Multi-Functional TEMPO Derivatives for High-Performance Lithium Oxygen Batteries

Abstract

Lithium oxygen batteries (LOBs) have been spotlighted as the next generation of rechargeable batteries due to their high theoretical capacity. One of the key issues of LOBs is how effectively lithium peroxide as the discharge product is removed. (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) was reported as a charge redox mediator to remove lithium peroxide during charge. TEMPO is oxidized to TEMPO+ at 3.70V vs. Li/Li+ and then withdraw electron from lithium peroxide. In this presentation, we present the effects of functional groups attached to 4'-C of TEMPO on LOB performances. Several TEMPO derivatives improved cycling stability significantly. In addition to redox mediation role on charging, a group of TEMPO derivatives promoted disproportionation reaction of superoxide radical during discharging to change the morphology of lithium peroxide. Another group of TEMPO derivatives improved the cycling stability by forming a protective interface film on lithium metal cathode.