Low-Bandgap Se-Deficient Antimony Selenide as a Multifunctional Polysulfide Barrier toward High-Performance Lithium-Sulfur Batteries.

Tian, Yuan; Li, Gaoran; Zhang, Yongguang; Luo, Dan; Wang, Xin; Zhao, Yan; Liu, Hui; Ji, Puguang et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPSs) represent the main obstructions to the practical application of lithium-sulfur (Li-S) batteries. Herein, an anion-deficient design of antimony selenide (Sb<sub>2</sub> Se<sub>3-</sub> <sub>x</sub> ) is developed to establish a multifunctional LiPS barrier toward the inhibition of polysulfide shuttling and enhancement of battery performance. The defect chemistry in the as-developed Sb<sub>2</sub> Se<sub>3-</sub> <sub>x</sub> promotes the intrinsic conductivity, strengthens the chemical affinity to LiPSs, and catalyzes the sulfur electrochemical conversion, which are verified by a series of computational and experimental results. Attributed to these unique superiorities, the obtained LiPS barrier efficiently promotes and stabilizes the sulfur electrochemistry, thus enabling excellent Li-S battery performance, e.g., outstanding cyclability over 500 cycles at 1.0 C with a minimum capacity fading rate of 0.027% per cycle, a superb rate capability up to 8.0 C, and a high areal capacity of 7.46 mAh cm<sup>-2</sup> under raised sulfur loading. This work offers a defect engineering strategy toward fast and durable sulfur electrochemistry, holding great promise in developing practically viable Li-S batteries as well as enlightening the material design of related energy storage and conversion systems.