Mo<sub>2</sub>N–W<sub>2</sub>N Heterostructures Embedded in Spherical Carbon Superstructure as Highly Efficient Polysulfide Electrocatalysts for Stable Room‐Temperature Na–S Batteries
Shipeng Zhang, Yu Yao, Xiaojuan Jiao, Mingze Ma, Huijuan Huang, Xuefeng Zhou, Lifeng Wang, Jintao Bai, Yan Yu
Abstract
Abstract Room‐temperature sodium–sulfur (RT Na–S) batteries are highly desirable for a sustainable large‐scale energy‐storage system due to their high energy density and low cost. Nevertheless, practical applications of RT Na–S batteries are still prevented by the shuttle effect of sodium polysulfides (NaPS), slow reaction kinetics of S, and incomplete conversion process of NaPS. Here, Mo 2 N–W 2 N heterostructures embedded in a spherical carbon superstructure (Mo 2 N–W 2 N@PC) are designed to efficiently suppress the “polysulfide shuttle” and promote NaPS redox reactions. The designed Mo 2 N–W 2 N@PC heterostructure with abundant heterointerfaces, high conductivity, and porosity can facilitate electron/ion diffusion and provide high catalytic activity for efficient NaPS conversion. The obtained Na–S battery delivers high reversible capacity with superior long‐term cyclability (517 mAh g −1 at 1 A g −1 after 400 cycles) and unprecedented rate capability (417 mAh g −1 at 2 A g −1 ). Furthermore, the electrocatalysis mechanism is revealed by combining in situ X‐ray diffraction (XRD), ex situ X‐ray photoelectron spectroscopy (XPS), UV–vis spectra, and precipitation experiments. This work demonstrates a novel heterostructure design strategy that enables high‐performance Na–S batteries.