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Sanz Matias A, Roncoroni F, Sundararaman S, Prendergast D. Ca-dimers, solvent layering, and dominant electrochemically active species in Ca(BH 4) 2 in THF. Nat Commun 2024; 15:1397. [PMID: 38360965 PMCID: PMC11258298 DOI: 10.1038/s41467-024-45672-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 02/01/2024] [Indexed: 02/17/2024] Open
Abstract
Divalent ions (Mg, Ca, and Zn) are being considered as competitive, safe, and earth-abundant alternatives to Li-ion electrochemistry, but present challenges for stable cycling due to undesirable interfacial phenomena. We explore the formation of electroactive species in the electrolyte Ca(BH4)2∣THF using molecular dynamics coupled with a continuum model of bulk and interfacial speciation. Free-energy analysis and unsupervised learning indicate a majority population of neutral Ca dimers and monomers with diverse molecular conformations and an order of magnitude lower concentration of the primary electroactive charged species - the monocation, CaBH[Formula: see text] - produced via disproportionation of neutral complexes. Dense layering of THF molecules within ~1 nm of the electrode surface strongly modulates local electrolyte species populations. A dramatic increase in monocation population in this interfacial zone is induced at negative bias. We see no evidence for electrochemical activity of fully-solvated Ca2+. The consequences for performance are discussed in light of this molecular-scale insight.
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Affiliation(s)
- Ana Sanz Matias
- Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Fabrice Roncoroni
- Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Siddharth Sundararaman
- Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - David Prendergast
- Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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2
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Fang C, Mistry A, Srinivasan V, Balsara NP, Wang R. Elucidating the Molecular Origins of the Transference Number in Battery Electrolytes Using Computer Simulations. JACS AU 2023; 3:306-315. [PMID: 36873702 PMCID: PMC9975840 DOI: 10.1021/jacsau.2c00590] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 01/10/2023] [Accepted: 01/24/2023] [Indexed: 05/05/2023]
Abstract
The rate at which rechargeable batteries can be charged and discharged is governed by the selective transport of the working ions through the electrolyte. Conductivity, the parameter commonly used to characterize ion transport in electrolytes, reflects the mobility of both cations and anions. The transference number, a parameter introduced over a century ago, sheds light on the relative rates of cation and anion transport. This parameter is, not surprisingly, affected by cation-cation, anion-anion, and cation-anion correlations. In addition, it is affected by correlations between the ions and neutral solvent molecules. Computer simulations have the potential to provide insights into the nature of these correlations. We review the dominant theoretical approaches used to predict the transference number from simulations by using a model univalent lithium electrolyte. In electrolytes of low concentration, one can obtain a quantitative model by assuming that the solution is made up of discrete ion-containing clusters-neutral ion pairs, negatively and positively charged triplets, neutral quadruplets, and so on. These clusters can be identified in simulations using simple algorithms, provided their lifetimes are sufficiently long. In concentrated electrolytes, more clusters are short-lived and more rigorous approaches that account for all correlations are necessary to quantify transference. Elucidating the molecular origin of the transference number in this limit remains an unmet challenge.
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Affiliation(s)
- Chao Fang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California94720, United States
- Joint
Center for Energy Storage Research, Argonne
National Laboratory, Lemont, Illinois60439, United States
| | - Aashutosh Mistry
- Joint
Center for Energy Storage Research, Argonne
National Laboratory, Lemont, Illinois60439, United States
- Chemical
Sciences and Engineering Division, Argonne
National Laboratory, Lemont, Illinois60439, United States
| | - Venkat Srinivasan
- Joint
Center for Energy Storage Research, Argonne
National Laboratory, Lemont, Illinois60439, United States
- Chemical
Sciences and Engineering Division, Argonne
National Laboratory, Lemont, Illinois60439, United States
| | - Nitash P. Balsara
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California94720, United States
- Joint
Center for Energy Storage Research, Argonne
National Laboratory, Lemont, Illinois60439, United States
| | - Rui Wang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California94720, United States
- Joint
Center for Energy Storage Research, Argonne
National Laboratory, Lemont, Illinois60439, United States
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3
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Melemed AM, Skiba DA, Gallant BM. Toggling Calcium Plating Activity and Reversibility through Modulation of Ca 2+ Speciation in Borohydride-based Electrolytes. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:892-902. [PMID: 35096216 PMCID: PMC8792997 DOI: 10.1021/acs.jpcc.1c09400] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Learning how to tailor Ca2+ speciation and electroactivity is of central importance to engineer next-generation battery electrolytes. Using an exemplar dual-salt electrolyte, Ca(BH4)2 + Ca(TFSI)2 in THF, this work examines how to modulate a critical parameter proposed to govern electroactivity, the BH4 -/Ca2+ ratio. Introduction of a more-dissociating source of Ca2+ via Ca(TFSI)2 drives re-speciation of strongly ion-paired Ca(BH4)2, confirmed by ionic conductivity, Raman spectroscopy, and reaction microcalorimetry measurements, generating larger populations of charged species and enhancing plating currents. Ca plating is possible when [Ca(TFSI)2] < [Ca(BH4)2] and thus BH4 -/Ca2+ >1, but a dramatic shut-down of plating activity occurs when [Ca(TFSI)2] > [Ca(BH4)2] (BH4 -/Ca2+ <1), directly evidencing the significance of coordination-shell chemistry on plating activity. Ca(BH4)2 + TBABH4 in THF, which enables enrichment of BH4 - concentrations compared to Ca2+, is also examined; ionic conductivity and plating currents also increase compared to Ca(BH4)2/THF, with the latter related in part to a decrease in solution resistance. These findings delineate future directions to modulate Ca2+ coordination towards achieving both high plating activity and reversibility.
