1
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Fang L, Nguyen H, Gonzalez R, Li T. A systematic study of solvation structure of asymmetric lithium salts in water. NANOTECHNOLOGY 2024; 35:365402. [PMID: 38776879 DOI: 10.1088/1361-6528/ad4ee7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
Aqueous electrolytes are promising in large-scale energy storage applications due to intrinsic low toxicity, non-flammability, high ion conductivity, and low cost. However, pure water's narrow electrochemical stability window (ESW) limits the energy density of aqueous rechargeable batteries. Water-in-salt electrolytes (WiSE) proposal has expanded the ESW to over 3 V by changing electrolyte solvation structure. The limited solubility and WIS electrolyte crystallization have been persistent concerns for imide-based lithium salts. Asymmetric lithium salts compensate for the above flaws. However, studying the solvation structure of asymmetric salt aqueous electrolytes is rare. Here, we applied small-angle x-ray scattering (SAXS) and Raman spectroscope to reveal the solvation structure of imide-based asymmetric lithium salts. The SAXS spectra show the blue shifts of the lowerqpeak with decreased intensity as the increasing of concentration, indicating a decrease in the average distance between solvated anions. Significantly, an exponential decrease in the d-spacing as a function of concentration was observed. In addition, we also applied the Raman spectroscopy technique to study the evolutions of solvent-separated ion pairs (SSIPs), contacted ion pairs (CIPs), and aggregate ions (AGGs) in the solvation structure of asymmetric salt solutions.
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Affiliation(s)
- Lingzhe Fang
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, United States of America
| | - Huong Nguyen
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, United States of America
| | - Rena Gonzalez
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, United States of America
| | - Tao Li
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, United States of America
- Chemistry and Material Science Group, X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439, United States of America
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2
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Ma L, Jiang J. Vehicular Motions Dominate the Ion Transport in Concentrated LiTFSI Aqueous Solutions? J Phys Chem Lett 2024; 15:4531-4537. [PMID: 38635898 DOI: 10.1021/acs.jpclett.4c00791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Water-in-salt electrolytes (WiSEs) show great promise for applications in grid-scale energy storage. The design of high-performance WiSEs requires a comprehensive understanding of their microstructures and ion transport properties. In the present work, based on the CL&Pol force field, we have developed a polarizable force field (PFF) tailored for high-concentration LiTFSI aqueous solutions, which accurately reproduces the structural and dynamical properties. Unlike the literature, we do not observe the presence of bulk-like water in LiTFSI solutions exceeding 19 mol/kg. Furthermore, we find that the vast majority of Li(H20)n+ are short-lived, and thus, the structural motion rather than the vehicular motion is the main mode of ion transport. Our results have significant implications for understanding the ion dynamics in WiSEs. Additionally, further in-depth experimental analyses are imperative.
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Affiliation(s)
- Linbo Ma
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jian Jiang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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3
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Goloviznina K, Serva A, Salanne M. Formation of Polymer-like Nanochains with Short Lithium-Lithium Distances in a Water-in-Salt Electrolyte. J Am Chem Soc 2024; 146:8142-8148. [PMID: 38486506 DOI: 10.1021/jacs.3c12488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Water-in-salts (WiSs) have recently emerged as promising electrolytes for energy storage applications ranging from aqueous batteries to supercapacitors. Here, ab initio molecular dynamics is used to study the structure of a 21 m LiTFSI WiS. The simulation reveals a new feature, in which the lithium ions form polymer-like nanochains that involve up to 10 ions. Despite the strong Coulombic interaction between them, the ions in the chains are found at a distance of 2.5 Å. They show a drastically different solvation shell compared to that of the isolated ions, in which they share on average two water molecules. The nanochains have a highly transient character due to the low free energy barrier for forming/breaking them. Providing new insights into the nanostructure of WiS electrolytes, our work calls for reevaluating our current knowledge of highly concentrated electrolytes and the impact of the modification of the solvation of active species on their electrochemical performances.
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Affiliation(s)
- Kateryna Goloviznina
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens, Cedex, France
| | - Alessandra Serva
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens, Cedex, France
| | - Mathieu Salanne
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens, Cedex, France
- Institut Universitaire de France (IUF), 75231 Paris, France
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4
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Lyu X, Wang H, Liu X, He L, Do C, Seifert S, Winans RE, Cheng L, Li T. Solvation Structure of Methanol-in-Salt Electrolyte Revealed by Small-Angle X-ray Scattering and Simulations. ACS NANO 2024; 18:7037-7045. [PMID: 38373167 DOI: 10.1021/acsnano.3c10469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
The solvation structure of water-in-salt electrolytes was thoroughly studied, and two competing structures─anion solvated structure and anion network─were well-defined in recent publications. To further reveal the solvation structure in those highly concentrated electrolytes, particularly the influence of solvent, methanol was chosen as the solvent for this proposed study. In this work, small-angle X-ray scattering, small-angle neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy were utilized to obtain the global and local structural information. With the concentration increment, the anion network formed by TFSI- became the dominant structure. Meanwhile, the hydrogen bonds among methanol were interrupted by the TFSI- anion and formed a new connection with them. Molecular dynamic simulations with two different force fields (GAFF and OPLS-AA) are tested, and GAFF agreed with synchrotron small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) results well and provided insightful information about molecular/ion scale solvation structure. This article not only deepens the understanding of the solvation structure in highly concentrated solutions, but more importantly, it provides additional strong evidence for utilizing SAXS/WAXS to validate molecular dynamics simulations.
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Affiliation(s)
- Xingyi Lyu
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Haimeng Wang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Xinyi Liu
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Lilin He
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Changwoo Do
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Soenke Seifert
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Randall E Winans
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Lei Cheng
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Tao Li
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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5
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Kim J, Koo B, Khammari A, Park K, Lee H, Kwak K, Cho M. Water-Ion Interaction Determines the Mobility of Ions in Highly Concentrated Aqueous Electrolytes. ACS APPLIED MATERIALS & INTERFACES 2024; 16:10033-10041. [PMID: 38373218 DOI: 10.1021/acsami.3c15609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Solvation engineering plays a critical role in tailoring the performance of batteries, particularly through the use of highly concentrated electrolytes, which offer heterogeneous solvation structures of mobile ions with distinct electrochemical properties. In this study, we employed spectroscopic techniques and molecular dynamics simulations to investigate mixed-cation (Li+/K+) acetate aqueous electrolytes. Our research unravels the pivotal role of water in facilitating ion transport within a highly viscous medium. Notably, Li+ cations primarily form ion aggregates, predominantly interacting with acetate anions, while K+ cations emerge as the principal charge carriers, which is attributed to their strong interaction with water molecules. Intriguingly, even at a concentration as high as 40 m, a substantial amount of water molecules persistently engages in hydrogen bonding with one another, creating mobile regions rich in K+ ions. Our observations of a redshift of the OH stretching band of water suggest that the strength of the hydrogen bond alone cannot account for the expansion of the electrochemical stability window. These findings offer valuable insights into the cation transfer mechanism, shedding light on the contribution of water-bound cations to both the ion conductivity and the electrochemical stability window of aqueous electrolytes for rechargeable batteries. Our comprehensive molecular-level understanding of the interplay between cations and water provides a foundation for future advances in solvation engineering, leading to the development of high-performance batteries with improved energy storage and safety profiles.
