Synthesis of LiNi1/3Mn1/3Co1/3O2 and Crystal Structure Studies by Electron Diffraction

Abstract

The performance of LiNi1/3Mn1/3Co1/3O2 depends largely on the distribution of transition metal ions over the available lattice sites within the layered rocksalt structure. Despite predictions that the TM ions take on an ordered arrangement described by a 3 x 3 R30º supercell little experimental evidence is available to confirm this model. On the other hand the observed cation distribution likely depends on synthesis conditions. Here we compare LiNi1/3Mn1/3Co1/3O2 synthesized on a small scale in our laboratory at 850ºC, subjected to chemical delithiation and annealing, to commercially produced LiNi1/3Mn1/3Co1/3O2 synthesized at 1000ºC before and after charge discharge cycling. Electron diffraction shows that in plane ordering is observed to small extents at the higher synthesis temperature but not at 850ºC. In both compounds a transformation towards the cubic spinel structure and significant changes towards a lamellar morphology are observed after annealing of the delithiated particles and after charge discharge cycling.