High-performance lithium sulfur batteries based on nitrogen-doped graphitic carbon derived from covalent organic frameworks

Abstract

Lithium sulfur battery (LSB) is considered as a most promising option of next-generation energy storage systems due to its high theoretical specific capacity and energy density. However, the practical application of LSB is hindered by capacity decay and low coulombic efficiency, mainly resulting from the insulation nature of sulfur and polysulfide shuttle effect. Herein, we demonstrate an innovative strategy for preparing the nitrogen-doped graphitic carbon (N-GC), which can be utilized as sulfur host material in the LSB, by carbonization of an imine-linked covalent organic framework. Because of the high porosity and electrical conductivity of N-GC, the electrode with a high sulfur loading of 67.5 wt% exhibited a superior initial discharge capacity of 1598 mAh g−1 at 0.03 C, excellent rate capacity of 869 mAh g−1 at 1 C and good cycling performance with nearly 100% coulombic efficiency during cycling. These results demonstrate its outstanding electrochemical performance and implied that the N-GC has great potential to be used as a cathode material for high-performance LSBs.