Direct tracking of the structure and composition evolution at the solid-state electrolyte/electrode interface and properly addressing the interfacial issues are crucial for the performance improvement of solid-state lithium metal batteries (SSLMBs). In this study, we investigate the structure evolution of the interface between Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) and the lithium anode using in situ transmission electron microscopy (TEM). It is found that the reaction between lithium and pristine LAGP results in a continuous volume expansion and contact loss, even without applying voltage. To stabilize the interface, we construct a multi-layer solid electrolyte where the LAGP is coated with the polymer electrolyte (P-DOL), enabling the interface layer to maintain its pristine morphology throughout the lithiation process. In addition, P-DOL promotes the formation of rich LiF at the interface, inhibiting the electron transport and volume expansion of LAGP, as further confirmed by the cryo-TEM and simulation analysis. The effectiveness and cyclability of the unique multi-layer electrolyte are demonstrated in various cells, even under harsh testing conditions, such as a high rate (10 C), a high active material loading (11.7 mg cm⁻²), a wide voltage range (2.8–4.45 V), and temperatures ranged from −20 to 50 °C. By applying the same interfacial modification method, LLZTO-based (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) electrolytes with both high ionic conductivity and interfacial stability are also prepared. This work provides valuable guidance for investigations of contact reactions and failure mechanisms at solid–solid interfaces, ultimately facilitating the design of high-performance SSLMBs.

中文翻译：

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稳定 LAGP/Li 界面并原位可视化高性能固态锂金属电池的界面结构演变


直接跟踪固态电解质/电极界面的结构和成分演变并正确解决界面问题对于固态锂金属电池（SSLMB）性能的提高至关重要。在本研究中，我们研究了 Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ （LAGP）和锂阳极使用原位透射电子显微镜（TEM）。研究发现，即使没有施加电压，锂和原始 LAGP 之间的反应也会导致持续的体积膨胀和接触损失。为了稳定界面，我们构建了多层固体电解质，其中 LAGP 涂有聚合物电解质（P-DOL），使界面层在整个锂化过程中保持其原始形态。此外，P-DOL 促进界面处丰富的 LiF 的形成，抑制 LAGP 的电子传输和体积膨胀，冷冻 TEM 和模拟分析进一步证实了这一点。即使在严酷的测试条件下，例如高倍率（10 C）、高活性材料负载量（11.7 mg cm ⁻² ），独特的多层电解质的有效性和可循环性在各种电池中得到了证明，宽电压范围（2.8–4.45 V），温度范围为-20至50°C。通过应用相同的界面改性方法，LLZTO基(Li _6.4 La ₃ Zr _1.4 Ta _0.6 O ₁₂