Pressure evolution and gas solubility of Li-ion battery electrolytes during thermal abuse conditions
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Understanding and controlling the evolution of pressure during thermal events of Li-ion batteries is a key aspect
when assessing the safety of Li-ion batteries. In this study we evaluate the impact of solvent composition, gas
solubility, and conductive salts on the pressure build-up during the exposure of the Li-ion battery electrolytes
to high temperatures.
We employ a vapour–liquid equilibrium model based on the statistical associating fluid theory (SAFT)-𝛾
Mie equation of state, extended to include an ion-pairing model to account for low degrees of salt dissociation
in solvents with a low dielectric constant, such as linear carbonates. The effect of the degradation gases is
accounted for by implementing a gas source mimicking a CO2
evolving reaction.
We find that argon or nitrogen are good choices as inert gases during solvent storage and cell assembly,
as they only gas out slightly during heating, i.e., they cause a negligible increase in pressure. Moreover, linear
carbonates are found to be preferable over their cyclic counterparts regarding battery safety, as the higher
solubility of degradation gases such as CO2
in the electrolytes will mitigate pressure evolution during a thermal
event. The presence of the conductive salt is found not to have a substantial effect on the pressure evolution.
The insights into the sensitivities of the pressure evolution presented here will allow to precisely tailor the
composition of an electrolyte mixture to mitigate safety-critical gas evolution during a thermal event in Li-ion
batteries.
when assessing the safety of Li-ion batteries. In this study we evaluate the impact of solvent composition, gas
solubility, and conductive salts on the pressure build-up during the exposure of the Li-ion battery electrolytes
to high temperatures.
We employ a vapour–liquid equilibrium model based on the statistical associating fluid theory (SAFT)-𝛾
Mie equation of state, extended to include an ion-pairing model to account for low degrees of salt dissociation
in solvents with a low dielectric constant, such as linear carbonates. The effect of the degradation gases is
accounted for by implementing a gas source mimicking a CO2
evolving reaction.
We find that argon or nitrogen are good choices as inert gases during solvent storage and cell assembly,
as they only gas out slightly during heating, i.e., they cause a negligible increase in pressure. Moreover, linear
carbonates are found to be preferable over their cyclic counterparts regarding battery safety, as the higher
solubility of degradation gases such as CO2
in the electrolytes will mitigate pressure evolution during a thermal
event. The presence of the conductive salt is found not to have a substantial effect on the pressure evolution.
The insights into the sensitivities of the pressure evolution presented here will allow to precisely tailor the
composition of an electrolyte mixture to mitigate safety-critical gas evolution during a thermal event in Li-ion
batteries.
Date Issued
2025-06-01
Date Acceptance
2025-02-21
Citation
Journal of Power Sources, 2025, 640
ISSN
0378-7753
Publisher
Elsevier
Journal / Book Title
Journal of Power Sources
Volume
640
Copyright Statement
© 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Subjects
Ar
ASSOCIATING FLUID THEORY
CARBON-DIOXIDE SOLUBILITY
Chemistry
Chemistry, Physical
CO2
DIMETHYL CARBONATE
DIRECTIONAL ATTRACTIVE FORCES
Electrochemistry
Energy & Fuels
EQUATION-OF-STATE
ETHYL METHYL CARBONATE
Gas solubility
Linear/cyclic carbonates
LiPF6
Materials Science
Materials Science, Multidisciplinary
PERTURBATION-THEORY
Physical Sciences
PLUS DIETHYL CARBONATE
PROPYLENE CARBONATE
SAFT-tau Mie
Science & Technology
Technology
THERMODYNAMIC PROPERTIES
Vapour-liquid equilibrium
Publication Status
Published
Article Number
236619
Date Publish Online
2025-03-21