Molecular Dynamics Simulations of Lithium-Doped Ionic-Liquid Electrolytes
Promit Ray1, Andrea Balducci, Barbara Kirchner1
1Mulliken Center for Theoretical Chemistry , Rheinische Friedrich-Wilhelms-Universität Bonn , Beringstr. 4+6 , D-53115 Bonn , Germany.
The Journal of Physical Chemistry. B
|October 27, 2018
Summary
Ionic liquids doped with lithium bis(trifluoromethanesulfonyl)imide show promise for lithium-ion batteries. Lithium ion mobility and transport correlate with interionic interactions, while solvation ease shows inverse trends.
Area of Science:
- Materials Science
- Electrochemistry
- Computational Chemistry
Background:
- Ionic liquids (ILs) containing lithium bis(trifluoromethanesulfonyl)imide (LiNTf2) are explored as advanced electrolytes for lithium-ion batteries.
- Understanding the structure-property relationships of these ILs is crucial for optimizing battery performance.
Purpose of the Study:
- To investigate the impact of different heterocyclic ammonium cations and LiNTf2 concentrations on the structural and dynamic properties of IL-based electrolytes.
- To elucidate the correlation between interionic interactions, solvation, and lithium ion transport in these systems.
Main Methods:
- Scaled-charge molecular dynamics simulations were employed to study four model ILs with varying LiNTf2 concentrations (0-1 M).
- The study examined pyrrolidinium, piperidinium, N-butyl-pyrrolidinium, and N-butyl-N-methyl-pyrrolidinium cations to assess effects of ring size and N-alkylation.
- Analysis included lithium coordination shells, ion bridging, aggregate formation, and velocity autocorrelation functions.
Main Results:
- Distinct lithium coordination shells and Li+-NTf2- bridging networks were observed across the different IL systems.
- [NTf2]- anions create a caging effect around lithium ions, influencing their mobility.
- Lithium ion mobility and transport were found to be directly proportional to the strength of interionic interactions.
Conclusions:
- The choice of cation significantly alters the liquid structure and lithium ion solvation in LiNTf2-doped ILs.
- Stronger interionic interactions enhance lithium ion mobility and transport, but reduce solvation ease.
- These findings provide insights for designing next-generation electrolytes for high-performance lithium-ion batteries.
Related Concept Videos
02:54Molecular and Ionic Solids
20.1K
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
20.1K
02:21Electrolyte and Nonelectrolyte Solutions
71.9K
Substances that undergo either a physical or a chemical change in solution to yield ions that can conduct electricity are called electrolytes. If a substance yields ions in solution, that is, if the compound undergoes 100% dissociation, then the substance is a strong electrolyte. Complete dissociation is indicated by a single forward arrow. For example, water-soluble ionic compounds like sodium chloride dissociate into sodium cations and chloride anions in aqueous solution.
71.9K
03:10Ionic Radii
33.5K
Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it is smaller than the atom from which it is derived. For example, the covalent radius of an aluminum atom (1s22s22p63s23p1) is 118 pm, whereas the ionic radius of an Al3+ (1s22s22p6) is 68 pm. As electrons are removed from the outer valence shell, the remaining core electrons occupying smaller shells experience a greater effective nuclear...
33.5K
02:55Solubility of Ionic Compounds
68.2K
Solubility is the measure of the maximum amount of solute that can be dissolved in a given quantity of solvent at a given temperature and pressure. Solubility is usually measured in molarity (M) or moles per liter (mol/L). A compound is termed soluble if it dissolves in water.
68.2K
02:48Ionic Bonding and Electron Transfer
49.1K
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
49.1K
03:08Electrolytes: van't Hoff Factor
36.6K
Colligative Properties of Electrolytes
The colligative properties of a solution depend only on the number, not on the identity, of solute species dissolved. The concentration terms in the equations for various colligative properties (freezing point depression, boiling point elevation, osmotic pressure) pertain to all solute species present in the solution. Nonelectrolytes dissolve physically without dissociation or any other accompanying process. Each molecule that dissolves yields one...
The colligative properties of a solution depend only on the number, not on the identity, of solute species dissolved. The concentration terms in the equations for various colligative properties (freezing point depression, boiling point elevation, osmotic pressure) pertain to all solute species present in the solution. Nonelectrolytes dissolve physically without dissociation or any other accompanying process. Each molecule that dissolves yields one...
36.6K