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Chakraborty S, Halat DM, Im J, Hickson DT, Reimer JA, Balsara NP. Lithium transference in electrolytes with star-shaped multivalent anions measured by electrophoretic NMR. Phys Chem Chem Phys 2023; 25:21065-21073. [PMID: 37525889 DOI: 10.1039/d3cp00923h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
One approach for improving lithium transference in electrolytes is through the use of bulky multivalent anions. We have studied a multivalent salt containing a bulky star-shaped anion with a polyhedral oligomeric silsesquioxane (POSS) center and lithium counterions dissolved in a solvent. The charge on each anion, z-, is equal to -20. The self-diffusion coefficients of all species were measured by pulsed field gradient NMR (PFG-NMR). As expected, anion diffusion was significantly slower than cation diffusion. An approximate transference number, also referred to as the current fraction (measured by Bruce, Vincent and Watanabe method), was higher than those expected from PFG-NMR. However, the rigorously defined cation transference number with respect to the solvent velocity measured by electrophoretic NMR was negative at all salt concentrations. In contrast, the approximate transference numbers based on PFG-NMR and current fractions are always positive, as expected. The discrepancy between these three independent approaches for characterizing lithium transference suggests the presence of complex cation-anion interactions in solution. It is evident that the slow self-diffusion of bulky multivalent anions does not necessarily lead to an improvement of lithium transference.
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Affiliation(s)
- Saheli Chakraborty
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - David M Halat
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Julia Im
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Darby T Hickson
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Jeffrey A Reimer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nitash P Balsara
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Bergstrom HK, Fong KD, Halat DM, Karouta CA, Celik HC, Reimer JA, McCloskey BD. Ion correlation and negative lithium transference in polyelectrolyte solutions. Chem Sci 2023; 14:6546-6557. [PMID: 37350831 PMCID: PMC10283486 DOI: 10.1039/d3sc01224g] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/13/2023] [Indexed: 06/24/2023] Open
Abstract
Polyelectrolyte solutions (PESs) recently have been proposed as high conductivity, high lithium transference number (t+) electrolytes where the majority of the ionic current is carried by the electrochemically active Li-ion. While PESs are intuitively appealing because anchoring the anion to a polymer backbone selectively slows down anionic motion and therefore increases t+, increasing the anion charge will act as a competing effect, decreasing t+. In this work we directly measure ion mobilities in a model non-aqueous polyelectrolyte solution using electrophoretic Nuclear Magnetic Resonance Spectroscopy (eNMR) to probe these competing effects. While previous studies that rely on ideal assumptions predict that PESs will have higher t+ than monomeric solutions, we demonstrate that below the entanglement limit, both conductivity and t+ decrease with increasing degree of polymerization. For polyanions of 10 or more repeat units, at 0.5 m Li+ we directly observe Li+ move in the "wrong direction" in an electric field, evidence of a negative transference number due to correlated motion through ion clustering. This is the first experimental observation of negative transference in a non-aqueous polyelectrolyte solution. We also demonstrate that t+ increases with increasing Li+ concentration. Using Onsager transport coefficients calculated from experimental data, and insights from previously published molecular dynamics studies we demonstrate that despite selectively slowing anion motion using polyanions, distinct anion-anion correlation through the polymer backbone and cation-anion correlation through ion aggregates reduce the t+ in non-entangled PESs. This leads us to conclude that short-chained polyelectrolyte solutions are not viable high transference number electrolytes. These results emphasize the importance of understanding the effects of ion-correlations when designing new concentrated electrolytes for improved battery performance.
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Affiliation(s)
- Helen K Bergstrom
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Kara D Fong
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - David M Halat
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Materials Sciences Division, Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Carl A Karouta
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Materials Sciences Division, Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Hasan C Celik
- College of Chemistry NMR Facility, University of California Berkeley CA 94720 USA
| | - Jeffrey A Reimer
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Materials Sciences Division, Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Bryan D McCloskey
- Department of Chemical & Biomolecular Engineering, University of California Berkeley CA 94720 USA
- Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
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Yu D, Troya D, Korovich AG, Bostwick JE, Colby RH, Madsen LA. Uncorrelated Lithium-Ion Hopping in a Dynamic Solvent-Anion Network. ACS ENERGY LETTERS 2023; 8:1944-1951. [PMID: 37090169 PMCID: PMC10112391 DOI: 10.1021/acsenergylett.3c00454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 03/09/2023] [Indexed: 05/03/2023]
Abstract
Lithium batteries rely crucially on fast charge and mass transport of Li+ in the electrolyte. For liquid and polymer electrolytes with added lithium salts, Li+ couples to the counter-anion to form ionic clusters that produce inefficient Li+ transport and lead to Li dendrite formation. Quantification of Li+ transport in glycerol-salt electrolytes via NMR experiments and MD simulations reveals a surprising Li+-hopping mechanism. The Li+ transference number, measured by ion-specific electrophoretic NMR, can reach 0.7, and Li+ diffusion does not correlate with nearby ion motions, even at high salt concentration. Glycerol's high density of hydroxyl groups increases ion dissociation and slows anion diffusion, while the close proximity of hydroxyls and anions lowers local energy barriers, facilitating Li+ hopping. This system represents a bridge between liquid and inorganic solid electrolytes, thus motivating new molecular designs for liquid and polymer electrolytes to enable the uncorrelated Li+-hopping transport needed for fast-charging and all-solid-state batteries.