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Affiliation(s)
- Jungyu Kim
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
| | - Bonhyeop Koo
- Department of Energy Science and Engineering, DGIST, Daegu 42988, Korea
| | - Anahita Khammari
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
| | - Kwanghee Park
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
| | - Hochun Lee
- Department of Energy Science and Engineering, DGIST, Daegu 42988, Korea
| | - Kyungwon Kwak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
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6
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Wróbel P, Kubisiak P, Eilmes A. Ab Initio Molecular Dynamics Simulations of Aqueous LiTFSI Solutions─Structure, Hydrogen Bonding, and IR Spectra. J Phys Chem B 2024; 128:1001-1011. [PMID: 38235720 PMCID: PMC10839825 DOI: 10.1021/acs.jpcb.3c06633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/30/2023] [Accepted: 01/05/2024] [Indexed: 01/19/2024]
Abstract
Simulations of Density Functional Theory-based ab initio molecular dynamics (AIMD) have been performed for a series of aqueous lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) solutions with concentrations ranging from salt-in-water to water-in-salt systems. Analysis of the structure of electrolytes has revealed a preference of Li+ cations to interact with water molecules. In concentrated LiTFSI solutions, water molecules form small associates. The total number of hydrogen bonds (HBs) in the system decreases with salt concentrations, with bonds to water acceptors being only partially replaced by interactions with TFSI anions. Infrared (IR) spectra in the region of the O-H stretching frequency calculated from AIMD trajectories are in good agreement with experimental data. Statistics of oscillations of individual O-H bonds have shown correlations between vibrational frequencies and the structure of HBs formed by water. The changes in the IR spectrum have been related to the varying contributions of different local environments of the water molecules. The abundances of the three spectral components calculated from the simulations agree well with the decomposition of the experimental IR spectra reported in the literature.
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Affiliation(s)
- Piotr Wróbel
- Faculty of Chemistry, Jagiellonian
University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Piotr Kubisiak
- Faculty of Chemistry, Jagiellonian
University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Andrzej Eilmes
- Faculty of Chemistry, Jagiellonian
University, Gronostajowa 2, 30-387 Kraków, Poland
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7
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Lin X, Tee SR, Kent PRC, Searles DJ, Cummings PT. Development of Heteroatomic Constant Potential Method with Application to MXene-Based Supercapacitors. J Chem Theory Comput 2024; 20:651-664. [PMID: 38211325 PMCID: PMC10809414 DOI: 10.1021/acs.jctc.3c00940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/20/2023] [Accepted: 12/18/2023] [Indexed: 01/13/2024]
Abstract
We describe a method for modeling constant-potential charges in heteroatomic electrodes, keeping pace with the increasing complexity of electrode composition and nanostructure in electrochemical research. The proposed "heteroatomic constant potential method" (HCPM) uses minimal added parameters to handle differing electronegativities and chemical hardnesses of different elements, which we fit to density functional theory (DFT) partial charge predictions in this paper by using derivative-free optimization. To demonstrate the model, we performed molecular dynamics simulations using both HCPM and conventional constant potential method (CPM) for MXene electrodes with Li-TFSI/AN (lithium bis(trifluoromethane sulfonyl)imide/acetonitrile)-based solvent-in-salt electrolytes. Although the two methods show similar accumulated charge storage on the electrodes, the results indicated that HCPM provides a more reliable depiction of electrode atom charge distribution and charge response compared with CPM, accompanied by increased cationic attraction to the MXene surface. These results highlight the influence of elemental composition on electrode performance, and the flexibility of our HCPM opens up new avenues for studying the performance of diverse heteroatomic electrodes including other types of MXenes, two-dimensional materials, metal-organic frameworks (MOFs), and doped carbonaceous electrodes.
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Affiliation(s)
- Xiaobo Lin
- Multiscale
Modeling and Simulation Center, Vanderbilt
University, Nashville, Tennessee 37235-1604, United States
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
| | - Shern R. Tee
- Australian
Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul R. C. Kent
- Computational
Sciences and Engineering Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Debra J. Searles
- Australian
Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
- School
of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Peter T. Cummings
- Multiscale
Modeling and Simulation Center, Vanderbilt
University, Nashville, Tennessee 37235-1604, United States
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
- School of
Engineering and Physical Sciences, Heriot-Watt
University, Edinburgh, Scotland EH14 4AS, U.K.
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8
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Yamaguchi T, Dukhin A, Ryu YJ, Zhang D, Borodin O, González MA, Yamamuro O, Price DL, Saboungi ML. Non-Newtonian Dynamics in Water-in-Salt Electrolytes. J Phys Chem Lett 2024; 15:76-80. [PMID: 38133800 DOI: 10.1021/acs.jpclett.3c03145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Water-in-salt electrolytes have attracted considerable interest in the past decade for advanced lithium-ion batteries, possessing important advantages over the non-aqueous electrolytes currently in use. A battery with a LiTFSI-water electrolyte was demonstrated in which an operating window of 3 V is made possible by a solid-electrolyte interface. Viscosity is an important property for such electrolytes, because high viscosity is normally associated with low ionic conductivity. Here, we investigate shear and longitudinal viscosities using shear stress and compressional longitudinal stress measurements as functions of frequency and concentration. We find that both viscosities are frequency-dependent and exhibit almost identical frequency and concentration dependences in the high-concentration region. A comparison to quasielastic neutron scattering experiments suggests that both are governed by structural relaxation of the TFSI- network. Thus, LiFTSI-water electrolytes appear to be an unusual case of a non-Newtonian fluid, where shear and longitudinal viscosities are determined by the same relaxation mechanism.
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Affiliation(s)
- Tsuyoshi Yamaguchi
- Graduate School of Engineering, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8603, Japan
| | - Andrei Dukhin
- Dispersion Technology, Incorporated, 364 Adams Street, Bedford Hills, New York 10507, United States
| | - Young-Jay Ryu
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
| | - Dongzhou Zhang
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, United States
| | - Oleg Borodin
- Energy Storage Branch, Sensor and Electron Devices Directorate, United States Army Research Laboratory, Adelphi, Maryland 20783, United States
| | - Miguel A González
- Institut Laue Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Osamu Yamamuro
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - David L Price
- CNRS and Université d'Orléans, CEMHTI, 1D Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France
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9
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Kacenauskaite L, Van Wyck SJ, Moncada Cohen M, Fayer MD. Water-in-Salt: Fast Dynamics, Structure, Thermodynamics, and Bulk Properties. J Phys Chem B 2024; 128:291-302. [PMID: 38118403 DOI: 10.1021/acs.jpcb.3c07711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
We present concentration-dependent dynamics of highly concentrated LiBr solutions and LiCl temperature-dependent dynamics for two high concentrations and compare the results to those of prior LiCl concentration-dependent data. The dynamical data are obtained using ultrafast optical heterodyne-detected optical Kerr effect (OHD-OKE). The OHD-OKE decays are composed of two pairs of biexponentials, i.e., tetra-exponentials. The fastest decay (t1) is the same as pure water's at all concentrations within error, while the second component (t2) slows slightly with concentration. The slower components (t3 and t4), not present in pure water, slow substantially, and their contributions to the decays increase significantly with increasing concentration, similar to LiCl solutions. Simulations of LiCl solutions from the literature show that the slow components arise from large ion/water clusters, while the fast components are from ion/water structures that are not part of large clusters. Temperature-dependent studies (15-95 °C) of two high LiCl concentrations show that decreasing the temperature is equivalent to increasing the room temperature concentration. The LiBr and LiCl concentration dependences and the two LiCl concentrations' temperature dependences all have bulk viscosities that are linearly dependent on τcslow, the correlation time of the slow dynamics (weighted averages of t3 and t4). Remarkably, all four viscosity vs 1/τCslow plots fall on the same line. Application of transition state theory to the temperature-dependent data yields the activation enthalpies and entropies for the dynamics of the large ion/water clusters, which underpin the bulk viscosity.
