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Understanding Fluoroethylene Carbonate and Vinylene Carbonate Based Electrolytes for Si Anodes in Lithium Ion Batteries with NMR Spectroscopy

Jin, Yanting; Kneusels, Nis Julian H.; Marbella, Lauren E.; Castillo-Mart�nez, Elizabeth; Magusin, Pieter C.M.M.; Weatherup, Robert S.; J�nsson, Erlendur; Liu, Tao; Paul, Subhradip; Grey, Clare P.


Yanting Jin

Nis Julian H. Kneusels

Lauren E. Marbella

Elizabeth Castillo-Mart�nez

Pieter C.M.M. Magusin

Robert S. Weatherup

Erlendur J�nsson

Tao Liu

Subhradip Paul

Clare P. Grey


© 2018 American Chemical Society. Fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are widely used as electrolyte additives in lithium ion batteries. Here we analyze the solid electrolyte interphase (SEI) formed on binder-free silicon nanowire (SiNW) electrodes in pure FEC or VC electrolytes containing 1 M LiPF6 by solid-state NMR with and without dynamic nuclear polarization (DNP) enhancement. We find that the polymeric SEIs formed in pure FEC or VC electrolytes consist mainly of cross-linked poly(ethylene oxide) (PEO) and aliphatic chain functionalities along with additional carbonate and carboxylate species. The formation of branched fragments is further confirmed by 13C-13C correlation NMR experiments. The presence of cross-linked PEO-type polymers in FEC and VC correlates with good capacity retention and high Coulombic efficiencies of the SiNWs. Using 29Si DNP NMR, we are able to probe the interfacial region between SEI and the Si surface for the first time with NMR spectroscopy. Organosiloxanes form upon cycling, confirming that some of the organic SEI is covalently bonded to the Si surface. We suggest that both the polymeric structure of the SEI and the nature of its adhesion to the redox-active materials are important for electrochemical performance.

Journal Article Type Article
Acceptance Date Jul 6, 2018
Online Publication Date Jul 6, 2018
Publication Date Aug 8, 2018
Deposit Date May 12, 2020
Journal Journal of the American Chemical Society
Print ISSN 0002-7863
Electronic ISSN 1520-5126
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 140
Issue 31
Pages 9854-9867
Public URL
Publisher URL

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