Abstract Practical lithium-sulfur batteries stipulate the use of a lean-electrolyte and a high Coulombic efficiency of the lithium metal anode. Herein, we employ 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether as a co-solvent in the electrolyte of Li-S batteries to meet the demands. The co-solvent fosters the formation of a LiF-rich solid electrolyte interphase on lithium metal anode, as revealed by Ab initio molecular dynamics and Femtosecond Stimulated Raman spectroscopy. The co-solvent results in an average Coulombic efficiency of 99.4% for lithium plating/stripping cycles. Full cells with a capacity ratio of 2 between lithium anode and the S@PAN cathode (3 mgs cm−2) exhibited a stable cycle life over 100 cycles at an electrolyte/sulfur ratio of 2 µL mg−1, validating the high Coulombic efficiency of the lithium anode and demonstrating the compatibility of the electrolyte with both electrodes. To enhance the energy density, we prepared a hybrid cathode composed of 45 wt.% VS2 mixed with ZnS-coated Li2S@graphene as the cathode. Based on the mass of both electrodes and the electrolyte, the full cell delivers an energy density of 483 Wh kg−1, which demonstrates viable Li-S batteries with the lean-electrolyte.

中文翻译：

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氟化共溶剂有望在贫电解质条件下实现锂硫电池

摘要 实用的锂硫电池规定了使用贫电解质和锂金属负极的高库仑效率。在此，我们采用 1,1,2,2-四氟乙基 2,2,2-三氟乙基醚作为 Li-S 电池电解液中的助溶剂来满足需求。正如 Ab initio 分子动力学和飞秒受激拉曼光谱所揭示的那样，共溶剂促进了锂金属负极上富含 LiF 的固体电解质界面的形成。共溶剂导致锂电镀/剥离循环的平均库仑效率为 99.4%。锂阳极和 S@PAN 阴极（3 mgs cm-2）之间容量比为 2 的全电池在 2 µL mg-1 的电解质/硫比下表现出超过 100 次循环的稳定循环寿命，验证了锂负极的高库仑效率，并证明了电解质与两个电极的兼容性。为了提高能量密度，我们制备了由 45 wt.% VS2 与 ZnS 涂层的 Li2S@石墨烯混合组成的混合阴极作为阴极。基于电极和电解质的质量，全电池提供 483 Wh kg-1 的能量密度，这表明使用贫电解质的锂硫电池是可行的。