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Affiliation(s)
- Laura Kacenauskaite
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen 2100, Denmark
| | - Stephen J Van Wyck
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Max Moncada Cohen
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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10
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Zhang Y, Carino E, Hahn NT, Becknell N, Mars J, Han KS, Mueller KT, Toney M, Maginn EJ, Tepavcevic S. Understanding the Surprising Ionic Conductivity Maximum in Zn(TFSI) 2 Water/Acetonitrile Mixture Electrolytes. J Phys Chem Lett 2023; 14:11393-11399. [PMID: 38079154 DOI: 10.1021/acs.jpclett.3c03048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Aqueous electrolytes composed of 0.1 M zinc bis(trifluoromethylsulfonyl)imide (Zn(TFSI)2) and acetonitrile (ACN) were studied using combined experimental and simulation techniques. The electrolyte was found to be electrochemically stable when the ACN V% is higher than 74.4. In addition, it was found that the ionic conductivity of the mixed solvent electrolytes changes as a function of ACN composition, and a maximum was observed at 91.7 V% of ACN although the salt concentration is the same. This behavior was qualitatively reproduced by molecular dynamics (MD) simulations. Detailed analyses based on experiments and MD simulations show that at high ACN composition the water network existing in the high water composition solutions breaks. As a result, the screening effect of the solvent weakens and the correlation among ions increases, which causes a decrease in ionic conductivity at high ACN V%. This study provides a fundamental understanding of this complex mixed solvent electrolyte system.
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Affiliation(s)
- Yong Zhang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Emily Carino
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Nathan T Hahn
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Material, Physical and Chemical Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
| | - Nigel Becknell
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Julian Mars
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Kee Sung Han
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Karl T Mueller
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Michael Toney
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Edward J Maginn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sanja Tepavcevic
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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11
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Rana R, Ali SM, Maity DK. Structure and dynamics of the Li + ion in water, methanol and acetonitrile solvents: ab initio molecular dynamics simulations. Phys Chem Chem Phys 2023; 25:31382-31395. [PMID: 37961866 DOI: 10.1039/d3cp04403c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Fundamental understanding of the structure and dynamics of the Li+ ion in solution is of utmost importance in different fields of science and technology, especially in the field of ion batteries. In view of this, ab initio molecular dynamics (AIMD) simulations of the LiCl salt in water, methanol and acetonitrile were performed to elucidate structural parameters such as radial distribution function and coordination number, and dynamical properties like diffusion coefficient, limiting ion conductivity and hydrogen bond correlation function. In the present AIMD simulation, one LiCl in water is equivalent to 0.8 M, which is close to the concentration of the lithium salt used in the Li-ion battery. The first sphere of coordination number of the Li+ ion was reaffirmed to be 4. The radial distribution function for different pairs of atoms is seen to be in good agreement with the experimental results. The calculated potential of mean force indicates the stronger interaction of the Li+ ion with methanol over water followed by acetonitrile. The dynamical parameters convey quite high diffusion and limiting ionic conductivity of the Li+ ion in acetonitrile compared to that in water and methanol which has been attributed to the transport of the Li-Cl ion pair in a non-dissociated form in acetonitrile. The AIMD results were found to be in accordance with the experimental findings, i.e. the limiting ion conductivity was found to follow the order acetonitrile > methanol > water. This study shows the importance of atomistic level simulations in evaluating the structural and dynamical parameters and in implementing the results for predicting and synthesizing better next generation solvents for lithium ion batteries (LIBs).
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Affiliation(s)
- Reman Rana
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
| | - Sk Musharaf Ali
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Dilip K Maity
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
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12
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Rezaei M, Sakong S, Groß A. Molecular Modeling of Water-in-Salt Electrolytes: A Comprehensive Analysis of Polarization Effects and Force Field Parameters in Molecular Dynamics Simulations. J Chem Theory Comput 2023; 19:5712-5730. [PMID: 37528639 DOI: 10.1021/acs.jctc.3c00171] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Accurate modeling of highly concentrated aqueous solutions, such as water-in-salt (WiS) electrolytes in battery applications, requires proper consideration of polarization contributions to atomic interactions. Within the force field molecular dynamics (MD) simulations, the atomic polarization can be accounted for at various levels. Nonpolarizable force fields implicitly account for polarization effects by incorporating them into their van der Waals interaction parameters. They can additionally mimic electron polarization within a mean-field approximation through ionic charge scaling. Alternatively, explicit polarization description methods, such as the Drude oscillator model, can be selectively applied to either a subset of polarizable atoms or all polarizable atoms to enhance simulation accuracy. The trade-off between simulation accuracy and computational efficiency highlights the importance of determining an optimal level of accounting for atomic polarization. In this study, we analyze different approaches to include polarization effects in MD simulations of WiS electrolytes, with an example of a Na-OTF solution. These approaches range from a nonpolarizable to a fully polarizable force field. After careful examination of computational costs, simulation stability, and feasibility of controlling the electrolyte properties, we identify an efficient combination of force fields: the Drude polarizable force field for salt ions and non-polarizable models for water. This cost-effective combination is sufficiently flexible to reproduce a broad range of electrolyte properties, while ensuring simulation stability over a relatively wide range of force field parameters. Furthermore, we conduct a thorough evaluation of the influence of various force field parameters on both the simulation results and technical requirements, with the aim of establishing a general framework for force field optimization and facilitating parametrization of similar systems.
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Affiliation(s)
- Majid Rezaei
- Institute of Theoretical Chemistry, Ulm University, Oberberghof 7, 89081 Ulm, Germany
| | - Sung Sakong
- Institute of Theoretical Chemistry, Ulm University, Oberberghof 7, 89081 Ulm, Germany
| | - Axel Groß
- Institute of Theoretical Chemistry, Ulm University, Oberberghof 7, 89081 Ulm, Germany
- Helmholtz Institute Ulm (HIU) for Electrochemical Energy Storage, Helmholtzstraße 11, 89069 Ulm, Germany
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13
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Zhou S, Shi J, Liu S, Li G, Pei F, Chen Y, Deng J, Zheng Q, Li J, Zhao C, Hwang I, Sun CJ, Liu Y, Deng Y, Huang L, Qiao Y, Xu GL, Chen JF, Amine K, Sun SG, Liao HG. Visualizing interfacial collective reaction behaviour of Li-S batteries. Nature 2023; 621:75-81. [PMID: 37673990 DOI: 10.1038/s41586-023-06326-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 06/14/2023] [Indexed: 09/08/2023]
Abstract
Benefiting from high energy density (2,600 Wh kg-1) and low cost, lithium-sulfur (Li-S) batteries are considered promising candidates for advanced energy-storage systems1-4. Despite tremendous efforts in suppressing the long-standing shuttle effect of lithium polysulfides5-7, understanding of the interfacial reactions of lithium polysulfides at the nanoscale remains elusive. This is mainly because of the limitations of in situ characterization tools in tracing the liquid-solid conversion of unstable lithium polysulfides at high temporal-spatial resolution8-10. There is an urgent need to understand the coupled phenomena inside Li-S batteries, specifically, the dynamic distribution, aggregation, deposition and dissolution of lithium polysulfides. Here, by using in situ liquid-cell electrochemical transmission electron microscopy, we directly visualized the transformation of lithium polysulfides over electrode surfaces at the atomic scale. Notably, an unexpected gathering-induced collective charge transfer of lithium polysulfides was captured on the nanocluster active-centre-immobilized surface. It further induced an instantaneous deposition of nonequilibrium Li2S nanocrystals from the dense liquid phase of lithium polysulfides. Without mediation of active centres, the reactions followed a classical single-molecule pathway, lithium polysulfides transforming into Li2S2 and Li2S step by step. Molecular dynamics simulations indicated that the long-range electrostatic interaction between active centres and lithium polysulfides promoted the formation of a dense phase consisting of Li+ and Sn2- (2 < n ≤ 6), and the collective charge transfer in the dense phase was further verified by ab initio molecular dynamics simulations. The collective interfacial reaction pathway unveils a new transformation mechanism and deepens the fundamental understanding of Li-S batteries.
