Co9S8@carbon porous nanocages derived from a metal-organic framework: a highly efficient bifunctional catalyst for aprotic Li-O2 batteries

Discovering effective bifunctional catalysts to facilitate Li2O2 oxidation and prolong the discharge life to ease the "sudden death" of batteries is a key task for developing high performance Li-O-2 batteries. Herein, an advanced aprotic Li-O-2 battery is designed using Co9S8@carbon porous nanocages as a bifunctional catalyst derived from a metal-organic framework. It achieves superior electrocatalytic activity, resulting in a high-energy efficiency of 72.7% and a long cycle life of up to 110 cycles at 100 mA g(-1) current density. Combined experimental studies and density functional theory calculations reveal that the promising electrochemical performance observed here could be attributed to the high catalytic activity of Co9S8. In addition, the open-framework porous structure of these carbon porous nanocages provides a facile mass transport pathway and fast charge transfer kinetics for the oxygen reduction/evolution reactions.