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

Abstract

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–O₂ batteries. Herein, an advanced aprotic Li–O₂ 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.