Porous graphitic carbon sheets with high sulfur loading and dual confinement of polysulfide species for enhanced performance of Li–S batteries

Abstract

Micro- and mesoporous graphitic carbon sheets (MGC) were synthesized from jute sticks (bio-waste) and employed as an efficient polysulfide inhibitor for sulfur cathode in a lithium–sulfur battery application. The as-prepared MGC possesses sheet-like morphological characteristics with unique textural properties such as high specific surface area (2047 m2 g−1), large pore volume (1.69 cc3 g−1) and has excellent graphitic carbon structures. Studies were made in order to optimize the sulfur loading into MGC and to modify the polypropylene separator by coating with a thin layer of as-prepared MGC to attain enhanced electrochemical performance. The optimized sulfur loaded MGC/S-2 cathode with modified separator delivered a high initial discharge capacity of 1542 mAh g−1 and retained a discharge capacity of 1016 mAh g−1 after 50 cycles at 0.2 C rate, attributed to high surface area and porosity of MGC, which act as host as well as barrier film that inhibits the migration of dissolved polysulfide species to the anode during the redox process. Furthermore, the novel cell configuration with modified separator renders high sulfur loading up to 9.3 mg cm−2 and the resulting cell delivered a high discharge capacity of 632 mAh g−1 at 0.2 C rate even at 50th cycle.