Hollow Carbon Spheres Embedded with VN Quantum Dots as an Efficient Cathode Host for Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are a prospective battery technology with high energy density, whereas the successful implementation of Li–S batteries is still impeded by many challenges, especially the shuttling effect of lithium polysulfides (LiPSs) and sluggish redox kinetics. Therefore, it is urgent to find a novel host material that could tackle these problems with a cost-effective manner. Herein, the mesoporous and hollow carbon sphere embedded with homogeneous VN quantum dots (noted as VN-H-C) is constructed and applied as an efficient host for a sulfur cathode, which features both physical and chemical trapping ability for soluble LiPSs. More importantly, VN quantum dots can significantly accelerate the electrochemical conversion of LiPSs. As a consequence, the S@VN-H-C cathode exhibits a high specific capacity of 856.5 mAh g–1 at 1 C and maintains 602.5 mAh g–1 after 500 cycles with a low capacity decay rate of only 0.059% per cycle. This study provides a feasible strategy for designing nanostructured materials as effective sulfur hosts in Li–S batteries.