Cu ++ and Li+ interaction with polyethylene oxide by ab initio molecular dynamics

Abstract

Equilibrium positions on the Li+–PEO and on the Cu++–PEO ground state potential energy surfaces have been determined by ab initio molecular dynamics. Our results confirm the previously proposed jump mechanism for ion diffusion in polymer electrolytes. The energy barriers for Li+ and Cu++ ionic diffusion along the PEO chain have been estimated.

Boosting Rechargeable Batteries R&D by Multiscale Modeling: Myth or Reality?

“…MD simulations of SPEs are, as for experiments, totally dominated by studies of poly­(ethylene oxide) (PEO)-based electrolytes, − with only a very limited amount of MD simulations of other SPEs published. , For PEO, several specific FFs have been developed, where the torsional parameters have been obtained by fitting analytical expressions to QC calculated data and validated against crystallographic or spectroscopic data. The main effort was taken by Borodin and Smith, who developed a polarizable FF for both pure PEO and LiX-PEO electrolytes validated against both structure factors, dielectric loss, and vs 13 C NMR spin–lattice relaxation times. ,, With the use of these FFs, amorphous linear and branched PEO of different molecular weights systems have been simulated, at different temperatures, and concentrations of 7 different salts, LiCl, LiI, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiClO 4 , and LiTFSI. ,,− This has provided a picture of several fundamental structure–property relationships in PEO-based SPEs (e.g., PEO usually coordinates lithium cation creating loop) that disturbs the normal structure of the polymer and slows down polymer chain motions. Borodin and Smith, however, examined earlier achievements when they showed that Li + motion is subdiffusive in amorphous PEO up to 30–40 ns at ambient temperatures .…”

Conformation Dependence of Electronic Structures of Poly(ethylene oxide)

“…The structure of the polymer alkali salts complexes and its correlation with the ionic transport properties of the PEO based electrolytes have attracted considerable attention. During the past decades, experimental and theoretical works have been extensively dedicated to the geometry and the crystal growth of the pure PEO, − and the PEO conformations in polymer electrolytes. ,− Equally important in this contest is the study of the electronic structure of PEO, which would lead, for example, to a fundamental understanding of the ionic conductivity, by revealing the interactions between polymer and salt at the molecular level. The valence band of the polymer has been studied by valence band photoelectron spectroscopy (VB-PES) and X-ray emission spectroscopy (XES).…”

Li+−(Diglyme)2 and LiClO4−Diglyme Complexes: Barriers to Lithium Ion Migration

“…Recently, there have been a number of theoretical studies − aimed at characterizing the ion−polymer and ion−ion interactions in poly(ethylene oxide) (PEO) based polymer electrolytes. Sutjianto and Curtiss 3 have studied the migration barriers for the lithium cation along a single PEO chain modeled by diglyme [CH 3 (OCH 2 CH 2 ) 2 OCH 3 ].…”

“…They reported transition states for tridentate-to-bidentate coordination and tetradentate-to-tridentate coordination and found barriers of 23 and 20 kcal/mol, respectively. Palma et al used ab initio molecular dynamics with Perdew−Wang generalized approximation density functional theory to study migration of Li + along a single PEO chain model by (CH 2 −CH 2 −O) n , for n = 6, 8, 10, and 20. They found energy barrier heights of 8.5 and 9.7 kcal/mol, but did not report the coordination numbers.…”