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Wang LX, Sun C, Huang SL, Kang B, Chen HY, Xu JJ. Single-Particle Imaging Reveals the Electrical Double-Layer Modulated Ion Dynamics at Crowded Interface. NANO LETTERS 2024; 24:9743-9749. [PMID: 39072414 DOI: 10.1021/acs.nanolett.4c02678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The dynamics of ion transport at the interface is the critical factor for determining the performance of an electrochemical energy storage device. While practical applications are realized in concentrated electrolytes and nanopores, there is a limited understanding of their ion dynamic features. Herein, we studied the interfacial ion dynamics in room-temperature ionic liquids by transient single-particle imaging with microsecond-scale resolution. We observed slowed-down dynamics at lower potential while acceleration was observed at higher potential. Combined with simulation, we found that the microstructure evolution of the electric double layer (EDL) results in potential-dependent kinetics. Then, we established a correspondence between the ion dynamics and interfacial ion composition. Besides, the ordered ion orientation within EDL is also an essential factor for accelerating interfacial ion transport. These results inspire us with a new possibility to optimize electrochemical energy storage through the good control of the rational design of the interfacial ion structures.
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Affiliation(s)
- Lu-Xuan Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Chao Sun
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Sheng-Lan Huang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Bin Kang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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Monteiro HBN, Tartakovsky DM. A meshless stochastic method for Poisson-Nernst-Planck equations. J Chem Phys 2024; 161:054106. [PMID: 39087897 DOI: 10.1063/5.0223018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Accepted: 07/16/2024] [Indexed: 08/02/2024] Open
Abstract
A plethora of biological, physical, and chemical phenomena involve transport of charged particles (ions). Its continuum-scale description relies on the Poisson-Nernst-Planck (PNP) system, which encapsulates the conservation of mass and charge. The numerical solution of these coupled partial differential equations is challenging and suffers from both the curse of dimensionality and difficulty in efficiently parallelizing. We present a novel particle-based framework to solve the full PNP system by simulating a drift-diffusion process with time- and space-varying drift. We leverage Green's functions, kernel-independent fast multipole methods, and kernel density estimation to solve the PNP system in a meshless manner, capable of handling discontinuous initial states. The method is embarrassingly parallel, and the computational cost scales linearly with the number of particles and dimension. We use a series of numerical experiments to demonstrate both the method's convergence with respect to the number of particles and computational cost vis-à-vis a traditional partial differential equation solver.
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Affiliation(s)
- Henrique B N Monteiro
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, USA
| | - Daniel M Tartakovsky
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, USA
- Department of Energy Science and Engineering, Stanford University, Stanford, California 94305, USA
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Nigam R, Kar KK. Effect of Mixed Morphology (Simple Cubic, Face-Centered Cubic, and Body-Centered Cubic)-Based Electrodes on the Electric Double Layer Capacitance of Supercapacitors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:14266-14280. [PMID: 38941262 DOI: 10.1021/acs.langmuir.4c00664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/30/2024]
Abstract
Supercapacitors store energy due to the formation of an electric double layer (EDL) at the interface of the electrodes and electrolyte. The present article deals with the finite element study of equilibrium electric double layer capacitance (EDLC) in the mixed morphology electrodes comprising all three fundamental crystal structures, simple cubic (SC), body-centered cubic (BCC), and face-centered cubic morphologies (FCC). Mesoporous-activated carbon forms the electrode in the supercapacitor with (C2H5)4NBF4/propylene carbonate organic electrolyte. Electrochemical interference is clearly demonstrated in the supercapacitors with the formation of the potential bands, as in the case of interference theory due to the increasing packing factor. The effects of electrode thickness varying from a wide range of 50 nm to 0.04 mm on specific EDLC have been discussed in detail. The interfacial geometry of the unit cell in contact with the electrolyte is the most important parameter determining the properties of the EDL. The critical thickness of the electrodes is 1.71 μm in all the morphologies. Polarization increases the interfacial potential and leads to EDL formation. The Stern layer specific capacitance is 167.6 μF cm-2 in all the morphologies. The maximum capacitance is in the decreasing order of interfacial geometry, as FCC > BCC > SC, dependent on the packing factor. The minimum transmittance in all the morphologies is 98.35%, with the constant figure of merit at higher electrode thickness having applications in the chip interconnects. The transient analysis shows that the interfacial current decreases with increasing polarization in the EDL. The capacitance also decreases with the increase of the scan rate.
