Solid-state polymer electrolytes can enable the safe operation of high energy density lithium metal batteries; unfortunately, they have low ionic conductivity and poor redox stability at electrode interfaces. Fluorinated ether polymer electrolytes are a promising approach because the ether units can solvate and conduct ions, while the fluorinated moieties can increase oxidative stability. However, current perfluoropolyether (PFPE) electrolytes exhibit deficient lithium-ion coordination and ion transport. Here, we incorporate cross-linked poly(ethylene glycol) (PEG) units within the PFPE matrix and increase the polymer blend electrolyte conductivity by 6 orders of magnitude as compared to pure PFPE at 60 °C from 1.55 × 10^–11 to 2.26 × 10^–5 S/cm. Blending varying ratios of PEG and PFPE induces microscale phase separation, and we show the impact of morphology on ion solvation and dynamics in the electrolyte. Spectroscopy and simulations show weak ion–PFPE interactions, which promote salt phase segregation into─and ion transport within─the PEG domain. These polymer electrolytes show promise for use in high-voltage lithium metal batteries with improved Li|Li cycling due to enhanced mechanical properties and high-voltage stability beyond 6 V versus Li/Li⁺. Our work provides insights into transport and stability in fluorinated polymer electrolytes for next-generation batteries.

中文翻译：

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氟化醚固态电解质中离子电导率和氧化稳定性的相形态依赖性


固态聚合物电解质可以使高能量密度锂金属电池安全运行；不幸的是，它们的离子电导率低，电极界面的氧化还原稳定性差。氟化醚聚合物电解质是一种有前途的方法，因为醚单元可以溶剂化并传导离子，而氟化部分可以提高氧化稳定性。然而，目前的全氟聚醚（PFPE）电解质表现出锂离子配位和离子传输不足。在这里，我们在 PFPE 基质中加入了交联聚乙二醇 (PEG) 单元，并将聚合物共混电解质的电导率在 60 °C 下比纯 PFPE 提高了 6 个数量级，从 1.55 × 10 ^–11 S/cm。混合不同比例的 PEG 和 PFPE 会引起微尺度相分离，我们展示了形态对电解质中离子溶剂化和动力学的影响。光谱学和模拟显示弱离子-PFPE 相互作用，促进盐相分离到 PEG 结构域中以及离子在 PEG 结构域内的传输。这些聚合物电解质有望用于高压锂金属电池，由于与 Li/Li ⁺ 相比，机械性能增强且电压稳定性超过 6 V，因此可改善 Li|Li 循环。我们的工作为下一代电池的氟化聚合物电解质的传输和稳定性提供了见解。