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Affiliation(s)
- Deyang Yu
- Department
of Chemistry, Virginia Polytechnic Institute
and State University, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia 24061, United States
| | - Diego Troya
- Department
of Chemistry, Virginia Polytechnic Institute
and State University, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia 24061, United States
| | - Andrew G. Korovich
- Department
of Chemistry, Virginia Polytechnic Institute
and State University, Blacksburg, Virginia 24061, United States
| | - Joshua E. Bostwick
- Department
of Materials Science and Engineering, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Ralph H. Colby
- Department
of Materials Science and Engineering, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
- Materials
Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Louis A. Madsen
- Department
of Chemistry, Virginia Polytechnic Institute
and State University, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia 24061, United States
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Steinforth P, Gómez-Martínez M, Entgelmeier LM, García Mancheño O, Schönhoff M. Relevance of the Cation in Anion Binding of a Triazole Host: An Analysis by Electrophoretic Nuclear Magnetic Resonance. J Phys Chem B 2022; 126:10156-10163. [PMID: 36409921 PMCID: PMC9744096 DOI: 10.1021/acs.jpcb.2c05064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/24/2022] [Indexed: 11/22/2022]
Abstract
Triazole hosts allow cooperative binding of anions via hydrogen bonds, which makes them versatile systems for application in anion binding catalysis to be performed in organic solvents. The anion binding behavior of a tetratriazole host is systematically studied by employing a variety of salts, including chloride, acetate, and benzoate, as well as different cations. Classical nuclear magnetic resonance (1H NMR) titrations demonstrate a large influence of cation structures on the anion binding constant, which is attributed to poor dissociation of most salts in organic solvents and corrupts the results of classical titration techniques. We propose an approach employing electrophoretic NMR (eNMR), yielding drift velocities of each species in an electric field and thus allowing a distinction between charged and uncharged species. After the determination of the dissociation constants KD for the salts, electrophoretic mobilities are measured for all species in the host-salt system and are analyzed in a model which treats anion binding as a consecutive reaction to salt dissociation, yielding a corrected anion binding constant KA. Interestingly, dependence of KA on salt concentration occurs, which is attributed to cation aggregation with the anion-host complex. Finally, by the extrapolation to zero salt concentration, the true anion-host binding constant is obtained. Thus, the approach by eNMR allows a fully quantitative analysis of two factors that might impair classical anion binding studies, namely, an incomplete salt dissociation as well as the occurrence of larger aggregate species.
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Affiliation(s)
- Pascal Steinforth
- Institute
of Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149Münster, Germany
| | - Melania Gómez-Martínez
- Institute
of Organic Chemistry, University of Münster, Corrensstrasse 36, 48149Münster, Germany
| | | | - Olga García Mancheño
- Institute
of Organic Chemistry, University of Münster, Corrensstrasse 36, 48149Münster, Germany
| | - Monika Schönhoff
- Institute
of Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149Münster, Germany
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Kulikovskaya NS, Denisova EA, Ananikov VP. A novel approach to study catalytic reactions via electrophoretic NMR on the example of Pd/NHC-catalyzed Mizoroki-Heck cross-coupling reaction. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:954-962. [PMID: 35727217 DOI: 10.1002/mrc.5295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 05/17/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
Investigation of catalytic reactions using nuclear magnetic resonance (NMR) is a crucial task, which is often challenging to perform due to rather complex transformations at the metal center. In this work, it was shown that electrophoretic NMR can be a suitable method for studying catalytic reactions and for observing the changes in the catalyst nature. As an important example involving palladium catalysts with N-heterocyclic carbine ligands (NHCs), the breakage of the Pd-NHC bond can occur during the catalytic process. Electrophoretic NMR allows the distinction of compounds in the spectra depending on the charge, thus bringing new opportunities to mechanistic studies. Here, we present independent evidence of R-NHC product formation in the Pd-catalyzed Mizoroki-Heck reaction-the key process for catalyst change from the molecular to nano-scale type.
