Direct Visualization of the Solid Electrolyte Interphase and Its Effects on Silicon Electrochemical Performance

Journal Article · Tue Aug 30 00:00:00 EDT 2016 · Advanced Materials Interfaces

DOI:https://doi.org/10.1002/admi.201600438· OSTI ID:1401010

Sina, Mahsa ^[1]; Alvarado, Judith ^[1]; Shobukawa, Hitoshi ^[1]; Alexander, Caleb ^[2]; Manichev, Viacheslav ^[3]; Feldman, Leonard ^[3]; Gustafsson, Torgny ^[3]; Stevenson, Keith J. ^[4]; Meng, Ying Shirley ^[1]

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1. Department of NanoEngineering Materials Science and Engineering Program University of California San Diego La Jolla CA 92093 USA
2. Department of Chemistry University of Texas at Austin Austin TX 78712 USA
3. Department of Physics and Astronomy Rutgers University Piscataway NJ 08854 USA
4. Materials Science &, Engineering Program Texas Materials Institute Center for Nano‐ and Molecular Science and Technology Department of Chemistry University of Texas at Austin Austin TX 78712 USA, Skolkovo Institute of Science and Technology Center for Electrochemical Energy Storage 3 Nobel Street Moscow 143026 Russia

Fluoroethylene carbonate (FEC) as an electrolyte additive can considerably improve the cycling performance of silicon (Si) electrodes in Li‐ion batteries. However, the fundamental mechanism for how FEC contributes to solid electrolyte interphase (SEI) morphological changes and chemical composition is not well understood. Here, scanning transmission electron microscopy coupled with electron energy loss spectroscopy gives a comprehensive insight as to how FEC affects the SEI evolution in terms of composition and morphology throughout electrochemical cycling. In the first lithiation cycle, the electrode cycled in ethylene carbonate (EC): diethylene carbonate (DEC) forms a porous uneven SEI composed of mostly Li ₂ CO ₃ . However, the electrode cycled in EC/DEC/FEC is covered in a dense and uniform SEI containing mostly LiF. Interestingly, the intrinsic oxide layer (Li _x SiO _y ) is not observed at the interface of electrode cycled in EC/DEC/FEC after 1 cycle. This is consistent with fluoride anion formation from the reduction of FEC, which leads to the chemical attack of any silicon‐oxide surface passivation layer. Furthermore, surface sensitive helium ion microscopy and X‐ray photoelectron spectroscopy techniques give further insights to the SEI composition and morphology in both electrodes cycled with different electrolytes.

• Sponsoring Organization: USDOE
• Grant/Contract Number: DE‐AC02‐05CH11231; 7073923
• OSTI ID: 1401010
• Journal Information: Advanced Materials Interfaces, Journal Name: Advanced Materials Interfaces Vol. 3 Journal Issue: 20; ISSN 2196-7350
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English