An Electro-Chemo-Mechanic Model Resolving Delamination between Components in Complex Microstructures of Solid-State Batteries

A novel approach is presented to model delamination and recontacting at internal interfaces of three-dimensional resolved microstructures of solid-state batteries. To resolve the effect of delaminations, we incorporate the consistent enforcement of contact constraints at those interfaces using Nitsche’s method. The model incorporates charge, mass, and momentum conservation to consider electrochemistry, solid mechanics, and their interaction. After introducing and verifying the model, we examine various scenarios to quantify the effect of delaminations at the electrode-solid electrolyte interface on cell performance. The simulations show that increased mechanical stack pressure during cycling mitigates delamination tendencies at the electrode-solid electrolyte interface. Consistent with existing literature, the simulations demonstrate that delaminations increase the internal resistance and reduce the amount of transferred charge. In contrast to experimental analyses, the presented model allows quantitative and in-depth investigations of delamination effects. Furthermore, our analysis of two cell concepts—one assembled in the discharged state and another assembled in the charged state—indicates that half-cells assembled in an initial state from which the active material shrinks in volume upon first charge or discharge show a higher delamination risk at the electrode-solid electrolyte interface. The study highlights the critical relationship between solid mechanics and electrochemistry in consideration of delamination phenomena in solid-state batteries, offering valuable insights for optimizing battery design and performance.