Mesoporous, conductive molybdenum nitride as efficient sulfur hosts for high-performance lithium-sulfur batteries

The insulating nature of sulfur and the shuttling of polysulfides are two major fundamental issues that have to be tackled in Lithium-sulfur (Li-S) batteries, generally leading to low sulfur utilization and fast capacity decay. Constructing sulfur hosts with both excellent conductivity and efficient polysulfides immobilization is critical to the successful implementation of Li-S batteries. Herein, mesoporous molybdenum nitride (Mo₂N) with interconnected structures is readily designed as sulfur hosts to resolve the low conductivity and polysulfides dissolution issues. The specific surface area and the conductivity of the mesoporous Mo₂N are verified to be 121 m² g⁻¹ and 1 × 10⁵ S m⁻¹, respectively. Along with its high polarity enabling the chemisorption of polysulfides, the as-obtained mesoporous Mo₂N is promising as sulfur host. The polysulfides dissolution is efficiently suppressed owing to the fruitful nanospaces in the mesoporous Mo₂N that offer more exposed polar interfaces for intensive chemical affinity/adsorption with polysulfides. Encouragingly, the as-prepared mesoporous, conductive and polar Mo₂N with sulfur delivers superior capacity of 995 mA h g⁻¹, long cycle stability (91.9% capacity retention after 100 cycles), superior to those of Nonporous-Mo₂N/S and Mesoporous-MoO₃/S. Our results reveal that vivid engineering of metal nitrides via creating nanopores is promising for pursuing high-performance Li-S batteries.