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Affiliation(s)
- Shiyuan Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Jie Shi
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, People's Republic of China
| | - Sangui Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Gen Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Fei Pei
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Youhu Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Junxian Deng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Qizheng Zheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Jiayi Li
- Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing, People's Republic of China
| | - Chen Zhao
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, USA
| | - Inhui Hwang
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - Cheng-Jun Sun
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
| | - Yuzi Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Yu Deng
- Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing, People's Republic of China
| | - Ling Huang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Yu Qiao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen, People's Republic of China
| | - Gui-Liang Xu
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, USA.
| | - Jian-Feng Chen
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, People's Republic of China
| | - Khalil Amine
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, USA.
| | - Shi-Gang Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China
| | - Hong-Gang Liao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People's Republic of China.
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen, People's Republic of China.
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14
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Paillot M, Wong A, Denisov SA, Soudan P, Poizot P, Montigny B, Mostafavi M, Gauthier M, Le Caër S. Predicting Degradation Mechanisms in Lithium Bistriflimide "Water-In-Salt" Electrolytes For Aqueous Batteries. CHEMSUSCHEM 2023:e202300692. [PMID: 37385952 DOI: 10.1002/cssc.202300692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/24/2023] [Accepted: 06/29/2023] [Indexed: 07/01/2023]
Abstract
Aqueous solutions are crucial to most domains in biology and chemistry, including in energy fields such as catalysis and batteries. Water-in-salt electrolytes (WISEs), which extend the stability of aqueous electrolytes in rechargeable batteries, are one example. While the hype for WISEs is huge, commercial WISE-based rechargeable batteries are still far from reality, and there remain several fundamental knowledge gaps such as those related to their long-term reactivity and stability. Here, we propose a comprehensive approach to accelerating the study of WISE reactivity by using radiolysis to exacerbate the degradation mechanisms of concentrated LiTFSI-based aqueous solutions. We find that the nature of the degradation species depends strongly on the molality of the electrolye, with degradation routes driven by the water or the anion at low or high molalities, respectively. The main aging products are consistent with those observed by electrochemical cycling, yet radiolysis also reveals minor degradation species, providing a unique glimpse of the long-term (un)stability of these electrolytes.
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Affiliation(s)
- Malaurie Paillot
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191, Gif sur Yvette Cedex, France
| | - Alan Wong
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191, Gif sur Yvette Cedex, France
| | - Sergey A Denisov
- Institut de Chimie Physique UMR8000, CNRS, Université Paris Saclay, Bâtiment 349, 91405, Orsay, France
| | - Patrick Soudan
- Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, IMN, Nantes, F-44000, France
| | - Philippe Poizot
- Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, IMN, Nantes, F-44000, France
| | - Benedicte Montigny
- Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l'Energie (EA 6299), Université de Tours, Parc de Grandmont, 37200, France
| | - Mehran Mostafavi
- Institut de Chimie Physique UMR8000, CNRS, Université Paris Saclay, Bâtiment 349, 91405, Orsay, France
| | - Magali Gauthier
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191, Gif sur Yvette Cedex, France
| | - Sophie Le Caër
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191, Gif sur Yvette Cedex, France
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15
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Wang F, Sun Y, Cheng J. Switching of Redox Levels Leads to High Reductive Stability in Water-in-Salt Electrolytes. J Am Chem Soc 2023; 145:4056-4064. [PMID: 36758145 DOI: 10.1021/jacs.2c11793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Developing nonflammable electrolytes with wide electrochemical windows is of great importance for energy storage devices. Water-in-salt electrolytes (WiSE) have attracted great interests due to their widely opened electrochemical windows and high stability. Previous theoretical investigations have revealed changes in solvation shell of water molecules result in opening of HOMO-LUMO gaps of water, leading to the formation of an anion-derived solid-electrolyte-interphase (SEI) in WiSE. However, how solvation structures affect electrochemical windows at atomic level is still a puzzle, which hinders optimization and design of aqueous electrolytes. Herein, machine learning molecular dynamics and free energy calculation method are applied to compute redox potentials of anions of Li-salts and water of aqueous electrolytes at a range of salt concentrations. Furthermore, an analysis based on local solvation structures is employed to demonstrate the structure-property relations. Our calculation shows that the hydrogen evolution reaction is impeded in WiSE due to switching of the order of redox levels of the anion and H2O, leading to formation of SEI and high reductive stability. Level switching is caused by the special solvation environments of isolated water molecules. Our work provides new insight into the electrochemistry of aqueous electrolytes which would benefit the electrolyte design in energy storage devices.
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Affiliation(s)
- Feng Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yan Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jun Cheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- Tan Kah Kee Innovation Laboratory, Xiamen 361005, China
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16
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Water-in-salt electrolytes made saltier by Gemini ionic liquids for highly efficient Li-ion batteries. Sci Rep 2023; 13:2154. [PMID: 36750658 PMCID: PMC9905052 DOI: 10.1038/s41598-023-29387-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
The water-in-salt electrolytes have promoted aqueous Li-ion batteries to become one of the most promising candidates to overcome safety concerns/issues of traditional Li-ion batteries. A simple increase of Li-salt concentration in electrolytes can successfully expand the electrochemical stability window of aqueous electrolytes beyond 2 V. However, necessary stability improvements require an increase in complexity of the ternary electrolytes. Here, we have explored the effects of novel, Gemini-type ionic liquids (GILs) as a co-solvent systems in aqueous Li[TFSI] mixtures and investigated the transport properties of the resulting electrolytes, as well as their electrochemical performance. The devices containing pyrrolidinium-based GILs show superior cycling stability and promising specific capacity in the cells based on the commonly used electrode materials LTO (Li4Ti5O12) and LMO (LiMn2O4).
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17
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Nickerson TR, Antonio EN, McNally DP, Toney MF, Ban C, Straub AP. Unlocking the potential of polymeric desalination membranes by understanding molecular-level interactions and transport mechanisms. Chem Sci 2023; 14:751-770. [PMID: 36755730 PMCID: PMC9890600 DOI: 10.1039/d2sc04920a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
Polyamide reverse osmosis (PA-RO) membranes achieve remarkably high water permeability and salt rejection, making them a key technology for addressing water shortages through processes including seawater desalination and wastewater reuse. However, current state-of-the-art membranes suffer from challenges related to inadequate selectivity, fouling, and a poor ability of existing models to predict performance. In this Perspective, we assert that a molecular understanding of the mechanisms that govern selectivity and transport of PA-RO and other polymer membranes is crucial to both guide future membrane development efforts and improve the predictive capability of transport models. We summarize the current understanding of ion, water, and polymer interactions in PA-RO membranes, drawing insights from nanofiltration and ion exchange membranes. Building on this knowledge, we explore how these interactions impact the transport properties of membranes, highlighting assumptions of transport models that warrant further investigation to improve predictive capabilities and elucidate underlying transport mechanisms. We then underscore recent advances in in situ characterization techniques that allow for direct measurements of previously difficult-to-obtain information on hydrated polymer membrane properties, hydrated ion properties, and ion-water-membrane interactions as well as powerful computational and electrochemical methods that facilitate systematic studies of transport phenomena.