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Affiliation(s)
- Ravi Nigam
- Advanced Nanoengineering Materials Laboratory, Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Kamal K Kar
- Advanced Nanoengineering Materials Laboratory, Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016, India
- Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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Wang LX, Huang SL, Wu P, Liu XR, Sun C, Kang B, Chen HY, Xu JJ. Tracking Ion Transport in Nanochannels via Transient Single-Particle Imaging. Angew Chem Int Ed Engl 2023; 62:e202315805. [PMID: 37973617 DOI: 10.1002/anie.202315805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/05/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023]
Abstract
The transport behavior of ions in the nanopores has an important impact on the performance of the electrochemical devices. Although the classical Transmission-Line (TL) model has long been used to describe ion transport in pores, the boundary conditions for the applicability of the TL model remain controversial. Here, we investigated the transport kinetics of different ions, within nanochannels of different lengths, by using transient single-particle imaging with temporal resolution up to microseconds. We found that the ion transport kinetics within short nanochannels may deviate significantly from the TL model. The reason is that the ion transport under nanoconfinement is composed of multi basic stages, and the kinetics differ much under different stage domination. With the shortening of nanochannels, the electrical double layer (EDL) formation would become the "rate-determining step" and dominate the apparent ion kinetics. Our results imply that using the TL model directly and treating the in-pore mobility as an unchanged parameter to estimate the ion transport kinetics in short nanopores/nanochannels may lead to orders of magnitude bias. These findings may advance the understanding of the nanoconfined ion transport and promote the related applications.
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Affiliation(s)
- Lu-Xuan Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Sheng-Lan Huang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Pei Wu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Xiao-Rui Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Chao Sun
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Bin Kang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
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Mo T, He H, Zhou J, Zeng L, Long Y, Feng G. Molecular Understanding of Charging Dynamics in Supercapacitors with Porous Electrodes and Ionic Liquids. J Phys Chem Lett 2023; 14:11258-11267. [PMID: 38060214 DOI: 10.1021/acs.jpclett.3c02561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Porous electrodes and ionic liquids could significantly enhance the energy storage of supercapacitors. However, they may reduce the charging dynamics and power density due to the nanoconfinement of porous electrodes and the high viscosity of ionic liquids. A comprehensive understanding of the charging mechanism in porous supercapacitors with ionic liquids provides a crucial theoretical foundation for their design optimization. Here, we review the progress of molecular simulations of the charging dynamics in supercapacitors consisting of porous electrodes and ionic liquids. We highlight and delve into the breakthroughs in the ion transport and charging mechanism for electrodes with subnanometer pores and realistic porous structures. We also discuss future directions for the charging dynamics of supercapacitors.
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Affiliation(s)
- Tangming Mo
- School of Mechanical Engineering, Guangxi University, Nanning, Guangxi 530004, China
- State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Guangxi University, Nanning, Guangxi 530004, China
| | - Haoyu He
- School of Mechanical Engineering, Guangxi University, Nanning, Guangxi 530004, China
| | - Jianguo Zhou
- School of Mechanical Engineering, Guangxi University, Nanning, Guangxi 530004, China
| | - Liang Zeng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, China
| | - Yu Long
- School of Mechanical Engineering, Guangxi University, Nanning, Guangxi 530004, China
- State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Guangxi University, Nanning, Guangxi 530004, China
| | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, China
- Institute of Interdisciplinary Research for Mathematics and Applied Science, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, China
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Zhang Z, Faez S. Iontronic microscopy of a tungsten microelectrode: "seeing" ionic currents under an optical microscope. Faraday Discuss 2023; 246:426-440. [PMID: 37404127 PMCID: PMC10568260 DOI: 10.1039/d3fd00040k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/27/2023] [Indexed: 07/06/2023]
Abstract
Optical methods for monitoring electrochemical reactions at an interface are advantageous because of their table-top setup and ease of integration into reactors. Here we apply EDL-modulation microscopy to one of the main components of amperometric measurement devices: a microelectrode. We present experimental measurements of the EDL-modulation contrast from the tip of a tungsten microelectrode at various electrochemical potentials inside a ferrocene-dimethanol Fe(MeOH)2 solution. Using the combination of the dark-field scattering microscope and the lock-in detection technique, we measure the phase and amplitude of local ion-concentration oscillations in response to an AC potential as the electrode potential is scanned through the redox-activity window of the dissolved species. We present the amplitude and phase map of this response, as such this method can be used to study the spatial and temporal variations of the ion-flux due to an electrochemical reaction close to metallic and semiconducting objects of general geometry. We discuss the advantages and possible extensions of using this microscopy method for wide-field imaging of ionic currents.
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Affiliation(s)
- Zhu Zhang
- Nanophotonics, Debye Institute for Nanomaterials Science, Utrecht University, 3584CC Utrecht, The Netherlands.
| | - Sanli Faez
- Nanophotonics, Debye Institute for Nanomaterials Science, Utrecht University, 3584CC Utrecht, The Netherlands.
