σ + and σ -are total contributions from the cation Li+ and the anion PF 6 -. The conductivity calculated using Eq. 4 includes both distinct and self correlation, and we call it ionic conductivity. Of course, the contribution of the self correlations, i.e. σ s ++ + σ s --, is exactly the Nernst-Einstein conductivity σ N E as expressed in Eq.( ).