2D Operando Acoustic Characterization of Lithium-Ion and Lithium-Metal Batteries

Abstract

Spatially sensitive operando characterization techniques provide fundamental insights into dynamic and complex electrode phase behaviors of electrochemical cells during operation. However, real-time characterization of cell-level phase behavior is challenging especially for fast- charging conditions. We demonstrate a spatially resolved operando acoustic characterization method with sufficient resolution to detect local variations in phase behavior for the entire cell area during charging at all practical rates. Amplitude attenuation during fast-charge is shown to arise from localized lithium metal plating near the welded tab locations. Differential amplitude analysis then takes advantage of the electrochemical-mechanical coupling of graphite staging dynamics to visualize the varying extent of graphite lithiation at different locations on the pouch cell. These time-domain modalities are then coupled with frequency-domain images from fast Fourier transforms. Analyzing anode-free lithium metal pouch cells demonstrates that rapid and spatially heterogenous attenuation in suboptimal electrolytes is due to electrolyte consumption initiating from electrode edges after deposition of an initial porous layer.