Huang Di, Liu Gao, Tong Wei
Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA.
Small. 2024 Dec;20(49):e2406862. doi: 10.1002/smll.202406862. Epub 2024 Sep 23.
Interfacial stability is one of the critical challenges in all-solid-state Li metal batteries. Multiple processes such as solid electrolyte (SE) decomposition and lithium dendrite growth take place at the solid interfaces during cycling, leading to the overall cell failure. To deconvolute these complex processes, in situ characterization is of paramount importance to elucidate the interfacial evolution on the SE upon Li plating/stripping. Herein, an all-solid-state asymmetric in situ cell is developed that allows the direct visualization of the highly localized Li plating/stripping processes under the optical microscope. Moreover, this cell configuration enables reliable post-mortem chemical and morphological analysis of the intact SE/Li interface. Using combined scanning electron microscopy and energy-dispersive X-ray spectroscopy, the study reveals that the evolution of the Li argyrodite interface is strongly influenced by the current density, particularly in terms of chemical distribution and Li plating morphology. More specifically, the solid interface is LiCl-rich with the formation of Li cubes at low current densities, while high currents result in more uniform elemental distribution and filament morphology. These findings elucidate the dynamic evolution mechanism at solid interfaces and offer valuable guidance for developing stable solid interfaces in all-solid-state Li metal batteries.
界面稳定性是全固态锂金属电池面临的关键挑战之一。在循环过程中，诸如固体电解质（SE）分解和锂枝晶生长等多种过程会在固体界面发生，从而导致整个电池失效。为了剖析这些复杂过程，原位表征对于阐明锂电镀/剥离过程中SE上的界面演变至关重要。在此，开发了一种全固态非对称原位电池，该电池能够在光学显微镜下直接观察高度局部化的锂电镀/剥离过程。此外，这种电池配置能够对完整的SE/Li界面进行可靠的事后化学和形态分析。通过结合扫描电子显微镜和能量色散X射线光谱，该研究表明，硫银锗矿型锂界面的演变受到电流密度的强烈影响，特别是在化学分布和锂电镀形态方面。更具体地说，在低电流密度下，固体界面富含LiCl并形成锂立方体，而高电流则导致更均匀的元素分布和丝状形态。这些发现阐明了固体界面的动态演变机制，并为在全固态锂金属电池中开发稳定的固体界面提供了有价值的指导。
