Structure and Reactivity of Alucone-Coated Films on Si and LixSiy Surfaces
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- 作者：Yuguang Ma ; Julibeth M. Martinez de la Hoz ; Ivette Angarita ; Jose M. Berrio-Sanchez ; Laura Benitez ; Jorge M. Seminario ; Seoung-Bum Son ; Se-Hee Lee ; Steven M. George ; Chunmei Ban ; Perla B. Balbuena
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2015
- 出版时间：June 10, 2015
- 年：2015
- 卷：7
- 期：22
- 页码：11948-11955
- 全文大小：466K
- ISSN：1944-8252
文摘
Coating silicon particles with a suitable thin film has appeared as a possible solution to accommodate the swelling of silicon upon lithiation and its posterior cracking and pulverization during cycling of Li-ion batteries. In particular, aluminum alkoxide (alucone) films have been recently deposited over Si anodes, and the lithiation and electrochemical behavior of the system have been characterized. However, some questions remain regarding the lithium molecular migration mechanisms through the film and the electronic properties of the alucone film. Here we use density functional theory, ab initio molecular dynamics simulations, and Green鈥檚 function theory to examine the film formation, lithiation, and reactivity in contact with an electrolyte solution. It is found that the film is composed of Al鈥揙 complexes with 3-O or 4-O coordination. During lithiation, Li atoms bind very strongly to the O atoms in the most energetically favorable sites. After the film is irreversibly saturated with Li atoms, it becomes electronically conductive. The ethylene carbonate molecules in liquid phase are found to be reduced at the surface of the Li-saturated alucone film following similar electron transfer mechanisms as found previously for lithiated silicon anodes. The theoretical results are in agreement with those from morphology and electrochemical analyses.