Little attention has been paid so far to limitations of the ion mobility due to structural constraints at the interface between the solid electrolyte and electrode. The interaction between solid-state electrolytes and electrode materials can limit the practical use in batteries as it may lead to interfacial structures that impede the transfer of ions. The reasons for these behavior are not well understood yet. Future research is necessary to comprehend the reaction mechanisms at the interface between fast ion conductors and conventional electrode materials, as well as between different fast ion conductors. The goal is to develop solutions that stabilize these interfaces. Understanding and controlling interfacial reactivity is crucial for leveraging space charge layers created in multicomponent ion conductors for enhanced