Hollow and Porous N-Doped Carbon Framework as Lithium-Sulfur Battery Interlayer for Accelerating Polysulfide Redox Kinetics

Lithium-sulfur batteries (LSBs) have become one of the most powerful candidates for next-generation battery technologies due to their high theoretical energy density and low cost. However, the notorious shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish conversion reaction kinetics cause low sulfur utilization and inferior cycle life. Rational catalyst design on hierarchical pore structures and composition optimization is highly desired to realize synergetic enrichment, accommodation, and catalytic redox capacity of sulfur species. In this consideration, the hollow and porous N-doped carbon framework is prepared, in which Co nanoparticles (NPs) are evenly embedded (denoted as Co-HMCF) to modulate electron cloud density of carbons. Electrochemical tests and density functional theory (DFT) calculations demonstrate that Co-HMCF could simultaneously deliver superior catalytic activity in accelerating LiPSs conversion as well as Li2S nucleation/decomposition to improve overall sulfur redox kinetics. Consequently, the Co-HMCF interlayer significantly improves the battery performance, including high discharge capacity output (1538 mAh g-1 at 0.2 C), stable long-term cycle (0.047% capacity decay per cycle for 800 cycles at 1.0 C), and exceptional rate capacity (582 mAh g-1 at 5.0 C). A hollow and porous N-doped carbon framework embedded with homogeneous Co nanoparticles is successfully prepared and employed as lithium-sulfur battery interlayer. The N-doping carbon frameworks with abundant pore structures greatly enhance chemisorption and confinement toward lithium polysulfides, thereby ensuring fast conversion of soluble LiPSs and solid Li2S and boosting the overall sulfur redox kinetics during discharge/charge. image