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Affiliation(s)
- Trisha R. Nickerson
- Department of Chemical and Biological Engineering, University of Colorado BoulderBoulderCO 80309USA
| | - Emma N. Antonio
- Department of Chemical and Biological Engineering, University of Colorado BoulderBoulderCO 80309USA,Materials Science and Engineering Program, University of Colorado BoulderBoulderCO 80309USA
| | - Dylan P. McNally
- Materials Science and Engineering Program, University of Colorado BoulderBoulderCO 80309USA
| | - Michael F. Toney
- Department of Chemical and Biological Engineering, University of Colorado BoulderBoulderCO 80309USA,Materials Science and Engineering Program, University of Colorado BoulderBoulderCO 80309USA,Renewable and Sustainable Energy Institute, University of Colorado BoulderBoulderCO 80309USA
| | - Chunmei Ban
- Materials Science and Engineering Program, University of Colorado Boulder Boulder CO 80309 USA .,Department of Mechanical Engineering, University of Colorado Boulder Boulder CO 80309 USA
| | - Anthony P. Straub
- Materials Science and Engineering Program, University of Colorado BoulderBoulderCO 80309USA,Department of Civil, Environmental and Architectural Engineering, University of Colorado BoulderBoulderColorado 80309USA
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18
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Son S, Yeo J, Chang J. Cl -/Cl 3- Redox Voltammetry to Recognize the Interfacial Layer on Positively Electrified Carbon in "Water-in-Salt" Electrolytes. Anal Chem 2022; 94:12691-12698. [PMID: 36074896 DOI: 10.1021/acs.analchem.2c02029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A "Water-in-Salt" electrolyte solution (WiSE) is a promising aqueous medium for lithium-ion batteries containing highly concentrated electrolytes. For the increased kinetic overpotential of water oxidation in WiSE, the formation of an interfacial layer (IFL) on a positively electrified electrode is crucial. Nonetheless, most related studies have been restricted to theoretical approaches. In this Article, we voltammetrically study the Cl-/Cl3-/Cl2 redox reaction on Pt and glassy carbon (GC) electrodes in WiSE containing LiTFSI (WiSELiTFSI) and demonstrate that careful monitoring of Cl-/Cl3- redox voltammetry can allow recognition of an IFL formed on a positively electrified electrode. The voltammetric wave attributed to the electro-oxidation of Cl- on a GC electrode was negatively more shifted as the molal concentration of LiTFSI was increased from 0.5 to 6 m, while there was no shift on Pt. Also, there was voltammetric resolution into two peaks associated with Cl-/Cl3- and Cl3-/Cl2 on the GC electrode in WiSELiTFSI, while only unresolved, one redox-paired voltammograms were observed on Pt, regardless of the molal concentration of LiTFSI. These two main voltammetric features indicate the LiTFSI-induced IFL coupled with Cl- and Cl3- on a GC electrode induced by an applied potential of ∼2 V versus the point of zero charge (PZC). We found other halide/halogen redox reactions did not show differentiated voltammetric behaviors in WiSELiTFSI, which demonstrates the uniqueness of the Cl-/Cl3- redox reaction for recognizing the IFL formed on a positively charged electrode surface. Lastly, a strong interaction between the IFL and Cl species was also confirmed by XPS measurements.
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Affiliation(s)
- Sungjun Son
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Jeongmin Yeo
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Jinho Chang
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea.,Department of HY-KIST Bio-convergence, Hanyang University, Seoul 04763, Republic of Korea
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19
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Zhang Y, Klein JM, Akolkar R, Gurkan BE, Maginn EJ. Solvation Structure, Dynamics, and Charge Transfer Kinetics of Cu 2+ and Cu + in Choline Chloride Ethylene Glycol Electrolytes. J Phys Chem B 2022; 126:6493-6499. [PMID: 35976689 DOI: 10.1021/acs.jpcb.2c04798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental measurements and classical molecular dynamics (MD) simulations were carried out to study electrolytes containing CuCl2 and CuCl salts in mixtures of choline chloride (ChCl) and ethylene glycol (EG). The study focused on the concentration of 100 mM of both CuCl2 and CuCl with the ratio of ChCl/EG varied from 1:2, 1:3, 1:4, to 1:5. It was found that the Cu2+ and Cu+ have different solvation environments in their first solvation shell. Cu2+ is coordinated by both Cl- anions and EG molecules, whereas Cu+ is only solvated by EG. However, both Cu2+ and Cu+ show strong interactions with their second solvation shells, which include both Cl- anions and EG molecules. Considering both the first and second solvation shells, the concentrations of Cu2+ and Cu+ that have various coordination numbers in each solution were calculated and were found to correlate qualitatively with the exchange current density trends reported in previous experiments of Cu2+ reduction to Cu+. This finding makes a connection between atomic solvation structure observed in MD simulations and redox reaction kinetics measured in electrochemical experiments, thus revealing the significance of the solvation environment of reduced and oxidized species for electrokinetics in deep eutectic solvents.
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Affiliation(s)
- Yong Zhang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jeffrey M Klein
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Rohan Akolkar
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Burcu E Gurkan
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Edward J Maginn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
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20
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Lewis NHC, Dereka B, Zhang Y, Maginn EJ, Tokmakoff A. From Networked to Isolated: Observing Water Hydrogen Bonds in Concentrated Electrolytes with Two-Dimensional Infrared Spectroscopy. J Phys Chem B 2022; 126:5305-5319. [PMID: 35829623 DOI: 10.1021/acs.jpcb.2c03341] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Superconcentrated electrolytes have emerged as a promising class of materials for energy storage devices, with evidence that high voltage performance is possible even with water as the solvent. Here, we study the changes in the water hydrogen bonding network induced by the dissolution of lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in concentrations ranging from the dilute to the superconcentrated regimes. Using time-resolved two-dimensional infrared spectroscopy, we observe the progressive disruption of the water-water hydrogen bond network and the appearance of isolated water molecules interacting only with ions, which can be identified and spectroscopically isolated through the intermolecular cross-peaks between the water and the TFSI- ions. Analyzing the vibrational relaxation of excitations of the H2O stretching mode, we observe a transition in the dominant relaxation path as the bulk-like water vanishes and is replaced by ion-solvation water with the rapid single-step relaxation of delocalized stretching vibrations into the low frequency modes being replaced by multistep relaxation through the intramolecular H2O bend and into the TFSI- high frequency modes prior to relaxing to the low frequency structural degrees of freedom. These results definitively demonstrate the absence of vibrationally bulk-like water in the presence of high concentrations of LiTFSI and especially in the superconcentrated regime, while additionally revealing aspects of the water hydrogen bond network that have been difficult to discern from the vibrational spectroscopy of the neat liquid.
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Affiliation(s)
- Nicholas H C Lewis
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Bogdan Dereka
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Yong Zhang
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Edward J Maginn
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
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21
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Dhattarwal HS, Kashyap HK. Heterogeneity and Nanostructure of Superconcentrated LiTFSI-EmimTFSI Hybrid Aqueous Electrolytes: Beyond the 21 m Limit of Water-in-Salt Electrolyte. J Phys Chem B 2022; 126:5291-5304. [PMID: 35819799 DOI: 10.1021/acs.jpcb.2c02822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionic liquids such as EmimTFSI (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide) have been found to improve the solubility of LiTFSI salt in water-in-salt electrolyte (WiSE) from 21 to 60 m. However, the molecular origin of such enhancement in the solubility is still unknown. In the present work, we elucidate the microscopic structures of LiTFSI-EmimTFSI-based hybrid aqueous electrolytes and compare them with the structure of LiTFSI-based WiSE using molecular dynamics simulations. Our analysis reveals the presence of alternating water-rich clusters and TFSI-rich extended domains in the WiSE. In these clusters and domains, the Li+ ions reside such that the total number of oxygen atoms around them is conserved to four, where water contributes about three oxygen atoms. The addition of EmimTFSI in the WiSE results in removal of water from the nearest-neighbor solvation shell of TFSI- ions but not from the Li+ ions. Significant structural changes are observed when LiTFSI salt is further added to LiTFSI-EmimTFSI aqueous solution. In both the hybrid electrolytes, water and Emim+ cations are found to avoid each other. The simulated X-ray scattering structure factor reveals the presence of larger length-scale heterogeneity in the most concentrated solution of the hybrid aqueous electrolyte. We observe that this nanoscale heterogeneity originates from a water-TFSI-Emim-TFSI-water-TFSI-Emim-TFSI-like arrangement in which Li+ ions are dispersed such that the coordination number of oxygen atoms around them is enhanced to five, wherein the major contribution comes from the TFSI- ions. We envision that the enhanced LiTFSI solubility originates from the replacement of water molecules with TFSI- ions in the first solvation shell of Li+ ions.
