Targeted Modulation of d-Band Center in MoS₂ Interlayer With n-Type Co/Fe Dopants Accelerating Sulfur Reaction Kinetics in Lithium-Sulfur Batteries.

Abstract

Although chalcogenide-based catalysts offer significant potential for enhancing lithium-sulfur (Li-S) battery performance, the absence of reliable descriptors linking the d-band center to sulfur conversion kinetics hinders the rational design of electrochemical systems. Herein, we address this limitation by engineering a catalytic interlayer through modification of 2H-MoS₂ electronic structure, achieved via substitutional doping of n-type Co/Fe transition metals (TM) at Mo sites. Comprehensive findings elucidate that such doping initiates a distinct S-mediated d-p hybridization involving Mo 4d-S 3p-TM 3d orbitals, thereby modulating electronic density of states near the Fermi level. Specifically, in the CoFe-MoS₂@carbon paper (CP) interlayer, synergistic effect of co-doping with two different TM drives optimized downshift of the Mo 4d-band center to intermediate energy states, fostering moderate catalyst-reactant interaction. Furthermore, the simultaneously lowered S 3p-band center enhances the degree of d-p orbital overlap. These electronic redistributions enhance both electrical and ionic conductivity, thereby facilitating accelerated redox kinetics with reduced activation energy, while mitigating the shuttle effect and promoting uniform Li₂S deposition. Consequently, the assembled cell delivers outstanding stability with a low decay rate of 0.024% for 2000 cycles even at 10C. This work emphasizes that a balanced d-band center is key to achieving highly active chalcogenide-based materials for advanced Li-S batteries.