A multi-functional TEMPO derivative for highly stable 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 3.74V vs. Li/Li+ and then withdraw electron from lithium peroxide. In this article, we introduce the effects of solvent-derived functional group attached to 4'-C of TEMPO on LOBs performances. 4-acetamido TEMPO, a kind of TEMPO derivatives, has a combined structure of acetamido functional group and TEMPO. This additive improved cycling stability significantly by several ways. Not only with original redox mediation role on charging, but also this additive promoted disproportionation reaction of lithium superoxide during discharging to change the morphology of lithium peroxide and improved the cycling stability.