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

Abstract

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.

Authors:

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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+ Show Author Affiliations

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

Publication Date:

Tue Aug 30 00:00:00 EDT 2016

Sponsoring Org.:

USDOE

OSTI Identifier:

1401010

Grant/Contract Number:  

DE‐AC02‐05CH11231; 7073923

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Advanced Materials Interfaces

Additional Journal Information:

Journal Name: Advanced Materials Interfaces Journal Volume: 3 Journal Issue: 20; Journal ID: ISSN 2196-7350

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English