Wrinkling Behavior of the Solid-Electrolyte Interphase in Li-Ion Batteries with Silicon-Graphite Composite Electrodes

The silicon-graphite (Si–C) composite electrode is considered a promising candidate for next-generation commercial electrodes due to its high capacity. However, lithium-ion batteries with silicon electrodes often experience capacity fading and poor cyclic performance, primarily due to the mechanical degradation of the solid-electrolyte interphase (SEI). In this work, we present a homogenized constitutive model for Si–C composite electrodes under finite deformation, incorporating lithium-ion concentration-dependent properties. We perform a wrinkling analysis and systematically examine the influence of key parameters, such as modulus and thickness ratios, on the critical conditions for instability. Additionally, we investigate the ratcheting effect across varying silicon contents. Our findings reveal that maintaining the silicon content within an optimal range effectively reduces plastic accumulation during charge–discharge cycles. These insights provide crucial guidance for optimizing the design and fabrication of Si–C electrode systems, enhancing their durability and performance.