Computational Study on the Solubility of Lithium Salts Formed on Lithium Ion Battery Negative Electrode in Organic Solvents

Tasaki, Ken; Harris, Stephen J.

doi:10.1021/jp100013h

Cited by 117 publications

(122 citation statements)

References 66 publications

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“…24 In order to characterize the chemical species formed by the reaction of CO 2 at the negative electrode, XPS analysis was done on lithiated graphite negative electrodes stored in electrolyte, either in pouch bags that were vacuum-sealed or in pouch bags injected with CO 2 . Figure 7b shows the C1s region of these negative electrodes, and illustrates one of two reactions which consume CO 2 .…”

Section: Reactions Of Co 2 -mentioning

confidence: 99%

Quantifying, Understanding and Evaluating the Effects of Gas Consumption in Lithium-Ion Cells

Ellis

Allen

Thompson

et al. 2017

J. Electrochem. Soc.

114

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Lithium-ion cells produce a considerable amount of gas in their first cycle. If the gases are not removed in a degassing step, most are consumed by the cell over time. This phenomenon has never been investigated explicitly in the literature. In this paper, the evolution and subsequent consumption of gas in typical lithium-ion cells are measured by Archimedes' principle and gas chromatography. It is found that all evolved gases are subsequently consumed to some degree, except for saturated hydrocarbons. The consumption of gas occurs predominantly at the negative electrode, where the gases are reduced to form part of the solid-electrolyte interphase (SEI). Changes to the negative electrode SEI upon gas consumption are investigated using X-ray photoelectron spectroscopy. The effect of gas consumption on cell performance is studied with ultra-high precision charging and high voltage storage experiments. It is found that gas consumption does not result in measurable adverse effects to cell performance. Lithium-ion cells can produce a significant amount of gas during the first charge (in the formation cycle), as electrolyte and additives react at the surfaces of the charging electrodes to form passivating films. If lithium-ion cells are packaged in a flexible casing, these gases are normally removed by the manufacturer in a degassing step, to prevent deformation of the cell and to ensure uniform stack pressure on the electrodes. If the degassing step is omitted, a large portion of the gas evolved is consumed over time.1 The reactions that consume gas are presumably prevalent in hard-cased cylindrical cells, such as 18650 s, which are often hermetically sealed before the first charge, and therefore cannot be easily degassed. The reactions that consume gas are presumably less prevalent in pouch-type cells, which are degassed.Several authors have speculated about the fates of gases in lithiumion cells.2-5 There has been no work explicitly dedicated to understanding the phenomenon of gas consumption. There is no consensus as to whether the effects of gas consumption are beneficial or harmful to cell performance. For example, it has been argued by some that the consumption of CO 2 is beneficial to cells, as it reacts to form a passivating film on the negative electrode. 3,4,6 However it has also been argued that the consumption of CO 2 is detrimental to cells, as it may reduce at the negative electrode to form Li 2 C 2 O 4 , which causes continual self-discharge at high voltage. 2It is important for both scientists and manufacturers of lithium-ion cells to understand the causes and the effects of gas consumption. If gas consumption is quick, benign, or even beneficial to cell performance, then the time-consuming degassing step for lithium-ion pouch cells might be skipped. 7 The gases evolved in lithium-ion pouch cells could be left for consumption within the cell, perhaps leaving the pouch cell flat and rigid after several hours if all the gases were consumed. If gas consumption in a cell produces undesirable effects, such...

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Section: Reactions Of Co 2 -mentioning

confidence: 99%

Quantifying, Understanding and Evaluating the Effects of Gas Consumption in Lithium-Ion Cells

Ellis

Allen

Thompson

et al. 2017

J. Electrochem. Soc.

114

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“…In the theoretical and computational researches, however, most focused on the first step of the reductive decompositions and the subsequent processes have been less explored. Recently, some theoretical studies on the solubility and adhesion properties of SFCs have been conducted by use of classical molecular dynamics (MD) [24][25][26][27][28] or density functional theory (DFT) calculations with cluster boundary condition (CBC). 31 With classical MD, however, it is difficult to treat the modulation of electronic charge where the solvation environment is changing.…”

mentioning

confidence: 99%

Near-Shore Aggregation Mechanism of Electrolyte Decomposition Products to Explain Solid Electrolyte Interphase Formation

