The known-unknowns of anomalous underscreening in concentrated electrolytes

Elliott, Gareth R.; Gregory, Kasimir P.; Robertson, Hayden; Craig, Vincent S.J.; Webber, Grant B.; Wanless, Erica J.; Page, Alister J.

doi:10.1016/j.cplett.2024.141190

Cited by 9 publications

(1 citation statement)

References 288 publications

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“…These interactions are purported to result in the formation of distinct, identifiable and persistent species in solution known as ion pairs, which have become an a priori explanation for many electrolyte phenomena, such as deviations from Nernst–Einstein conductivity behavior, activity coefficients, and anomalous underscreening. ,, Nevertheless, there is as yet no consensus regarding the degree of ion pairing in any particular electrolyte. The existence of ion pairing in electrolytes has been discussed extensively in the literature, as reviewed by Marcus and van der Vegt, however the effect of ion pairing in determining macroscopic properties of electrolytes is debated. , Conversely, ions in electrolytes have been suggested to exhibit correlations on the order of several nanometres and collective plasma-like behavior that cannot be explained via ion pairing.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes

Elliott,

Wanless,

Webber

et al. 2024

J. Phys. Chem. B

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Electrolytes are central to many technological applications, as well as life itself. The behavior and properties of electrolytes are often described in terms of ion pairs, whereby ions associate as either contact ion pairs (in which ions are "touching") solvent-separated ion pairs (in which ions' solvent shells overlap) or solvent−solvent-separated ion pairs (in which ions' solvent shells are distinct). However, this paradigm is generally restricted to statistically averaged descriptions of solution structure and ignores temporal behavior. Here we elucidate the time-resolved dynamics of these ion−ion interactions in aqueous metal chloride electrolytes using the partial van Hove correlation function, based on polarizable molecular dynamics simulations. Our results show that the existence and persistence of ion pairs in aqueous metal chloride electrolytes should not be assumed a priori, but in fact are ion specific features of the solution with lifetimes on subpicosecond time scales.

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Section: Introductionmentioning

confidence: 99%

Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes

Elliott,

Wanless,

Webber

et al. 2024

J. Phys. Chem. B

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Reentrant Condensation of Polyelectrolytes Induced by Diluted Multivalent Salts: The Role of Electrostatic Gluonic Effects

Yong

2024

Biomacromolecules

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We explore the reentrant condensation of polyelectrolytes triggered by multivalent salts, whose phase-transition mechanism remains under debate. We propose a theory to study the reentrant condensation, which separates the electrostatic effect into two parts: a short-range electrostatic gluonic effect because of sharing of multivalent ions by ionic monomers and a long-range electrostatic correlation effect from all ions. The theory suggests that the electrostatic gluonic effect governs reentrant condensation, requiring a minimum coupling energy to initiate the phase transition. This explains why diluted salts with selective multivalency trigger a polyelectrolyte phase transition. The theory also uncovers that strong adsorption of multivalent ions onto ionic monomers causes low-salt concentrations to induce both collapse and reentry transitions. Additionally, we highlight how the incompatibility of uncharged polyelectrolyte moieties with water affects the polyelectrolyte phase behaviors. The obtained results will contribute to the understanding of biological phase separations if multivalent ions bound to biopolyelectrolytes play an essential role.

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The Polarity of Co-solvents Regulates the Charge Storage Mechanisms in Supercapacitors with Concentrated Electrolytes

Martins,

Wang,

Dai

et al. 2024

J. Phys. Chem. Lett.

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Developing better energy storage devices depends on comprehending the underlying mechanisms involved in charge storage. With the continuous conception of new electrolytes, this task becomes progressively more urgent and complex. An example is the utilization of co-solvated concentrated solutions. While these show promising electrochemical responses, their dynamic properties (especially under confinement) and their relationships with performance are not fully understood. Here, we combined modified step potential electrochemical spectroscopy and quasielastic neutron scattering to investigate systems composed of activated mesoporous carbon (AMC) and concentrated solutions of lithium bis-(trifluoromethanesulfonyl)imide in acetonitrile co-solvated with either toluene or acetone. We report that acetone does not impair surface-controlled mechanisms, contrary to the case with toluene, which competes with charged species to populate the AMC's pores without contributing to charge storage. In turn, toluene promotes a greater overall capacitance owing to Faradaic processes, which may be related to changes in the solvation structures under confinement.

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The known-unknowns of anomalous underscreening in concentrated electrolytes

Cited by 9 publications

References 288 publications

Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes

Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes

Reentrant Condensation of Polyelectrolytes Induced by Diluted Multivalent Salts: The Role of Electrostatic Gluonic Effects

The Polarity of Co-solvents Regulates the Charge Storage Mechanisms in Supercapacitors with Concentrated Electrolytes

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