Fully coupled mechano-electrochemical modeling of 3D-resolved microstructures for solid state batteries manufactured by wet processing

Charge and discharge of solid-state lithium-ion battery electrodes cause significant volume changes, which can compromise mechanical stability and affect battery performance. In a confined space, the volume cannot expand freely, leading to significant pressures induced by local microstructural changes within the battery composite electrode. While volume change appears to be less critical in batteries with liquid electrolytes, which have the advantage of not transferring stresses, it becomes much more critical in composite electrodes with solid electrolytes. In this work, we present a new full mechano-electrochemical computational workflow model for the simulation of 3D-resolved electrode microstructures functioning in a solid-state battery cell. The model accounts for the bi-directional coupling between mechanics, electrochemistry and transport processes. Two mechano-electrochemical coupling approaches were compared. Second, the overall mechanical behavior and the spatial distribution of mechanical strain and stress of solid phases within the composite cathode, arising from active material (de)lithiation-induced volume changes and under external pressure was studied. Third, the numerical galvanostatic cycling results were validated against experimental data.