Sigma-Holes in Battery Materials Using Iso-Electrostatic Potential Surfaces

Abstract

Abstract:The presence of highly electronegative atoms in Li-ion batteries anticipates the formation of σ-hole regions that may strongly affect the ionic conductivity. The σ-hole consists of a region of positive electrostatic potential extending in the direction of the covalent bond between atoms of groups IV-VII due to anisotropic charge distribution. Graphite electrodes in Li-ion batteries that become halogenated due to the electrolyte, as well as some solid electrolyte materials, can exhibit these σ-holes. Since Li-ions should be able to drift in any part of the battery, the fact that they can be attracted and eventually absorbed by regions of strong negative potentials produced by high-electronegativity counterions becomes detrimental to ionic conductivity. Therefore, the presence of positive well-defined regions, repulsive to the Li-ions, might act as lubricant for Li-ions drifting through electrolytes, thus improving the Li-ion conductivity. In addition, the σ-holes might also have a strong effect on the formation of the passivating layer, known as the solid electrolyte interphase (SEI) at electrode surfaces, which is of paramount importance for the performance of rechargeable batteries. Here we investigate the existence of σ-holes on surfaces of graphite anodes and of a few solid electrolytes by examining the electrostatic potentials calculated using density functional theory.

Unveiling the First Nucleation and Growth Steps of Inorganic Solid Electrolyte Interphase Components

“…Thus, a low electrostatic potential (the most negative value) indicates the relative electron abundance and vice versa. The main purposes of determining the EPS is to figure out the reactive sites of a molecule and then to be able to predict the growth mechanism and even the most reactive surface orientation of the cluster to be favorably adsorbed on the electrode surface or prone to attract other monomers or clusters, thus favoring their nucleation …”

“…predict the growth mechanism and even the most reactive surface orientation of the cluster to be favorably adsorbed on the electrode surface or prone to attract other monomers or clusters, thus favoring their nucleation. 77 Figure 7 shows a calculated 3D electrostatic potential of open-cage LiF and Li 2 CO 3 clusters of various sizes. We considered only the negative electrostatic potential as it corresponds to the nucleophilic sites of the system.…”

Solid electrolyte interphase formation between the Li0.29La0.57TiO3solid-state electrolyte and a Li-metal anode: anab initiomolecular dynamics study

“…17 For that reason, interfacial studies are a priority to determine if a material can be a potential SSE. 18 The SSE must have a large electrochemical window and thermal stability at the interface with the lithium metal anode, assuring a controlled plating and stripping of lithium atoms in the anode. Therefore, computational tools such as density functional theory (DFT) calculations, classical molecular dynamics (CMD), and ab initio molecular dynamics (AIMD) allow us to study these interfaces in a detailed localized mode, 19 including their morphology, composition, electrochemical, and thermal interfacial reactivity, complementing and expanding experimental information as some of these information cannot be obtained experimentally.…”

A phenyl S–Te bond with unique redox activity in dilute electrolyte of a lithium battery

“…Considering that highly electronegative atoms may in general be detrimental to ion conductivity, 26 we might have expected a strong dependence of the electrochemical performance of PhS-TePh on the concentration of Li + . Therefore, we prepared a range of electrolytes containing different concentrations of lithium salts.…”