Title: Factors Influencing Preferential Anion Interactions during Solvation of Multivalent Cations in Ethereal Solvents

Abstract

Most multivalent secondary batteries have employed electrolytes composed of cyclic ether solvents such as tetrahydrofuran or linear glycol ether solvents (glymes) such as 1,2-dimethoxyethane (G1). A robust understanding of multivalent cation solvation tendencies in these classes of solvents provides insight into corresponding structure–property relationships which, in turn, promotes the design and discovery of improved electrolytes. In this work, our goal is to systematically address how electrolyte constituent properties, namely, ether solvent structure and dication size, direct the solvation interactions of divalent electrolytes and their resultant properties. This study utilizes pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy in conjunction with Raman spectroscopy and ionic conductivity measurements to elucidate the preferential interactions between multivalent cations, anions, and solvent molecules along with their correlated ion dynamics. These investigations incorporate two representative divalent cations (Ca²⁺ and Zn²⁺) as well as two ethereal solvent representatives from both the cyclic ether and glyme structural classes. The results reveal that anions coordinate more readily with divalent cations in cyclic ethers than in glymes. Furthermore, the coordination of the anions with Ca²⁺, i.e., contact-ion pair (CIP) formation is more pronounced than with Zn²⁺ in a glyme solvent of limited chain length (G1), providing insight into cation sizemore » effects that are important for translating solvation behavior across various multivalent electrolytes. Importantly, we find that specific anion coordination is more strongly controlled by solvent structure than by salt concentration in the practical range of 0.1–0.5 M. However, simply reducing these inner-sphere inter-ionic interactions by changing solvent structure does not necessarily de-correlate ionic motion. Instead, concentration-dependent changes in molar ionic conductivity suggest that second-shell interactions, i.e., solvent separated ion pairs (SSIPs), are prevalent in these electrolytes and that the solution dielectric constant, which is increased by the presence of dipolar ion pairs, is critical for controlling these interactions. These findings thus provide a basis for understanding the physical chemistry of multivalent battery electrolytes.« less

Authors:

Han, Kee Sung  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-3535-1818"

Hahn, Nathan T.  ^[2];

• Search DOE PAGES for author "Hahn, Nathan T."
• Search DOE PAGES for ORCID "0000-0001-6187-4068"

Zavadil, Kevin R.  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-3791-424X"

Jaegers, Nicholas R.  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-9930-7672"

Chen, Ying  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-7417-0991"

Hu, Jian Zhi  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-8879-747X"

Murugesan, Vijayakumar  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-6149-1702"

Mueller, Karl T.  ^[1]

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• Search DOE PAGES for ORCID "0000-0001-9609-9516"

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+ Show Author Affiliations

1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Argonne National Lab. (ANL), Lemont, IL (United States). Joint Center for Energy Storage Research (JCESR)
2. Argonne National Lab. (ANL), Lemont, IL (United States). Joint Center for Energy Storage Research (JCESR); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Publication Date:

Thu Mar 11 00:00:00 EST 2021

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1774646

Alternate Identifier(s):

OSTI ID: 1772953

Report Number(s):

PNNL-SA-156316; SAND2021-3360J
Journal ID: ISSN 1932-7447

Grant/Contract Number:  

AC05-76RL01830; NA0003525; AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 125; Journal Issue: 11; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY