Ea represents the activation energy, σ0 the Arrhenius pre-factor, and kB the Boltzmann constant. All Na1+xZnxAl1-xCl4 (x ≥ 0.25) compositions exhibit activation energies in the range of 0.450 -0.485 eV, which is higher than pure NAC (0.413 eV). This apparent contradiction indicates that the NAC and NZCtype phases involve different Na + hopping mechanisms as well as distinct energy barriers. As a result, despite exhibiting a lower σ compared to the optimal NZAC (x = 0.625) samples, the NAC phase has a lower Ea. For the samples that have predominantly NZC-type structure, such as x = 0.625 and x = 0.75, only a slight difference in Ea is present (0.450 -0.485 eV), which indicates the same hopping mechanism. The sample x = 0.625, which displays the highest conductivity, also shows the lowest activation energy of 0.45 eV among NZC-type structures. However, the significant difference in σ between the NAC and NZC-type phases cannot be explained by the activation energies, hence could be attributed to the prefactor σ0, which is an empirical parameter related to charge carrier concentration. In fact, for the same type of structure, the ionic conductivity (σ) can be also defined as: