A High-Rate Ionic Liquid Lithium-O2 Battery with LiOH Product

Abstract

The open characteristic of lithium-O2 batteries results in issues of drying out and explosion hazards. Ionic liquids (ILs) are reliable in terms of these issues because they have near-zero vapor pressure and are generally nonflammable. However, the rate capability of Li–O2 batteries with ionic liquids is currently limited to 0.05–0.5 mA/cm2 owing to poor oxygen solubility, poor wettability with solid cathode, and high viscosity. Herein, an ether-functionalized ammonium ionic liquid Li–O2 battery sustains repeated cycling at 5.0 mA/cm2 (80 °C), enhancing 1 order of magnitude in rate capability. The unprecedented high rate is attributed to the improved 3-phase interfacial properties (mainly O2 diffusion and wettability), LiOH-based cycling process at the cathode, and stable passivation film on the Li anode. Our results demonstrate that a substantial improvement in rate capability can be achieved by coordinating cathode/IL electrolyte/anode interface and reaction mechanism. The high rate capability is an enc...