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Kondrat S, Feng G, Bresme F, Urbakh M, Kornyshev AA. Theory and Simulations of Ionic Liquids in Nanoconfinement. Chem Rev 2023; 123:6668-6715. [PMID: 37163447 DOI: 10.1021/acs.chemrev.2c00728] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Room-temperature ionic liquids (RTILs) have exciting properties such as nonvolatility, large electrochemical windows, and remarkable variety, drawing much interest in energy storage, gating, electrocatalysis, tunable lubrication, and other applications. Confined RTILs appear in various situations, for instance, in pores of nanostructured electrodes of supercapacitors and batteries, as such electrodes increase the contact area with RTILs and enhance the total capacitance and stored energy, between crossed cylinders in surface force balance experiments, between a tip and a sample in atomic force microscopy, and between sliding surfaces in tribology experiments, where RTILs act as lubricants. The properties and functioning of RTILs in confinement, especially nanoconfinement, result in fascinating structural and dynamic phenomena, including layering, overscreening and crowding, nanoscale capillary freezing, quantized and electrotunable friction, and superionic state. This review offers a comprehensive analysis of the fundamental physical phenomena controlling the properties of such systems and the current state-of-the-art theoretical and simulation approaches developed for their description. We discuss these approaches sequentially by increasing atomistic complexity, paying particular attention to new physical phenomena emerging in nanoscale confinement. This review covers theoretical models, most of which are based on mapping the problems on pertinent statistical mechanics models with exact analytical solutions, allowing systematic analysis and new physical insights to develop more easily. We also describe a classical density functional theory, which offers a reliable and computationally inexpensive tool to account for some microscopic details and correlations that simplified models often fail to consider. Molecular simulations play a vital role in studying confined ionic liquids, enabling deep microscopic insights otherwise unavailable to researchers. We describe the basics of various simulation approaches and discuss their challenges and applicability to specific problems, focusing on RTIL structure in cylindrical and slit confinement and how it relates to friction and capacitive and dynamic properties of confined ions.
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Affiliation(s)
- Svyatoslav Kondrat
- Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
- Institute for Computational Physics, University of Stuttgart, Stuttgart 70569, Germany
| | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
- Nano Interface Centre for Energy, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Fernando Bresme
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, London W12 0BZ,United Kingdom
- Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
- London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, United Kingdom
| | - Michael Urbakh
- School of Chemistry and the Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Alexei A Kornyshev
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, London W12 0BZ,United Kingdom
- Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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Ratschow AD, Pandey D, Liebchen B, Bhattacharyya S, Hardt S. Resonant Nanopumps: ac Gate Voltages in Conical Nanopores Induce Directed Electrolyte Flow. PHYSICAL REVIEW LETTERS 2022; 129:264501. [PMID: 36608199 DOI: 10.1103/physrevlett.129.264501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/27/2022] [Accepted: 11/10/2022] [Indexed: 06/17/2023]
Abstract
Inducing transport in electrolyte-filled nanopores with dc fields has led to influential applications ranging from nanosensors to DNA sequencing. Here we use the Poisson-Nernst-Planck and Navier-Stokes equations to show that unbiased ac fields can induce comparable directional flows in gated conical nanopores. This flow exclusively occurs at intermediate driving frequencies and hinges on the resonance of two competing timescales, representing space charge development at the ends and in the interior of the pore. We summarize the physics of resonant nanopumping in an analytical model that reproduces the results of numerical simulations. Our findings provide a generic route toward real-time controllable flow patterns, which might find applications in controlling the translocation of small molecules or nanocolloids.
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Affiliation(s)
- Aaron D Ratschow
- Institute for Nano- and Microfluidics, TU Darmstadt, Alarich-Weiss-Straße 10, D-64237 Darmstadt, Germany
| | - Doyel Pandey
- Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India-721302
| | - Benno Liebchen
- Theory of Soft Matter, Department of Physics, TU Darmstadt, Hochschulstraße 12, D-64289 Darmstadt, Germany
| | - Somnath Bhattacharyya
- Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India-721302
| | - Steffen Hardt
- Institute for Nano- and Microfluidics, TU Darmstadt, Alarich-Weiss-Straße 10, D-64237 Darmstadt, Germany
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Henrique F, Zuk PJ, Gupta A. Impact of asymmetries in valences and diffusivities on the transport of a binary electrolyte in a charged cylindrical pore. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Aslyamov T, Janssen M. Analytical solution to the Poisson–Nernst–Planck equations for the charging of a long electrolyte-filled slit pore. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140555] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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