Porous\nGraphitic Carbon Loading Ultra High Sulfur as High-Performance Cathode\nof Rechargeable Lithium–Sulfur Batteries

Abstract

Porous\ngraphitic carbon of high specific surface area of 1416 m² g^–1 and high pore volume of 1.11 cm³ g^–1 is prepared by using commercial CaCO₃ nanoparticles as template and sucrose as carbon source followed\nby 1200 °C high-temperature calcination. Sulfur/porous graphitic\ncarbon composites with ultra high sulfur loading of 88.9 wt % (88.9%S/PC)\nand lower sulfur loading of 60.8 wt % (60.8%S/PC) are both synthesized\nby a simple melt-diffusion strategy, and served as cathode of rechargeable\nlithium–sulfur batteries. In comparison with the 60.8%S/PC,\nthe 88.9%S/PC exhibits higher overall discharge capacity of 649.4\nmAh g^–1_(S–C), higher capacity\nretention of 84.6% and better coulombic efficiency of 97.4% after\n50 cycles at a rate of 0.1<i>C</i>, which benefits from\nits remarkable specific capacity with such a high sulfur loading.\nMoreover, by using BP2000 to replace the conventional acetylene black\nconductive agent, the 88.9% S/PC can further improve its overall discharge\ncapacity and high rate property. At a high rate of 4<i>C</i>, it can still deliver an overall discharge capacity of 387.2 mAh\ng^–1_(S–C). The porous structure,\nhigh specific surface area, high pore volume and high electronic conductivity\nthat is originated from increased graphitization of the porous graphitic\ncarbon can provide stable electronic and ionic transfer channel for\nsulfur/porous graphitic carbon composite with ultra high sulfur loading,\nand are ascribed to the excellent electrochemical performance of the\n88.9%S/PC.