Assessment of Simple Models for Molecular Simulation of Ethylene Carbonate and Propylene Carbonate as Solvents for Electrolyte Solutions

Abstract

Progress in understanding liquid ethylene carbonate (EC) and propylene carbonate (PC) on the basis of molecular simulation, emphasizing simple models of interatomic forces, is reviewed. Results on the bulk liquids are examined from the perspective of anticipated applications to materials for electrical energy storage devices. Preliminary results on electrochemical double-layer capacitors based on carbon nanotube forests and on model solid-electrolyte interphase (SEI) layers of lithium ion batteries are considered as examples. The basic results discussed suggest that an empirically parameterized, non-polarizable force field can reproduce experimental structural, thermodynamic, and dielectric properties of EC and PC liquids with acceptable accuracy. More sophisticated force fields might include molecular polarizability and Buckingham-model description of inter-atomic overlap repulsions as extensions to Lennard-Jones models of van der Waals interactions. Simple approaches should be similarly successful also for applications to organic molecular ions in EC/PC solutions, but the important case of Li deserves special attention because of the particularly strong interactions of that small ion with neighboring solvent molecules. To treat the Li ions in liquid EC/PC solutions, we identify interaction models defined by empirically scaled partial charges for ion-solvent interactions. The empirical adjustments use more basic inputs, electronic structure calculations and ab initio molecular dynamics simulations, and also experimental results on Li thermodynamics and transport in EC/PC solutions. Application of such models to the mechanism of Li transport in glassy SEI models emphasizes the advantage of long time-scale molecular dynamics studies of these non-equilibrium materials.

Solvent and Salt Effect on Lithium Ion Solvation and Contact Ion Pair Formation in Organic Carbonates: A Quantum Chemical Perspective

“…Note however that, as in the case of mixed EC/PC clusters, Li + (PC)4 is more stable than the mixed structures. These findings are also in agreement with recent experimental studies by Seo et al31 .The structural properties of Li + (EC)n(PC)m and Li + (PC)n(DMC)m clusters (with m+n=4)…”

“…Although several experimental and theoretical works have focused on systems formed by pure EC, PC and DMC with the Li + ion [24][25][26][27][28][29][30][31] , solvation structure and dynamics of the cation in these solvents is still a subject of debate. More in details, Density Functional Theory (DFT) studies have shown that a (four-coordinated) tetrahedral geometry Li + (EC)4, is the dominant species [32][33][34] .…”

Structural and Transport Properties of Li/S Battery Electrolytes: Role of the Polysulfide Species

“…Our simulation results of PS solutions reveal that structural and transport properties are subject to subtle interactions among ions and solvents molecules, which should be considered carefully when it comes to the design of electrolytes for Li/S batteries. 80 In the next step, studies on different types of anions in Li/PS solutions 81 as well as in confining electrode materials are envisioned.…”

Preparation of electrospun nanofibrous polycaprolactone scaffolds using nontoxic ethylene carbonate and glacial acetic acid solvent system

“…Moreover, the use of EC has been seldom reported in electrospinning process, probably due to its high boiling point of 248 °C . On the other hand, EC exhibits high dielectric constant (89.6 F/m) (see Supporting Information Table S1), which may play an important role in generating charges on the surface of the polymer solution during the electrospinning process . Several works have been focused on the use of high dielectric constant solvents as supplementary elements to produce finer fibers .…”