Determining the intrinsic role of Mg doping in LiCoO2

The electrochemical performance of LiCoO2 can be substantially improved via multielemental doping to enable high-voltage applications. However, the limitations and the intrinsic functions of each element in doping have not been identified to date. In this study, we employed commercial LiCoO2 samples and identified Mg doping limitations in Al, Ti, and Mg tri-elemental-doped materials. The results demonstrate that excessive Mg doping is unfavorable to the dynamics of LiCoO2 due to the formation of a similar to 2 nm MgO coating layer and randomly distributed MgO islands, which directly resulted in a decrease of the discharge plateau. Calculations demonstrated the functions of Mg doping and MgO coating. To the best of our knowledge, this report is the first to describe a comprehensive study on the intrinsic role of Mg doping in commercial LiCoO2. (C) 2020 Elsevier B.V. All rights reserved.