Structure formation and surface chemistry of ionic liquids on model electrode surfaces-Model studies for the electrode | electrolyte interface in Li-ion batteries
Structure formation and surface chemistry of ionic liquids on model electrode surfaces-Model studies for the electrode | electrolyte interface in Li-ion batteries
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DOI：
10.1063/1.5012878
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发表时间：
2018-05-21
影响因子：
4.4
通讯作者：
Behm, R. Juergen
中科院分区：
文献类型：
--
作者：
Buchner, Florian;Uhl, Benedikt;Behm, R. Juergen
离子液体（IL）被认为是现代电池概念如Li离子电池中有吸引力的电解质溶剂。本文对电池相关的IL-1-丁基-1-甲基吡咯烷鎓双离子相互作用的先前模型研究结果进行了全面的综述。（三氟甲基磺酰基）酰亚胺（[BMP]（+）[TFSI]（-）），其具有一系列结构和化学上明确定义的模型电极表面，其越来越复杂并且与电池应用相关[Ag（111），Au（111），Cu（111），原始的和锂化的高取向热解石墨（HOPG）和金红石TiO 2（110）]。结合表面科学技术，如高分辨率扫描隧道显微镜和X射线光电子能谱表征表面结构和化学组成的沉积（亚）单层吸附层与分散校正密度泛函理论为基础的计算，这项工作的目的是在分子尺度上的基本过程的理解在电极垂直杆电解质界面，这对于电池中所谓的固体电解质中间相（SEI）层的发展是至关重要的。在理想化条件下，在一个高真空的环境中进行，这些模型研究提供了详细的见解在吸附层的结构形成，基质-吸附物和吸附物-吸附物的相互作用负责这一点，和化学诱导的IL分解的趋势。为了模拟电解质中的情况，我们还研究了吸附IL（子）单分子膜与共吸附锂的相互作用。即使在80 K下，发现后沉积的Li与IL反应，导致分解产物如LiF、Li 3 N、Li 2S、LixSOy和Li 2 O。在不存在[BMP]（+）[TFSI]（-）吸附层的情况下，其倾向于吸附、溶解或嵌入到基材（金属，HOPG）中，或者在高于临界温度时与基材（TiO 2）反应，在后一种情况下形成LiOx和Ti 3+物质。最后，发现稳定分解产物的形成敏感地改变了表面Li和本体嵌入的Li+之间的平衡，导致在>230 K下存在吸附的IL吸附层的情况下从锂化HOPG中脱嵌。总的来说，这些结果提供了对固体垂直棒电解质界面处的表面化学和在没有施加电势的情况下电极表面处的SEI形成的初始阶段的详细见解，这对于未来锂离子电池的进一步改进是必不可少的。出版社：AIP Publishing
Ionic liquids (ILs) are considered as attractive electrolyte solvents in modern battery concepts such as Li-ion batteries. Herewepresent a comprehensive reviewof the results of previous model studies on the interaction of the battery relevant IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide ([BMP](+)[TFSI](-)) with a series of structurally and chemically well-defined model electrode surfaces, which are increasingly complex and relevant for battery applications [Ag(111), Au(111), Cu(111), pristine and lithiated highly oriented pyrolytic graphite (HOPG), and rutile TiO2(110)]. Combining surface science techniques such as high resolution scanning tunneling microscopy and X-ray photoelectron spectroscopy for characterizing surface structure and chemical composition in deposited (sub-) monolayer adlayers with dispersion corrected density functional theory based calculations, this work aims at a molecular scale understanding of the fundamental processes at the electrode vertical bar electrolyte interface, which are crucial for the development of the so-called solid electrolyte interphase (SEI) layer in batteries. Performed under idealized conditions, in an ultrahigh vacuum environment, these model studies provide detailed insights on the structure formation in the adlayer, the substrate-adsorbate and adsorbate-adsorbate interactions responsible for this, and the tendency for chemically induced decomposition of the IL. To mimic the situation in an electrolyte, we also investigated the interaction of adsorbed IL (sub-) monolayers with coadsorbed lithium. Even at 80 K, postdeposited Li is found to react with the IL, leading to decomposition products such as LiF, Li3N, Li2S, LixSOy, and Li2O. In the absence of a [BMP](+)[TFSI](-) adlayer, it tends to adsorb, dissolve, or intercalate into the substrate (metals, HOPG) or to react with the substrate (TiO2) above a critical temperature, forming LiOx and Ti3+ species in the latter case. Finally, the formation of stable decomposition products was found to sensitively change the equilibrium between surface Li and Li+ intercalated in the bulk, leading to a deintercalation from lithiated HOPG in the presence of an adsorbed IL adlayer at >230 K. Overall, these results provide detailed insights into the surface chemistry at the solid vertical bar electrolyte interface and the initial stages of SEI formation at electrode surfaces in the absence of an applied potential, which is essential for the further improvement of future Li-ion batteries. Published by AIP Publishing.