Blessing and Curse: How a Supercapacitor's Large Capacitance Causes its Slow Charging

Cheng Lian*, Mathijs Janssen, Honglai Liu, Rene van Roij

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The development of novel electrolytes and electrodes for supercapacitors is hindered by a gap of several orders of magnitude between experimentally measured and theoretically predicted charging time scales. Here, we propose an electrode model, containing many parallel stacked electrodes, that explains the slow charging dynamics of supercapacitors. At low applied potentials, the charging behavior of this model is described well by an equivalent circuit model. Conversely, at high potentials, charging dynamics slow down and evolve on two relaxation time scales: a generalized
R
C
time and a diffusion time, which, interestingly, become similar for porous electrodes. The charging behavior of the stack-electrode model presented here helps to understand the charging dynamics of porous electrodes and qualitatively agrees with experimental time scales measured with porous electrodes.
Original languageEnglish
Article number076001
Pages (from-to)1-6
Number of pages6
JournalPhysical Review Letters
Volume124
Issue number7
DOIs
Publication statusPublished - 20 Feb 2020

Keywords

  • Capacitance
  • Electrochemistry
  • Electrokinetic flows
  • Thermodynamics
  • Porous media
  • Nonequilibrium systems
  • Capacitors

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