The adjustment of the numerical values of the density of IL/carbonate mixtures could have an effect on the dynamics of the system, and the results could suggest an intriguing point for understanding and designing electrolytes of lithium ion batteries for better performance and safety (see also Chapter 6) . The density of electrolytes in LIB technology can induce a dramatic effect on the dynamics of electrolytes. Fundamental studies of bulk electrolytes indicate that organic liquid electrolytes consisting of EC and DMC can induce larger effect on the diffusive dynamics and density of IL based electrolytes than other liquids . A common strategy to enhance the mobility at a given temperature of IL based electrolytes has been an increasing fraction of linear carbonates . However, increasing the content of linear solvents such as DMC is often limited by the ion-pairing of salts, which results in a decrease in the ionic conductivity. Therefore, it is recommended to find an optimal ratio of EC/DMC co-solvent mixtures to give a maximal ionic conductivity. Although density significantly affects the activation energy for diffusion, it does not, however, affect the 3 , respectively was in good agreement with other reported experimental and theoretical studies10,33 . Our study shows that the calculated value of 1M