Lithium-ion batteries are the most popular rechargeable batteries and are now been widely used in portable electronic devices and electric vehicles due to their relative high energy density, good cycle life and good power performance.  However, research to find better anode materials with higher energy density has shown that silicon is a promising solution.       Just as in graphite anodes, a solid electrolyte interphase (SEI) has been reported to be formed on the surface of silicon electrodes during the first charging cycles.  Since battery performance, cycle life and safety are highly dependent on the quality of the SEI in graphite anodes, understanding the nature, the structure and the surface chemistry of the SEI formed on silicon is of high importance.      In this work, we used ab initio computational methods to study the electron transport characteristics of selected finite models of SEI layers formed on silicon surface, and to examine the electron density of the frontier molecular orbitals participating in the electron transfer process.  We use the generalized electron-nanointerface program (GENIP) which uses a combined ab initio density functional theory (DFT) and Green's function approach to calculate the current-voltage characteristics of the selected configurations of SEI.  We also consider various lithiated silicon-cluster instances for the anode as well as the presence of surface oxide films.

Electron transport study through SEI layer formed on Si anodes

247th National Meeting (2014)

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