Sucrose Derived Hierarchical Porous Carbon as Sulfur Encapsulation Host for Durable Cycled Lithium-Sulfur Batteries

Porous carbons with abundant pores and good conductivity are the dominant sulfur host in lithium sulfur batteries. Herein, a facile simultaneous activation/carbonization with inexpensive FeCl3 and ZnCl2 as activators is employed to prepare sucrose derived porous carbon at a relatively low pyrolysis temperature of 600°C. The as-prepared carbon materials not only have partial graphitization due to the FeCl3 catalysis, but also show abundant hierarchical porous structure with high specific surface area of 2104.31 m2 g-1 and large pore volume of 1.29 cm3 g-1, whilst obtaining a high yield of about 30 wt%. When used to encapsulate sulfur, the abundant porous structure is conductive to immobilizing polysulfides and buffering volume effect during charge/discharge. Owing to these structure merits and good electrical conductivity, the corresponding porous carbon/sulfur cathode with a sulfur content of 53 wt% delivers high first discharge capacity of 811 mAh g-1 at 0.2 C. Even with 75 wt% sulfur, the reversible capacity of 446 mAh g-1 are also obtained after 200 cycles at 0.2 C. Especially, a durable long life of 1000 cycles with a low capacity decay of 0.035% per cycle can be achieved at 1 C when the sulfur content is 45 wt%. This work provides a scientific foundation for preparing high-performance porous carbon applied in energy-related storage/conversion.