Poplar flower-like nitrogen-doped carbon nanotube@VS4 composites with excellent sodium storage performance

Abstract

As a new anode material for sodium-ion batteries (SIBs), VS₄ shows impressive energy storage potential due to its unique one-dimensional parallel chain structure, large chain spacing and high sulfur content. Here, poplar flower-like nitrogen-doped carbon nanotube@VS₄ composites (NCNt@VS₄) with a three-dimensional structure were successfully synthesized via a solvothermal reaction using nitrogen-doped carbon nanotube (NCNt) as a template. The unique three-dimensional structure can enhance the transmission of electrons and sodium ions, conducive to wetting of the electrolyte and buffering the huge volume change. Therefore, NCNt@VS₄ delivers excellent sodium storage performance. It presents a reversible capacity of 430 mA h g⁻¹ after 2000 cycles at 1 A g⁻¹, and demonstrates a high initial coulombic efficiency (81.6%). At the same time, the electrode exhibits superior rate-performance (460 mA h g⁻¹ at 5 A g⁻¹) and high ability to tolerate current changes. This work develops a reliable method for the preparation of other 3D NCNt@transition metal sulfide composites, which exhibit great potential as an anode for SIBs.