Interface engineering for silicon/carbon composite anode in all-solid-state batteries

Silicon-based anode is a promising candidate for all-solid-state batteries (ASSBs). However, it must be further improved because of its tremendous volume change. In this study, various interface treatment strategies for SiO/carbon composite anodes in ASSBs were investigated using a multiphysics modeling framework. By evaluating the effects of active (carbon) and inactive coating materials, as well as the geometric and mechanical parameters, this research provides critical insights into optimizing their electrochemical performance and mechanical stability. Computational results indicate that carbon coatings can greatly enhance lithiation kinetics by regulating the interfacial electrochemical potential gradients, reducing the residual lithium concentration, and homogenizing the lithium-ion distribution compared with uncoated or inactive-coated configurations. In addition, thinner carbon coatings further improve capacity retention and stress management by balancing shorter lithium diffusion pathways with mitigated interfacial stress accumulation. Despite their ability to mechanically stabilize the anode, inactive coatings exhibit tradeoffs between lithium transport kinetics and stress modulation, with optimal performance achieved at lower Young’s moduli. Mechanical analyses highlight distinct failure mechanisms at the anode–electrolyte (shear driven) and particle-coating (tension driven) interfaces, emphasizing the need for tailored adhesion strategies. These findings provide actionable guidelines for designing robust SiO-based anodes, emphasizing the interplay among electrochemical efficiency, stress regulation, and interfacial durability in ASSBs.