Abstract:

The commercialization of the lithium-sulfur (Li-S) batteries is severely hampered by the shuttle effect and sluggish kinetics of lithium polysulfides (LiPSs). In this study, porous tubular graphitic carbon nitride (PTCN) was synthesized as the sulfur host by hydrothermal treatment, thermal shock and etching methods. By etching technology, the hollow nanotube tentacles grow on the tube wall of PTCN, the mesoporous appears on the inner wall, and a large number of nitrogen defects are introduced. The vertically-rooted hollow nanotube tentacles on the PTCN surface facilitate electron conduction for sulfur redox reactions. The hollow and porous architecture exposes plentiful active interfaces for accelerated redox conversion of polysulfide. Furthermore, the nitrogen defects in PTCN enable more excellent intrinsic conductivity, higher adsorbability and conversion catalytic activity to LiPSs. Based on the above synergetic effect, the batteries with PTCN/S cathodes realize a high discharge capacity of 504 mAh g^-1 at 4 C and a stable cycling behavior over 500 cycles with a low capacity decay of 0.063% per cycle. The results indicate a promising approach todesigning a high performance electrode material for Li-S batteries.

Key words: Lithium-sulfur batteries, Porous tubular graphitic carbon nitride, Sulfur host, Nitrogen defects