Materials Science and Engineering Program & Texas Materials Institute, The University of Texas at Austin , Austin, Texas 78712, United States.
J Am Chem Soc. 2018 Jan 10;140(1):250-257. doi: 10.1021/jacs.7b09531. Epub 2017 Dec 28.
Benefiting from extremely high shear modulus and high ionic transference number, solid electrolytes are promising candidates to address both the dendrite-growth and electrolyte-consumption problems inherent to the widely adopted liquid-phase electrolyte batteries. However, solid electrolyte/electrode interfaces present high resistance and complicated morphology, hampering the development of solid-state battery systems, while requiring advanced analysis for rational improvement. Here, we employ an ultrasensitive three-dimensional (3D) chemical analysis to uncover the dynamic formation of interphases at the solid electrolyte/electrode interface. While the formation of interphases widens the electrochemical window, their electronic and ionic conductivities determine the electrochemical performance and have a large influence on dendrite growth. Our results suggest that, contrary to the general understanding, highly stable solid electrolytes with metal anodes in fact promote fast dendritic formation, as a result of less Li consumption and much larger curvature of dendrite tips that leads to an enhanced electric driving force. Detailed thermodynamic analysis shows an interphase with low electronic conductivity, high ionic conductivity, and chemical stability, yet having a dynamic thickness and uniform coverage is needed to prevent dendrite growth. This work provides a paradigm for interphase design to address the dendrite challenge, paving the way for the development of robust, fully operational solid-state batteries.
得益于极高的剪切模量和高离子迁移数，固体电解质是解决广泛采用的液相电解质电池中固有枝晶生长和电解质消耗问题的有前途的候选材料。然而，固体电解质/电极界面呈现高电阻和复杂的形态，阻碍了固态电池系统的发展，同时需要先进的分析方法来进行合理的改进。在这里，我们采用超灵敏的三维（3D）化学分析来揭示固体电解质/电极界面上的中间相的动态形成。虽然中间相的形成拓宽了电化学窗口，但它们的电子和离子电导率决定了电化学性能，并对枝晶生长有很大影响。我们的结果表明，与普遍的理解相反，实际上具有金属阳极的高稳定固体电解质会促进快速的枝晶形成，这是由于锂消耗较少和枝晶尖端曲率较大，导致增强的电动驱动力。详细的热力学分析表明，具有低电子电导率、高离子电导率和化学稳定性的中间相，然而需要具有动态厚度和均匀覆盖的中间相来防止枝晶生长。这项工作为解决枝晶问题的中间相设计提供了范例，为开发坚固、全功能的固态电池铺平了道路。
