Gao Xin, Yu Zhiao, Wang Jingyang, Zheng Xueli, Ye Yusheng, Gong Huaxin, Xiao Xin, Yang Yufei, Chen Yuelang, Bone Sharon E, Greenburg Louisa C, Zhang Pu, Su Hance, Affeld Jordan, Bao Zhenan, Cui Yi
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305.
Department of Chemical Engineering, Stanford University, Stanford, CA 94305.
Proc Natl Acad Sci U S A. 2023 Aug;120(31):e2301260120. doi: 10.1073/pnas.2301260120. Epub 2023 Jul 24.
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 ingle-olvent, ingle-alt, tandard alt concentration with oderate LPSs soubility lectrolytes (termed ) for Li-S batteries. Among the designed electrolytes, Li-S cells using fluorinated-1,2-diethoxyethane SMILE (F4DEE-SMILE) showed the highest capacity of 1,160 mAh g at 0.05 C at room temperature. At 60 °C, fluorinated-1,4-dimethoxybutane SMILE (F4DMB-SMILE) gave the highest capacity of 1,526 mAh g 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 observed a long calendar aging life, with a capacity increase/recovery of 4.3% after resting for 30 d using F4DMB-SMILE. Furthermore, the correlation between LiPS solubility, degree of fluorination of the electrolyte solvent, and battery performance was systematically investigated.
具有高能量密度和低成本的锂硫（Li-S）电池在下一代储能领域颇具前景。然而，多硫化锂（LiPS）中间体的高溶解度困扰着它们的循环稳定性，导致快速的容量衰减和严重的自放电。探索具有低LiPS溶解度的电解质在应对这些挑战方面已显示出有希望的结果。然而，在此我们报告，具有适度LiPS溶解度的电解质对于同时限制穿梭效应和实现良好的Li-S反应动力学更为有效。我们探索了一系列从37到1100 mM（基于S原子，[S]）的溶解度，发现50到200 mM [S]的适度溶解度表现最佳。使用一系列具有不同氟化程度的电解质溶剂，我们为Li-S电池配制了具有适度LiPS溶解度的单溶剂、单盐、标准盐浓度电解质（称为 ）。在所设计的电解质中，使用氟化1,2 - 二乙氧基乙烷SMILE（F4DEE - SMILE）的Li - S电池在室温下0.05 C时显示出最高容量1160 mAh g。在60°C时，氟化1,4 - 二甲氧基丁烷SMILE（F4DMB - SMILE）在0.05 C时给出最高容量1526 mAh g，并且在贫电解质条件下于0.2 C下进行150次循环时平均库仑效率为99.89%。与其他传统醚基电解质相比，这是循环寿命的五倍增加。此外，我们观察到了较长的日历老化寿命，使用F4DMB - SMILE静置30天后容量增加/恢复了4.3%。此外，还系统地研究了LiPS溶解度、电解质溶剂的氟化程度与电池性能之间的相关性。
