Insights into Charge-Redistribution in Double Layer Capacitors

Madabattula, Ganesh; Kumar, Sanjeev

doi:10.1149/2.0941803jes

Cited by 19 publications

(36 citation statements)

References 60 publications

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“…found that the temperature rise in EDLCs for Δ ψ s =2 V under galvanostatic cycling predicted by considering only Joule heating was smaller than that measured experimentally . The analysis suggested that the irreversible heat generation rate in EDLCs was the summation of (i) Joule heating and (ii) heat generation owing to charge redistribution effects modeled as dissipation through the pore resistance . In fact, the charges redistribute themselves during cycling because of the non‐uniform charging/discharging processes in the complex porous electrode structure .…”

Section: Introductioncontrasting

confidence: 54%

“…This could be attributed to the heat generation associated with charge redistribution effects in the porous carbon electrode and modeled as the leakage current dissipated through the pore resistance . Indeed, the pore resistance is responsible for self‐discharge (leakage current) in EDLCs along with other parasitic reactions, such as electrolyte decomposition, and oxidation/reduction of carbon surface functional groups . In addition, this contribution increased with increasing potential window as the pore resistance also increased with increasing potential window .…”

Section: Resultsmentioning

confidence: 99%

“…The analysis suggested that the irreversible heat generation rate in EDLCs was the summation of (i) Joule heating and (ii) heat generation owing to charge redistribution effects modeled as dissipation through the pore resistance . In fact, the charges redistribute themselves during cycling because of the non‐uniform charging/discharging processes in the complex porous electrode structure . Moreover, the measured temperature rise increased with increasing potential window suggesting that the pore resistance increased with increasing potential …”

Section: Introductionmentioning

confidence: 87%

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In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows

et al. 2020

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This study aims to investigate the effect of the potential window on heat generation in carbon‐based electrical double layer capacitors (EDLCs) with ionic‐liquid (IL)‐based electrolytes using in operando calorimetry. The EDLCs consisted of two identical activated‐carbon electrodes with either neat 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethane‐sulfonyl)imide ([Pyr14][TFSI]) electrolyte or 1.0 m [Pyr14][TFSI] in propylene carbonate (PC) as electrolyte. The instantaneous heat generation rate at each electrode was measured under galvanostatic cycling for different potential windows ranging from 1 to 4 V. First, the heat generation rates at the positive and negative electrodes differed significantly in neat IL owing to the differences in the ion sizes and diffusion coefficients. However, these differences were minimized when the IL was diluted in PC. Second, for EDLC in neat [Pyr14][TFSI] at high potential window (4 V), a pronounced endothermic peak was observed at the beginning of the charging step at the positive electrode owing to TFSI− intercalation in the activated carbon. On the other hand, for EDLC in 1.0 m [Pyr14][TFSI] in PC at potential window above 3 V, an endothermic peak was observed only at the negative electrode owing to the decomposition of PC. Third, for both neat and diluted [Pyr14][TFSI] electrolytes, the irreversible heat generation rate increased with increasing potential window and exceeded Joule heating. This was attributed to the effect of potential‐dependent charge redistribution resistance. A further increase in the irreversible heat generation rate was observed for the largest potential windows owing to the degradation of the PC solvent. Finally, for both types of electrolyte, the reversible heat generation rate increased with increasing potential window because of the increase in the amount of ion adsorbed/desorbed at the electrode/electrolyte interface.

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Section: Introductioncontrasting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 87%

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In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows

et al. 2020

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“…Over the past three decades, numerous studies have been conducted that exploit some form of the RC transmission line model to understand the selfdischarge mechanism [8][9][10], the effect of pore size and shape [11][12][13][14][15][16][17][18], and the effect of electrolyte concentration [19,20], among others [21]. More recently, several studies have argued for more detailed analysis of ion transport inside the DL [4,5,[22][23][24][25][26].…”

mentioning

confidence: 99%

Charging Dynamics of Overlapping Double Layers in a Cylindrical Nanopore

2020

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The charging of electrical double layers inside a cylindrical pore has applications to supercapacitors, batteries, desalination and biosensors. The charging dynamics in the limit of thin double layers, i.e., when the double layer thickness is much smaller than the pore radius, is commonly described using an effective RC transmission line circuit. Here, we perform direct numerical simulations (DNS) of the Poisson-Nernst-Planck equations to study the double layer charging for the scenario of overlapping double layers, i.e., when the double layer thickness is comparable to the pore radius. We develop an analytical model that accurately predicts the results of DNS. Also, we construct a modified effective circuit for the overlapping double layer limit, and find that the modified circuit is identical to the RC transmission line but with different values and physical interpretation of the capacitive and resistive elements. In particular, the effective surface potential is reduced, the capacitor represents a volumetric current source, and the charging timescale is weakly dependent on the ratio of the pore radius and the double layer thickness.

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“…[27] Kroupa et al [28] extended the model of Verbugge and Liu by an additional dimension to account for the transport into the carbon particles. Madabattula and Kumar [29] gave insights in the charge redistribution that occurs during high current charging and discharging.…”

Section: Introductionmentioning

confidence: 99%

Simulative Approach for Linking Electrode and Electrolyte Properties to Supercapacitor Performance

Krois

Hüfner

Gläsel

et al. 2019

Chemie Ingenieur Technik

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Supercapacitors as energy storage devices show distinct advantages like high power density and high cycle stability. While in current applications, mainly the high power density is leveraged, future non-mobile storage devices could also benefit from the robustness and materials employed, while lower charging/discharging time constants are acceptable. In this study, a simulative approach is employed to investigate the complex interplay of mass transfer, electric losses, double layer capacitance for different electrode thicknesses, electrode and electrolyte conductivities as well as charging/discharging time constants. Within the simulation cyclic voltammetry, galvanostatic cycling as also electrochemical impedance spectroscopy experiment could be realized, showing the dependency of achievable maximum capacitance and voltage efficiency on various properties.

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Insights into Charge-Redistribution in Double Layer Capacitors

Cited by 19 publications

References 60 publications

In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows

In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows

Charging Dynamics of Overlapping Double Layers in a Cylindrical Nanopore

Simulative Approach for Linking Electrode and Electrolyte Properties to Supercapacitor Performance

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