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Affiliation(s)
| | - Ekaterina A Denisova
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Valentine P Ananikov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
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Halat DM, Fang C, Hickson D, Mistry A, Reimer JA, Balsara NP, Wang R. Electric-Field-Induced Spatially Dynamic Heterogeneity of Solvent Motion and Cation Transference in Electrolytes. PHYSICAL REVIEW LETTERS 2022; 128:198002. [PMID: 35622024 DOI: 10.1103/physrevlett.128.198002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/30/2022] [Accepted: 04/19/2022] [Indexed: 05/21/2023]
Abstract
While electric fields primarily result in migration of charged species in electrolytic solutions, the solutions are dynamically heterogeneous. Solvent molecules within the solvation shells of the cation will be dragged by the field while free solvent molecules will not. We combine electrophoretic NMR measurements of ion and solvent velocities under applied electric fields with molecular dynamics simulations to interrogate different solvation motifs in a model liquid electrolyte. Measured values of the cation transference number (t_{+}^{0}) agree quantitatively with simulation-based predictions over a range of electrolyte concentrations. Solvent-cation interactions strongly influence the concentration-dependent behavior of t_{+}^{0}. We identify a critical concentration at which most of the solvent molecules lie within solvation shells of the cations. The dynamic heterogeneity of solvent molecules is minimized at this concentration where t_{+}^{0} is approximately equal to zero.
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Affiliation(s)
- David M Halat
- Materials Sciences Division and Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Chao Fang
- Materials Sciences Division and Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Darby Hickson
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Aashutosh Mistry
- Chemical Sciences and Engineering Division and Joint Center for Energy Storage Research (JCESR), Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Jeffrey A Reimer
- Materials Sciences Division and Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Nitash P Balsara
- Materials Sciences Division and Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Rui Wang
- Materials Sciences Division and Joint Center for Energy Storage Research (JCESR), Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
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Fang Y, Furó I. Weak Anion Binding to Poly( N-isopropylacrylamide) Detected by Electrophoretic NMR. J Phys Chem B 2021; 125:3710-3716. [PMID: 33821651 PMCID: PMC8154593 DOI: 10.1021/acs.jpcb.1c00642] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/16/2021] [Indexed: 11/28/2022]
Abstract
Ion specific effects are ubiquitous in solutions and govern a large number of colloidal phenomena. To date, a substantial and sustained effort has been directed at understanding the underlying molecular interactions. As a new approach, we address this issue by sensitive 1H NMR methods that measure the electrophoretic mobility and the self-diffusion coefficient of poly(N-isopropylacrylamide) (PNIPAM) chains in bulk aqueous solution in the presence of salts with the anion component varied from kosmotropes to chaotropes along the Hofmeister series. The accuracy of the applied electrophoretic NMR experiments is exceptionally high, on the order of 10-10 m2/(V s), corresponding to roughly 10-4 elementary charges per monomer effectively associated with the neutral polymer. We find that chaotropic anions associate to PNIPAM with an apparent Langmuir-type saturation behavior. The polymer chains remain extended upon ion association, and momentum transfer from anion to polymer is only partial which indicates weak attractive short-range forces between anion and polymer and, thereby and in contrast to some other ion-polymer systems, the lack of well-defined binding sites.
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Affiliation(s)
- Yuan Fang
- Division of Applied Physical
Chemistry, Department of Chemistry, KTH
Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - István Furó
- Division of Applied Physical
Chemistry, Department of Chemistry, KTH
Royal Institute of Technology, SE-10044 Stockholm, Sweden
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Pfeifer S, Ackermann F, Sälzer F, Schönhoff M, Roling B. Quantification of cation-cation, anion-anion and cation-anion correlations in Li salt/glyme mixtures by combining very-low-frequency impedance spectroscopy with diffusion and electrophoretic NMR. Phys Chem Chem Phys 2021; 23:628-640. [PMID: 33332521 DOI: 10.1039/d0cp06147f] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Directional correlations between the movements of cations and anions exert a strong influence on the charge and mass transport properties of concentrated battery electrolytes. Here, we combine, for the first time, very-low-frequency impedance spectroscopy on symmetrical Li|electrolyte|Li cells with diffusion and electrophoretic NMR in order to quantify cation-cation, anion-anion and cation-anion correlations in Li salt/tetraglyme (G4) mixtures with Li salt to G4 ratios between 1 : 1 and 1 : 2. We find that all correlations are negative, with like-ion anticorrelations (cation-cation and anion-anion) being generally stronger than cation-anion anticorrelations. In addition, we observe that like-ion anticorrelations are stronger for the heavier type of ion and that all anticorrelations become weaker with decreasing Li salt to G4 ratio. These findings are in contrast to theories considering exclusively anion-cation correlations in form of ion pairs, as the latter imply positive cation-anion correlations. We analyze in detail the influence of anticorrelations on Li+ transference numbers and on the Haven ratio. In order to rationalize our results, we derive linear response theory expressions for all ion correlations. These expressions show that the Li+ ion transport under anion-blocking conditions in a battery is governed by equilibrium center-of-mass fluctuations in the electrolytes. This suggests that in future electrolyte theories and computer simulations, more attention should be paid to equilibrium center-of-mass fluctuations.
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Affiliation(s)
- Sandra Pfeifer
- Department of Chemistry and Center of Materials Science (WZMW), University of Marburg, Hans-Meerwein-Straße 4, D-35032 Marburg, Germany.
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