Optimizing Adsorption-Catalysis Synergy to Accelerate Sulfur Conversion Kinetics in Room-Temperature Na-S Batteries

Abstract

Room-temperature sodium-sulfur (RT Na-S) batteries are expected to become the next-generation energy storage system due to their ultrahigh theoretically energy density of 1274 Wh kg⁻¹, abundant sulfur resource, and low cost. However, practical application is hindered by challenges of severe shuttle effect and sluggish S conversion kinetics. In this study, a series of nano-sized nickel-based chalcogenides are designed and fabricated as electrocatalysts for S cathode. The p orbitals originated from different anions show great effect on the partial-filled d orbital of the metal Ni site, which further regulates the electronic states of the catalytic site. Theoretical and experimental results confirm the excellent electrocatalytic performance of NiSe electrocatalyst with low reaction energy barriers, moderate adsorption capability, and strong catalytic conversion ability, consistent with Sabatier's principle. The optimized NiSe catalyst presents a high reversible capacity of 720.4 mAh g⁻¹ with excellent durability over 200 cycles at 0.2 A g⁻¹ retained a capacity of 401.4 mAh g⁻¹ after 1000 cycles at 2 A g⁻¹ in RT Na-S batteries. This work presents the balancing of adsorption and catalytic conversion toward polysulfides via the modulation of d/p orbitals of active sites.