Sulfur-Immobilized Nitrogen and Oxygen Co-Doped Hierarchically Porous Biomass Carbon for Lithium-Sulfur Batteries: Influence of Sulfur Content and Distribution on Its Performance

Hierarchically porous carbon with inherently doped heteroatoms and the quantity of active material (sulfur) confined within this carbon matrix play a major role for the high performance of Li-S batteries. Herein, we discuss the influence of sulfur content and distribution onto the N and O co-doped hierarchically porous biomass carbon matrix (PC) to achieve high specific capacitance and cycling stability. Sulfur encapsulated PC was prepared from an eco-friendly source with a high surface area of 2065 m(2)g(-1) and a pore volume of 1.5 cm(3)g(-1). PC with 54, 68 & 73% of sulfur content (PCSCs) have been investigated as cathode materials for Li-S battery. PC with 54% sulfur displayed better performance with an initial discharge capacity of 1606 mA hg(-1) and a cycling stability of 1269 mA hg(-1) at 0.1C rate after 100 cycles due to better dispersion of sulfur in the porous architecture. The higher cycling stability of PCSC (54%) is due to the N and O co-doped hierarchical porous carbon layers, enhancing the sulfur utilization ratio and mitigating the polysulfide shuttle during the cycling process.