Improving rate capacity and cycling performance of lithium-rich high-Mn Li1.8[Mn0.7Co0.15Ni0.15]O2.675 cathode materials by Li2SiO3 coating

Abstract

Spherical lithium-excess high manganese layered oxides, Li1.8[Mn0.7Co0.15Ni0.15]O2.675, were successfully synthesized by carbonate co-precipitation method. To further improve the electrochemical performance of this cathode materials, spherical Li1.8[Mn0.7Co0.15Ni0.15]O2.675 particles were functionally modified with fast Li+-ion conductor Li2SiO3 via a sol-gel method. The structural change features were systematically characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, cyclic voltammograms and electrochemical impedance spectroscopy. The results show that Li2SiO3 coating layer can greatly improves the diffusion rate of Lithium ions at the interface between cathode materials and electrolyte, Li1.8[Mn0.7Co0.15Ni0.15]O2.675@Li2SiO3 composite cathode materials exhibits outstanding rate capability(*), cycle stability and low polarization. This excellent performance is attributes to Li2SiO3 coating layer can prevent electrode from the corrosion of electrolyte and improve the diffusion rate of lithium ion. 1.5wt% Li2SiO3 coating sample shows the highest rate capacity (approximately 250mAhg−1 at 0.1C and 160mAhg−1 at 1C) and stable cyclic performance when cycled between 2.5-4.8V at 25°C.