Redox mediator with the function of intramolecularly disproportionating superoxide intermediate enabled high-performance Li-O${}_2$ batteries

The large charge overpotential and poor cycling stability triggered by sluggish Li${}_2$O${}_2$ oxidation kinetics and severe superoxide-related side reactions greatly restrict the development and application of lithium-oxygen batteries. Finding out high-efficiency catalysts that can effectively facilitate a highly reversible formation/decomposition of lithium peroxide is still a crucial challenge in the field of Li-O${}_2$ batteries. Herein, a soluble catalyst of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) that can promote highly reversible formation and decomposition of Li${}_2$O${}_2$ during discharge and charge processes is reported for the first time. During discharge, it can capture and couple two LiO${}_2$ intermediates via its sulfonate and ammonium ions, and induce the intramolecular disproportionation reaction to produce Li${}_2$O${}_2$ through ionic microenvironment, which not only prompts the solution-phase growth of Li${}_2$O${}_2$, but also restricts the reactivity of LiO${}_2$ intermediate, thus significantly alleviating the electrode surface passivation issue and suppressing the superoxide-related side reactions. During charge, it can quickly transport electrons between the electrode and Li${}_2$O${}_2$ by serving as a new kind of redox mediator (RM), thus greatly facilitating the Li${}_2$O${}_2$ oxidation kinetics. As a result, the Li-O${}_2$ batteries that incorporate ABTS exhibit outstanding electrochemical performance, low charge overpotential, high discharge capacity, and high cycling stability. (© 2022 Wiley‐VCH GmbH)