High-rate lithium-sulfur batteries enabled via vanadium nitride nanoparticle/3D porous graphene through regulating the polysulfides transformation

The practical deployment of high-energy Lithium-sulfur (Li/S) batteries has been largely impeded by inferior cycling performance and poor rate capability owning to polysulfides shuttling and sluggish reaction kinetics. To conquer both the two problems simultaneously, herein, an effective sulfur host has been demonstrated through implanting vanadium nitride (VN) nanoparticles homogeneously into nitrogen doped 3D interconnected-pore graphene (VN/N-rGO) hybrid architecture. The VN nanoparticles derived from the cracking and transformation of V2O5 nanowire have an average size below 20 nm not only provide abundant adsorption sites for trapping sulfur species but facilitate accelerate the conversion reaction between Li2S6 and Li2S2/Li2S by a catalytic effect. In addition, the interconnected highly conductive frameworks of N-rGO with abundant hierarchical pore structure enable fast electron/ion transportation and sufficient accommodation to absorb/entrap polysulfides. Own to these synergistic advantages, the designed VN/N-rGO based sulfur cathodes with high sulfur loadings (7.3 mg cm−2) manifests a high initial capacity of 698 mAh g−1 and retains 78% capacity after 200cycles at 1.0 C, providing novel insights for high-energy-density and stable Li/S batteries.