in situ Monitoring of Lithium Electrodeposition using Transient Grating Spectroscopy

The mechanisms of lithium electrodeposition, which overwhelmingly affect lithium metal battery performance and safety, remain insufficiently understood due to its electrochemical complexity. Novel, non-destructive and in situ techniques to probe electrochemical interfaces during lithium electrodeposition are highly desirable. In this work, we demonstrate the capability of transient grating spectroscopy to monitor lithium electrodeposition at the micrometer scale by generating and detecting surface acoustic waves that sensitively interact with the deposited lithium. Specifically, we show that the evolution of the frequency, velocity and damping rate of the surface acoustic waves strongly correlate with the lithium nucleation and growth process. Our work illustrates the sensitivity of high-frequency surface acoustic waves to micrometer scale changes in electrochemical cells and establishes transient grating spectroscopy as a versatile platform for future in situ investigation of electrochemical inte