Direct Observation of the Interfacial Instability of the Fast Ionic Conductor Li10GeP2S12 at the Lithium Metal Anode

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• 作者：Sebastian Wenzel ; Simon Randau ; Thomas Leichtweiß ; Dominik A. Weber ; Joachim Sann ; Wolfgang G. Zeier ; Jürgen Janek
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 12, 2016
• 年：2016
• 卷：28
• 期：7
• 页码：2400-2407
• 全文大小：518K
• 年卷期：0
• ISSN：1520-5002

文摘

The very high ionic conductivity of Li₁₀GeP₂S₁₂ (LGPS) makes it a potential solid electrolyte for lithium all-solid-state batteries. Besides the high ionic conductivity, another key requirement is the stability of the solid electrolyte against degradation reactions with the electrodes; here, we analyze the reaction of LGPS with lithium metal. In situ X-ray photoelectron spectroscopy (XPS), in combination with time-resolved electrochemical measurements offers detailed information on the chemical reactions at the Li/LGPS interface. The decomposition of Li₁₀GeP₂S₁₂ leads to the formation of an interphase composed of Li₃P, Li₂S, and Li–Ge alloy, which is in perfect agreement with theoretical predictions, and an increase of the interfacial resistance. These results highlight the necessity to perform long-term, time-resolved electrochemical measurements when evaluating potential new solid electrolytes for solid-state batteries. The kinetics of this interphase growth—comparable to SEI formation on lithium anodes in liquid electrolytes—seems to be governed by diffusion across the interphase, as a square root time dependence is observed.