Factors Controlling the Ionic Mobility of Lithium Electrolyte Solutions in Separator Membranes

The interactions between the mobile ions and membrane substrate were investigated for lithium electrolyte solutions confined within the separator membrane in lithium batteries through NMR and electrochemical measurements as well as theoretical analyses. Fundamental dynamic properties such as ionic mobility, dissociation degree of the salt, and microviscosities of the ion, which are responsible for ionic mobility, were different for the electrolyte confined within the membranes compared with the corresponding values for the free electrolyte. We also found that the interactions between the ion and membrane substrate depend on the type of membrane. The results of this study suggest that the ionic mobility of the electrolyte in a lithium battery can be controlled by selecting separator membranes with suitable chemical or physical properties, which would be significant for improving the performance of the battery system.