Tubular Nanoarchitectonics of Titania@Vanadium-Sulfide/Bismuth-Sulfide Composite for Effective Sodium-Ion Storage

Vanadium sulfide, as a transition metal sulfide with a unique layered structure and good redox properties, has become a research hotspot for anodic materials of sodium-ion batteries (SIBs) due to its high theoretical capacity, good structural tunability, and low cost. However, the electrochemical performance of vanadium sulfide is hindered by its poor structural stability and slow ion diffusion kinetics during charge and discharge processes, which limits its practical applications. Herein, a dual metal-sulfide-based tubular nanoarchitectonic (TiO₂@VS₄/Bi₂S₃ composite) with cellulose-derived titania nanotubes as the structural scaffold was constructed through the sol-gel and hydrothermal methods. In this composite material, the VS₄/Bi₂S₃ nanorods were uniformly coated on the surface of the titania nanotubes, forming a three-dimensional (3D) network porous structure. Transmission electron microscopy results confirmed the formation of the abundant phase interfaces during cycling, which greatly improved the structural integrity of the material. Compared to the VS₄/Bi₂S₃ anodic materials, the TiO₂@VS₄/Bi₂S₃ nanotubular composite exhibited superior sodium storage performances, especially in terms of long cycling stability. At a current density of 5.0 A g^-1, the nanotubular composite retained a reversible capacity of 669.5 mA h g^-1 after 1000 cycles. The cross-linked TiO₂@VS₄/Bi₂S₃ nanotubular composite effectively enhanced charge transfer and sodium-ion transport kinetics, alleviating the volume expansions and voltage failure issues. Meanwhile, the TiO₂@VS₄/Bi₂S₃//Na₃V₂(PO₄)₃ full cells maintained a capacity of 276.8 mA h g^-1 and an energy density of 392.7 Wh kg^-1 after 400 cycles at 1.0 A g^-1, demonstrating good practical application potential.