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

摘要

High concentration LiBr is beneficial to enhance the Br-3(-) 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 Br-3(-), 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 Br-3(-) 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 Br-3(-) 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-O-2 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-O-2 batteries and other halogen batteries.