Ionic liquids (ILs) are promising electrolytes for high‐performance Li‐ion batteries (LIBs), which can significantly improve the safety and energy storage capacity. Although extensive experimental and computational studies have reported, further exploration is needed to understand the properties of IL systems, their microscopic structures and dynamics, and the behavior of Li ions in ILs. We report here results of molecular dynamics simulations as a function of electric field for Li diffusion in two IL systems, [EMIM][TFSI] and [BMIM][TFSI] doped with various concentrations of LiTFSI. We find that the migration of each individual Li ion depends largely on its micro‐environment, leading to differences by factors of up to 100 in the diffusivity. The structural and dynamical properties indicate that Li diffusion is affected significantly by the coordination and interaction with the oxygen species in the TFSI anions. Moreover, the IL cations also contribute to the Li diffusion mechanism by attenuating the Li–TFSI interaction.
Ionic liquid (IL)‐containing polymers garner attention for electrochemical applications. This article overviews recent experimental and theoretical studies of polymer electrolytes that would be likely to cultivate new theoretical and computational frameworks for IL‐containing polymers. The first two sections outline the uniqueness of ILs that differentiates them from inorganic salts in polymers and explore deviation from the concept of the metaphor “room‐temperature molten salt.” Such distinct properties include (1) large intrinsic dipole moment and electronic polarizability, (2) hydrogen bonding, (3) π‐interactions, (4) a broad distribution of charges over the entire ion, and (5) the anisotropy of the ions. Moreover, the complexity of these properties substantially increases when the ions are polymerized. Indeed, their exceptional features would overcome the hurdle due to a trade‐off between ionic conductivity and mechanical robustness in inorganic salt‐doped polymers. Given these facts, the rest of the article focuses on emerging trends in the study of the dielectric response, phase separation, ion conductivity, and mechanical robustness of the polymer electrolytes, highlighting outstanding observations in experiments that may inspire existing theory and simulation. Our discussion also includes improving computational complexity for IL‐containing polymers. To this end, recent machine learning studies that consider ILs and polymer liquids are presented.
more » « less- Award ID(s):
- 1944211
- NSF-PAR ID:
- 10365120
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science
- Volume:
- 59
- Issue:
- 21
- ISSN:
- 2642-4150
- Page Range / eLocation ID:
- p. 2434-2457
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Single‐ion conducting polymer electrolytes are of interest for use with advanced battery electrodes such as lithium metal, but achieving sufficiently high conductivity has been challenging. In this work, a model system containing charged sites that are precisely spaced along the polymer backbone is explored. Precision sulfonated poly(4‐phenylcyclopentene) lithium salt (
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Computational simulations of ionic liquid solutions have become a useful tool to investigate various physical, chemical and catalytic properties of systems involving these solvents. Classical molecular dynamics and hybrid quantum mechanical/molecular mechanical (QM/MM) calculations of IL systems have provided significant insights at the atomic level. Here, we present a review of the development and application of the multipolar and polarizable force field AMOEBA for ionic liquid systems, termed AMOEBA–IL. The parametrization approach for AMOEBA–IL relies on the reproduction of total quantum mechanical (QM) intermolecular interaction energies and QM energy decomposition analysis. This approach has been used to develop parameters for imidazolium– and pyrrolidinium–based ILs coupled with various inorganic anions. AMOEBA–IL has been used to investigate and predict the properties of a variety of systems including neat ILs and IL mixtures, water exchange reactions on lanthanide ions in IL mixtures, IL–based liquid–liquid extraction, and effects of ILs on an aniline protection reaction.more » « less
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