Recently, Li-air batteries have attracted enormous research attention as a promising next-generation energy-storage system because of their high theoretical energy density. However, they still face several obstacles that must be overcome before practical application becomes feasible. The basic reaction of the non-aqueous Li-air batteries is the formation of Li₂O₂ during the discharging process and its dissociation during the charging process on the surface of air electrode. One of the major issues is that the dissociation of solid and electrical insulating Li₂O₂ is relatively slow and inefficient. This feature of non-aqueous Li-air batteries results in undesirable electrochemical properties, such as large over-potential, low rate-capability, and limited cyclic performance. Moreover, the instability of the Li metal anode is another major issue surrounding Li-air batteries. The chief problem associated with using the Li metal anode concerns the dendritic growth and low coulombic efficiency that occur during cycling. In this study, we introduce CsI as a new redox mediator in order to enhance Li-air batteries. The CsI dissolved in the electrolyte will be ionized to Cs⁺ and I⁻. The Cs⁺ ions can then attach at sharp morphological spots on the Li metal surface, and electrostatically repel the incoming Li⁺ ions, which can suppress the growth of Li dendrites. At the same time, the I⁻ ions in the electrolyte can react with Li₂O₂ on the surface of the air electrode and act as a redox mediator, which can facilitate the dissolution of Li₂O₂. In this way, our new redox mediator can act as an electron-hole transfer agent at the cathode as well as an electrostatic shied for the suppression of dendritic growth at the anode.