Determination of the Solid Electrolyte Interphase Structure Grown on a Silicon Electrode Using a Fluoroethylene Carbonate Additive

作者：Veith Gabriel M; Doucet Mathieu; Sacci Robert L; Vacaliuc Bogdan; Baldwin J Kevin; Browning James F

来源：Scientific Reports, 2017, 7(1): 6326.

DOI：10.1038/s41598-017-06555-8

<jats:title>Abstract</jats:title><jats:p>In this work we explore how an electrolyte additive (fluorinated ethylene carbonate – FEC) mediates the thickness and composition of the solid electrolyte interphase formed over a silicon anode <jats:italic>in situ</jats:italic> as a function of state-of-charge and cycle. We show the FEC condenses on the surface at open circuit voltage then is reduced to C-O containing polymeric species around 0.9 V (vs. Li/Li<jats:sup>+</jats:sup>). The resulting film is about 50 Å thick. Upon lithiation the SEI thickens to 70 Å and becomes more organic-like. With delithiation the SEI thins by 13 Å and becomes more inorganic in nature, consistent with the formation of LiF. This thickening/thinning is reversible with cycling and shows the SEI is a dynamic structure. We compare the SEI chemistry and thickness to 280 Å thick SEI layers produced without FEC and provide a mechanism for SEI formation using FEC additives.</jats:p>

• 出版日期2017-7-24