Localized high-concentration electrolytes (LHCEs) have unique solvation structures that do not affect the original salt–solvent coordination from highly concentrated electrolytes. LHCEs enable a wide electrochemical voltage window and mitigate the extensive dendritic growth of metallic anodes. However, in K metal batteries, LHCE undergoes undesirable side reactions because of potasside (K), triggering aggressive chemistry with a diluent, represented as hydrofluoroethers (HFEs), eventually resulting in poor cycle life. In this study, 1, 3, 5-trifluorobenzene (TFB) was introduced as a functional additive to prevent the parasitic K reaction. The three symmetrically substituted fluorines prevented TFB from disrupting the as-formed solvation structure of LHCE located in the outer sphere. This characteristic increases the reaction energy barrier between K and HFE, suppressing the deterioration of the metal anode by adding only 3 wt.% of TFB in LHCE. Moreover, TFB preferentially decomposes at each electrode because of its molecular energy level and increases the reversibility of the cell, reducing unnecessary consumption of electrolytes with a stable interface. This study discusses a novel method to prevent the K reaction at the electrolyte level and the utilization of LHCE in K batteries to pursue higher energy densities, sustaining the advantage of using a metal anode.

中文翻译：

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利用氟代苯作为钾金属电池双功能添加剂抑制局部高浓度电解液中的钾苷反应

局部高浓度电解质（LHCE）具有独特的溶剂化结构，不会影响高浓度电解质原有的盐-溶剂配位。 LHCE 可实现较宽的电化学电压窗口，并减轻金属阳极的广泛枝晶生长。然而，在钾金属电池中，LHCE 由于钾苷 (K) 会发生不良副反应，引发与氢氟醚 (HFE) 等稀释剂的侵蚀性化学反应，最终导致循环寿命不佳。在这项研究中，引入1,3,5-三氟苯（TFB）作为功能添加剂来防止寄生K反应。三个对称取代的氟阻止 TFB 破坏位于外球的 LHCE 的溶剂化结构。这一特性增加了 K 和 HFE 之间的反应能垒，通过在 LHCE 中仅添加 3 wt.% 的 TFB 来抑制金属阳极的劣化。此外，由于其分子能级，TFB优先在每个电极上分解，并增加了电池的可逆性，通过稳定的界面减少了不必要的电解质消耗。本研究讨论了一种在电解质水平上防止 K 反应的新方法，以及在 K 电池中利用 LHCE 来追求更高的能量密度，同时保持使用金属阳极的优势。