Operando Visualization of Morphological Dynamics in All‐Solid‐State Batteries

Abstract All‐solid‐state batteries (SSBs) are considered as attractive options for next‐generation energy storage owing to the favorable properties (unit transference number and thermal stabilities) of solid electrolytes. However, there are also serious concerns about mechanical deformation of solid electrolytes leading to the degradation of the battery performance. Therefore, understanding the mechanism underlying the electromechanical properties in SSBs is essentially important. Here, 3D and time‐resolved measurements of an all‐solid‐state cell using synchrotron radiation X‐ray tomographic microscopy are shown. The gradient of the electrochemical reaction and the morphological evolution in the composite layer can be clearly observed. Volume expansion/compression of the active material (Sn) is strongly oriented along the thickness of the electrode. While this results in significant deformation (cracking) in the solid electrolyte region, organized cracking patterns depending on the particle size and their arrangements is also found. This study based on operando visualization therefore opens the door toward rational design of particles and electrode morphology for all‐solid‐state batteries.