Improving SiOx Electrode Performance in Pressurized Pouch Cells with a Ceramic Coated Separator

Abstract

The global electric vehicle (EV) landscape, driven by environmental concerns, has propelled the demand for high-capacity battery materials. Silicon-based anode materials have emerged as promising candidates due to their remarkable capacity. However, the inherent challenge lies in their substantial volume expansion during operation, exceeding 300%, which causes structural instability within the electrode.To counteract this issue, a direct compression method is employed to mitigate the anode's volumetric expansion, ensuring sustained adhesion between active materials and current collectors. This approach promotes consistent electrical connectivity and augments capacity retention. Nevertheless, excessive pressure can detrimentally affect separators with limited mechanical resilience, resulting in pore constriction. This constriction impedes the efficient flow of electrolytes between the separator and electrode, leading to premature lithium depletion.In our study, we compressed SiOx electrodes using Ceramic Coated Separator (CCS). CCS's unique combination of mechanical reinforcement, improved wetability, and enhanced ionic conductivity played a pivotal role, ultimately contributing to the overall improvement in electrode performance. We employed digital-twin simulations, utilizing the Finite Volume Method (FVM), to investigate the influence of CCS on various aspects. Digital-twin simulations involve creating a computational replica of the real object's geometry, allowing us to replicate its behavior and characteristics in a virtual environment, thereby enabling a detailed and accurate assessment of CCS effects. This included analyzing the enhancement of mechanical properties, such as the evaluation of von Mises stress and effective stiffness. Furthermore, we explored how CCS impacted the deformation of separators under pressure and closely monitored the movement of lithium ions within them.The findings underscore the successful integration of CCS into SiOx electrodes, resulting in a substantial improvement in life and performance under pressure conditions. This research contributes valuable insights to the advancement of battery technology, particularly in the context of EVs, by addressing critical challenges associated with silicon-based anode materials.