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Affiliation(s)
- Aaron M. Melemed
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Dhyllan A. Skiba
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Betar M. Gallant
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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4
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Su L, Gao X, Mariani A, Liu X, Passerini S, Gao Y, Zheng L. Molecular Insight into Microstructural and Dynamical Heterogeneities in Magnesium Ionic Liquid Electrolytes. J Phys Chem Lett 2022; 13:105-111. [PMID: 34962126 DOI: 10.1021/acs.jpclett.1c03605] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ionic liquids (ILs) are promising designer solvents for multivalent electrolytes, enabling the modulation of molecular-level interactions of solvate species. The molecular mechanism of multivalent-ion clustering and its impact on electrolytes properties is far less studied than that of ion pairs. Herein, we explore the effect of ion clusters on the transport and electrochemical behavior of IL-based electrolytes for Mg batteries. Simulation and small-angle X-ray scattering results indicate that ILs with higher denticity effectively suppress ion agglomeration and parasitic reactions of the Mg electrolytes. Although ion clustering reduces the diffusivity of Mg2+, the Coulombic efficiency for the reversible Mg deposition/stripping process is improved, highlighting the importance of microstructural and dynamical heterogeneities in the rational design of enhanced multivalent electrolytes.
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Affiliation(s)
- Long Su
- Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, 250100, P. R. China
| | - Xinpei Gao
- Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Hainan University, No 58, Renmin Avenue, Haikou 570228, P. R. China
| | - Alessandro Mariani
- Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081 Ulm, Germany
- Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Xu Liu
- Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081 Ulm, Germany
- Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Stefano Passerini
- Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081 Ulm, Germany
- Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Yanan Gao
- Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Hainan University, No 58, Renmin Avenue, Haikou 570228, P. R. China
| | - Liqiang Zheng
- Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, 250100, P. R. China
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5
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Hahn NT, Self J, Driscoll DM, Dandu N, Han KS, Murugesan V, Mueller KT, Curtiss LA, Balasubramanian M, Persson KA, Zavadil KR. Concentration-dependent ion correlations impact the electrochemical behavior of calcium battery electrolytes. Phys Chem Chem Phys 2021; 24:674-686. [PMID: 34908060 DOI: 10.1039/d1cp04370f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ion interactions strongly determine the solvation environments of multivalent electrolytes even at concentrations below that required for practical battery-based energy storage. This statement is particularly true of electrolytes utilizing ethereal solvents due to their low dielectric constants. These solvents are among the most commonly used for multivalent batteries based on reactive metals (Mg, Ca) due to their reductive stability. Recent developments in multivalent electrolyte design have produced a variety of new salts for Mg2+ and Ca2+ that test the limits of weak coordination strength and oxidative stability. Such electrolytes have great potential for enabling full-cell cycling of batteries based on these working ions. However, the ion interactions in these electrolytes exhibit significant and non-intuitive concentration relationships. In this work, we investigate a promising exemplar, calcium tetrakis(hexafluoroisopropoxy)borate (Ca(BHFIP)2), in the ethereal solvents 1,2-dimethoxyethane (DME) and tetrahydrofuran (THF) across a concentration range of several orders of magnitude. Surprisingly, we find that effective salt dissociation is lower at relatively dilute concentrations (e.g. 0.01 M) than at higher concentrations (e.g. 0.2 M). Combined experimental and computational dielectric and X-ray spectroscopic analyses of the changes occurring in the Ca2+ solvation environment across these concentration regimes reveals a progressive transition from well-defined solvent-separated ion pairs to de-correlated free ions. This transition in ion correlation results in improvements in both conductivity and calcium cycling stability with increased salt concentration. Comparison with previous findings involving more strongly associating salts highlights the generality of this phenomenon, leading to important insight into controlling ion interactions in ether-based multivalent battery electrolytes.
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Affiliation(s)
- Nathan T Hahn
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Material, Physical and Chemical Sciences Center, Sandia National Laboratories, Albuquerque, NM 87185, USA.
| | - Julian Self
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 60439, USA.,Department of Materials Science and Engineering, UC Berkeley, CA 94720, USA
| | - Darren M Driscoll
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Naveen Dandu
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Kee Sung Han
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Vijayakumar Murugesan
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Karl T Mueller
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Larry A Curtiss
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Mahalingam Balasubramanian
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Kristin A Persson
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Department of Materials Science and Engineering, UC Berkeley, CA 94720, USA.,Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Kevin R Zavadil
- Joint Center for Energy Storage Research, Lemont, IL, 60439, USA.,Material, Physical and Chemical Sciences Center, Sandia National Laboratories, Albuquerque, NM 87185, USA.
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6
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Wang H, Ryu J, Shao Y, Murugesan V, Persson K, Zavadil K, Mueller KT, Liu J. Advancing Electrolyte Solution Chemistry and Interfacial Electrochemistry of Divalent Metal Batteries. ChemElectroChem 2021. [DOI: 10.1002/celc.202100484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Hui Wang
- Energy & Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Jaegeon Ryu
- Energy & Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Yuyan Shao
- Energy & Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Vijayakumar Murugesan
- Physical and Computational Sciences Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Kristin Persson
- Energy Technologies Area Lawrence Berkeley National Laboratory Berkeley, California 94720 United States
- Department of Materials Science and Engineering University of California, Berkeley Berkeley California 94720 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Kevin Zavadil
- Material, Physical, and Chemical Sciences Sandia National Laboratories Albuquerque New Mexico 87185 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Karl T. Mueller
- Physical and Computational Sciences Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
- Joint Center for Energy Storage Research (JCESR) Lemont Illinois 60439 United States
| | - Jun Liu
- Energy & Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 United States
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