Investigation of local structure of LiNi_0.5Mn_0.5 O₂ prepared by oxalic acid-ethanol coprecipitation method as a cathode active material for Li-ion battery

Abstract

We investigated the local, crystal and electronic structures of LiNi_0.5Mn_0.5O₂which prepared by oxalic acid-ethanol coprecipitation method. XRD pattern showed extra peak at 20∼23° which could be attributed to superlattice peaks originated from 3b ordering. The analytical composition of this sample corresponded to the nominal composition extremely well and it showed better cycle performance than the samples by solid-state method and solution method. From EXAFS spectra, the peak of the first coordinate of Ni showed the minimum intensity in the case of the coprecipitation method and thus Ni-O octahedra was the most distorted. On the other hands, the Mn-O octahedra showed the smallest distortion. PDF showed that Ni/Mn formed zigzag ordering at transition metal layer.