Core-Shell-Structured Carbon Nanotube@VS4 Nanonecklaces as a High-Performance Cathode Material for Magnesium-Ion Batteries

As a typical layered transition metal chalcogenide, VS4 is considered as a promising cathode material for advanced magnesium-ion batteries. However, the poor electronic conductivity and severe polarization effect restrict its practical applications. Herein, we report a betaine-assisted solvothermal strategy to coat VS4 nanoblocks on the surface of carbon nanotubes (CNTs), obtaining unique core-shell-structured CNT@VS4 nanonecklaces. As a result of the morphology-controlling effect of betaine, VS4 exhibits an unusual nanoblock morphology, which renders abundant active sites and promotes the contact between the electrode and electrolyte. CNTs serve as a highly conductive skeleton, combining with the VS4 nanoblocks and ensuring their uniform distribution. As a benefit from the synergistic effect of abundant active sites and electron-conductive highways, the as-synthesized CNT@VS4 nanonecklaces manifest remarkable performance for magnesium storage, including a large reversible capacity of 170 mAh g(-1) at 0.1 A g(-1), outstanding cycle stability (76.3 mAh g(-1) after 800 cycles at 0.5 A g(-1)), and superior rate performance (77.2 mAh g(-)(1) at 2 A g(-1)).

Automated summary

In this study, a betaine-assisted solvothermal strategy was used to improve the electronic conductivity and polarization effect of VS4. By coating VS4 nanoblocks onto carbon nanotubes (CNTs), the contact between the electrode and electrolyte was promoted, and the uniform distribution of nanoblocks was ensured. The as-synthesized CNT@VS4 nanonecklaces exhibited excellent performance for magnesium-ion batteries, thanks to their abundant active sites and electron-conductive highways.