Influence of Enhanced O2 Provision on the Discharge Performance of Li–air Batteries by Incorporating Fluoroether

As the first step during discharge, the mass transfer of oxygen should play a crucial role in Li–air batteries to tailor the growth of discharge products, however, not enough attention has been paid to this issue. Herein, we introduce an oxygen-enriching cosolvent, 1,2-(1,1,2,2-tetrafluoroethoxy) ethane (FE1), into the electrolyte, and investigate its influence on the discharge performance. The incorporation of this novel cosolvent consistently enhances the oxygen solubility of the electrolyte, and improves the oxygen diffusivity following a volcano-shape trend peaking at 50 % FE1. It is interesting that the discharge capacities obtained with the investigated electrolytes share the similar volcano trends as the oxygen transport under 50 mA g carbon −1 and higher current densities. The improved oxygen diffusion could benefit the volumetric utilization of the air cathode, especially at the separator side, probably owing to the fast oxygen transport to moderate its concentration gradient. Our results demonstrate the importance of oxygen provision, which easily becomes the capacity-determining factor. Graphical Got Oxygen? The enhancement of oxygen provision is achieved by incorporating 1,2-(1,1,2,2-tetrafluoroethoxy) ethane as the cosolvent in the electrolyte. The oxygen's diffusivity, rather than solubility, exerts the principal effect on discharge performance of the Li–air battery, especially at higher current density, owing to the ameliorated oxygen's accessibility, which improves the utilization ratio of the whole air cathode.