Controlled Single Step Synthesis, Structural and Electrode response of Honeycomb Layered Li3Co2SbO6

We report, for the first time, a single step synthesis process of Li3Co2SbO6 in air medium using the solid state reaction route. The structural analysis confirmed single phase layered crystal structure comprising 2D diffusion path along a-axis and b-axis. The Rietveld refinement of Li3Co2SbO6 yielded monoclinic crystal structure with C2/m space group having cell parameters, a = 5.216, b = 8.989 and c = 5.171 A˚ with Li/Co mixed occupancy. The TEM analysis corroborated layered structure consistent with X-ray analysis. Raman and FTIR analysis confirmed the presence of CoO6 and SbO6 octahedra in Li3Co2SbO6 with edge shared arrangement to form a layered stack comprising tunnel type pathway for Li+ ion transport. The estimated electrical conductivity of Li3Co2SbO6 is found to be ~ 6.9×10-8 Scm-1 with a band gap ~ 3.5 eV that suggests poor electronic transport for storage cells. This, in fact, was observed in the electrochemical response of the Li || LiPF6(EC/EMC) || Li3Co2SbO6 cell. The 1st discharge capacity of Li3Co2SbO6 has been found to be a meagre 45 mAhg-1. Despite lower reversible capacity due to poor electrical transport, stable coulombic efficency observed up to 100 cycles suggest the feasibility of improvements in the electrical and charge transport properties.