LAUSR

Abstract Substitution with 4d/5d-elements has been recently established as promising solution for suppressing capacity and voltage fading in Li-Mn-rich layered oxide cathodes for lithium ion batteries. This study aims at understanding of the underlying working principles of this concept through a systematic study on an Nb substituted Co-free material, i.e. Li1.2Ni0.2Mn0.6O2. Nb is confirmed by XRD to be located at the position of Li in the transition metal layer of the C/2 m phase of the composite material thereby increasing the kinetics of activation significantly. Due to substitution, the material experiences a lager extent of reversible anionic redox activity while it also gains an increased thermal stability and shows less oxygen loss than the pristine material during cycling. In addition, substitution also improves the electrochemical performance by increasing the energy efficiency of the material. This study provides insights into the effects of Nb substitution and could be a useful guide for the study of other substitution elements and the ongoing improvement of Li-Mn-rich layered oxide cathodes.