The lithium metal anode (LMA) instability at deep cycle with high utilization is a crucial barrier for developing lithium (Li) metal batteries, resulting in excessive Li inventory and electrolyte demand. This issue becomes more severe in capacity-type lithium–sulfur (Li–S) batteries. High-concentration or localized high-concentration electrolytes are noted as effective strategies to stabilize Li metal but usually lead to a high electrolyte density (>1.4 g mL⁻¹). Here we propose a bifunctional fluorinated silane-based electrolyte with a low density of 1.0 g mL⁻¹ that not only is much lighter than conventional electrolytes (≈1.2 g mL⁻¹) but also form a robust solid electrolyte interface to minimize Li depletion. Therefore, the Li loss rate is reduced over 4.5-fold with the proposed electrolyte relative to its conventional counterpart. When paired with onefold excess LMA at the electrolyte weight/cell capacity (E/C) ratio of 4.5 g Ah⁻¹, the Li–S pouch cell using our electrolyte can survive for 103 cycles, much longer than with the conventional electrolyte (38 cycles). This demonstrates that our electrolyte not only reduces the E/C ratio but also enhances the cyclic stability of Li–S batteries under limited Li amounts.

中文翻译：

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低密度氟化硅烷溶剂增强深循环锂 – 硫电池的使用寿命

高利用率的深循环锂金属负极（LMA）不稳定性是开发锂（Li）金属电池的关键障碍，导致锂库存和电解质需求过多。这个问题在容量型锂硫（Li-S）电池中变得更加严重。高浓度或局部高浓度电解质被认为是稳定锂金属的有效策略，但通常会导致高电解质密度（> 1.4 g mL ^-1）。在这里，我们提出了一种具有 1.0 g mL ^-1低密度的双功能氟化硅烷基电解质，它不仅比传统电解质 (≈1.2 g mL ^-1)，但也形成了坚固的固体电解质界面，以最大限度地减少锂消耗。因此，与传统电解质相比，所提出的电解质的锂损失率降低了 4.5 倍以上。当以 4.5 g Ah ^-1的电解质重量 / 电池容量 (E / C) 比率与一倍过量的 LMA 配对时，使用我们电解质的 Li-S 软包电池可以存活 103 个循环，比使用传统电解质的时间长得多 (38循环）。这表明我们的电解液不仅降低了 E / C 比，而且在有限的锂含量下提高了 Li-S 电池的循环稳定性。