Ru Single Atoms on N-Doped Carbon by Spatial Confinement and Ionic Substitution Strategies for High-Performance Li-O Batteries.

Nonaqueous rechargeable lithium-oxygen batteries (LOBs) are one of the most promising candidates for future electric vehicles and wearable/flexible electronics. However, their development is severely hindered by the sluggish kinetics of the ORR and OER during the discharge and charge processes. Here, we employ MOF-assisted spatial confinement and ionic substitution strategies to synthesize Ru single atoms riveted with nitrogen-doped porous carbon (Ru SAs-NC) as the electrocatalytic material. By using the optimized Ru SAs-NC as electrocatalyst in the oxygen-breathing electrodes, the developed LOB can deliver the lowest overpotential of only 0.55 V at 0.02 mA cm. Moreover, in-situ DEMS results quantify that the e/O ratio of LOBs in a full cycle is only 2.14, indicating a superior electrocatalytic performance in LOB applications. Theoretical calculations reveal that the Ru-N serves as the driving force center, and the amount of this configuration can significantly affect the internal affinity of intermediate species. The rate-limiting step of the ORR on the catalyst surface is the occurrence of 2e reactions to generate LiO, while that of the OER pathway is the oxidation of LiO. This work broadens the field of vision for the design of single-site high-efficiency catalysts with maximum atomic utilization efficiency for LOBs.