Effects of the strong oxidant treatment of precursor on the electrochemical properties of LiNi0.8Mn0.1Co0.1O2 for lithium-ion batteries

LiNi0.8Mn0.1Co0.1O2 cathode material with excellent electrochemical properties was successfully prepared by treating a precursor with strong oxidant KMnO4. The effects of KMnO4 on the precursor were analyzed in detail. The results indicated that there was an MnO2 layer of nanoscale thickness that formed on LiNi0.8Mn0.1Co0.1O2, and some Mn4+ ions were introduced into the surface layer. The cathode material prepared by the precursor treated with KMnO4 exhibited an improved capacity retention of 92.5% after 50 cycles at room temperature. Electrochemical impedance spectroscopy analysis confirmed that the increase of the electrochemical impedance for the electrode after 50 cycles was significantly suppressed. Combined with XPS (X-ray photoelectron spectroscopy) tests of the cycled electrodes, it was proven that electrolyte decomposition on the surface of the modified LiNi0.8Mn0.1Co0.1O2 was greatly suppressed, and a thin SEI film was formed. In addition, the lithium-ion diffusion rates before and after 50 cycles were greatly improved, since the MnO2 layer suppressed side reactions between the cathode material and electrolyte and stabilized the structure of LiNi0.8Mn0.1Co0.1O2. (C) 2019 Elsevier B.V. All rights reserved.