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

Leung, Kevin; Rempe, Susan; Foster, Michael E.; Ma, Yan; Hoz, Julibeth M. Martinez del la; Sai, Na; Balbuena, Perla B.

doi:10.1149/2.092401jes

Cited by 141 publications

(233 citation statements)

References 68 publications

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“…We speculate that the fast release of F À and SO 2 may be correlated to the high cycling performance exhibited by the Si-PYR 13 FSI system. This argument dovetails with earlier modelling studies of FEC decomposition, which show that FEC also rapidly releases F À to form LiF, as well as empirical data, showing favourable Si half-cell cycling behaviour when using FEC as an electrolyte additive in organic carbonate-based electrolyte 45 .…”

Section: Articlesupporting

confidence: 83%

“…2e,g, respectively). The same model surface was previously studied in the context of fluoroethylene carbonate (FEC) decomposition 45 and represents a low-potential anode surface with Si directly exposed to the liquid electrolyte, serving as an electron source that can readily reduce electrolyte molecules in its vicinity.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that FEC decomposition also releases large organic fragments 45 not found in the RTIL reduction pathway. Therefore, FEC and FSI À are not expected to yield identical SEI chemical compositions.…”

Section: Articlementioning

confidence: 99%

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Stable silicon-ionic liquid interface for next-generation lithium-ion batteries

et al. 2015

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We are currently in the midst of a race to discover and develop new battery materials capable of providing high energy-density at low cost. By combining a high-performance Si electrode architecture with a room temperature ionic liquid electrolyte, here we demonstrate a highly energy-dense lithium-ion cell with an impressively long cycling life, maintaining over 75% capacity after 500 cycles. Such high performance is enabled by a stable half-cell coulombic efficiency of 99.97%, averaged over the first 200 cycles. Equally as significant, our detailed characterization elucidates the previously convoluted mechanisms of the solid-electrolyte interphase on Si electrodes. We provide a theoretical simulation to model the interface and microstructural-compositional analyses that confirm our theoretical predictions and allow us to visualize the precise location and constitution of various interfacial components. This work provides new science related to the interfacial stability of Si-based materials while granting positive exposure to ionic liquid electrochemistry.

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Section: Articlesupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

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Stable silicon-ionic liquid interface for next-generation lithium-ion batteries

et al. 2015

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“…The presence of higher concentrations of F for cells cycled with electrolytes containing FEC is likely due to the reduction of FEC generating additional LiF in the SEI on the surface of the Sn electrode. [22][23][24][25][26] The SEI for cells cycled with electrolyte containing FEC has a similar evolution to the SEI for the cells cycled with the standard electrolyte, although the evolution results in significantly less capacity fade and related electrolyte decomposition (Table I). 27 Hard XPS (HAXPES).-The C 1s core level HAXPES spectra of the cycled tin anode taken with photon energies of 1487 eV (lab XPS), 2200 eV, and 5000 eV are provided in Figure 5.…”

Section: 19-23mentioning

confidence: 78%

Characterizing Solid Electrolyte Interphase on Sn Anode in Lithium Ion Battery

Seo

Nguyen

Young

et al. 2015

J. Electrochem. Soc.

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Tin (Sn) nanoparticle electrodes have been prepared and battery cycling performance has been investigated with 1.2 M LiPF 6 in ethylene carbonate (EC) / diethyl carbonate (DEC) electrolyte (1:1, w/w) with and without added vinylene carbonate (VC) or fluoroethylene carbonate (FEC). Incorporation of either VC or FEC improves the capacity retention of Sn nanoparticle electrodes although incorporation of VC also results in a significant increase in cell impedance. The best electrochemical performance was observed with electrolyte containing 10% of added FEC. In order to develop a better understanding of the role of the electrolyte in capacity retention and solid electrolyte interface (SEI) structure, ex-situ surface analysis has been performed on cycled electrodes with infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Hard XPS (HAXPES). The ex-situ analysis reveals a correlation between electrochemical performance, electrolyte composition, and SEI structure. Graphite has been widely used as an anode material in lithium ion batteries. However, there is significant interest in increasing the energy density of lithium ion batteries for electric vehicle applications.1 One method of current interest for increasing the energy density of lithium ion batteries includes the use of high capacity metal alloy anode materials, such as silicon (Si) and tin (Sn).2-6 Sn has almost three times more capacity (944 mAh/g) than graphite (372 mAh/g). However, a major challenge for the use Sn as an anode material is the large volume expansion/contraction during lithium insertion and extraction. The large surface area changes result in damage to the anode solid electrolyte interface (SEI) and continuous decomposition of the electrolyte. There have been many investigations of novel fabrication methods for Sn-based anodes to mitigate the problems with the SEI due to the volume changes.2,7-9 However, few investigations have focused on developing a better understanding of SEI formation on Sn anodes. [10][11][12] In order to develop Sn anodes for lithium ion batteries, a better understanding of the structure and function of the SEI on Sn is required.In this investigation, Sn nanoparticle electrodes were prepared and tested with different electrolytes. A standard electrolyte composed of 1.2 M LiPF 6 in EC/DEC with and without 5 or 10% of the SEI film forming additives FEC or VC has been investigated for optimization of an electrolyte formulation for Sn electrodes. 13 The cells have been analyzed via electrochemical cycling and electrochemical impedance spectroscopy. In order to develop a better understanding of the role of the electrolyte in SEI formation and stability, the Sn nanoparticle electrodes were extracted from cells and ex-situ surface analysis with infrared with attenuated total reflectance (IR-ATR), X-ray photoelectron spectroscopy (XPS) and Hard XPS (HAXPES) was conducted. While IR-ATR and XPS are frequently utilized analytical techniques for the investigation of the SEI, 14 HAXPES has been less utilized due to...

