Effects of carbon coating on LiNi0.5Mn1.5O4 cathode material for lithium ion batteries using an atmospheric microwave plasma torch

Abstract

A novel carbon coating method on LiNi0.5Mn1.5O4 (LNMO) cathode active material powders for lithium-ion batteries is reported. Carbon coated LNMO (LNMO/C) cathode is prepared by an atmospheric 2.45 GHz microwave plasma torch system using an acetylene gas as carbon precursor. This method is one-step process. Therefore, its method is not only an easy control, short manufacturing time, and low-cost operation, but also gives similar results on LNMO/C produced by other carbon coating methods. The morphology and structure of prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis, and elemental analyzer (EA). Electrochemical properties of LNMO/C are tested in lithium half coin cells. The results show that the carbon coating on LNMO could greatly enhance the rate capability and cycle performance especially at high temperature compared to bare LNMO. At 10 C rate with increased temperature, the discharge capacity is 0.15 mAhg−1 for bare LNMO, while 104 mAhg−1 for LNMO/C. Also, the capacity retention of LNMO/C sample is 97% at 0.5 C rate after 50 cycles at elevated temperature. The simple carbon coating method used in this work may easily provide a surface modification approach to other materials for commercialization.