Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries
Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries
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DOI：
10.1016/j.electacta.2014.05.018
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发表时间：
2014-09-10
影响因子：
6.6
通讯作者：
Balbuena, P. B.
中科院分区：
文献类型：
--
作者：
Benitez, L.;Cristancho, D.;Balbuena, P. B.
由于电解液的还原或氧化产物的聚集，在电极表面形成了固体电解质界面(SEI)膜。这些薄膜可以生长到50-100纳米量级的厚度，并包含各种有机和无机产品，但它们的结构没有很好的定义。虽然在某些情况下，薄膜起到钝化作用，但情况并不总是如此，这些现象在硅阳极上尤其复杂，因为在锂化和脱氢过程中电极会膨胀和破裂。由于SEI生长的驱动力是电子转移，因此重要的是要了解一旦裸露的电子表面被覆盖，电子如何通过异质膜继续发生转移。本文介绍了一种研究模型膜中电子转移的新方法，并给出了由电极/SEI层/电解液集成的模型复合界面体系中电子转移的初步分析结果。用从头算分子动力学方法模拟了SEI组分的沉积，并用密度泛函理论/格林函数方法对电子转移进行了表征。模拟了电极的三个锂化度，SEI膜由LiF或Li2O组成，并研究了碳酸乙烯的还原。使用外加电势作为漏电流的驱动力，作为外加电势的函数来评估漏电流。对LiF和Li2O模型SEI层进行了对比分析。(C)2014爱思唯尔有限公司。保留所有权利。
Solid-electrolyte interphase (SEI) films are formed on the electrode surfaces due to aggregation of products of reduction or oxidation of the electrolyte. These films may grow to thicknesses in the order of 50-100 nm and contain a variety of organic and inorganic products but their structure is not well defined. Although in some cases the films exert a passivating role, this is not always the case, and these phenomena are particularly more complex on Silicon anodes due to swelling and cracking of the electrode during lithiation and delithiation. Since the driving force for SEI growth is electron transfer, it is important to understand how electron transfer may keep occurring through the heterogeneous film once the bare electron surface is covered. Here we introduce a novel approach for studying electron transfer through model films and show preliminary results for the analysis of electron transfer through model composite interfacial systems integrated by electrode/SEI layer/electrolyte. Ab initio molecular dynamics simulations are used to identify deposition of SEI components, and a density functional theory/Green's function approach is utilized for characterizing electron transfer. Three degrees of lithiation are modeled for the electrodes, the SEI film is composed by LiF or Li2O, and the ethylene carbonate reduction is studied. An applied potential is used as driving force for the leakage current, which is evaluated as a function of the applied potential. Comparative analyses are done for LiF and Li2O model SEI layers. (C) 2014 Elsevier Ltd. All rights reserved.