Descriptors reflect correlations between the materials properties and wanted or unwanted functions of these materials. The determination of descriptors can considerably speed up the search for novel materials with desired functional or multi-functional properties because once they are identified, only the particular descriptor needs to be optimized in the first step. One of the most famous examples of descriptors is the correlation between the oxygen binding energy of a metallic catalyst and its reactivity in terms of the oxygen reduction reaction , following the Sabatier principle. Descriptors have also been established in battery research. One example is the self-diffusion barrier of alkali and alkaline earth metals, which is correlated with the tendency of the corresponding metal anodes to exhibit dendrite growth . With respect to the ion mobility in crystalline materials, there was the notion and Al. The energies are determined relative to the energy of the charge carrier in the tetrahedral coordination whereas the minima in the middle of the path correspond to the octahedral sites, using the set-up described in Ref. .