for Ni 2 + to replace Li + in the Li + layers decreases with decreasing nickel content. Li in the Ni/Mn layers preferentially occupies sites near Mn 4 + and avoids the Ni 2 + ions, leading to nonrandom configurations. Calculations indicate that the ground state of Li(Ni 0 . 5 Mn 0 . 5 )O 2 contains zigzag rows of Ni 2 + and Mn 4 + 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.