Insight into the Solid Electrolyte Interphase Formation in Bis(fluorosulfonyl)Imide Based Ionic Liquid Electrolytes

Jafta, Charl; Sun, Xiao-Guang; Lyu, Hailong; Chen, Hao; Thapaliya, Bishnu; Heller, William T.; Cuneo, Matthew; Mayes, Richard; Paranthaman, Parans; Dai, Sheng; Bridges, Craig A.

doi:10.1002/adfm.202008708

Insight into the Solid Electrolyte Interphase Formation in Bis(fluorosulfonyl)Imide Based Ionic Liquid Electrolytes

Journal Article · Wed Feb 17 00:00:00 EST 2021 · Advanced Functional Materials

DOI:https://doi.org/10.1002/adfm.202008708· OSTI ID:1822082

^[1]; ^[1]; Lyu, Hailong ^[1]; Chen, Hao ^[2]; Thapaliya, Bishnu ^[2]; ^[3]; Cuneo, Matthew ^[3]; ^[3]; ^[1]; ^[4]; ^[1]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of Tennessee, Knoxville, TN (United States)
ORNLOak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
ORNLOak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)

The formation of the solid electrolyte interphase (SEI) in an ionic liquid electrolyte of 0.5 m lithium bis(fluorosulfonyl)imide (LiFSI) in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide at high cell voltages (1.7–1.9 V) is investigated in ordered mesoporous carbon (OMC) based Li metal cells using an operando small-angle neutron scattering (SANS) technique coupled with electrochemical impedance spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS). It is demonstrated that discharging the OMC Li metal cells to ≈2 V and holding the cell voltage constant induces a rapid current increase with time, confirming extensive reduction and SEI formation. XPS analysis reveals that LiF is formed at open cell voltage (OCV), which is attributed to the carbenes generated at the lithium negative electrode because of its reaction with EMIm cation diffusing to and initiating the reaction with FSI^-anions at the carbon positive electrode. It is confirmed that the chemical reaction at OCV and electrochemical reduction at high cell voltage of the FSI^- anion plays a protective role against EMIm cation co-intercalation into the carbon positive electrode during the initial discharge. Operando SANS studies also suggest that slight differences occur in the surface composition and reaction mechanism as a function of cell voltage.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1822082

Alternate ID(s):: OSTI ID: 1785742

Journal Information:: Advanced Functional Materials, Journal Name: Advanced Functional Materials Journal Issue: 23 Vol. 31; ISSN 1616-301X

Publisher:: WileyCopyright Statement

Country of Publication:: United States

Language:: English

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