Self-discharge of carbon-based supercapacitors with organic electrolytes

Ricketts, B.W.; Ton-That, Cuong

doi:10.1016/s0378-7753(00)00387-6

Cited by 279 publications

(204 citation statements)

References 2 publications

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“…[1][2][3] On the positive electrode, the positive charge is balanced in the double-layer by electrolyte anions. The high positive potential on this electrode may be higher than the thermodynamic oxidation potential of species in solution or on the electrode surface.…”

Section: Theoretical Underpinningsmentioning

confidence: 99%

“…This issue is exacerbated in warm climates, since self-discharge increases with increasing temperature. [1][2][3] In other applications where the EC is * Electrochemical Society Active Member. z E-mail: heather.andreas@dal.ca coupled with a battery (e.g.…”

mentioning

confidence: 99%

“…Often self-discharge rates are higher in ECs than in batteries, [1][2][3][4][5] making self-discharge an important EC consideration. A high selfdischarge rate results in a significant and rapid voltage drop after charging, resulting in lower available EC energy and power since both quantities are related to voltage.…”

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confidence: 99%

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Self-Discharge in Electrochemical Capacitors: A Perspective Article

Andreas

2015

J. Electrochem. Soc.

228

155

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This perspective article outlines some of the key considerations and literature that have been published on self-discharge in electrochemical capacitors. While for some consumer applications self-discharge is not considered to be a significant issue (e.g. energy storage from regenerative breaking) in applications where the electrochemical capacitor is stored in the charged state for significant times (e.g. coupled with a battery in a cell phone), the impact on energy, power and recharging frequency of both the capacitor and battery can be significant. A description is provided here of the common methods of self-discharge study: half cell vs. full cell measurements and open-circuit potential decay versus float currents. A description of some of the models used to evaluate faradaic self-discharge is presented, with a synopsis of the important aspects of the many available charge redistribution models. An overview of the current self-discharge mechanisms for various ECs is provided, highlighting that for many systems there are significant factors of the self-discharge process which remain unknown. Finally, some future directions are anticipated for the field of self-discharge in electrochemical capacitors. While significant efforts are being made to improve the energy and power characteristics of electrochemical capacitor materials, the research into electrochemical capacitor (EC) self-discharge has lagged behind. Self-discharge is the voltage drop experienced by the EC while stored in the charged state. The term self-discharge is sometimes associated with the chemical (faradaic) reactions discharging the surface and excluding any physical processes which cause the voltage drop (e.g. charge redistribution). However, since often the mechanism causing the voltage drop is unknown, in this paper, as in many others, "self-discharge" will be used as an umbrella term encompassing both the chemical reactions and physical processes leading to the voltage drop. Where appropriate, the self-discharge mechanism will be defined in the description; for instance, the term "activationcontrolled faradaic self-discharge" will denote both the rate limitation (activation-control) and the fact that it is a faradaic chemical reaction.Often self-discharge rates are higher in ECs than in batteries, To counteract self-discharge, the EC requires frequent recharging or the application of a small constant current (a float current) to keep it fully charged. Self-discharge can significantly impact how ECs are used in commercial devices. For instance, replacing a vehicle's lead acid battery with an EC capable of a long cycle-life, is currently impractical for personal vehicles since self-discharge can result in the EC having insufficient voltage to start the vehicle, unless recharged regularly by the engine. Thus, a person who did not start their vehicle for several days (e.g. at the airport while on vacation) may find upon their return that the EC is unable to start the vehicle's engine. This issue is exacerbated in warm climates, since self-dis...

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Section: Theoretical Underpinningsmentioning

confidence: 99%

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confidence: 99%

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Self-Discharge in Electrochemical Capacitors: A Perspective Article

Andreas

2015

J. Electrochem. Soc.

228

155

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“…the presence of a faradaic leakage current through a path of fixed resistance), although there is scant physical evidence for this [105]. An alternative explanation is that ions might diffuse from regions of high electrochemical potential to regions of low electrochemical potential [106], but, again, there is little proof. A third suggestion is that the Fe(II)/ Fe(III) redox couple might act as a charge shuttle between the terminals of the device [107,108].…”

Section: Comparison Of Theory and Experimentsmentioning

confidence: 99%

A universal equivalent circuit for carbon-based supercapacitors

Fletcher

Black

Kirkpatrick

2013

J Solid State Electrochem

137

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A universal equivalent circuit is proposed for carbon-based supercapacitors. The circuit, which actually applies to all porous electrodes having non-branching pores, consists of a single vertical ladder network in series with an RC parallel network. This elegant arrangement explains the three most important shortcomings of present-day supercapacitors, namely open circuit voltage decay, capacitance loss at high frequency, and voltammetric distortion at high scan rate. It also explains the shape of the complex plane impedance plots of commercial devices and reveals why the equivalent series capacitance increases with temperature. Finally, the construction of a solid-state supercapacitor simulator is described. This device is based on a truncated version of the universal equivalent circuit, and it allows experimenters to explore the responses of different supercapacitor designs without having to modify real supercapacitors.

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“…Problems may appear at the positive electrode, where high positive potentials can be reached at the end of a constant current charge, thus leading to the degradation of the current collector by anodic oxidation. Aluminium is the most commonly used current collector in organic electrolytes, due to the passive Al 2 O 3 layer protecting the under-lying metal [7,8]. In aqueous electrolytes such as sulphuric acid, stainless steels can be used [9].…”

Section: Introductionmentioning

confidence: 99%

Electrode surface treatment and electrochemical impedance spectroscopy study on carbon/carbon supercapacitors

2005

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID : 2600 ABSTRACT Power improvement in supercapacitors is mainly related to lowering the internal impedance. The real part of the impedance at a given frequency is called ESR (equivalent series resistance). Several contributions are included in the ESR: the electrolyte resistance (including the separator), the active material resistance (with both ionic and electronic parts) and the active material/current collector interface resistance. The first two contributions have been intensively described and studied by many authors. The first part of this paper is focused on the use of surface treatments as a way to decrease the active material/current collector impedance. Al current collector foils have been treated following a two-step procedure: electrochemical etching and sol-gel coating by a highly-covering, conducting carbonaceous material. It aims to increase the Al foil/active material surface contact leading to lower resistance. In a second part, carbon-carbon supercapacitor impedance is discussed in term of complex capacitance and complex power from electrochemical impedance spectroscopy data. This representation permits extraction of a relaxation time constant that provides important information on supercapacitor behaviour. The influence of carbon nanotubes addition on electrochemical performance of carbon/carbon supercapacitors has also been studied by electrochemical impedance spectroscopy.

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Self-discharge of carbon-based supercapacitors with organic electrolytes

Cited by 279 publications

References 2 publications

Self-Discharge in Electrochemical Capacitors: A Perspective Article

Self-Discharge in Electrochemical Capacitors: A Perspective Article

A universal equivalent circuit for carbon-based supercapacitors

Electrode surface treatment and electrochemical impedance spectroscopy study on carbon/carbon supercapacitors

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