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Title: The Interplay of Solvation and Polarization Effects on Ion Pairing in Nanoconfined Electrolytes

Journal Article · · Nano Letters

The nature of ion–ion interactions in electrolytes confined to nanoscale pores has important implications for energy storage and separation technologies. However, the physical effects dictating the structure of nanoconfined electrolytes remain debated. Here we employ machine-learning-based molecular dynamics simulations to investigate ion–ion interactions with density functional theory level accuracy in a prototypical confined electrolyte, aqueous NaCl within graphene slit pores. We find that the free energy of ion pairing in highly confined electrolytes deviates substantially from that in bulk solutions, observing a decrease in contact ion pairing but an increase in solvent-separated ion pairing. These changes arise from an interplay of ion solvation effects and graphene’s electronic structure. Notably, the behavior observed from our first-principles-level simulations is not reproduced even qualitatively with the classical force fields conventionally used to model these systems. The insight provided in this work opens new avenues for predicting and controlling the structure of nanoconfined electrolytes.

Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); European Research Council; Engineering and Physical Sciences Research Council
Grant/Contract Number:
SC0012704
OSTI ID:
2469559
Journal Information:
Nano Letters, Journal Name: Nano Letters Journal Issue: 16 Vol. 24; ISSN 1530-6984
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

References (56)

Nanofluidics: A New Arena for Materials Science journal November 2017
Porous Electrode Materials for Lithium-Ion Batteries - How to Prepare Them and What Makes Them Special journal August 2012
Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface journal August 2018
Improved grid-based algorithm for Bader charge allocation journal January 2007
Nanofluidics: what is it and what can we expect from it? journal April 2005
A fast and robust algorithm for Bader decomposition of charge density journal June 2006
Carbon nanotube membranes for water purification: A bright future in water desalination journal March 2014
Mechanisms of lithium selection from mixed LiCl-NaCl solution by nanopores: The synergistic effects of nanoconfinement and electric fields journal May 2023
Machine Learning Force Fields journal March 2021
Ab Initio Molecular Dynamics Investigation of the Solvation States of Hydrated Ions in Confined Water journal October 2023
Free Energy Profile of NaCl in Water: First-Principles Molecular Dynamics with SCAN and ωB97X-V Exchange–Correlation Functionals journal January 2018
PhysNet: A Neural Network for Predicting Energies, Forces, Dipole Moments, and Partial Charges journal April 2019
A Deep Neural Network Potential for Water Confined in Graphene Nanocapillaries journal June 2022
Machine Learning Force Fields: Construction, Validation, and Outlook journal December 2016
Molecular Dynamics of Graphene–Electrolyte Interface: Interfacial Solution Structure and Molecular Diffusion journal October 2019
Insights into Water Permeation through hBN Nanocapillaries by Ab Initio Machine Learning Molecular Dynamics Simulations journal August 2020
Effective Polarization in Pairwise Potentials at the Graphene–Electrolyte Interface journal January 2017
Onsager Transport Coefficients and Transference Numbers in Polyelectrolyte Solutions and Polymerized Ionic Liquids journal October 2020
Nanoscale Confinement Effects on Ionic Conductivity of Solid Polymer Electrolytes: The Interplay between Diffusion and Dissociation journal May 2023
Dehydration as a Universal Mechanism for Ion Selectivity in Graphene and Other Atomically Thin Pores journal July 2017
Ion Structure Transition Enhances Charging Dynamics in Subnanometer Pores journal January 2020
Molecular Dynamics Study of Interfacial Confinement Effects of Aqueous NaCl Brines in Nanoporous Carbon journal August 2010
Kinetic Pathways of Ion Pair Dissociation in Water journal May 1999
Ion Adsorption at the Graphene/Electrolyte Interface journal June 2011
Probing the Structure of Salt Water under Confinement with First-Principles Molecular Dynamics and Theoretical X-ray Absorption Spectroscopy journal September 2012
Graphene-Based Supercapacitor with an Ultrahigh Energy Density journal December 2010
Water Desalination across Nanoporous Graphene journal June 2012
Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene Membranes journal February 2014
Molecular transport through capillaries made with atomic-scale precision journal September 2016
Direct observation of ion dynamics in supercapacitor electrodes using in situ diffusion NMR spectroscopy journal February 2017
Efficient storage mechanisms for building better supercapacitors journal May 2016
Two-dimensional monolayer salt nanostructures can spontaneously aggregate rather than dissolve in dilute aqueous solutions journal September 2021
Rich proton dynamics and phase behaviours of nanoconfined ices journal January 2024
The first-principles phase diagram of monolayer nanoconfined water journal September 2022
Nanofluidics, from bulk to interfaces journal January 2010
Temperature dependence of ion diffusion coefficients in NaCl electrolyte confined within graphene nanochannels journal January 2017
Confinement-enhanced Li+ ion dynamics in an ionic liquid-based electrolyte in porous material journal January 2023
A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu journal April 2010
Accurate and efficient algorithm for Bader charge integration journal February 2011
Perspective: Machine learning potentials for atomistic simulations journal November 2016
When do short-range atomistic machine-learning models fall short? journal January 2021
Interaction confinement and electronic screening in two-dimensional nanofluidic channels journal September 2022
Machine learning potentials for complex aqueous systems made simple journal September 2021
Ion Pairing in Confined Electrolytes journal January 2003
A grid-based Bader analysis algorithm without lattice bias journal January 2009
Charge storage mechanism in nanoporous carbons and its consequence for electrical double layer capacitors
  • Simon, P.; Gogotsi, Y.
  • Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 368, Issue 1923, p. 3457-3467 https://doi.org/10.1098/rsta.2010.0109
journal June 2010
High-dimensional neural-network potentials for multicomponent systems: Applications to zinc oxide journal April 2011
Comment on “Generalized Gradient Approximation Made Simple” journal January 1998
Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins journal August 2017
Ion-capture electrodialysis using multifunctional adsorptive membranes journal April 2021
Modeling of emergent memory and voltage spiking in ionic transport through angstrom-scale slits journal August 2021
Machine learning potentials for extended systems: a perspective journal July 2021
Water Treatment: Are Membranes the Panacea? journal June 2020
Neural Network Potentials: A Concise Overview of Methods journal April 2022
Crumbling Crystals: On the Dissolution Mechanism of NaCl in Water preprint January 2022
To Pair or not to Pair? Machine-Learned Explicitly-Correlated Electronic Structure for NaCl in Water preprint January 2023