The local environments and short-range ordering of Li_x(NiMn)_0.5O₂ (0<x<1), a potential Li-ion battery positive electrode material, were investigated by using a combination of X-ray and neutron diffraction with isotopic substitution, Li MAS NMR spectroscopy, first principles calculations, X-ray and neutron Pair Distribution Function (PDF) analysis, and Reverse Monte Carlo (RMC) calculations. The structure of Li(NiMn)_0.5O₂ comprises separate Li layers, transition metal (Ni,Mn) layers and O layers.

Both NMR and RMC calculations showed the presence of short-range order in the transition metal layers comprising LiMn₆ and LiMn₅Ni clusters and Ni/Mn contacts that are consistent with a disordered ‘flower' structure.

The results will be contrasted with recent NMR and RMC calculations of Li(NiMn)_0.5O₂ derived from Na(NiMn)_0.5O₂ via ion-exchange. This material showed very little Li/Ni exchange and non-random ordering in transition metal layers and excellent electrochemical behavior.