However, in chemistry typically so-called Brønsted-Evans-Polanyi-type scaling relation between reaction and activation energies are observed. Such BEP relations also occur upon the insertion of atoms or ions into solid materials: The stronger the binding energies of the interstitials in the host materials, the larger the diffusion barriers hindering the migration from one binding site to the next. This is illustrated in Fig. . ∆G 1 is the relatively low binding energy of a metal atom in a host cathode material with respect to the cohesive energy of the metal. In order to increase the energy density of the corresponding battery, a stronger binding energy ∆G 2 is required. However, typically this is also associated with a higher diffusion barrier ∆E barr 2 hindering migration in this cathode.