Transition of the Reaction from Three-Phase to Two-Phase by Using a Hybrid Conductor for High-Energy-Density High-Rate Solid-State Li-O2 Batteries.

Solid-state Li-O2 batteries possess the ability to deliver high energy density with enhanced safety. However, designing a highly functional solid-state air electrode is the main bottleneck for its further development. Herein, we adopt a hybrid electronic and ionic conductor to build solid-state air electrode that makes the transition of Li-O2 battery electrochemical mechanism from a three-phase process to a two-phase process. The solid-state Li-O2 battery with this hybrid conductor solid-state air electrode shows decreased interfacial resistance and enhanced reaction kinetics. The Coulombic efficiency of Li-O2 battery is also significantly improved, benefiting from the good contact between discharge products and electrode materials. In situ environmental transmission electron microscopy under oxygen was used to illustrate the reversible deposition and decomposition of discharge products on the surface of this hybrid conductor, visually verifying the two-phase reaction.