Modeling Electrochemical Decomposition of Fluoroethylene Carbonate on Silicon Anode Surfaces in Lithium Ion Batteries

Abstract

Fluoroethylene carbonate (FEC) shows promise as an electrolyte additive for improving passivating solid-electrolyte interphase (SEI) films on silicon anodes used in lithium ion batteries (LIB). We apply density functional theory (DFT), ab initio molecular dynamics (AIMD), and quantum chemistry techniques to examine excess-electron-induced FEC molecular decomposition mechanisms that lead to FEC-modified SEI. We consider one- and two-electron reactions using cluster models and explicit interfaces between liquid electrolyte and model Li(x)Si(y) surfaces, respectively. FEC is found to exhibit more varied reaction pathways than unsubstituted ethylene carbonate. The initial bond-breaking events and products of one- and two-electron reactions are qualitatively similar, with a fluoride ion detached in both cases. However, most one-electron products are charge-neutral, not anionic, and may not coalesce to form effective Li+-conducting SEI unless they are further reduced or take part in other reactions. The implications of these reactions to silicon-anode based LIB are discussed.

31 pages, 10 figures. We apologize for the poor quality of the composite figures, the result of being forced to use pdf formats for figures

References in corpus (5)

• Using atomic layer deposition to hinder solvent decomposition in lithium ion batteries: first principles modeling and experimental studies
• Quantifying Capacity Loss due to Solid-Electrolyte-Interphase Layer Formation on Silicon Negative Electrodes in Lithium-ion Batteries
• Electronic Structure Modeling of Electrochemical Reactions at Electrode/Electrolyte Interfaces in Lithium Ion Batteries
• Two-electron reduction of ethylene carbonate: a quantum chemistry re-examination of mechanisms
• Towards First Principles prediction of Voltage Dependences of Electrolyte/Electrolyte Interfacial Processes in Lithium Ion Batteries

Cited by in corpus (4)

• Stability of Solid Electrolyte Interphase Components on Lithium Metal and Reactive Anode Material Surfaces
• Predicting the Voltage Dependence of Interfacial Electrochemical Processes at Lithium-Intercalated Graphite Edge Planes
• Spatial Heterogeneities and Onset of Passivation Breakdown at Lithium Anode Interfaces
• Kinetics-Controlled Degradation Reactions at Crystalline LiPON/Li(x)CoO(2) and Crystalline LiPON/Li-metal Interfaces