Abstract: Recently, high-entropy oxides (HEOs) have emerged as an alternative conversion electrode material for next-generation Li-ion batteries. The concept of entropy stabilization of numerous transition metal oxides (TMOs) in a single solid solution phase opens new boundaries of materials design, providing the possibility of overcoming individual TMOs’ limitations by tailorable properties. This promising electrochemical performance was first demonstrated for the (MgCoNiCuZn)O compound but still needs to be better described. 

In this talk, I use ex-situ and operando X-ray absorption spectroscopy to assess the individual contribution of each metal in this composition to the electrochemical reaction mechanism by examining the change in local (EXAFS) and electronic (XANES) structure under different battery operations. I also discuss the role of the entropy stabilization and tunability effects on battery performance, and the origins of the extra-storage capacity encountered in those electrodes as Li-ion anodes.