Electrode–Electrolyte Interface Stability in Solid State Electrolyte Systems: Influence of Coating Thickness Under Varying Residual Stresses

摘要

We introduce a model of electrode–electrolyte interfacial growth which focuses on theeffect of thin coating layers on the interfacial stability in prestressed systems. We take into accounttransport resulting from deposition from the electrolyte, from capillarity driven surface diffusion, andfrom changes of the chemical potential due to the elastic energy associated with the interface profile.As model system, we use metallic lithium as electrode, LLZO as electrolyte and Al2O3 as a thin filminterlayer, which is a highly relevant interfacial system in state of the art all-solid-electrolyte batteries.We consider the stability of the electrode-coating-electrolyte interface depending on the thickness ofthe thin film interlayer and the magnitude of the elastic prestresses. Our central approach is a linearstability analysis based on the mass conservation at the planar interface, employing approximationswhich are appropriate for solid state electrolytes (SSEs) like LLZ, a thin Li metal electrode and a thincoating layer with a thickness in the range of nanometres.