Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Institute of Physical Chemistry & Center for Materials Research, Justus Liebig University Giessen, Heinrich-Buff Ring 17, 35392, Giessen, Germany.
Nat Commun. 2023 Mar 9;14(1):1300. doi: 10.1038/s41467-023-36792-7.
The growth of lithium dendrites in inorganic solid electrolytes is an essential drawback that hinders the development of reliable all-solid-state lithium metal batteries. Generally, ex situ post mortem measurements of battery components show the presence of lithium dendrites at the grain boundaries of the solid electrolyte. However, the role of grain boundaries in the nucleation and dendritic growth of metallic lithium is not yet fully understood. Here, to shed light on these crucial aspects, we report the use of operando Kelvin probe force microscopy measurements to map locally time-dependent electric potential changes in the LiAlLaZrO garnet-type solid electrolyte. We find that the Galvani potential drops at grain boundaries near the lithium metal electrode during plating as a response to the preferential accumulation of electrons. Time-resolved electrostatic force microscopy measurements and quantitative analyses of lithium metal formed at the grain boundaries under electron beam irradiation support this finding. Based on these results, we propose a mechanistic model to explain the preferential growth of lithium dendrites at grain boundaries and their penetration in inorganic solid electrolytes.
锂枝晶在无机固体电解质中的生长是阻碍可靠全固态锂电池发展的一个基本缺陷。通常，对电池组件进行的原位事后测量表明，在固体电解质的晶界处存在锂枝晶。然而，晶界在金属锂成核和枝晶生长中的作用尚不完全清楚。在这里，为了阐明这些关键方面，我们报告了使用原位 Kelvin 探针力显微镜测量来局部地映射 LiAlLaZrO 石榴石型固体电解质中随时间变化的电势变化。我们发现，在电镀过程中，靠近锂金属电极的晶界处的 Galvani 电势下降，这是电子优先积累的反应。在电子束辐照下在晶界处形成的锂金属的时间分辨静电力显微镜测量和定量分析支持了这一发现。基于这些结果，我们提出了一个机械模型来解释锂枝晶在晶界处的优先生长及其在无机固体电解质中的渗透。