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Affiliation(s)
- Harender S Dhattarwal
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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22
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Popov I, Khamzin A, Matsumoto RA, Zhao W, Lin X, Cummings PT, Sokolov AP. Controlling the Ion Transport Number in Solvent-in-Salt Solutions. J Phys Chem B 2022; 126:4572-4583. [PMID: 35687852 DOI: 10.1021/acs.jpcb.2c02218] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Solvent-in-salt (SIS) systems present promising materials for the next generation of energy storage applications. The ion dynamics is significantly different in these systems from that of ionic liquids and diluted salt solutions. In this study, we analyze the ion dynamics of two salts, Li-TFSI and Li-FSI, in highly concentrated aqueous and acetonitrile solutions. We performed high-frequency dielectric measurements covering the range of up to 50 GHz and molecular dynamics simulations. The analysis of the conductivity spectra provides the characteristic crossover time between individual charge rearrangements and the normal charge diffusion regime resulting in DC conductivity. Analysis revealed that the onset of normal charge diffusion occurs at the scale of ∼1.5-3.5 Å, comparable to the average distance between the ions. Based on the idea of momentum conservation, distinct ion correlations were estimated experimentally and computationally. The analysis revealed that cation-anion correlations can be suppressed by changing the solvent concentration in SIS systems, leading to an increase of the light ion (Li+ in our case) transport number. This discovery suggests a way for improving the light cation transport number in SIS systems by tuning the solvent concentration.
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Affiliation(s)
- Ivan Popov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Airat Khamzin
- Institute of Physics, Kazan Federal University, Kazan, Tatarstan 420008, Russia
| | - Ray A Matsumoto
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Wei Zhao
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Xiaobo Lin
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Peter T Cummings
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Alexei P Sokolov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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23
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Yao N, Chen X, Fu ZH, Zhang Q. Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries. Chem Rev 2022; 122:10970-11021. [PMID: 35576674 DOI: 10.1021/acs.chemrev.1c00904] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rechargeable batteries have become indispensable implements in our daily life and are considered a promising technology to construct sustainable energy systems in the future. The liquid electrolyte is one of the most important parts of a battery and is extremely critical in stabilizing the electrode-electrolyte interfaces and constructing safe and long-life-span batteries. Tremendous efforts have been devoted to developing new electrolyte solvents, salts, additives, and recipes, where molecular dynamics (MD) simulations play an increasingly important role in exploring electrolyte structures, physicochemical properties such as ionic conductivity, and interfacial reaction mechanisms. This review affords an overview of applying MD simulations in the study of liquid electrolytes for rechargeable batteries. First, the fundamentals and recent theoretical progress in three-class MD simulations are summarized, including classical, ab initio, and machine-learning MD simulations (section 2). Next, the application of MD simulations to the exploration of liquid electrolytes, including probing bulk and interfacial structures (section 3), deriving macroscopic properties such as ionic conductivity and dielectric constant of electrolytes (section 4), and revealing the electrode-electrolyte interfacial reaction mechanisms (section 5), are sequentially presented. Finally, a general conclusion and an insightful perspective on current challenges and future directions in applying MD simulations to liquid electrolytes are provided. Machine-learning technologies are highlighted to figure out these challenging issues facing MD simulations and electrolyte research and promote the rational design of advanced electrolytes for next-generation rechargeable batteries.
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Affiliation(s)
- Nan Yao
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Xiang Chen
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Zhong-Heng Fu
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Qiang Zhang
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
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24
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González MA, Akiba H, Borodin O, Cuello GJ, Hennet L, Kohara S, Maginn EJ, Mangin-Thro L, Yamamuro O, Zhang Y, Price DL, Saboungi ML. Structure of water-in-salt and water-in-bisalt electrolytes. Phys Chem Chem Phys 2022; 24:10727-10736. [PMID: 35451439 DOI: 10.1039/d2cp00537a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a systematic diffraction study of two "water-in-salt" electrolytes and a "water-in-bisalt" electrolyte combining high-energy X-ray diffraction (HEXRD) with polarized and unpolarized neutron diffraction (ND) on both H2O and D2O solutions. The measurements provide three independent combinations of correlations between the different pairs of atom types that reveal the short- and intermediate-range order in considerable detail. The ND interference functions show pronounced peaks around a scattering vector Q ∼ 0.5 Å-1 that change dramatically with composition, indicating significant rearrangements of the water network on a length scale around 12 Å. The experimental results are compared with two sets of Molecular Dynamics (MD) simulations, one including polarization effects and the other based on a non-polarizable force field. The two simulations reproduce the general shapes of the experimental structure factors and their changes with concentration, but differ in many detailed respects, suggesting ways in which their force fields might be modified to better represent the actual systems.
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Affiliation(s)
| | - Hiroshi Akiba
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Oleg Borodin
- Battery Science Branch, U.S. Army Combat Capabilities Development Command, Army Research Laboratory, Adelphi, Maryland 20783, USA.
| | | | - Louis Hennet
- ICMN, Université d'Orléans/CNRS, 45071 Orléans, France
| | - Shinji Kohara
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Edward J Maginn
- Dept. of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Lucile Mangin-Thro
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Osamu Yamamuro
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yong Zhang
- Dept. of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - David L Price
- CEMHTI, CNRS/Université d'Orléans, 45071 Orléans, France
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25
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Dereka B, Lewis NHC, Zhang Y, Hahn NT, Keim JH, Snyder SA, Maginn EJ, Tokmakoff A. Exchange-Mediated Transport in Battery Electrolytes: Ultrafast or Ultraslow? J Am Chem Soc 2022; 144:8591-8604. [PMID: 35470669 DOI: 10.1021/jacs.2c00154] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding the mechanisms of charge transport in batteries is important for the rational design of new electrolyte formulations. Persistent questions about ion transport mechanisms in battery electrolytes are often framed in terms of vehicular diffusion by persistent ion-solvent complexes versus structural diffusion through the breaking and reformation of ion-solvent contacts, i.e., solvent exchange events. Ultrafast two-dimensional (2D) IR spectroscopy can probe exchange processes directly via the evolution of the cross-peaks on picosecond time scales. However, vibrational energy transfer in the absence of solvent exchange gives rise to the same spectral signatures, hiding the desired processes. We employ 2D IR on solvent resonances of a mixture of acetonitrile isotopologues to differentiate chemical exchange and energy-transfer dynamics in a comprehensive series of Li+, Mg2+, Zn2+, Ca2+, and Ba2+ bis(trifluoromethylsulfonyl)imide electrolytes from the dilute to the superconcentrated regime. No exchange phenomena occur within at least 100 ps, regardless of the ion identity, salt concentration, and presence of water. All of the observed spectral dynamics originate from the intermolecular energy transfer. These results place the lower experimental boundary on the ion-solvent residence times to several hundred picoseconds, much slower than previously suggested. With the help of MD simulations and conductivity measurements on the Li+ and Zn2+ systems, we discuss these results as a continuum of vehicular and structural modalities that vary with concentration and emphasize the importance of collective electrolyte motions to ion transport. These results hold broadly applicable to many battery-relevant ions and solvents.
