Synthesis and Performance Evaluation of SiO₂ Coated Li-Rich Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ Cathode Materials for Li-Ion Batteries

Abstract

Lithium rich layered oxides (LLO) are one of the potential candidates for Li-ion batteries. however, LLO materials have serious drawbacks such as poor cyclic stability, poor rate capability and rapid voltage decay upon cycling, which needs to be overcome in order to successfully commercialize them. In this work, SiO2 coating is employed (1.0%, 1.5%, and 2.0 wt. %) to combat these issues. Li1.2Ni0.13Mn0.54Co0.13O2 synthesis was carried out by sol-gel process and SiO2 coating was done using dry ball milling method. XRD analysis confirmed the synthesis of phase pure materials without the presence of any impurity phases. SEM and TEM analysis showed the synthesis of nanometric sized particles. Furthermore, TEM elemental mapping displayed the homogeneous distribution of SiO2 on the cathode particles. XPS was further employed to confirm the SiO2 on the cathode material. The electrochemical analysis showed that 1.0 wt.% SiO2 displayed the best performance in terms of rate capability. Uncoated Li1.2Ni0.13Mn0.54Co0.13O2 displayed a fast capacity fade, especially at higher C-rate. On the other hand, SiO2 coated Li1.2Ni0.13Mn0.54Co0.13O2 materials showed improved rate capability. Coated materials also showed improved cycling performance when compared with bare Li1.2Ni0.13Mn0.54Co0.13O2. The improved electrochemical performance can be attributed to the positive impact of SiO2 coating, which impedes the electrolyte oxidation by preventing the direct contact of cathode active material and electrolyte. Overall, the SiO2 coating had a positive impact on the electrochemical performance of Li1.2Ni0.13Mn0.54Co0.13O2 and can pave the way for commercialization of LLO materials.