Sandwiching Sulfur into the Dents Between N, O Co-Doped Graphene Layered Blocks with Strong Physicochemical Confinements for Stable and High-Rate Li–S Batteries

Abstract

Abstract The development of lithium–sulfur batteries (LSBs) is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect. Herein, an N, O co-doped graphene layered block (NOGB) with many dents on the graphene sheets is designed as effective sulfur host for high-performance LSBs. The sulfur platelets are physically confined into the dents and closely contacted with the graphene scaffold, ensuring structural stability and high conductivity. The highly doped N and O atoms can prevent the shuttle effect of sulfur species by strong chemical adsorption. Moreover, the micropores on the graphene sheets enable fast Li+ transport through the blocks. As a result, the obtained NOGB/S composite with 76 wt% sulfur content shows a high capacity of 1413 mAh g−1 at 0.1 C, good rate performance of 433 mAh g−1 at 10 C, and remarkable stability with 526 mAh g−1 at after 1000 cycles at 1 C (average decay rate: 0.038% per cycle). Our design provides a comprehensive route for simultaneously improving the conductivity, ion transport kinetics, and preventing the shuttle effect in LSBs.

Keywords

• Graphene
• Physicochemical confinement
• Cycle stability
• Shuttle effect
• Li–S batteries