An organometallic salt as the electrolyte additive to regulate lithium polysulfide redox and stabilize lithium anodes for robust lithium-sulfur batteries

• Published in: Science China materials Vol. 67; no. 9; pp. 2880 - 2888
• Main Authors: Meng, Yixuan, Zhang, Meifang, Wang, Youliang, Liu, Chen, Zhang, Ze, Yu, Ji, Cai, Jianxin, Yang, Zhenyu
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.09.2024
• Subjects: Chemistry and Materials Science; Chemistry/Food Science; Materials Science; stabilizing Li anode; regulating LiPSs redox; nickel bromide dimethoxyethane; electrolyte additive; Li-S batteries
• ISSN: 2095-8226; 2199-4501
• DOI: 10.1007/s40843-024-2969-3

Lithium-sulfur (Li-S) batteries with high theoretical specific energy are considered to be one of the highly promising next-generation energy storage systems. However, the shuttle effect of lithium polysulfides (LiPSs) and the interfacial instability of Li anodes have seriously hindered the practical application of Li-S batteries. Optimizing the electrolyte composition with additives can significantly improve the battery performance and has attracted great attention. Herein, we propose an organometallic salt, i.e., nickel bromide dimethoxyethane (NiBr 2 DME), as an electrolyte additive, which serves as the dual function of regulating LiPSs redox and synchronously stabilizing Li anodes. We reveal that NiBr 2 DME can interact with LiPSs via Ni–S and Li–Br bonds, and accelerate the mutual transformation of LiPSs, thus reducing the accumulation of LiPSs in the electrolyte. In addition, NiBr 2 DME can form a stable LiBr-containing interfacial layer on the Li metal surface, and promote the uniform electrodeposition of Li + ions, and inhibit the formation of Li dendrites. Thus, Li-S batteries with a concentration of 0.5 mmol L −1 NiBr 2 DME show an initial capacity of 919.8 mAh g −1 at 0.2 C, and a high capacity retention of 89.3% after 100 cycles. Even at the 4 C rate, a high discharge capacity of 602.9 mAh g −1 is achieved. Surprisingly, the good cycling performance is maintained under poor electrolyte conditions with sulfur loading of 4.8 mg cm −2 and electrlyte/sulfur ratio of 5 µL mg −1 . This work provides a positive solution to achieve the suppression of shuttle effect, the regulation of LiPSs redox and the stabilization of Li anodes.