Acoustic Characterization of Structural Reversibility in Lithium Metal Anodes

Abstract

A commercially relevant lithium metal battery is still hindered by issues such as rapid consumption of the electrolyte and an unstable interface. Relative success in stabilizing the solid-electrolyte-interphase and achieving higher Coulombic efficiencies has been found using organoborate electrolyte salts, highly fluorinated solvents, external pressure and surface modification strategies. However, initially dense close-packed plating does not necessarily exhibit structural or mechanical reversibility. Operando acoustic analysis is a reliable technique for interrogating physical changes within a closed-form battery. Specifically, the effective stiffness can be accurately measured to probe changes in the intrinsic material properties of plate metal. Stiffness, in addition to stress and strain, is an important metric in mechanical characterization of phase change or plate metal electrodes. Here, we describe recent efforts to diagnose common failure mechanisms using acoustics and extension of the technique to dynamically probe structural changes in plate metal anodes. Figure 1