Surface modification of carbon black by anodic oxidation and electrochemical characterization

Horita, Kiyoshi; Nishibori, Yasushi; Ohshima, Takao

doi:10.1016/0008-6223(96)00167-4

Cited by 35 publications

(19 citation statements)

References 14 publications

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“…The increase of C p when increasing the voltage window can be attributed to the creation of functionalities upon cycling. It has been demonstrated by our group, as well as others, that electro-oxidation of electrode materials can occur upon cycling [28][29][30]. The newly introduced functionalities lead to a pseudocapacitance contribution as it has been evidenced in the literature and by some authors.…”

Section: 1-active Materials Characteristics-supporting

confidence: 63%

Voltage dependence of carbon-based supercapacitors for pseudocapacitance quantification

Ruíz¹,

Roldán²,

Villar³

et al. 2013

Electrochimica Acta

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Abstract.-In order to understand the participation of electrical double layer and pseudocapacitance to the overall behavior of supercapacitors, a new approach to the analysis of the electrochemical data is proposed. Both the variation of the specific capacitance values and the dependence of these values with the operating voltage window (varying from 0-0.2 V to 0-1 V) were evaluated and used to quantify the contribution arising from each mechanism of energy storage to the total capacitance of the system. The suitability of the methodology here proposed was tested in various carbon materials (multiwalled carbon nanotubes, a carbon aerogel and two activated carbons), different both in nature and physicochemical characteristics. For all of the carbons studied, the capacitance with an exclusive faradic and non -faradic origin was quantified. Whereas some of the carbons studied showed a behavior close to an ideal Electrical Double Layer Capacitor (EDLC) with virtually no pseudocapacitance contribution (case of the carbon nanotubes), others presented up to a 40 % of pseudocapacitance contribution (case of KOH -activated carbon).

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Section: 1-active Materials Characteristics-supporting

confidence: 63%

Voltage dependence of carbon-based supercapacitors for pseudocapacitance quantification

Ruíz¹,

Roldán²,

Villar³

et al. 2013

Electrochimica Acta

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“…The amount of CO-evolving groups does not change substantially, whereas the groups responsible for the CO 2 evolution significantly increased (from 0.2 to 0.8 mmol/g). When moderate oxidation takes place, the morphology of the carbon material does not change significantly, although some oxygen functional groups can be created at the surface of the material (i.e., hydroxyl groups) that could lead to an improvement in wettability [32] and/or could lead to enhanced specific capacitance values [33]. However, a strong oxidation can lead to deeper structural modifications that can cause the degradation of the carbon material (i.e.…”

Section: -Results and Discussionmentioning

confidence: 99%

Long-term cycling of carbon-based supercapacitors in aqueous media

Ruíz

Santamarı́a

Granda

et al. 2009

Electrochimica Acta

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Abstract.-The behaviour of mesophase-derived electrodes on long-duration cycling conditions was studied in 1M sulfuric acid and 6M potassium hydroxide. Variation in the specific capacitance values with the number of cycles shows a good cycling life performance in acidic media but very poor in an alkaline electrolyte. The total loss of capacitance after 7,000 cycles in acidic media is 8 % at 0.6 V and 16 % at 1 V, whereas in the basic electrolyte the reduction in the capacitance values is 72 %, even at a very small operating voltage (0.6 V). This wide range of applications related to their fast energy delivery (e.g. telecommunications systems, maintenance-free traffic lights, uninterruptible power sources, and hybrid electric vehicles among others) [1]. The storage of energy in electrochemical capacitors can arise from either electrostatic charging or from pseudocapacitative chage-discharge [2]. In the first case, electrolyte ions are accumulated at the electrode/electrolyte interface forming the socalled double layer in a similar way as in conventional capacitors. By utilizing high surface area electrodes the amount of charge stored, and consequently the capacitance of the device, is several orders of magnitude higher than that of conventional electrolytic capacitors. In the second case, pseudocapacitance arises from faradaic processes of electroactive species, such as polymeric materials [3], metal oxides [4,5] and certain functionalities at the surface of carbon materials [6,7,8].It is generally believed that pseudocapacitance in carbon materials is largely based on the redox reactions of surface quinoid functionalities, whose reduction requires protons to proceed [9,10]. Nevertheless, some other oxygenated functional groups might be electrochemically active at the working potentials of the acidic solutions, such as some pyrone groups [11,6]. Therefore, and as may be expected, faradic phenomena have a large dependence on the pH of the solution. In this sense, enormous differences in capacitance values can be found depending on the electrolyte used. For carbon materials in neutral solutions, specific capacitance values between 8-12 μF cm -2 have been reported and between 15-20 μF cm -2 in the case of acidic media [12]. Despite that its study is not so frequent, redox reactions in basic media are also possible [13]. In general terms, the presence of the so-called pseudocapacitance has been related in literature to poor cycle life [19] contrary to what occurs in organic media, where only purely charge separation occurs and good cycling stability is typically reported [20]. Investigations in this field are rarely reported, despite that the cyclability of supercapacitors is a property of mayor importance. The present work investigates the effect of the electrolyte (basic or acidic)in the long-term stability of carbon-based supercapacitors. The electro-oxidation of the activated carbon M-AC was carried out in a conventional three-electrode system. Around 100 mg of material was subjected to +0.4 V vs. NHE in a N 2 bu...

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“…Many treatments have been developed for surface modification of carbon for electrochemical applications: acid treatment [147,148], oxidizing [149][150][151], electrochemical [152], thermal [153], by laser [154], by plasma [155,156], by polishing [157], or by washing in a solvent [158], hydrogenation followed by a sulfonation [159], a first halogenation step by chlorine or bromine and a second step consisting in a dehalogenation under hydrogen [160] and so on.…”

Section: Surface Group Impact On Performance and Solutionsmentioning

confidence: 99%

Manufacturing of Industrial Supercapacitors

Azaïs¹

2013

Supercapacitors

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Surface modification of carbon black by anodic oxidation and electrochemical characterization

Cited by 35 publications

References 14 publications

Voltage dependence of carbon-based supercapacitors for pseudocapacitance quantification

Voltage dependence of carbon-based supercapacitors for pseudocapacitance quantification

Long-term cycling of carbon-based supercapacitors in aqueous media

Manufacturing of Industrial Supercapacitors

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