Trifunctional imidazolium bromide: a high-efficiency redox mediator for high-performance Li-O2 batteries

In this work, 1-aminopropyl-3-methylimidazolium bromide (APMImBr) is introduced in dimethyl sulfoxide-based Li-O-2 batteries. The Br- functions as a redox mediator to catalyze the decomposition of the Li2O2 products. Meanwhile, the APMIm(+) serves as a scavenging agent for superoxide radicals as well as protects the lithium metal anodes via an in situ formed Li3N-rich solid electrolyte interface layer. As a result, the Li-O-2 batteries containing APMImBr delivered an enlarged discharge capacity, a reduced charge overpotential of around 0.61 V and a prolonged cyclic life of over 200 cycles.