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

Abstract

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 Nb 2 C/Nb 2 O 5 heterostructure via water-steam etching at the first time to achieve fast trapping-diffusion-conversion of LiPSs by combining the trapping ability of Nb 2 C with catalytic activity of Nb 2 O 5 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. Nb 2 C nanosheets with high conductivity provide the basal planes for Nb 2 O 5 contact, which suppresses the aggregation of Nb 2 O 5 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-Nb 2 C/Nb 2 O 5 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. • The accordion-like Nb 2 C/Nb 2 O 5 was prepared via water-steam etching method. • Nb 2 C/Nb 2 O 5 offered enhanced trapping effect and redox conversion of LiPSs. • Li-S battery with S-Nb 2 C/Nb 2 O 5 exhibited excellent electrochemical performance.