In-Operando Detection of the Physical Property Changes of an Interfacial Electrolyte during the Li-Metal Electrode Reaction by Atomic Force Microscopy

The physical properties of an interfacial electrolyte near the electrode surface essentially affect the electrochemical behavior of the Li metal negative electrode. Therefore, probing the interfacial electrolyte under in-operando conditions is highly desired to determine the true electrochemical interface and electrode performance. In this study, dissipation recording by force-distance analysis based on atomic force microscopy was applied for the first time to address these challenges and a notable performance was observed during this study. The energy dissipation of the cantilever during the force curve motion is an important indicator to evaluate the conditions of the interfacial electrolyte because the solution drag is based on the physical properties of the electrolyte. In the in-operando electrochemical experiments of the Li metal electrode with a tetraglyme-based electrolyte, the dissipation energy clearly changed corresponding to the charge-discharge reaction. Recording the dissipation based on the force-distance analysis coupled with electrochemical operation improved the understanding of the actual characteristics of the electrochemical interface based on the direct measurement of the physical properties.