Operando soft X-ray spectroscopy probing of the electrode/electrolyte interfacial dynamics

There has been a considerable interest in the study of electrochemical processes in multivalent batteries. In this work, the coordination of Ca²⁺ at this electrolyte/electrode interface as a function of the type of anions is probed by the in-situ/operando soft X-ray absorption (XAS) spectroscopy under operando electrochemical conditions. The solvation of an electrolyte near the electrolyte/electrode interphase dictates the charge transfer efficiency and therefore affects the performance of a battery. However, current understanding regarding this interphase was limited due to the lack of direct interphase probing approaches under in-situ/operando conditions. In this report, using synchrotron-based X-ray absorption spectroscopy and resonant soft X-ray scattering through a patterned e-chip, the solvation of a calcium organic electrolyte was investigated under operando conditions. The disruption of the solvation structure by a secondary anion or cation were evaluated using the methodologies developed, which will guide the designing of electrolytes for future energy storage. The strategy of these new methodologies developed will also benefit the investigation of catalysis at interphases and electrochemical microenvironments in general.