Single Mo-N4 Atomic Sites Anchored on N-doped Carbon Nanoflowers as Sulfur Host with Multiple Immobilization and Catalytic Effects for High-Performance Lithium-Sulfur Batteries

Rational design of sulfur hosts for effectively confining lithium polysulfides (LiPS) and optimizing the sluggish sulfur kinetics is still a major challenge in lithium-sulfur batteries (LSBs). In this work, a simple strategy of introducing single Mo-N-4 atoms into N-doped carbon nano-flower matrix (Mo-N-CNF) as sulfur host cathode materials is developed to realize high-performance LSBs. These single Mo-N-4 atoms have been demonstrated to regulate the hydrophilic nature, Li-ion diffusion, adsorption capacity, and catalytic conversion of polysulfides via experimental evidences and theoretical calculations. The resulting Mo-N-CNF with high loading content of sulfur (>72 wt.%) exhibits a high specific capacity (1248 mAh g(-1) at 0.2 C) and excellent rate capability (715 mAh g(-1) at 5 C). More importantly, the outstanding cycling performance with a low attenuation rate of only 0.004% per cycle over 400 cycles at 4.27 mA cm(-2) is achieved with the area sulfur loading of 5.1 mg cm(-2). This work demonstrates a viable strategy for using single atoms-based carbon materials with high exposed sites as multiple captors for LiPS and an efficient accelerator for sulfur redox kinetics toward next-generation LSBs with boosted electrochemical performance.

Automated summary

This study presents a simple and effective strategy for high-performance lithium-sulfur batteries by introducing single Mo-N-4 atoms into N-doped carbon nano-flower matrix as sulfur hosts. Experimental and theoretical evidences demonstrate that these single atoms can regulate the characteristics of sulfur and improve the cycling and rate performance of the batteries.