Ion Pairing and Redissociaton in Low-Permittivity Electrolytes for Multivalent Battery Applications
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- Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Detailed speciation of electrolytes as a function of chemical system and concentration provides the foundation for understanding bulk transport as well as possible decomposition mechanisms. In particular, multivalent electrolytes have shown a strong coupling between anodic stability and solvation structure. Furthermore, solvents that are found to exhibit reasonable stability against alkaline-earth metals generally exhibit low permittivity, which typically increases the complexity of the electrolyte species. To improve our understanding of ionic population and associated transport in these important classes of electrolytes, the speciation of Mg(TFSI)2 in monoglyme and diglyme systems is studied via a multiscale thermodynamic model using first-principles calculations for ion association and molecular dynamics simulations for dielectric properties. The results are then compared to Raman and dielectric relaxation spectroscopies, which independently confirm the modeling insights. We find that the significant presence of free ions in the low-permittivity glymes in the concentration range from 0.02 to 0.6 M is well-explained by the low-permittivity redissociation hypothesis. Here, salt speciation is largely dictated by long-range electrostatics, which includes permittivity increases due to polar contact ion pairs. The present results suggest that other low-permittivity multivalent electrolytes may also reach high conductivities as a result of redissociation.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC04-94AL85000; AC02-05CH11231
- OSTI ID:
- 1630283
- Alternate ID(s):
- OSTI ID: 1765557
- Report Number(s):
- SAND-2020-5025J; 686057
- Journal Information:
- Journal of Physical Chemistry Letters, Vol. 11, Issue 6; ISSN 1948-7185
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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