Operando Ultrasonic Characterization of Lithium Metal Batteries

Abstract

Significant progress has been made in understanding and engineering rechargeable lithium metal batteries. Here, I discuss ultrasound as a technique to probe cell-level dynamics for lithium metal batteries in liquid and solid electrolytes. Multiple imaging modalities provide information on physical properties of lithium metal cells, including electrode wetting and consumption, lithium microstructural change and gas evolution. In a first case study, I discuss correlations between ultrasonic transmission signals and lithium microstructure size in liquid electrolytes, as a function of stack pressure and temperature. Anode and cathode effects can be decoupled. In a second case, acoustic amplitude is used to detect void formation in solid-state electrolytes. Third, ultrasound is used to characterize the formation process for various anode-free cells, where the improved chemical and electrochemical stability of localized ether electrolytes is correlated with decreased rates of cell swelling and minimal gas formation. Ultrasonic characterization and imaging is a portable and non-invasive means of probing commercial lithium metal cells after manufacturing, during use, or at the end-of-service.