Operando Quantification and Visualisation of Dendrite-Induced Stresses in Ceramic Electrolytes Via Photoelasticity

Abstract

The measurement of stress fields around lithium metal dendrites in solid electrolytes in operating conditions is critical for the design of next-generation, dendrite-resistant solid electrolytes. Prior work, both experimental and theoretical, indicates that the developed stresses in the in the electrolyte can be significantly high. However, direct stress measurements are still missing as they entail inherent experimental difficulties associated with probing stress fields at small scale brittle specimens operando.By employing the principle of photoelasticity combined with electrochemical cycling in a plan-view cell the aforementioned challenges are bypassed, allowing not only to track the stress field as the dendrite events progress, but also to obtain whole-field stress information on a propagating dendrite in an LLZTO electrolyte. This new experimental methodology allows for direct stress measurements around the dendrite tip. The experimental data demonstrate that the dendritic events at such current densities can be understood by the classic Griffith - Irwin fracture theory.