Synthesis of ZIF-Derived CoS<sub>2</sub> Nanocages Interconnected by CNTs for Rechargeable Li–O<sub>2</sub> Batteries
Xiujing Lin, Tingting Zhang, Chengcheng Chu, Zhuang Li, Ruiqing Liu, Li Pan, Yi Li, Zhen‐Dong Huang, Yanwen Ma
Abstract
Lithium–oxygen (Li–O2) batteries, profiting by their super high theoretical energy density and oxygen-breathing electrodes, have attracted extensive concern. The synthesis of the electrode materials with high conductivity and promising cycling durability will be a critical aspect for Li–O2 batteries. In this article, a hybrid composite of CoS2 nanocages derived from ZIF-67 and interconnected by carbon nanotubes (CoS2/CNTs) is prepared and used in the air electrode fabrication for Li–O2 batteries. A reversible capacity of 2398.9 mAh g–1 is obtained, equivalent to 90% of the discharge capacity. When restricting the cycling capacity to 500 mAh g–1, the battery exhibits cycling stability for 52 cycles, with the cutoff potential keeping above 2.0 V. The key point of this material is the formation of porous CoS2 nanocages and insertion of the nanocages with CNTs, forming interconnected electrically conducting networks. The incorporation of CNTs serves as channels for fast electron transfer, which overcomes the poor conductivity of CoS2. Furthermore, the porous CoS2 nanocages could provide affluent active sites for an oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which also facilitates the diffusion of O2 and the infiltration of electrolytes. The combination of highly conductive CNTs and CoS2 with efficient catalytic activity renders improvement in the battery performance.