Lithium-rich Li1.2Ni0.13Co0.13Mn0.54O2 oxide coated by Li3PO4 and carbon nanocomposite layers as high performance cathode materials for lithium ion batteries

Abstract

Lithium-rich layered oxide Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ (LNCMO) coated with a nanocomposite layer of Li₃PO₄ and carbon (LNCMO@Li₃PO₄/C) is designed and facilely prepared as the cathode material for rechargeable lithium ion batteries. The structure and morphology of the LNCMO@Li₃PO₄/C material are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and its electrochemical performance is measured by the constant current charge and discharge, electrochemical impedance spectroscopy and cyclic voltammetry. It is clearly revealed that the LNCMO surface is uniformly coated by the Li₃PO₄/C nanocomposite layer. Moreover, the coating process induces the layer-to-spinel phase transformation, leading to the formation of a spinel nanophase in the LNCMO@Li₃PO₄/C material. The presence of Li₃PO₄/C composite coating with high ionic and electronic conductivity and the spinel nanophase synergistically contribute to the electrochemical properties. Therefore, the LNCMO@Li₃PO₄/C material shows a high discharge capacity of 124.4 mA h g⁻¹ even at a current density of 1000 mA g⁻¹, a remarkable capacity retention of 87.3% after 200 cycles, and a desirable initial coulombic efficiency of 87.0%. The LNCMO@Li₃PO₄/C material represents an attractive alternative to high-rate and long-life electrode materials for lithium-ion batteries.