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

Silicon-based anode is one of the most promising candidates for all-solid-state batteries (ASSBs), which however needs to be further improved for its tremendous volume change. This study investigates interface treatment strategies for SiO/carbon composite anodes in ASSBs through a multiphysics modeling framework. By evaluating the effects of active (carbon) and inactive coating materials, as well as geometric and mechanical parameters, the research reveals critical insights into optimizing electrochemical performance and mechanical stability. Computational results demonstrate that carbon coatings significantly enhance lithiation kinetics by regulating interfacial electrochemical potential gradients, reducing residual lithium concentration, and homogenizing lithium-ion distribution compared to uncoated or inactive-coated configurations. Thinner carbon coatings further improve capacity retention and stress management by balancing shorter lithium diffusion pathways with mitigated interfacial stress accumulation. Inactive coatings, while mechanically stabilizing the anode, 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 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 between electrochemical efficiency, stress regulation, and interfacial durability in ASSBs.