In-situ constructed accordion-like Nb₂C/Nb₂O₅ heterostructure as efficient catalyzer towards high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have become one of the most promising next-generation battery systems. Nevertheless, Li-S batteries are still restricted by the dissolution and ‘shuttling’ of intermediate electrochemical products, lithium polysulfides (LiPSs), and the sluggish redox kinetics. Herein, we design a Nb₂C/Nb₂O₅ heterostructure via water-steam etching at the first time to achieve fast trapping-diffusion-conversion of LiPSs by combining the trapping ability of Nb₂C with catalytic activity of Nb₂O₅ toward LiPSs. The porous structure form in the water-steam etching process and the accordion-like structure can effectively contribute to the Li⁺ transportation enhancement. Nb₂C nanosheets with high conductivity provide the basal planes for Nb₂O₅ contact, which suppresses the aggregation of Nb₂O₅ nanoparticles, leading to the overall structural and interface stabilization. In addition, the heterostructured interface ensures a rapid diffusion of anchored LiPSs. Benefiting from synergetic contributions of the above merits, Li-S batteries with the S-Nb₂C/Nb₂O₅ electrode display a superior electrochemical performance with large initial discharge capacity of 844 mAh g⁻¹ with a low capacity fading rate of only 0.05% per cycle during 500 cycles at 1.0 C. This work holds considerable instructive toward development of high-performance Li-S batteries.