DFT Study of Reduction Mechanisms of Ethylene Carbonate and Fluoroethylene Carbonate on Li<sup>+</sup>-Adsorbed Si Clusters

Ma, Yan; Balbuena, Perla B.

doi:10.1149/2.014408jes

Cited by 41 publications

(72 citation statements)

References 57 publications

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“…Leung and Budzien compared EC decomposition on the basal plane of lithiated graphite (LiC 6 ), terminated with =O, -OH and -H and found that C = O edges provide a larger driving force for EC reduction 62 The observation that EC is more inclined to decompose in the presence of oxygen/ hydroxyl termination is consistent with other simulation results. 96 Besides graphite, EC decomposition was simulated on Li, 57,60,97 Si, 45,64,98 and Sn 99 electrodes as well. Due to the lower potential of Li metal than graphite, the decomposition of EC on Li metal is spontaneous and much faster than that on LiC 6 surfaces.…”

Section: Ec Solvent Decomposition Mechanismmentioning

confidence: 99%

“…When Si becomes lithiated, its voltage drops, and therefore the lithium concentration in silicon greatly influences the electrolyte reduction reactions. 53,64,98,99 Martinez de la Hoz et al 64 found that EC can be reduced by two different twoelectron mechanisms (one simultaneous and one sequential) on intermediately lithiated silicon surfaces (LiSi). A later work done by Ma and Balbuena 98 provided a more detailed reduction mechanism of EC under the low lithiated state of silicon anode.…”

Section: Ec Solvent Decomposition Mechanismmentioning

confidence: 99%

“…Fluoroethylene carbonate (FEC) gained renewed interests, 56,64,98,120,121 as it shows promise as an electrolyte additive for improved SEI passivation on Si-and Sn-based anode. 122,123 It is insightful to compare how EC, VC, and FEC reduce differently on these electrode surfaces.…”

Section: In Vivo Modification and Design Of The Seimentioning

confidence: 99%

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Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

et al. 2018

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A passivation layer called the solid electrolyte interphase (SEI) is formed on electrode surfaces from decomposition products of electrolytes. The SEI allows Li + transport and blocks electrons in order to prevent further electrolyte decomposition and ensure continued electrochemical reactions. The formation and growth mechanism of the nanometer thick SEI films are yet to be completely understood owing to their complex structure and lack of reliable in situ experimental techniques. Significant advances in computational methods have made it possible to predictively model the fundamentals of SEI. This review aims to give an overview of state-of-the-art modeling progress in the investigation of SEI films on the anodes, ranging from electronic structure calculations to mesoscale modeling, covering the thermodynamics and kinetics of electrolyte reduction reactions, SEI formation, modification through electrolyte design, correlation of SEI properties with battery performance, and the artificial SEI design. Multiscale simulations have been summarized and compared with each other as well as with experiments. Computational details of the fundamental properties of SEI, such as electron tunneling, Li-ion transport, chemical/mechanical stability of the bulk SEI and electrode/(SEI/) electrolyte interfaces have been discussed. This review shows the potential of computational approaches in the deconvolution of SEI properties and design of artificial SEI. We believe that computational modeling can be integrated with experiments to complement each other and lead to a better understanding of the complex SEI for the development of a highly efficient battery in the future.

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Section: Ec Solvent Decomposition Mechanismmentioning

confidence: 99%

Section: Ec Solvent Decomposition Mechanismmentioning

confidence: 99%

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Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

et al. 2018

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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 …”

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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.

253

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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“…For instance, the results presented in Figure 2 and Table III indicate that FEC may be consumed through reactions with generated lithium alkoxides. In a recent publication, Ma et al 80 also showed using DFT calculations that FEC may be reduced following 2-electron reduction pathways that do not generate gaseous products. In their calculations, they showed that FEC may readily be reduced at the surface of Si clusters with a low lithiation state following pathways with very low energy barriers.…”

mentioning

confidence: 99%

Studies of the Capacity Fade Mechanisms of LiCoO₂/Si-Alloy: Graphite Cells

Petibon

Chevrier

Aiken

et al. 2016

J. Electrochem. Soc.

126

137

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The capacity fade mechanisms of LiCoO 2 /Si-alloy:graphite pouch cells filled with a 1M LiPF 6 EC:EMC:FEC (27:63:10) electrolyte were studied using galvanostatic cycling, electrochemical impedance spectroscopy on symmetric cells, gas-chromatography and differential voltage analysis. Analysis of the gas generated during the first cycle indicated that FEC reacts at the negative electrode following a 1-electron reduction pathway and other pathways that do not lead to the formation of gaseous products. An analysis of the electrolyte showed that FEC is continuously consumed during the first 80% of the first charge (formation cycle). Typical cells charged and discharged at 40 • C showed a gradual capacity loss for the first 250 cycles followed by a sudden capacity drop associated with a large polarization growth. Analysis of the electrolyte showed that this sudden failure is associated with the depletion of FEC. The capacity loss as well as the consumption of FEC prior to the sudden failure was fitted using a model that includes a time dependence and a cycle number dependence. The time dependence was associated with the thickening solid electrolyte interface at the surface of the negative electrode particles (Si-alloy and graphite) and the cycle number dependence was associated with the solid electrolyte interface repair at the surface of Si-alloy particles during repeated expansion and contraction. Cost reduction and an increase in the volumetric energy density of Li-ion cells can possibly be attained using silicon-based negative electrodes.1-3 While these benefits have been known for many years, commercial implementation remains limited due to silicon's inherent challenges.Si-based electrodes can suffer from particle pulverization upon cycling (e.g. micron sized silicon), 1,4-7 can have loss of electronic contact between particles after repeated expansion and contraction during cycling, 2,8-10 can have high irreversible first cycle coulombic efficiency 11,[12][13][14][15] and can have low coulombic efficiency (compared to graphite electrodes) during cycling. 1,16,17 The root cause of these challenges is the large volume expansion 1,18 of the material during lithiation and subsequent contraction during delithiation. Several issues have been solved through the use of either nanosized Si or nanostructured Si. For instance the use of nanosized Si particles solves some of the pulverization problems encountered by micron sized Si particles. 1,4,11,[19][20][21] However, nanosized Si still suffers from inter-particle contact loss during cycling as well as low coulombic efficiency due to large specific surface area. 1,16In a recent publication, Chevrier et al. 16 presented a rational way to design commercially relevant Si-based negative electrodes. They showed that confining nano-domains of silicon in an alloy matrix suppresses particle pulverization and greatly reduces the surface area of Si exposed to the electrolyte. This approach yields materials with lower first cycle irreversible capacity (IRC) loss, better coulombic e...

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DFT Study of Reduction Mechanisms of Ethylene Carbonate and Fluoroethylene Carbonate on Li⁺-Adsorbed Si Clusters

Cited by 41 publications

References 57 publications

Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

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

Studies of the Capacity Fade Mechanisms of LiCoO₂/Si-Alloy: Graphite Cells

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DFT Study of Reduction Mechanisms of Ethylene Carbonate and Fluoroethylene Carbonate on Li+-Adsorbed Si Clusters

Cited by 41 publications

References 57 publications

Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries

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

Studies of the Capacity Fade Mechanisms of LiCoO2/Si-Alloy: Graphite Cells

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DFT Study of Reduction Mechanisms of Ethylene Carbonate and Fluoroethylene Carbonate on Li⁺-Adsorbed Si Clusters

Studies of the Capacity Fade Mechanisms of LiCoO₂/Si-Alloy: Graphite Cells