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“…It will be shown that FEC nearly suppresses the reduction of any other electrolyte component, which is consistent with the previous literature and suggests that the rate of FEC reduction is greater than the reduction of EC and linear carbonates. [26][27][28][29][30][31] Furthermore, due to the continuous consumption of FEC quantified by 19 F-NMR, the number of charge/discharge cycles over which silicon anodes can by stabilized by FEC is directly proportional to the total moles of FEC per …”

mentioning

confidence: 99%

Consumption of Fluoroethylene Carbonate (FEC) on Si-C Composite Electrodes for Li-Ion Batteries

Jung

Metzger

Haering

et al. 2016

J. Electrochem. Soc.

243

311

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The electrolyte additive fluoroethylene carbonate (FEC) is known to significantly improve the lifetime of Li-ion batteries with silicon anodes. In this work, we show that FEC can indeed improve the lifetime of silicon-carbon composite anodes but is continuously consumed during electrochemical cycling. By the use of 19 F-NMR spectroscopy and charge/discharge cycling we demonstrate that FEC is only capable to stabilize the cell performance as long as FEC is still remaining in the cell. Its total consumption causes a significant increase of the cell polarization leading to a rapid capacity drop. We show with On-line Electrochemical Mass Spectrometry (OEMS) that the presence of FEC in the electrolyte prohibits the reduction of other electrolyte components almost entirely. Consequently, the cumulative irreversible capacity until the rapid capacity drop correlates linearly with the specific amount of FEC (in units of μmol FEC /mg electrode ) in the cell. The latter quantity therefore determines the lifetime of silicon anodes rather than the concentration of FEC in the electrolyte. By correlating the cumulative irreversible capacity and the specific amount of FEC in the cell, we present an easy tool to predict how much cumulative irreversible capacity can be tolerated until all FEC will be consumed in either half-cells or full-cells. We further demonstrate that four electrons are consumed for the reduction of one FEC molecule and that one carbon dioxide molecule is released for every FEC molecule that is reduced. Using all information from this study and combining it with previous reports in literature, a new reductive decomposition mechanism for FEC is proposed yielding CO 2 , LiF, In the emerging market of electric vehicles (EVs), the development of batteries with higher energy density and improved cycle-life is essential.1 However, their penetration of the mass market significantly depends on cost and the available driving range.2 The US Advanced Battery Consortium (USABC) defined the target value of 235 Wh/kg (at a C/3 rate) on a battery level until 2020.3 As outlined in the recent review by Andre et al., 4 reaching this goal requires an increase of the energy density of today's batteries by a factor of roughly 2 to 2.5 and can only be achieved by the development and integration of novel anode and cathode active materials. A critical element to reach this goal is the implementation of anode active materials with much higher specific capacity than currently used graphite anodes (372 mAh/g 1,5,6 ), with silicon being considered as the most likely next generation anode material due to its high natural abundance and very high theoretical specific capacity of roughly 3600 mAh/g (corresponding to the Li 15 Si 4 phase 7 ). The alloying of silicon with lithium is accompanied by large structural changes, resulting in a volume increase by 310% upon full lithiation.5,7-11 These huge volumetric changes upon lithium insertion and extraction are responsible for the generally shorter cycle-life of silicon electrode materials comp...

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

Cited by 141 publications

References 68 publications

Stable silicon-ionic liquid interface for next-generation lithium-ion batteries

Stable silicon-ionic liquid interface for next-generation lithium-ion batteries

Characterizing Solid Electrolyte Interphase on Sn Anode in Lithium Ion Battery

Consumption of Fluoroethylene Carbonate (FEC) on Si-C Composite Electrodes for Li-Ion Batteries

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