Structure sensitivity in the decomposition of ethylene carbonate on Si anodes
Jochen Rohrer1, Payam Kaghazchi
1Institut für Materialwissenschaft, Fachgebiet Materialmodellierung, Technische Universität Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt (Germany).
Abstract:
The interaction of ethylene carbonate (EC) with Si surfaces is studied by density functional theory. The results show a strong structure sensitivity in the adsorption of EC on Si surfaces. While the adsorbed EC molecule readily decomposes on the Li/Si(111) surface, it does not dissociate on the Li/Si(100) and Li/Si(110) surfaces. On Si(111), the O atom at the top of EC is detached from the EC molecule and binds to the Li adatom, forming Li-O molecules. The mechanism of EC decomposition is the transfer of 2.4 electrons from the surface to the EC molecule, as well as the formation of a covalent bond between the Li adatom and the EC molecule. This result shows that in lithium-ion batteries with Si anodes, dissociation of the solvent and formation of a solid electrolyte interphase layer start as soon as the Li atoms cover the anode surface.
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