Atomic-level Nb-doped mesoporous TiO₂ as multifunctional catalyst for efficient and stable Lithium‑sulfur batteries

Due to their exceptional electrochemical properties, lithium-sulfur batteries are regarded as one of the most promising candidates for energy storage systems. Yet, their commercialization is significantly hindered by severe shuttle effects and sluggish redox kinetics. Herein, a highly ordered mesoporous TiO₂ (OMT) material with atomic-level Nb doping (Nb-OMT) was innovatively constructed as a bifunctional electrocatalyst, enabling superior performance in lithium‑sulfur (LiS) batteries. Density functional theory (DFT) calculations confirm that Nb doping could effectively enhance the electrical conductivity of the mesoporous TiO₂, facilitating simultaneous adsorption and catalytic conversion of lithium polysulfides (LiPSs) on the material surface, thereby accelerating sulfur redox kinetics. Therefore, the LiS cell with Nb-OMT-20 modified separator demonstrates an exceptional specific capacity of 1348.9 mAh g^-1 in LiS batteries at 0.2C, meanwhile exhibiting an ultralow capacity decay rate of merely 0.036% per cycle over 900 cycles at 1C. Notably, even under challenging conditions, including a high sulfur loading of 5.12 mg cm^-2 and a low temperature of 273 K, the LiS battery still delivers a considerable capacity of 1146.1 mAh g^-1 at 0.1C with a capacity retention of 83.4% of its capacity over 100 cycles at 0.2C, suggesting promising potential for practical applications. This work presents a novel approach to developing bifunctional electrocatalysts through atomic-scale structural modulation, thereby advancing the industrial application of LiS batteries.