Vanadium Nitride Quantum Dots/Holey Graphene Matrix Boosting Adsorption and Conversion Reaction Kinetics for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) have been considered as potential next-generation energy storage systems due to their high specific energy of 2600 Wh kg(-1) and 2800 Wh L-1. Nevertheless, the practical application of LSBs still faces several hazards, including the shuttle effect of soluble lithium polysulfides, low electrical conductivities of solid sulfur and lithium sulfides, and large volume expansion during charge/discharge cycles. To address this critical challenge, we innovatively proposed facile synthesis of nanostructured VN quantum dots (VNQD)/holey graphene matrix for stabilizing the sulfur cathode by simultaneously promoting the trapping, anchoring, and catalyzing efficiencies of both LiPSs and Li2S. Benefiting from abundant edge catalytic sites of VNQD, in-plane nanopores of graphene, and high electrical conductivity, the sulfur host not only provides high adsorption capability toward soluble polysulfides, strong binding ability for anchoring solid Li2S, and their rapid conversion kinetics but also contributes abundant sulfur storage sites and efficient transport pathways for lithium ions (Li+) and electrons. Consequently, the sulfur cathode exhibits high initial capacities of 1320 mAh g(-1), high rate capability (850 mAh g(-1) @ 4 mA cm(-2)), and high capacity retention of 99.95% per cycle after 500 cycles, providing a feasible solution for the practical utilization of shuttle-free Li-S batteries.

Automated summary

The study proposed a novel solution by synthesizing VN quantum dots/holey graphene matrix to stabilize the sulfur cathode, achieving positive results in enhancing the adsorption capacity and transport pathways of the sulfur host towards lithium polysulfides and lithium sulfides. The sulfur cathode demonstrated excellent performance in various aspects, providing a feasible solution for practical utilization of shuttle-free Li-S batteries.