POS10-1402
Computational Study on Vanadium Nitride-Enabled Bidirectional Polysulfide Redox in Sodium–Sulfur Batteries
Topic
S10. AI-assisted Design and Simulation of Polymers
When and Where
Sep 30, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Heesuk KIM
Jinhye BAE
Presenter(s)
Seongwon Lee (Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea)
Co-Author(s)
Abstract
Sodium–sulfur batteries offer high theoretical capacity and low material cost, but soluble sodium polysulfides cause shuttle loss and insoluble solid species limit charge reversibility. To clarify the catalytic role of vanadium nitride (VN), we performed density functional theory calculations to compare polysulfide adsorption and redox conversion on VN, graphene, and N-doped graphene. VN exhibited the strongest affinity for polysulfide intermediates among the examined surfaces, which supported effective polysulfide confinement at the cathode interface. pCOHP analysis revealed that the V–S bond in Na2S6 on VN was much stronger than the C–S interactions on graphene-based surfaces and confirmed V atoms as the main sulfur-affinitive sites. pDOS analysis also confirmed clear overlap between V d orbitals and S p orbitals, which indicated strong electronic coupling at the VN–polysulfide interface. Reaction pathway analysis showed that VN reduced the energy barrier for Na2S4-to-Na2S2 conversion, which was the rate-determining step on graphene and N-doped graphene. For the reverse process, VN lowered the activation barrier for Na2S decomposition and made the reaction both kinetically and thermodynamically more favorable than on graphene-based surfaces. In addition, pCOHP analysis of Na2S on the catalyst surfaces showed weaker Na–S bonds on VN, which suggested that VN facilitated the reactivation and reoxidation of solid discharge products during the charge process. These results demonstrated that VN acted not only as a polysulfide adsorbent but also as a bidirectional catalyst that regulated V–S interaction and Na–S bond activation in both discharge and charge reactions. Our computational study provides a molecular-level basis for vanadium nitride-based interfacial design to suppress the polysulfide shuttle, accelerate sulfur redox kinetics, and improve the reversibility of sodium–sulfur batteries.
