Electrolytes with moderate lithium polysulfide solubility for high-performance long-calendar-life lithium–sulfur batteries

作者：Xin Gao, Zhiao Yu, Jingyang Wang, X. R. Zheng, Yusheng Ye, Huaxin Gong, Xin Xiao, Yufei Yang, Yuelang Chen, Sharon Bone, Louisa C. Greenburg, Pu Zhang, Hance Su, Jordan Otto Affeld, Zhenan Bao, Yi Ping Cui · 发表于：Proceedings of the National Academy of Sciences · 年份：2023 · DOI：10.1073/pnas.2301260120 · 被引用次数：99 · 研究领域：Advanced Battery Materials and Technologies、Advanced Battery Technologies Research、Advancements in Battery Materials

Lithium–sulfur (Li-S) batteries with high energy density and low cost are promising for next-generation energy storage. However, their cycling stability is plagued by the high solubility of lithium polysulfide (LiPS) intermediates, causing fast capacity decay and severe self-discharge. Exploring electrolytes with low LiPS solubility has shown promising results toward addressing these challenges. However, here, we report that electrolytes with moderate LiPS solubility are more effective for simultaneously limiting the shuttling effect and achieving good Li-S reaction kinetics. We explored a range of solubility from 37 to 1,100 mM (based on S atom, [S]) and found that a moderate solubility from 50 to 200 mM [S] performed the best. Using a series of electrolyte solvents with various degrees of fluorination, we formulated the S ingle- S olvent, S ingle- S alt, S tandard S alt concentration with M oderate L i PSs so l ubility E lectrolytes (termed S 6 MILE ) for Li-S batteries. Among the designed electrolytes, Li-S cells using fluorinated-1,2-diethoxyethane S 6 MILE (F4DEE-S 6 MILE) showed the highest capacity of 1,160 mAh g −1 at 0.05 C at room temperature. At 60 °C, fluorinated-1,4-dimethoxybutane S 6 MILE (F4DMB-S 6 MILE) gave the highest capacity of 1,526 mAh g −1 at 0.05 C and an average CE of 99.89% for 150 cycles at 0.2 C under lean electrolyte conditions. This is a fivefold increase in cycle life compared with other conventional ether-based electrolytes. Moreover, we obser...