Balancing high graphitization and porous structure in N-doped carbon lamella for effective sulfur host of Li[sbnd]S battery

Abstract

Porous carbon synchronously with high conductivity and abundant porous structure is considered to be an effective sulfur host material for boosting the lithium-storage property in battery fields. Herein, a natural silk cocoon derived in-situ N-doping porous carbon lamella with ultrahigh graphitization degree is prepared by a facile synchronous carbonization and catalysis using the bimetallic mixed salts of FeCl3 and ZnCl2. The pore structure and graphitization degree are easily regulated by changing carbonization temperature to balance the synergistic adsorption and conversion actions toward the polysulfides adhered to porous carbon lamellar. When the carbon lamellar is used to design sulfur cathode, the abundant porous structure not only encapsulates active sulfur, but also facilitates electrolyte infiltration. The shuttle effect of polysulfides can be restrained by the synergistic adsorption of porous structure and N-doping. Especially, the ultrahigh graphitized carbon lamellas provide an excellent conductive network for the favorable redox conversion of polysulfide species during charge/discharge. Owing to the structure merits of the porous carbon lamella prepared at 1000 °C, the corresponding carbon/sulfur composite cathode delivers a first discharge capacity of 807.7 mAh g−1 at 0.2C. Even at a current rate of 1C, the stable long cycling performance of 1000 cycles is still maintained. This high graphitized porous carbon materials will provide potential application in other energy-storage fields.