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The modelling of carbon-based supercapacitors: distributions of time constants and Pascal Equivalent Circuits

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posted on 2017-03-06, 12:31 authored by Stephen Fletcher, Iain Kirkpatrick, Rod DringRod Dring, Robert Puttock, Rob Thring, Simon Howroyd
Supercapacitors are an emerging technology with applications in pulse power, motive power, and energy storage. However, their carbon electrodes show a variety of non-ideal behaviours that have so far eluded explanation. These include Voltage Decay after charging, Voltage Rebound after discharging, and Dispersed Kinetics at long times. In the present work, we establish that a vertical ladder network of RC components can reproduce all these puzzling phenomena. Both software and hardware realizations of the network are described. In general, porous carbon electrodes contain random distributions of resistance R and capacitance C, with a wider spread of log R values than log C values. To understand what this implies, a simplified model is developed in which log R is treated as a Gaussian random variable while log C is treated as a constant. From this model, a new family of equivalent circuits is developed in which the continuous distribution of log R values is replaced by a discrete set of log R values drawn from a geometric series. We call these Pascal Equivalent Circuits. Their behaviour is shown to resemble closely that of real supercapacitors. The results confirm that distributions of RC time constants dominate the behaviour of real supercapacitors.

Funding

This work was sponsored by the EPSRC (UK) Grant Number EP/M009394/1, “Electrochemical Vehicle Advanced Technology” (ELEVATE).

History

School

  • Science

Department

  • Chemistry

Published in

Journal of Power Sources

Volume

345

Pages

247 - 253

Citation

FLETCHER, S. ... et al, 2017. The modelling of carbon-based supercapacitors: distributions of time constants and Pascal Equivalent Circuits. Journal of Power Sources, 345, pp. 247 - 253.

Publisher

Elsevier / © The Authors

Version

  • VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

2017-02-04

Publication date

2017-02-11

Notes

This is an Open Access article published by Elsevier and distributed under the terms of the Creative Commons Attribution Licence, CC BY 4.0, https://creativecommons.org/licenses/by/4.0/

ISSN

0378-7753

Language

  • en

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