Regulating the Polysulfide Behavior by a Large-Scale Two-Dimensional Superlattice Interface in Li-S Chemistry.

Abstract

Heterojunction engineering, serving as a key framework for building blocks between diverse functional materials, has emerged as a highly promising strategy to address the demand for efficient catalysts in lithium-sulfur (Li-S) batteries. However, achieving full matrix electronic control in the bulk phase is a bottleneck in regulating the electrochemical catalytic behavior of heterostructure catalysts. Herein, we report a "tube-in-tube" multifunctional catalyst that can strengthen the sulfur redox reaction (SRR) in Li-S batteries. Benefiting from a large-scale and oriented two-dimensional (2D) superlattice interface, the tailored heterostructure catalysts (MoSe2/MoS2@CNTs) show a "1 + 1 > 2" synergistic effect in lithium polysulfide (LiPSs) adsorption and catalytic conversion during SRR. In situ studies and theoretical results reveal that this 2D Moiré superlattice interface not only optimizes the adsorption of polysulfides but also moderates the overall electronic density of catalysts. Consequently, Li-S batteries assembled with MoSe2/MoS2@CNTs-PP as a modified separator deliver an outstanding discharge capacity of 1225 mAh g-1 at 0.2 C with a Ketjenblack/S cathode while maintaining a specific capacity of 870 mAh g-1 even at 5 C. Additionally, due to the inhibited "shuttle effect" by heterostructure catalysts, the modified separators exhibit a less capacity fading of 0.063% per cycle after 1000 cycles (1 C) even with a high sulfur loading (3.8 mg cm-2). This work focuses on designing an adsorption-catalysis synergistic interface within a full matrix of catalysts for Li-S chemistry and providing insights into the design of multifunctional catalysts for energy-storage systems based on the catalytic reaction, e.g., Zn-I2 and metal-air batteries, etc.