Vanadium based carbide–oxide heterogeneous V2O5@V2C nanotube arrays for high-rate and long-life lithium–sulfur batteries

Abstract

Due to their ultra-high theoretical energy density, low cost, and environmental friendliness, lithium–sulfur batteries have become a potentially strong competitor for next-generation energy storage devices. The search for a host material that can effectively anchor sulfur to a cathode to solve the adverse effects of the shuttle effect on batteries has become a research hotspot in the academic world. Here, we propose a three-dimensional heterostructure of V₂O₅ nanotube arrays vertically grown on V₂C-MXenes as a sulfur-supporting host material for the cathode of lithium–sulfur batteries. Through first-principles calculations, we found that V₂O₅@V₂C exhibits an extreme adsorption capacity for polysulfides. Besides, thanks to the excellent catalytic performance of V₂O₅ for oxidation reactions, the conversion reaction potential of polysulfides to Li₂S and Li₂S₂ is significantly reduced, and the shuttle effect of lithium–sulfur batteries is effectively suppressed. Also, the larger specific surface area and tubular structure of the composite host material can increase the sulfur loading of the cathode while ensuring the stability of the electrode structure. The V₂O₅@V₂C/S electrode exhibits higher initial capacity (1173 mA h g⁻¹ at 0.2C), longer cycle life (1000 cycles with 0.047% decay per period), and higher sulfur loading (8.4 mg cm⁻²). We believe that this work can provide a reference for the design of cathode host materials for lithium–sulfur batteries with long cycle life.