The achievement of high ionic conductivity for solid-state electrolyte and low interface resistance between electrodes and electrolyte are keys to successful solid-state lithium ion batteries. In this paper, an efficient solid-state electrolyte with dual-layer structure for dendrite-free lithium metal battery is designed. A Li metal-friendly poly(ethylene oxide) (PEO) can serve as low-voltage stable polymer electrolyte and ceramic-dominating poly(vinylidene fluoride)–lithium aluminum titanium phosphate (PVDF–LATP) composite solid electrolyte is able to resist higher voltage facing cathode. More importantly, bistrifluoroacetamide (BTFA), as a polar molecular plasticizer, can simultaneously inhibit polymer crystallization, coordinate the delocalization of negative charges, and facilitate the solvation of lithium salts, providing absorption sites for lithium ion migration. The obtained BTFA-activated PEO/PVDF–LATP double-layer solid electrolyte exhibits satisfied ionic conductivity (4.4 × 10⁻⁴ S cm⁻¹ at 25 °C), high Li⁺-transfer number (0.68), and wide electrochemical stable windows (0–5.092 V vs Li/Li⁺). Moreover, both the assembled full cells with LiFePO₄ and high-voltage LiNi_0.8Co_0.1Mn_0.1O₂ cathodes show high initial discharge capacities (163.3 and 219.5 mAh g⁻¹ at 0.1 C, respectively), excellent cycling, and rate performance.

中文翻译：

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用于无枝晶锂金属电池的双三氟乙酰胺活化双层复合固体电解质

实现固态电解质的高离子电导率以及电极和电解质之间的低界面电阻是固态锂离子电池成功的关键。本文设计了一种高效的双层结构固态电解质，用于无枝晶锂金属电池。锂金属友好型聚（环氧乙烷）（PEO）可作为低压稳定的聚合物电解质，而以陶瓷为主的聚（偏二氟乙烯）-磷酸铝钛锂（PVDF-LATP）复合固体电解质能够抵抗更高的电压面对阴极。更重要的是，双三氟乙酰胺（BTFA）作为极性分子增塑剂，可以同时抑制聚合物结晶，协调负电荷离域，促进锂盐的溶剂化，为锂离子迁移提供吸收位点。获得的 BTFA 活化的 PEO/PVDF-LATP 双层固体电解质表现出令人满意的离子电导率（4.4 × 10⁻⁴ S cm ^-1 at 25 °C)、高 Li ⁺转移数 (0.68) 和宽电化学稳定窗口（0–5.092 V vs Li/Li ⁺）。此外，具有 LiFePO ₄和高压 LiNi _0.8 Co _0.1 Mn _0.1 O ₂正极的组装全电池均显示出高初始放电容量（分别为 163.3 和 219.5 mAh g ^-1在 0.1 C）、优异的循环和倍率性能。