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Affiliation(s)
- Bogdan Dereka
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States.,Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Nicholas H C Lewis
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States.,Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Yong Zhang
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Nathan T Hahn
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Material, Physical and Chemical Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Jonathan H Keim
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Scott A Snyder
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Edward J Maginn
- Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Andrei Tokmakoff
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States.,Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont, Illinois 60439, United States
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26
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Kinnibrugh T, Fister T. Structure of Sulfuric Acid Solutions Using Pair Distribution Function Analysis. J Phys Chem B 2022; 126:3099-3106. [PMID: 35435687 DOI: 10.1021/acs.jpcb.2c00523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solvation and mesoscale ordering of sulfuric acid and other strong acid solutions leads to suppressed freezing points and strong rheological changes with varying concentration. While the solid-state structures are well-understood, studies focused on the evolving solvation structure in the solution phase have probed a limited concentration range (∼1-6 M). This study applies a total scattering approach in both the wide-angle X-ray scattering (WAXS) and pair distribution function (PDF) regimes to elucidate the evolving solvation structure over its full range of acid concentration (0-18 M). The emergence of a prepeak in the WAXS regime at intermediate concentrations indicates a transition from noninteracting sulfate molecules in the dilute limit to sterically limited sulfates at concentrations near its deep eutectic point. Fits to the PDF data quantify this trend, showing a transition from octahedrally hydrated sulfates up to 6-7 M concentrations, followed by gradual dehydration, and eventually reaching a solution structure similar to that of water-in-salt electrolyte systems at high acid concentrations.
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Affiliation(s)
- Tiffany Kinnibrugh
- X-ray Science Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States
| | - Tim Fister
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States
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27
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Qu M, Li S, Chen J, Xiao Y, Xiao J. Ion Transport in the EMITFSI/PVDF System at Different Temperatures: A Molecular Dynamics Simulation. ACS OMEGA 2022; 7:9333-9342. [PMID: 35356691 PMCID: PMC8945056 DOI: 10.1021/acsomega.1c06160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 02/02/2022] [Indexed: 05/13/2023]
Abstract
We used all-atom molecular dynamics simulations to study the ion transport in the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/poly(vinylidene fluoride) (EMITFSI/PVDF) system with 40.05 wt % EMITFSI at different temperatures. The glass-transition temperature (T g = 204 K) of this system shows a good agreement with the experimental value (200 K). With the increase of temperature, the peaks of the pair correlation function show an increasing trend. Interestingly, the coordination numbers of ion pairs and the degree of independent ion motion are mainly affected by the binding energy between ion pairs as the temperature increases. In addition, the ion transport properties with increasing temperature can be studied by the ion-pair relaxation times, ion-pair lifetimes, and diffusion coefficients. The simulation results illustrate that the ion transport is intensified. Especially, the cations can always diffuse faster than the anions. The power law shows that mobilities of anions and cations are seen to exhibit a "superionic" behavior. With the increase of temperature, transference numbers of anions decrease first and then increase and transference numbers of cations show the opposite changes; ionic conductivity increases gradually; and viscosity decreases gradually, indicating that the diffusion resistance of ions decreases. In general, after adding PVDF into the EMITFSI system, the glass-transition temperature and viscosity increase, the ionic conductivity and degree of independent ion motion decrease, and diffusion coefficients of cations decrease faster than those of the anions.
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Affiliation(s)
- Minghe Qu
- Molecules
and Materials Computation Institute, School of Chemistry and Chemical
Engineering, Nanjing University of Science
and Technology, Nanjing 210094, P. R. China
| | - Shenshen Li
- Molecules
and Materials Computation Institute, School of Chemistry and Chemical
Engineering, Nanjing University of Science
and Technology, Nanjing 210094, P. R. China
| | - Jian Chen
- Chuannan
Machinery Manufacturing Plant, Luzhou 646000, P. R. China
| | - Yunqin Xiao
- Molecules
and Materials Computation Institute, School of Chemistry and Chemical
Engineering, Nanjing University of Science
and Technology, Nanjing 210094, P. R. China
- Science
and Technology on Aerospace Chemical Power Laboratory, Hubei Institute of Aerospace Chemical Technology, Xiangyang 441003, P. R. China
| | - Jijun Xiao
- Molecules
and Materials Computation Institute, School of Chemistry and Chemical
Engineering, Nanjing University of Science
and Technology, Nanjing 210094, P. R. China
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28
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Kirchner B, Blasius J, Alizadeh V, Gansäuer A, Hollóczki O. Chemistry Dissolved in Ionic Liquids. A Theoretical Perspective. J Phys Chem B 2022; 126:766-777. [PMID: 35034453 DOI: 10.1021/acs.jpcb.1c09092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The theoretical treatment of ionic liquids must focus now on more realistic models while at the same time keeping an accurate methodology when following recent ionic liquids research trends or allowing predictability to come to the foreground. In this Perspective, we summarize in three cases of advanced ionic liquid research what methodological progress has been made and point out difficulties that need to be overcome. As particular examples to discuss we choose reactions, chirality, and radicals in ionic liquids. All these topics have in common that an explicit or accurate treatment of the electronic structure and/or intermolecular interactions is required (accurate methodology), while at the same time system size and complexity as well as simulation time (realistic model) play an important role and must be covered as well.
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Affiliation(s)
- Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany
| | - Jan Blasius
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany
| | - Vahideh Alizadeh
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Gerhard-Domagk-Straße 1, D-53121 Bonn, Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany.,Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary
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29
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Tot A, Kloo L. Water-in-Salt Electrolytes – Molecular Insights to the High Solubility of Lithium-Ion Salts. Chem Commun (Camb) 2022; 58:9528-9531. [DOI: 10.1039/d2cc03062d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The recently established water-in-salt electrolyte (WISE) concept indicates the possibile application of aqueous electrolytes in lithium-ion batteries (LiBs). The application of this type of highly concentrated electrolytes has been questioned...
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30
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Messias A, C da Silva DA, Fileti EE. Salt-in-water and water-in-salt electrolytes: the effects of the asymmetry in cation and anion valence on their properties. Phys Chem Chem Phys 2021; 24:336-346. [PMID: 34889921 DOI: 10.1039/d1cp04259a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We investigated the structural, dynamic, energetic, and electrostatic properties of electrolytes based on the ion pairs LiCl and Li2SO4. Atomistic molecular dynamics simulations were used to simulate these aqueous electrolytic solutions at two different concentrations 2 M (normal) and 21 M (superconcentrated, WiSE). The effects of the valence asymmetry of the Li2SO4 electrolyte were also discussed for both salt concentrations. Our results differ in the physical aspect of pure electrolytes, showing the drastic effect of high concentration, in particular on the viscosity, which is dramatically increased in WiSE. This is a consequence of their reduced ionic mobility and has a direct effect on ionic conductivity. Also, our results for graphene-based supercapacitors, as indicated by some experimental work, do not indicate any better performance of WiSEs over normal electrolytes. In fact, the differences in the total capacitance, due to the concentration of ions, presented by both electrolytes are negligible. The valence asymmetry can be clearly observed in some properties but for most of them its effects could not be quantified or isolated.
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Affiliation(s)
- Andresa Messias
- Center of Natural and Human Sciences, Federal University of ABC, 09210-170, Santo André, SP, Brazil.
| | - Débora A C da Silva
- Center for Innovation on New Energies, Advanced Energy Storage Division, Carbon Sci-Tech Labs, University of Campinas, School of Electrical and Computer Engineering, Av. Albert Einstein 400, Campinas - SP, 13083-852, Brazil
| | - Eudes E Fileti
- Institute of Science and Technology of the Federal University of São Paulo, 12247-014, São José dos Campos, SP, Brazil.
