2.5 V compact supercapacitors based on ultrathin carbon nanotube films for AC line filtering

Yoo, Young A.; Kim, Seung Wook; Kim, Byungwoo; Kim, Woong

doi:10.1039/c5ta02073e

Cited by 91 publications

(141 citation statements)

References 24 publications

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“…The C 1s core-level XPS spectrum of each graphene material can be divided into five types of carbon bonds: CC (284.8 eV), CC (285.5 eV), CO (286.7 eV), CO (287.9 eV), and OCO (289.0 eV). This phase angle is comparable to those of the ultrafast OEC based on CNTs [10] and commercial AEC (−83.4° with a C A of 19 µF cm −2 at 120 Hz, Figure S6 line at low frequencies, indicating a pure double layer capacitive behavior. [22] These structural defects were further decreased upon deep reduction, because the C1s XPS spectrum of DRsLGO showed the weakest peaks of oxygenated groups.…”

Section: Introductionsupporting

confidence: 75%

“…[3,15] The phase angle of OEC-4 was measured to be −80.5° at 120 Hz ( Figure 3a). [4,7,10,15,17,28] Cyclic voltammetric (CV) tests further confirmed the fast response performance of OEC-4 (Figure 4a−c). [15] The absence of a 45° line at high frequencies in Figure 3b confirms the fast electron transfer and ion diffusion within DRsLGO electrodes.…”

Section: Introductionsupporting

confidence: 54%

“…[3] Unfortunately, the bulky sizes and low specific capacitances of AECs greatly impede the integration and miniaturization of electronic circuits. [2][3][4][5][6][7][8][9][10] In fact, several ultrahigh-rate ECs based on graphene, [4,7,8] carbon nanotubes (CNTs), [10][11][12] or conducting polymers [6,13,14] can respond harmonically at 120 Hz (the double value of the AC power standard in the United States), implying that they can be applied to develop next-generation AC line filters. [2][3][4][5][6][7][8][9][10] In fact, several ultrahigh-rate ECs based on graphene, [4,7,8] carbon nanotubes (CNTs), [10][11][12] or conducting polymers [6,13,14] can respond harmonically at 120 Hz (the double value of the AC power standard in the United States), implying that they can be applied to develop next-generation AC line filters.…”

Section: Introductionmentioning

confidence: 99%

“…Most of these ECs are workable only in aqueous media because of the high ionic conductivities of aqueous electrolytes. [10,12,16] Therefore, ultrafast organic electrochemical capacitors (OECs) with a much wider voltage Figure S3, Supporting Information). [4,7,13,[15][16][17][18] A low operating voltage (U) makes the EC have a low energy density (E A ∝ U 2 ), greatly increasing the size and weight of corresponding AC line filter.…”

Section: Introductionmentioning

confidence: 99%

“…[10] However, the preparation of CNT electrodes involved complicated processes of vacuum filtration and expensive chemical vapor deposition. Up to date, only an ultrafast OEC based on CNT films has been reported in literature.…”

mentioning

confidence: 99%

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Graphene‐Based Organic Electrochemical Capacitors for AC Line Filtering

