Pinpointing the Blip: Coupled Transient Chemo-Mechanical Properties in Lithium-Metal Batteries

Abstract

Lithium-metal batteries experience significant mechanical stress as lithium is plated and stripped from the copper current collector during charge and discharge, respectively. Minimizing the negative effects of this stress on cell’s capacity retention over its cycle life is paramount to propel the high-density chemistry to the mainstream. To address this, acoustics have recently emerged as a viable experimental tool to monitor chemo-mechanical properties*.* In this work, we probe the underlying effects of coupled transient phenomena previously reported for Lithium-ion cells. By complimenting physical parameters—Young’s Modulus and damping coefficient, extracted from operando acoustics and pressure measurements—with simulations, we demonstrate that transient chemo-mechanical properties are in part resultant of ionic gradients in the electrolyte. These findings are in agreement with and build upon previous work on the acoustic signals of electrolytes by Wang et al, where acoustics were leveraged to extract mechanical parameters in situ, and of Lithium-ion cells by Hodson et al, where nonlinearities in full-cell Lithium-ion acoustic signals were were hypothesized to be a result of electrolytes. Our results highlight the viability of acoustics as a valuable tool in battery research to non-invasively inspect transient phenomena in batteries.