x Ionic Conductivity Ionic conductivities σ NE were computed from the system-size independent self-diffusion coefficients D 0 via the Nernst-Einstein (NE) approach. Here, the D 0 were determined from our OrthoBoXY simulations. The "true" ionic conductivities σ EH were determined via the Einstein-Helfand (EH) formalism using simulation data from MD simulations with cubic boundary conditions, making use of the observation that the σ EH are devoid of system-size effects. All simulation-based conductivity data are summarized in Tables and, and in Figure in the SI. In addition, experimental data were also determined, which can be found in Table in the SI.