Unveiling discharge dynamics through 1D modeling and structural analysis of VS4/rGO/S cathode in room temperature sodium sulfur battery

• VS 4 /rGO/S cathode (62.5 wt% of S) synthesized via hydrothermal–melt diffusion and structurally confirmed. • A 1D discharge model for RT-Na/S batteries incorporating Na⁺ transport, polysulfide conversion, and Na 2 S precipitation. • Simulated voltage profiles (0.1 C, 0.2 C) match experiments, revealing Na⁺ depletion and precipitation as key limitations. Room-temperature sodium-sulfur (RT-Na/S) batteries offer a promising alternative to lithium-ion systems because of their high theoretical energy density and inexpensive raw materials. Practical application is limited by slow sodium-ion transport, polysulfide shuttling, and insulating discharge products that causes capacity fading. In this work, a VS 4 /rGO/S composite cathode was synthesized to overcome these drawbacks, coupling the strong chemical affinity of vanadium sulfide toward polysulfides with the high conductivity and structural compliance of reduced graphene oxide. Comprehensive material characterization confirmed successful composite formation such as XRD and Raman confirmed phase composition. SEM and HRTEM confirmed a layered morphology with high surface area, XPS confirmed V–O and C–S interactions, TGA confirmed 62.5 wt% sulfur content, and BET analysis confirmed mesoporosity. EIS showed a high charge transfer resistance, indicating transport restrictions, whereas electrochemical measurements showed an initial discharge capacity of 908 mAh g −1 at 0.1C. A 1D multiphysics model was developed in COMSOL to explain these behaviours, and it predicted voltage–capacity profiles at 0.1 and 0.2C. Discharge dynamics such Na + depletion, polysulfide accumulation, Na 2 S precipitation, and rate-dependent capacity loss were predicted by the model with significant accuracy. The simulated trends corresponded with the experimental observations, which emphasized transport-limited performance at higher discharge rates. This combined experimental–modeling research explains discharge mechanisms in RT-Na/S systems and offers valuable guidance for cathode design improvements and mitigation of rate-dependent performance losses.