NiPS3 monolayer as an efficient sulfur host for Na–S batteries with polysulfide immobilization and catalytic enhancement

Abstract

Sodium-sulfur (Na–S) batteries hold great promise as next-generation energy storage systems due to their high theoretical capacity and abundant electrode materials. However, their commercialization is significantly hindered by issues such as the polysulfide (Na₂S_n) shuttle effect, the poor electrical conductivity of sulfur, and sluggish reaction kinetics. In this study, we propose monolayer NiPS₃ as an effective sulfur host material to address these challenges. Our computational results indicate that Ni atoms play a crucial role in facilitating electron transport, while the moderate binding strength between NiPS₃ and Na₂S_n helps suppress the polysulfide shuttle effect. Additionally, NiPS₃ exhibits favorable catalytic activity in both the sulfur reduction reaction (SRR) and Na₂S decomposition. Specifically, NiPS₃ reduces the energy barriers associated with intermediate conversions in the SRR and lowers the dissociation barrier of Na₂S, thereby promoting more efficient redox kinetics and improving sulfur utilization in Na–S batteries. Furthermore, we find that NiPS₃ also demonstrates good Na-storage capability, contributing to an increased theoretical capacity. Our study provides insights into improving the electrochemical performance of Na–S batteries and highlights the potential of NiPS₃ as a multifunctional anchoring and catalytic material.