Enabling shuttle-free of high concentration redox mediators by metal organic framework derivatives in lithium–oxygen batteries

High concentration LiBr is beneficial to enhance the Br− oxidation rate, displaying stable low voltage plateau during charging process for lithium–oxygen batteries. However, the sufficient cyclic performance is generally restricted by uncontrollable high level Br3−, resulting in the low energy efficiency and shuttle effect. Herein, a nanoreactor, red-ox mediators shuttling suppressor and lithium-metal protector with the combination of the high concentration and shuttle-free LiBr are successfully constructed by anchoring the Br3− to carbonized ZIF-8 supported on reduced graphene oxide substrate (ZC-rGO). ZnO-decorated/nitrogen-doped 3D carbon framework of ZC-rGO cathode can accurately capture Br3− by space confinement effects and/or chemisorption, which is beneficial to improve the oxidation of discharge products (Li2O2) and avoid the anode corrosion. The Li–O2 battery demonstrates enormous advantages of the RMs in comparation with the typical rGO-based batteries, such as better cycling performance (>90 cycles) and more stable overpotential (<1.0 V). The proposed strategy in this study opens up a new way of inhibiting the shuttle effect of RMs in Li–O2 batteries and other halogen batteries.