to space limitations at the narrow transition states for migration making Pauli repulsion the main factor determining the barrier heights. There are also some studies studying the diffusion properties of Ca. The calculations of Juran et al. 168 reach a voltage of 2.1 and 1.8 V for the respective intercalation steps of Ca using the HSE functional, which agree reasonably well with another study, which found values of 1.9 and 1.4 V for a comparable PBE functional reference calculation. There are also numerous experimental studies addressing not only the diffusion of Mg, but also other cations such as Ca, 173 Al, 174,175 Zn, 164,165,176 Na 169 and Li. The electronic structure and ionic diffusion properties were evaluated by phonon dispersion 156 and in another approach continuum modeling is employed to monitor the system. Usually the efficiency of the solid state system is limited by the reachable capacity, but was found by The first commercially used cathode materials for Li-ion batteries TiS A decade later, they were adapted as positive and negative electrode materials as well. NASICONs are polyanionic materials, which exhibit great structural stability and high ionic conductivity -especially for sodium ions. They belong to the family of superionic conductors, which are materials that display exceptionally high ionic conductivity at or near room temperature.