The unique structure and exceptionally high lithium ion conductivity over 10 mS cm−1 of Li10GeP2S12 have gained extensive attention in all‐solid‐state lithium batteries. However, its poor resistivity to moisture and chemical/electrochemical incompatibility with lithium metal severely impede its practical application. Herein, a fluorine functionalized Li10GeP2S12 is synthesized by stannous fluoride doping and employed as a monolayer solid electrolyte to realize stable all‐solid‐state lithium batteries. The atomic‐scale mechanism underlying the impact of fluorine doping on both moisture and electrochemical stability of Li10GeP2S12 is revealed by density functional theory calculations. Fluorine surface doping significantly reduces surface hydrophilicity by electronic regulation, thereby retarding the hydrolysis reaction of Li10GeP2S12. After exposed to a relative humidity of 35%–40% for 20 min, the ionic conductivity of Li9.98Ge0.99Sn0.01P2S11.98F0.02 maintains as high as 2.21 mS cm−1, nearly one order of magnitude higher than that of Li10GeP2S12 with 0.31 mS cm−1. Meanwhile, bulk doping of highly electronegative fluorine promotes the formation of lithium vacancies in the Li10GeP2S12 system, thus allowing stable lithium plating/stripping in Li | Li symmetric batteries, boosting a critical current density reaching 2.1 mA cm−2. The LiCoO2 | lithium all‐solid‐state batteries display improved cycling stability and rate capability, showing 80.1% retention after 600 cycles at 1C.

中文翻译：

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用于全固态锂电池的高导电且稳定的 Li10GeP2S12 固体电解质的均质氟掺杂


Li10GeP2S12独特的结构和超过10 mS cm−1的极高锂离子电导率在全固态锂电池中获得了广泛关注。然而，其较差的耐湿性以及与锂金属的化学/电化学不相容性严重阻碍了其实际应用。本文通过氟化亚锡掺杂合成了氟功能化的Li10GeP2S12，并将其用作单层固体电解质以实现稳定的全固态锂电池。通过密度泛函理论计算揭示了氟掺杂对 Li10GeP2S12 的水分和电化学稳定性影响的原子尺度机制。氟表面掺杂通过电子调节显着降低表面亲水性，从而延缓Li10GeP2S12的水解反应。在35%~40%的相对湿度下暴露20 min后，Li9.98Ge0.99Sn0.01P2S11.98F0.02的离子电导率保持高达2.21 mS cm−1，比Li10GeP2S12，0.31 mS cm−1。同时，高负电性氟的大量掺杂促进了Li10GeP2S12体系中锂空位的形成，从而实现了Li | 中稳定的锂沉积/剥离。 Li对称电池，将临界电流密度提高到2.1 mA cm−2。钴酸锂|全固态锂电池显示出更高的循环稳定性和倍率性能，在 1C 下循环 600 次后显示出 80.1% 的保留率。