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31
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Zhang Y, Maginn EJ. Water-In-Salt LiTFSI Aqueous Electrolytes (2): Transport Properties and Li + Dynamics Based on Molecular Dynamics Simulations. J Phys Chem B 2021; 125:13246-13254. [PMID: 34813336 DOI: 10.1021/acs.jpcb.1c07581] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transport properties of water-in-salt lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) aqueous electrolytes were studied using classical molecular dynamics (MD) simulations. At high salt concentrations of 20 m, the calculated viscosity, self-diffusion coefficients, ionic conductivity, the inverse Haven ratio, and the Li+ apparent transference number all agree with previous experimental results quantitatively. Furthermore, analyses show that the high apparent transference number for Li+ is due to the fact that the dynamics of TFSI- decrease more quickly with increasing salt concentration than the dynamics of Li+ ions due to the formation of a TFSI- network. In addition, it was shown that the conduction of Li+ ions through the highly concentrated electrolyte occurs mainly via a hopping mechanism instead of a vehicular mechanism hypothesized in earlier studies of this system.
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Affiliation(s)
- Yong Zhang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame 46556, Indiana, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont 60439, Illinois, United States
| | - Edward J Maginn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame 46556, Indiana, United States.,Joint Center for Energy Storage Research, Argonne National Laboratory, Lemont 60439, Illinois, United States
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32
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Triolo A, Di Lisio V, Lo Celso F, Appetecchi GB, Fazio B, Chater P, Martinelli A, Sciubba F, Russina O. Liquid Structure of a Water-in-Salt Electrolyte with a Remarkably Asymmetric Anion. J Phys Chem B 2021; 125:12500-12517. [PMID: 34738812 PMCID: PMC9282637 DOI: 10.1021/acs.jpcb.1c06759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Water-in-salt
systems, i.e., super-concentrated aqueous electrolytes,
such as lithium bis(trifluoromethanesulfonyl)imide (21 mol/kgwater), have been recently discovered to exhibit unexpectedly
large electrochemical windows and high lithium transference numbers,
thus paving the way to safe and sustainable charge storage devices.
The peculiar transport features in these electrolytes are influenced
by their intrinsically nanoseparated morphology, stemming from the
anion hydrophobic nature and manifesting as nanosegregation between
anions and water domains. The underlying mechanism behind this structure–dynamics
correlation is, however, still a matter of strong debate. Here, we
enhance the apolar nature of the anions, exploring the properties
of the aqueous electrolytes of lithium salts with a strongly asymmetric
anion, namely, (trifluoromethylsulfonyl)(nonafluorobutylsulfonyl)
imide. Using a synergy of experimental and computational tools, we
detect a remarkable level of structural heterogeneity at a mesoscopic
level between anion-rich and water-rich domains. Such a ubiquitous
sponge-like, bicontinuous morphology develops across the whole concentration
range, evolving from large fluorinated globules at high dilution to
a percolating fluorous matrix intercalated by water nanowires at super-concentrated
regimes. Even at extremely concentrated conditions, a large population
of fully hydrated lithium ions, with no anion coordination, is detected.
One can then derive that the concomitant coexistence of (i) a mesoscopically
segregated structure and (ii) fully hydrated lithium clusters disentangled
from anion coordination enables the peculiar lithium diffusion features
that characterize water-in-salt systems.
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Affiliation(s)
- Alessandro Triolo
- Laboratorio Liquidi Ionici, Istituto Struttura della Materia, Consiglio Nazionale delle Ricerche (ISM-CNR), Rome 00133, Italy
| | - Valerio Di Lisio
- Department of Chemistry, University of Rome Sapienza, Rome 00185, Italy
| | - Fabrizio Lo Celso
- Laboratorio Liquidi Ionici, Istituto Struttura della Materia, Consiglio Nazionale delle Ricerche (ISM-CNR), Rome 00133, Italy.,Department of Physics and Chemistry, Università di Palermo, Palermo 90133, Italy
| | | | - Barbara Fazio
- Istituto Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche (IPCF-CNR), Messina 98158, Italy
| | - Philip Chater
- Diamond House, Harwell Science & Innovation Campus, Diamond Light Source, Ltd., Didcot OX11 0DE, U.K
| | - Andrea Martinelli
- Department of Chemistry, University of Rome Sapienza, Rome 00185, Italy
| | - Fabio Sciubba
- Department of Chemistry, University of Rome Sapienza, Rome 00185, Italy.,NMR-Based Metabolomics Laboratory (NMLab), Sapienza University of Rome, Rome 00185, Italy
| | - Olga Russina
- Laboratorio Liquidi Ionici, Istituto Struttura della Materia, Consiglio Nazionale delle Ricerche (ISM-CNR), Rome 00133, Italy.,Department of Chemistry, University of Rome Sapienza, Rome 00185, Italy
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33
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Kumar K, Bharti A, Kumar R. Molecular insight into the structure and dynamics of LiTf2N/deep eutectic solvent: an electrolyte for Li-ion batteries. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1983178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kishant Kumar
- Department of Chemical Engineering, National Institute of Technology Warangal, Warangal, India
| | - Anand Bharti
- Department of Chemical Engineering, Birla Institute of Technology Mesra, Ranchi, India
| | - Rudra Kumar
- EIC Sustainable and Civil Technologies, Tecnologico de Monterrey, Monterrey, Mexico
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34
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Horwitz G, Härk E, Steinberg PY, Cavalcanti LP, Risse S, Corti HR. The Nanostructure of Water-in-Salt Electrolytes Revisited: Effect of the Anion Size. ACS NANO 2021; 15:11564-11572. [PMID: 34255484 DOI: 10.1021/acsnano.1c01737] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The increasing interest in developing safe and sustainable energy storage systems has led to the rapid rise in attention to superconcentrated electrolytes, commonly called water-in-salt (WiS). Several works indicate that the transport properties of these liquid electrolytes are related to the presence of nanodomains, but a detailed characterization of such structure is missing. Here, the structural nano-heterogeneity of lithium WiS electrolytes, comprising lithium trifluoromethanesulfonate (LiTf) and bis(trifluoromethanesulfonyl)imide (LiTFSI) solutions as a function of concentration and temperature, was assessed by resorting to the analysis of small-angle neutron scattering (SANS) patterns. Variations with the concentration of a correlation peak, rather temperature-independent, in a Q range around 3.5-5 nm-1 indicate that these electrolytes are composed of nanometric water-rich channels percolating a 3D dispersing anion-rich network, with differences between Tf and TFSI anions related to their distinct volumes and interactions. Furthermore, a common trend was found for both systems' morphology above a salt volume fraction of ∼0.5. These results imply that the determining factor in the formation of the nanostructure is the salt volume fraction (related to the anion size), rather than its molality. These findings may represent a paradigm shift for designing WiS electrolytes.
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Affiliation(s)
- Gabriela Horwitz
- Departamento de Física de la Materia Condensada and Instituto de Nanociencia y Nanotecnología (INN-CONICET), Comisión Nacional de Energía Atómica, Avenida General Paz 1499, B1650, San Martín, Buenos Aires, Argentina
| | - Eneli Härk
- Department for Electrochemical Energy Storage, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Paula Y Steinberg
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, B1650, San Martín, Buenos Aires, Argentina
| | - Leide P Cavalcanti
- Rutherford Appleton Laboratory, ISIS Neutron and Muon Source, OX110QX Didcot, United Kingdom
| | - Sebastian Risse
- Department for Electrochemical Energy Storage, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Horacio R Corti
- Departamento de Física de la Materia Condensada and Instituto de Nanociencia y Nanotecnología (INN-CONICET), Comisión Nacional de Energía Atómica, Avenida General Paz 1499, B1650, San Martín, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, INQUIMAE, Intendente Güiraldes 2160, C1428EGA Buenos Aires, Argentina
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