Experimental determination of Li diffusivity in LLZO using isotopic exchange and FIB-SIMS
Experimental determination of Li diffusivity in LLZO using isotopic exchange and FIB-SIMS
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DOI：
10.1088/2515-7655/abe2f7
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发表时间：
2021-07-01
影响因子：
6.9
通讯作者：
Aguadero, Ainara
中科院分区：
文献类型：
--
作者：
Brugge, Rowena H.;Chater, Richard J.;Aguadero, Ainara
目前的锂离子电池技术使用易燃的液体电解质，因此为下一代全固态电池开发固体陶瓷电解质可以提供更安全的替代品。然而，这些固体电解质中的锂扩散行为尚未得到很好的表征，尽管该信息对于优化电池性能很重要。类似地，金属阳极界面处的输运性质是至关重要的，但还没有很好地理解。我们提出了一种方法来获得锂扩散系数的散装固体陶瓷石榴石型Li 7 La 3 Zr 2 O 12（LLZO）电解质通过耦合致密颗粒与同位素标记的锂金属，然后用聚焦离子束二次离子质谱分析。我们报告了掺杂LLZO的室温锂扩散系数为2-8 × 10（-13）m（2）s（-1），使用与电化学阻抗谱良好一致的锂扩散长度估计。通过西姆斯同时检测正和负二次离子物种，使得在深度剖析期间由金属锂、腐蚀/表面降解产物和本体LLZO组成的分层界面的相关性成为可能。在离子溅射过程中的陶瓷充电进行了研究，并示出在当前设置中获得的锂同位素分数具有最小的影响。此外，腐蚀产物的存在下，在石榴石的表面作为一个结果的空气暴露的影响进行了研究。该方法可以扩展到任何Li金属稳定的固体电解质，或者具有与稳定夹层耦合的反应性固体电解质。因此，这项工作为进一步定量扩散分析锂导电固体陶瓷电解质及其与电极的界面的方法奠定了基础，如在固态锂电池和耦合固体和液体电解质的混合系统中所使用的。
Current lithium ion battery technology makes use of flammable liquid electrolytes and so the development of solid ceramic electrolytes for the next generation of all-solid-state batteries can offer a safer alternative. However, the lithium diffusion behaviour in these solid electrolytes is not yet well characterised, despite the importance of this information for optimising cell performance. Similarly, the transport properties at the metal anode interface are critically important, but not well understood. We propose a methodology for obtaining lithium diffusion coefficients of bulk solid ceramic garnet-type Li7La3Zr2O12 (LLZO) electrolytes by coupling dense pellets with isotopically labelled lithium metal, followed by analysis with focused-ion-beam secondary ion mass spectrometry. We report room temperature lithium diffusivities of 2-8 x 10(-13) m(2) s(-1) for doped LLZO using an estimate of the lithium diffusion length in good agreement with electrochemical impedance spectroscopy. Simultaneous detection of positive and negative secondary ion species by SIMS enables correlation of layered interfaces consisting of metallic lithium, corrosion/surface degradation products and bulk LLZO during depth profiling. Charging of the ceramic during ion sputtering is investigated and shown to have a minimal effect on the obtained lithium isotopic fractions in the current setup. Additionally, the effect of the presence of corrosion products at the surface of garnets as a result of air-exposure is investigated. This method could be extended to any Li-metal stable solid electrolyte, or with a reactive solid electrolyte coupled with a stable interlayer. As such, this work sets the basis of a methodology for further quantitative diffusion analyses for Li-conducting solid ceramic electrolytes and their interfaces with electrodes, as used in both solid-state lithium batteries and hybrid systems coupling solid and liquid electrolytes.