In Situ Phase Separation Strategy to Construct Zinc Oxide Dots-Modified Vanadium Nitride Flower-like Heterojunctions as an Efficient Sulfur Nanoreactor for Lithium-Sulfur Batteries.

Exploring advanced sulfur cathode materials is important for the development of lithium-sulfur batteries (LSBs), but they still present challenges. Herein, zinc oxide dots-modified vanadium nitride flower-like heterojunctions (Zn-QDs-VN) as sulfur hosts are prepared by a phase separation strategy. Characterizations confirm that the flower structure with high specific surface area and pores improves active site exposure and electron/mass transfer. In situ phase separation enriches the Zn-QDs-VN interface, addressing the issues of uneven distribution and interface reduction of Zn-QDs-VN. Further theoretical computations reveal that ZnO-QDs-VN with optimized intermediate spin states can constitute a stable LiS* bond sequence, which can conspicuously facilitate the adsorption and conversion of LiPSs and reduce the battery reaction energy barrier. Therefore, the ZnO-QDs-VN@S cathode shows a high initial specific capacity of 1109.6 mAh g at 1.0 C and long cycle stability (maintaining 984.2 mAh g after 500 cycles). Under high S loading (8.5 mg cm) and lean electrolyte conditions (E/S = 6.5 μL mg), it also exhibits a high initial area capacity (10.26 mAh cm) at 0.2 C. The interfacial synergistic effect accelerates the adsorption and conversion of LiPSs and reduces the energy barriers in cell reactions. The study provides a new method for designing heterojunctions to achieve high-performance LSBs.