Modeling and simulation of a composite solid-state battery: The effects of stack pressure on electrochemical and mechanical behavior

The high interfacial resistance of solid electrolyte/electrode interfaces impedes the development of solid-state batteries (SSBs). To mitigate this issue, it is necessary to apply external pressure to SSBs during cell fabrication and cycling. In this study, we investigated the influence of the stack pressure on the electrochemical and mechanical behavior of composite SSBs. A pseudo-3D physics-based model was developed using semi-empirical parameters to examine the impact of pressure on the physical, electrochemical, and mechanical properties of SSBs. Our findings revealed that increasing pressure leads to higher volume fractions of active materials and solid electrolytes, thereby enhancing the electrochemical performance of SSBs. However, pressure-induced changes also affect the electronic conductivity of solid electrolytes, necessitating careful optimization. Additionally, the effect of the C-rate on SSB performance was explored, highlighting the importance of optimizing the ionic and electronic conductivities for higher C-rates. Finally, the influence of Young's modulus of the solid electrolyte on the volume fraction, voltage profile, and mechanical behavior was investigated. This study provides valuable insights for optimizing SSB design and offers guidance for achieving the desired balance between electrochemical performance and mechanical stability.