Organic Alkali Metal Salt Derived Three-Dimensional N-Doped Porous Carbon/Carbon Nanotubes Composites with Superior Li-S Battery Performance

摘要

The organic alkali metal salt of sodium 4-(methylamino)butanoate has been synthesized and used as a precursor for N-doped porous carbon/carbon nanotubes composite (NPC/CNTs). The cheap and easy obtained CNTs slurry and metal Na were used as raw materials. NPC provided polysulfides (LiPS) adsorption sites and CNTs constructed the conductive network. The obtained S/NPC/CNTs cathode material, which has strong adsorption capacity and high conductivity, restrained the shuttle effect to a large extent and enhanced the sulfur utilization, especially at high current density. The synergy of N doping, addition of CNTs, and existence of mesopores enhanced the suppression of shuttle effects. When the S/NPC/CNTs material was used as cathode electrode for Li-S battery, a reversible capacity of 785 mA h g(-1) was obtained after 500 cycles, with an average fading rate of 0.08% per cycle at the current density of 0.3 C. The S/NPC/CNTs material also showed superior rate performance, and the specific discharge capacity maintained at 880 mA h g(-1) at 2 C rate. Moreover, the single-layered pouch cell with a nominal capacity of 200 mA h was assembled and could discharge at a current of 38.6 mA stably. The S/NPC/CNTs cathode material is promising in application of Li-S battery.