Li1.2Mn0.6Ni0.1Co0.1O2 microspheres constructed by hierarchically arranged nanoparticles as lithium battery cathode with enhanced electrochemical performance

Abstract

Novel lithium-rich layered Li_1.2Mn_0.6Ni_0.1Co_0.1O₂ microspheres containing hierarchically arranged and interconnected nanostructures have been synthesized by a combination of template-free co-precipitation and solid-state methods. The in situ formed γ-MnO₂ spherical template upon co-precipitation gets sacrificed during the course of solid-state fusion of cobalt, nickel and lithium precursors to produce the title compound in the form of microspheres constructed by nanoparticles as building blocks. Porous and hollow microspheres of Li_1.2Mn_0.6Ni_0.1Co_0.1O₂ are formed out of the spontaneous aggregation of nanoparticles, obtained from the custom-designed synthesis protocol. The growth mechanism of Li_1.2Mn_0.6Ni_0.1Co_0.1O₂ spheres could be understood in terms of the Kirkendall effect and Ostwald ripening. The nanocrystalline Li_1.2Mn_0.6Ni_0.1Co_0.1O₂ compound is obtained as a solid solution consisting of rhombohedral Rm and monoclinic C2/m group symmetries, as evidenced by XRD, Raman spectra and HRTEM equipped with FFT and STEM. The currently synthesized Li_1.2Mn_0.6Ni_0.1Co_0.1O₂ cathode exhibits an appreciable discharge capacity of 242 mA h g⁻¹ at a current density of 50 mA g⁻¹, due to the synergistic effect of the capacity obtained from the rhombohedral and monoclinic phases.