Ushirogata

Sodeyama

Futera

et al. 2015

J. Electrochem. Soc.

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To get insight of the formation mechanism of solid electrolyte interphase (SEI) film in Lithium-ion battery (LIB), we examine a probable scenario, referred to as "surface growth mechanism," for electrolyte involving ethylene carbonate (EC) solvent and vinylene carbonate (VC) additive by using density functional theory (DFT). We first extracted stable SEI film components (SFCs) for the EC/VC electrolyte and constructed probable SFC aggregates via DFT molecular dynamics. We then examined their solubility in the EC solution, their adhesion to a model graphite electrode, and the electronic properties. The results showed that the SFC aggregates are characterized by "unstable adhesion" to the graphite surface and "high electronic insulation" against the EC solution. These characteristics preclude explaining SEI growth up to a typical thickness of several tens of nanometers based on the surface growth mechanism. With the present results, we propose "near-shore aggregation" mechanism, where the SFCs formed at the electrode surface desorb into the near-shore region and form aggregates. The SFC aggregates coalesce and come into contact with the electrode to complete the SEI formation. The present model provides a novel perspective for the long-standing problem of SEI formation. Lithium-ion batteries (LIBs) have attracted considerable attention for use in larger power sources like electric vehicles and energy storage system because of their high energy densities.1,2 For such use, a higher degree of safety, a longer cycle life, higher voltage and capacity will be indispensable in the future. An important key of the stability and durability of the LIB is the solid electrolyte interphase (SEI) formed at the negative electrode-electrolyte interface.3,4 It is generally accepted that molecules in the electrolyte solution reductively decompose to form various SEI film components (SFCs), such as organic oligomers (e.g., (CH 2 OCO 2 Li) 2 , and ROCO 2 Li) and inorganic moieties (e.g., Li 2 CO 3 , LiF) at the first charging, 5 and that the SFCs precipitate on the electrode surface to form a stable SEI film with a thickness of several tens of nanometers. 6 The SEI hinders electron transport from the electrode to the electrolyte solution, preventing further electrolyte decomposition, while allowing Li + ion transport. This property decreases the irreversible capacity and improves the safety of LIBs. Additives to the electrolyte solution also have a large impact on SEI performance. Even a small amount of additive up to a few wt% significantly improves the irreversible capacity and cyclability.7 In general, the additive molecules modify the SFCs and lead to different properties of the SEI film. Despite the important roles of the SEI in LIB operation, the microscopic formation processes are still unclear because of the difficulty in operando observations of chemical reactions at the electrodeelectrolyte interfaces.The detailed formation processes of SEI have been typically assumed to involve "surface growth mechanism", mainly in the firs...

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“…Electronic structure methods for modeling the atomistic structures and properties [8] that provide fundamental insight into the atomistic and electronic processes governing energy and power densities, as well as structural integrity; Classical force-field methods for the dynamics and structure of materials [9,10], which are used to study defect formations and evolution;…”

Section: Introductionmentioning

confidence: 99%

Safer Batteries through Coupled Multiscale Modeling

Turner

Allu

Berrill

et al. 2015

Procedia Computer Science

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Batteries are highly complex electrochemical systems, with performance and safety governed by coupled nonlinear electrochemical-electrical-thermal-mechanical processes over a range of spatiotemporal scales. We describe a new, open source computational environment for battery simulation known as VIBE -the Virtual Integrated Battery Environment. VIBE includes homogenized and pseudo-2D electrochemistry models such as those by Newman-Tiedemann-Gu (NTG) and DoyleFuller-Newman (DFN, a.k.a. DualFoil) as well as a new advanced capability known as AMPERES (Advanced MultiPhysics for Electrochemical and Renewable Energy Storage). AMPERES provides a 3D model for electrochemistry and full coupling with 3D electrical and thermal models on the same grid. VIBE/AMPERES has been used to create three-dimensional battery cell and pack models that explicitly simulate all the battery components (current collectors, electrodes, and separator). The models are used to predict battery performance under normal operations and to study thermal and mechanical response under adverse conditions.

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Computational Study on the Solubility of Lithium Salts Formed on Lithium Ion Battery Negative Electrode in Organic Solvents

Cited by 117 publications

References 66 publications

Quantifying, Understanding and Evaluating the Effects of Gas Consumption in Lithium-Ion Cells

Quantifying, Understanding and Evaluating the Effects of Gas Consumption in Lithium-Ion Cells

Near-Shore Aggregation Mechanism of Electrolyte Decomposition Products to Explain Solid Electrolyte Interphase Formation

Safer Batteries through Coupled Multiscale Modeling

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