Chi

Zhou

et al. 2017

Advanced Energy Materials

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window (around 3 V) are more favorable for practical applications. Up to date, only an ultrafast OEC based on CNT films has been reported in literature. [10] However, the preparation of CNT electrodes involved complicated processes of vacuum filtration and expensive chemical vapor deposition. Therefore, a facile and scalable method to fabricate OECs with excellent AC line-filtering performances still remains as a challenge.In this paper, we report the fabrication of OECs based on electrochemically reduced less defective graphene oxide (ERLGO) films with oriented 3D interconnected porous structures. For optimizing the performance of ERLGO electrode, LGO sheets with a small average size of 0.7 µm (sLGO) were used and the resulting ERsLGO electrode was further deeply reduced in an organic electrolyte. The typical OEC exhibited high areal specific energy density, excellent electrochemical stability, and superior rate capability, promising for AC line filtering. These OECs can also be connected in series or parallel to meet various demands in industrial levels. Results and DiscussionThe graphene electrode (Figure 1a) was prepared by electrochemical reduction of LGO or sLGO sheets in their aqueous dispersion (3 mg mL −1 ) at −1.1 V for 4 s, then further deeply reduced in an organic electrolyte at −2.0 V for 20 s. The organic electrolyte was 1 mol L −1 acetonitrile (AN) solution of tetraethylammonium-tetrafluoroborate (TEABF 4 ). LGO sheets were prepared by oxidation of graphite flakes at a low temperature of 0 °C. [19] They have an average lateral dimension of 7 µm (Figure 1b, Figure S1, Supporting Information). During the electrodeposition process, LGO sheets were selfassembled onto the surface of substrate electrode upon the driving by directional electric field. [20] Simultaneously, they were electrochemically reduced to ERLGO sheets to form a porous network because of π-π stacking and hydrophobic interactions. However, the ERLGO electrode has a relatively disordered porous structure ( Figure S2, Supporting Information) because of the steric obstacles of these large graphene sheets during their self-assembling process. Therefore, we pulverized LGO sheets in their aqueous dispersion by sonication, significantly reducing their average size to around 0.7 µm (Figure 1c, Less-defective graphene oxide sheets with a small average size of 0.7 µm are electrochemically reduced to form a hydrogel film with highly oriented porous structure. It is applied as the electrode of organic electrochemical capacitor (OEC) after solvent change with organic electrolyte and deep reduction in this organic medium. At 120 Hz, the typical OEC exhibits a high areal specific energy density of 472 µF V 2 cm −2 with a wide workable voltage window of 2.5 V, a phase angle of −80.5°, a resistor-capacitor time constant (τ RC ) of 0.219 ms, and an excellent electrochemical stability. Thus, it is promising to replace aluminum electrolytic capacitors for AC line filtering. Furthermore, two identical OECs connected in series keep the performance of single...

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Section: Introductionsupporting

confidence: 75%

Section: Introductionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Graphene‐Based Organic Electrochemical Capacitors for AC Line Filtering

Chi

Zhou

et al. 2017

Advanced Energy Materials

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Bridged Carbon Fabric Membrane with Boosted Performance in AC Line‐Filtering Capacitors

et al. 2022

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High-frequency responsive capacitors with lightweight, flexibility, and miniaturization are among the most vital circuit components because they can be readily incorporated into various portable devices to smooth out the ripples for circuits. Electrode materials no doubt are at the heart of such devices. Despite tremendous efforts and recent advances, the development of flexible and scalable high-frequency responsive capacitor electrodes with superior performance remains a great challenge. Herein, a straightforward and technologically relevant method is reported to manufacture a carbon fabric membrane "glued" by nitrogen-doped nanoporous carbons produced through a polyelectrolyte complexation-induced phase separation strategy. The as-obtained flexible carbon fabric bearing a unique hierarchical porous structure, and high conductivity as well as robust mechanical properties, serves as the free-standing electrode materials of electrochemical capacitors. It delivers an ultrahigh specific areal capacitance of 2632 μF cm −2 at 120 Hz with an excellent alternating current line filtering performance, fairly higher than the state-of-the-art commercial ones. Together, this system offers the potential electrode material to be scaled up for AC line-filtering capacitors at industrial levels.

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Ultrahigh‐Rate Supercapacitor Based on Carbon Nano‐Onion/Graphene Hybrid Structure toward Compact Alternating Current Filter

Zhang

et al. 2020

Advanced Energy Materials

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friction into direct current (DC) signal, [1,2] or bypassing the main power to serve as temporary backup for suppressing the high-frequency noise caused by voltage decline or switching of the components in the circuit. The commonly used filtering device serving these purposes are electrolytic capacitor, such as aluminum electrolytic capacitor (AEC), which is the bulkiest component in the integrated circuit. [3] Therefore, reducing the size of electrolytic capacitor is crucial for achieving higher integration level and the miniaturization of wearable/portable electronics. Although the miniaturization of active components, such as transistors and sensors, have been extensively studied, the small-scale design of the AEC encounters a major obstacle since it suffers from low volumetric specific energy density (E v). [1-3] This challenge makes the AEC increasingly incompatible with the rapid development of miniaturized wearable and portable electronics.

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2.5 V compact supercapacitors based on ultrathin carbon nanotube films for AC line filtering

Abstract: We demonstrate 2.5 V AC-line-filtering supercapacitors with unprecedentedly high volumetric energy density based on ultrathin carbon nanotube films.

Cited by 91 publications

References 24 publications

Graphene‐Based Organic Electrochemical Capacitors for AC Line Filtering

Graphene‐Based Organic Electrochemical Capacitors for AC Line Filtering

Bridged Carbon Fabric Membrane with Boosted Performance in AC Line‐Filtering Capacitors

Ultrahigh‐Rate Supercapacitor Based on Carbon Nano‐Onion/Graphene Hybrid Structure toward Compact Alternating Current Filter

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