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

Abstract

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.