Layered oxide solids have attracted considerable attention as potential materials for Sodium-ion batteries since Na x CoO 2 was first introduced as a cathode material. Typical layered honeycomb oxides consist of alkali or coinage metal atoms sandwiched between slabs made exclusively of transition metal and chalcogen (or pnictogen) atoms arranged in edge-shared octahedra in a honeycomb fashion (Fig. ). These materials offer several advantages, such as wider interstitial spaces between two-dimensional polyhedral framework layers that facilitate cation migration, enabling high ionic conductivity at RT, and excellent chemical and ambient stability . However, a rigid octahedral framework layer completely hinders diffusion along the crystalline c-direction. The materials are classified based on the local cationic environment, with oxygen (tetrahedral, octahedral, or prismatic) sharing rectangular faces, thereby creating a wide BN for facile cation transport . In this context, layered honeycomb oxides differ from the β-alumina structure, where oxygen atoms are located in the conduction layer. Van der Waals forces weakly connect the framework layers in these honeycomb oxides, and the inter-layer distance can be adjusted by framework modifications or a larger size cationic substitution. Alkali ion conductivity is significantly influenced by the inter-slab distance, cationic concentration, and their different octahedral arrangements in the framework layer. Several experimental and theoretical studies, including MD simulations and topological analysis, have been conducted to gain insights into alkaline ion conduction and material stability mechanisms .