Multivariate curve resolution analysis of operando XAS data for the investigation of the lithiation mechanisms in high entropy oxides

Transition metal-based high entropy oxides (TM-HEO) have recently been gaining interest for their potential use as anodes in next-generation Li-ion batteries. In such systems, however, the lithiation/delithiation mechanisms remain a matter of ongoing investigation. In this work we demonstrate the suitability of Multivariate Curve Resolution (MCR) of operando X-ray absorption spectroscopy (XAS) data to study the lithiation mechanisms in the TM-HEO (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O. Through the MCR analysis, the number, nature and concentration evolution as a function of stored charge of all Cu-, Ni- and Co-related active species present during the first lithiation cycle is obtained.