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

1-Aminopropyl-3-methylimidazolium bromide is introduced into dimethyl sulfoxide-based Li–O 2 batteries, which delivered an enlarged discharge capacity, a reduced charge overpotential of around 0.61 V and a prolonged cyclic life of over 200 cycles.