Rational Integration of Spatial Confinement and Polysulfide Conversion Catalyst for High Sulfur Loading Lithium-Sulfur Batteries

The spatial confinement is a desirable successful strategy to trap sulfur within its porous host and has been widely applied in lithium-sulfur (Li-S) batteries. However, the physical confinement alone is yet not enough to reduce the lithium polysulfide (Li2Sn, 4≤n≤8, LIPSs) shuttle effect with a sluggish LIPSs-dissolving kinetic. In this work, we have integrated spatial confinement with a polar catalyst, and designed a Co decorated, N doped porous three-dimensional (3D) interconnected carbon nanofibers network (Co/N-PCNF). This Co/N-PCNF film serves as freestanding host for the sulfur trapping, and which could effectively facilitate the infiltration of electrolyte and electron transport. In addition, the polar Co species possess strong chemisorption with LIPSs, catalyzing their reaction kinetics as well. As a result of this rational design and integration, the Co/N-PCNF@S cathode with sulfur loading of 2 mg cm−2 exhibits a high initial discharge capacity of 878 mAh g-1 at 1 C, and maintains discharge capacity of 728 mAh g-1 after 200 cycles. Even with high sulfur loading of 9.33 mg cm−2, the composite;;; cathode still keeps a stable areal capacity of 7.16 mAh cm−2 at 0.2 C after 100 cycles, which is much higher than current areal capacity (4 mAh cm-2) of commercialized lithium-ion batteries (LIBs). This rational design may provide direction for future development of high-density Li-S batteries with high sulfur loading.