Mesoporous Niobium Nitride Nanowires Encapsulated in Carbon for High-Performance Lithium–Sulfur Batteries

The shuttle effect of lithium polysulfides (LiPSs) is a fundamental problem restricting the commercialization of lithium–sulfur batteries. A polar conductive substrate serving as the sulfur positive host is proven to be an excellent strategy for the efficient immobilization and rapid conversion of LiPSs. Herein, a heterostructure material of niobium nitride nanowires encapsulated in carbon (NbN-NW@C) as a positive host for the sulfur cathode was designed and investigated. First-principles calculation confirms the existence of a strong chemical interaction between NbN-NW and LiPSs, which catalytically promotes the mutual conversion of LiPSs and insoluble Li 2 S/Li 2 S 2, thus enhancing the redox reaction kinetics. The carbon layer with an adjustable thickness effectively improves the adsorption capacity of the host for LiPSs, and N 2 adsorption–desorption shows that the maximum specific surface area of NbN-NW@C-800 is 81.0 m 2 g –1 . Besides, the metallic property of NbN-NW facilitates electron transmission and improves sulfur utilization. Benefiting from the rational design of the electrode structure, the cathode exhibits excellent cycle stability (the capacity retention is 81.8% after 100 cycles) and rate properties (783 mAh g –1 at 1 C).