Enhancing conversion of polysulfides via porous carbon nanofiber interlayer with dual-active sites for lithium-sulfur batteries.

ABSTRACT

Lithium-sulfur (Li-S) batteries are promising candidates for next-generation energy storage. However, the notorious lithium polysulfides (LiPSs) shuttle effect and torpid redox kinetics hinder their practical application. Enhancing phase conversion efficiency and limiting the dissolution of LiPSs are critical for stabilizing Li-S batteries. Herein, sulfiphilic defective TiO2 nanoparticles (D-TiO2) were integrated into the lithiophilic N-doped porous carbon nanofiber membrane (D-TiO2@NPCNF) to construct interlayer for catalyzing the conversion of LiPSs. The D-TiO2@NPCNF provides hierarchical porous structure and large specific surface area, and the formed 3D conductive network accelerates the transport of electrons and ions. The dual-active sites (N and D-TiO2) enhance the interface conversion and chemisorption ability of LiPSs via forming "Li-N and Ti-S" bonds. Due to the structural advantage of the D-TiO2@NPCNF, the Li-S batteries exhibit excellent cycling stability (only 0.049% decay per cycle in 800cycles at 1.0C) and impressive specific capacity (608 mAh g-1 at 3.0C). This work is expected to deepen the comprehension of complex interphase conversion processes of LiPSs and provide novel ideas for the design of new interlayer materials.