Properties of the Interphase Formed between Argyrodite-Type Li6PS5Cl and Polymer-Based PEO10:LiTFSI,ACS Applied Materials & Interfaces

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Properties of the Interphase Formed between Argyrodite-Type Li6PS5Cl and Polymer-Based PEO10:LiTFSI
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2019-10-31 , DOI: 10.1021/acsami.9b14506
Fabian J. Simon _{1,

2} , Matthias Hanauer ₁ , Anja Henss _{2,

3} , Felix H. Richter _{2,

3} , Jürgen Janek _{2,

3}

Affiliation

All-solid-state lithium metal batteries using thiophosphate solid electrolytes (SE) present a promising alternative to state-of-the-art lithium-ion batteries due to their potentially superior energy and power. However, reactions occurring at the lithium metal | SE interface result in an increasing internal resistance and limited cycle life. A stable solid polymer electrolyte (SPE) may be used as protective interlayer to prevent the SE from direct contact and reaction with lithium metal. This creates a new and rarely studied heteroionic interface between the inorganic SE and the SPE, which we investigate here. The interface resistance between argyrodite-type Li₆PS₅Cl and a poly(ethylene oxide)/LiTFSI-based SPE is quantified by four-point electrochemical impedance measurements using two wire-shaped reference electrodes (2.4 Ω cm² at 80 °C). Two distinct processes are observed and attributed to lithium-ion conduction through a formed solid-polymer electrolyte interphase (SPEI) and an ionic charge-transfer (CT) process. The SPEI predominantly consists of polysulfides and lithium fluoride (LiF), as identified by X-ray photoelectron spectroscopy (XPS) analysis. A temperature-enhanced SPEI growth is observed using electrochemical impedance spectroscopy (EIS) and depth profiling combined with time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results highlight the importance of four-point measurements to determine electrolyte-electrolyte interface properties. Overall, the low resistance and low activation energy of the SPEI makes the SPE interlayer an attractive candidate to protect Li₆PS₅Cl from decomposition at the lithium metal anode.

中文翻译：

菱铁矿型Li ₆ PS ₅ Cl与聚合物基PEO ₁₀：LiTFSI之间形成的相变性质

由于使用了硫代磷酸盐固体电解质（SE）的全固态锂金属电池具有潜在的优越能量和功率，因此可以替代最先进的锂离子电池。然而，在锂金属上发生的反应 SE接口导致内部电阻增加，循环寿命有限。稳定的固态聚合物电解质（SPE）可用作保护性中间层，以防止SE与锂金属直接接触并发生反应。这在无机SE和SPE之间创建了一个新的且很少研究的杂离子界面，我们将在此进行研究。菱锰矿型Li ₆ PS ₅之间的界面电阻Cl和基于聚环氧乙烷/ LiTFSI的SPE通过使用两个线形参比电极（2.4Ωcm ²在80°C时）。观察到两个不同的过程，这归因于通过形成的固体-聚合物电解质中间相（SPEI）和离子电荷转移（CT）过程进行的锂离子传导。通过X射线光电子能谱（XPS）分析确定，SPEI主要由多硫化物和氟化锂（LiF）组成。使用电化学阻抗谱（EIS）和深度分析结合飞行时间二次离子质谱（ToF-SIMS），观察到温度增强的SPEI的生长。结果强调了四点测量对确定电解质-电解质界面特性的重要性。总体而言，SPEI的低电阻和低活化能使SPE中间层成为保护Li ₆ PS ₅的有吸引力的候选材料Cl从锂金属阳极分解而来。

更新日期：2019-11-01

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