Cobalt-doped vanadium nitride composite carbon hollow spheres for enhanced lithium–sulfur battery performance: overcoming sulfur dissolution and the shuttle effect†

Abstract

This study addresses the challenges of sulfur dissolution and the shuttle effect in the practical application of lithium–sulfur (Li–S) batteries by developing cobalt-doped vanadium nitride composite carbon hollow spheres (CoVN/C-HS). The embedding of CoVN nanoparticles within the carbon hollow spheres creates an efficient charge transport network that significantly reduces electrode interfacial resistance, accelerates charge transfer during charging and discharging, and effectively mitigates polarization, thereby ensuring battery stability under high-rate conditions. Additionally, the strong interaction between CoVN nanoparticles and the carbon hollow sphere matrix enhances the material's adsorption capacity for polysulfides, effectively suppressing their dissolution and shuttle effect, which prolongs battery cycle life. Therefore, the prepared CoVN/C-HS material has demonstrated excellent performance in Li–S battery applications. At a low current density of 0.05C, the battery achieved an initial discharge capacity of up to 1475 mA h g⁻¹, fully demonstrating the efficient utilization of sulfur by the material. Remarkably, even after 100 cycles at 0.2C, the battery retains a capacity of 1067 mA h g⁻¹, showcasing excellent cycle stability. Notably, at a high current density of 2C, the battery achieves an initial capacity of 918.8 mA h g⁻¹ and maintains 662 mA h g⁻¹ after 400 cycles. This success not only presents a novel approach for optimizing Li–S battery performance by meticulously tuning the material structure and composition to concurrently address sulfur dissolution and the shuttle effect but also lays a solid foundation for the large-scale commercialization of this battery type.