Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO2 Layer
Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO2 Layer
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DOI：
10.1149/2.0731603jes
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发表时间：
2016-01-01
影响因子：
3.9
通讯作者：
Wittstock, Gunther
中科院分区：
文献类型：
--
作者：
Buelter, Heinz;Sternad, Michael;Wittstock, Gunther
硅被认为是石墨作为锂离子电池负极材料的有前途的替代品之一。以2，5-二叔丁基-1，4-二甲氧基苯为氧化还原介体，采用扫描电化学显微镜（SECM）的反馈模式，研究了不带电微结构和平面硅上的电子转移.接近曲线和图像表明，在原始Si的电子转移速率常数是相对较小的，由于原生SiO2表面层。此外，电子转移速率常数显示局部变化，因为SiO2的异质覆盖。SiO2层通过与微电极探针的机械接触和磨损而至少部分地被去除。通过微电极或氢氟酸浸渍去除SiO2后，电子转移速率常数强烈增加，并保持异质性。此外，Si电极的表面在去除SiO2之后至少在数小时内是稳定的。研究硅上固体电解质界面（SEI）的形成的后果进行了讨论。(C)作者（s）2015由ECS发布。All rights reserved.
Silicon is considered as one of the promising alternatives to graphite as negative electrode material in lithium-ion batteries. The electron transfer at uncharged microstructured and planar Si was characterized using the feedback mode of scanning electrochemical microscopy (SECM) and 2,5-di-tert-butyl-1,4-dimethoxybenzene as redox mediator. Approach curves and images demonstrate that the electron transfer rate constants at pristine Si are relatively small due to the native SiO2 surface layer. In addition, the electron transfer rate constants show local variations because of the heterogeneous coverage of SiO2. The SiO2 layer is at least partially removed by mechanical contact and abrasion with the microelectrode probe. After SiO2 removal by the microelectrode or by a hydrofluoric acid dip, the electron transfer rate constants increase strongly and remain heterogeneous. Moreover, the surface of the Si electrodes is at least stable over hours after SiO2 removal. The consequences for investigating the formation of the solid electrolyte interphase (SEI) on Si are discussed. (C) The Author(s) 2015 Published by ECS. All rights reserved.