Nitrogen-regulated d-p orbital interaction in MoS2@Porous carbon nanofiber interlayers for accelerated sulfur redox kinetics in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are promising next-generation energy-storage systems because of their high theoretical energy density. However, their practical application is severely hindered by sluggish sulfur redox kinetics and the shuttle effect of soluble lithium polysulfides (LiPSs). Herein, a MoS 2 @NPCNFs interlayer is designed to immobilize LiPSs and accelerate bidirectional sulfur conversion. The porous and conductive carbon nanofiber framework provides rapid electron/ion transport pathways and facilitates electrolyte penetration, while the MoS 2 component offers abundant catalytic sites for polysulfide adsorption and conversion. As revealed by density functional theory (DFT) calculations, the nitrogen-regulated electronic environment modulates the Δd-p value associated with MoS 2 . This optimized d-p orbital interaction strengthens the coupling between MoS 2 and lithium polysulfides, thereby promoting their chemical adsorption and catalytic conversion. X-ray photoelectron spectroscopy shows obvious binding-energy shifts after Li 2 S 6 adsorption, indicating strong interfacial electronic interactions. Density functional theory calculations further demonstrate that this electronic-structure regulation enhances the LiPSs chemisorption, optimizes the Gibbs free-energy evolution of sulfur redox reactions, and lowers the energy barriers for Li 2 S decomposition and Li  +  diffusion. Consequently, the MoS 2 @NPCNFs interlayer enables efficient bidirectional catalysis of polysulfide reduction, effectively suppressing the shuttle effect and improving reaction kinetics. The assembled Li-S battery delivers high initial discharge capacities of 1262.9 mAh·g −1 at 0.2C and 916.0 mAh·g −1 at 1C, and maintains excellent cycling stability over 1000 cycles at 1C with a low capacity decay rate of 0.043% per cycle. This work provides an electronic-structure-regulation strategy for designing advanced interlayers toward high-performance Li-S batteries. Download: Download high-res image (276KB) Download: Download full-size image