Interestingly the Arrhenius prefactor of LNCl-I-BM is hardly larger than for LNCl-I. For LNCl-I-BM we obtain log10(σ0/S cm -1 ) = 2.22 and for LNCl-I log10( σ0/S cm -1 ) = 2.05. The Arrhenius prefactor comprises factors such as the charge-carrier concentration, the attempt frequency, the jump distance and the correlation factor. These factors are thus only slightly modified by milling and the improved RT conductivity of LNCl-I-BM is predominantly a consequence of the decreased (macroscopic) activation energy. The origin of the reduced macroscopic activation energy of LNCl-I-BM is not entirely understood. Previous studies suggested that amorphous fractions in SEs introduced by high-energy milling may reduce the macroscopic activation energy and consequently improve ion conductivity. It was equally suggested that surfacerelated regions show faster ion diffusion due to increased structural disorder. An increased volume fraction of surface-related regions (concomitant with smaller particle size) may thus enhance bulk diffusion in nanocrystalline ceramics. The activation energy of LNCl-I-BM obtained from a Hendrickson-Bray fit of the Li NMR lineshape narrowing profile is increased by 20 meV as compared to LNCl-I. This may suggest an increased activation barrier in LNCl-I-BM for the fast, locally confined Li diffusion probed by NMR. However, the accuracy of activation energies obtained from motional narrowing data relies on highly precise line-width measurements. Small errors in the line-width measurements may largely impact the fit result, so that the uncertainty in activation energies obtained by this method typically amounts to a few tens of meV. This argument is visualized in Figure where a fit line obtained from a H.B.-fit with Ea as a fixed parameter set to 0.22 eV shows a good fit for the narrowing profile of LNCl-I and LNCl-I-BM .