Diffuse charge dynamics in ionic thermoelectrochemical systems

Stout, Robert F.; Khair, Aditya S.

doi:10.1103/physreve.96.022604

Cited by 27 publications

(33 citation statements)

References 26 publications

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“…For κL = 1, the system behaves mainly as explained in Ref. [15]: The quenched temperature relaxes quickly, after which the electrostatic potential and ionic charge and salt densities relax slowly. Conversely, for κL = 100, the rearrangement of ions in thermal gradients is sufficiently fast that the ionic charge density can track the thermal relaxation.…”

Section: Discussionmentioning

confidence: 92%

“…This parameter set is representative for an aqueous KCl solution ( ≈ 10 6 g m −3 , c p ≈ 4 J g −1 , a/D, and α ± from Ref. [15]) subject to a thermal quench of 0.3 K around room temperature. Because κ −1 amounts to several tens of nanometers at most (at 1 mM, κ −1 = 9.6 nm), large n values can be easily achieved experimentally by using L values in the micrometer regime (or larger).…”

Section: Resultsmentioning

confidence: 99%

“…Theoretical models were developed by Agar and Turner [14] and later by Stout and Khair [15], who both considered electrolytes with equal cationic and anionic diffusivities, D + = D − ≡ D. Motivated by the typically large ratio a/D ≈ 100, with a being the thermal diffusivity, their analyses departed from the ansatz that the steady-state temperature profile develops instantaneously [T (x, t) = T (x), with x being the spatial coordinate of their one-dimensional model electrolytic cells], after which ions relax slowly. With this ansatz, an exact expression for the transient response of the neutral salt density c(x, t) [14] and approximate expressions for the ionic charge density q(x, t) and corresponding V T (t) [15] were found. As we show in the present article, the corresponding exact solutions to q and V T decay at late times with a common timescale τ q = L 2 /(D[(κL) 2 + π 2 /4]), with κ being the inverse Debye length.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, an instantaneous steady-state temperature profile onto which ions rearrange slowly is a special case of a more general problem. Given the longstanding experimental and theoretical interest in thermodiffusion of electrolytes [3][4][5][6][7][8][13][14][15], it is timely to discuss its solution.…”

Section: Introductionmentioning

confidence: 99%

“…(6a) and (13) to transform the PDEs forψ 1 ,q 1 , andc 1 into ODEs for their Laplace transformed counterpartsψ 1 ,q 1 , and c 1 [we denote the Laplace transform of a function f (x,t ) byf (x, s) = ∞ 0 dt exp (−st )f (x,t )]. Stout and Khair [15] already found solutions to these ODEs [see their Eq. (20)], which in our notation read…”

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confidence: 99%

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Transient response of an electrolyte to a thermal quench

Janssen

Bier

2019

Phys. Rev. E

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We study the transient response of an electrolytic cell subject to a small, suddenly applied temperature increase at one of its two bounding electrode surfaces. An inhomogeneous temperature profile then develops, causing, via the Soret effect, ionic rearrangements towards a state of polarized ionic charge density q and local salt density c. For the case of equal cationic and anionic diffusivities, we derive analytical approximations to q, c, and the thermovoltage VT for early (t τT ) and late (t τT ) times as compared to the relaxation time τT of the temperature. We challenge the conventional wisdom that the typically large Lewis number, the ratio a/D of thermal to ionic diffusivities, of most liquids implies a quickly reached steady-state temperature profile onto which ions relax slowly. Though true for the evolution of c, it turns out that q (and VT ) can respond much faster. Particularly when the cell is much bigger than the Debye length, a significant portion of the transient response of the cell falls in the t τT regime, for which our approximated q (corroborated by numerics) exhibits a density wave that has not been discussed before in this context. For electrolytes with unequal ionic diffusivities, VT exhibits a two-step relaxation process, in agreement with experimental data of Bonetti et al. [J. Chem. Phys. 142, 244708 (2015)].

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Section: Discussionmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Transient response of an electrolyte to a thermal quench

Janssen

Bier

2019

Phys. Rev. E

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Robust High Thermoelectric Harvesting Under a Self‐Humidifying Bilayer of Metal Organic Framework and Hydrogel Layer

Kim

Lim

et al. 2018

Adv Funct Materials

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Robust thermoelectric harvesting is explored from a proton-doped mixed ionic conductive (PMIC) film under water-harvesting metal organic framework (MOF) film coupled with hydrogel layer (MOF/HG). As a PMIC, highly doped poly(3,4-ethylenedioxythiophene)s with poly(styrene sulfonate) (PEDOT:PSS) is prepared by precisely controlling the proton doping to afford a stable and high thermoelectric PMIC. Among the PMICs, the PEDOT:PSS film doped with 30 wt% of poly(styrene sulfonic acid) (PSSH) recorded a Seebeck coefficient of over 16.2 mV K −1 and a thermal voltage of 81 mV for a temperature gradient (ΔT) of 5 K. The thermal charging on PMICs afforded high thermal voltage and current output, reproducibly, to show cumulative thermoelectric nature. Environmentally sustainable thermoelectric harvesting is achieved from a PMIC under a MOF/HG, prepared by water-harvesting MOF-801 coupled with a HG layer, to provide constant relative humidity of 90% and V oc over 72 h at ambient condition.

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Direct Electricity Generation Mediated by Molecular Interactions with Low Dimensional Carbon Materials—A Mechanistic Perspective

Liu

Zhang

Cottrill

et al. 2018

Advanced Energy Materials

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Next generation off-the-grid electronic systems call for alternative modes of energy harvesting. The past two decades have witnessed the evolution of a wide spectrum of low dimensional carbon materials with extraordinary physical and chemical properties, ideal for micro-scale electrical energy storage and generation. Tremendous progress has been made in harnessing the energy associated with the interactions between these nano-structured carbon substrates and the surrounding molecular phases, subsequently converting them into useful electricity. This review summarizes the important theoretical and experimental milestones the field has reached to date, and further classifies these energy harvesting processes based on underlying physics, into five mechanistically distinct classesphonon coupling, Coulombic scattering, electrokinetic streaming, asymmetric doping, and capacitive discharging. With a special mechanistic focus, the authors hope to resolve the fundamental attributes shared by this diverse array of molecular scale energy harvesting schemes, offer perspectives on key challenges, and ultimately establish design principles that guide further device optimization.

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Diffuse charge dynamics in ionic thermoelectrochemical systems

Cited by 27 publications

References 26 publications

Transient response of an electrolyte to a thermal quench

Transient response of an electrolyte to a thermal quench

Robust High Thermoelectric Harvesting Under a Self‐Humidifying Bilayer of Metal Organic Framework and Hydrogel Layer

Direct Electricity Generation Mediated by Molecular Interactions with Low Dimensional Carbon Materials—A Mechanistic Perspective

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