Band‐Pass Filter and Relaxation Oscillator using Electric Double‐Layer Capacitor

Allagui, Anis; Elwakil, Ahmed S.; Said, Zafar; Abdelkareem, Mohammad Ali; Zhang, Di

doi:10.1002/celc.201800872

Cited by 9 publications

(6 citation statements)

References 49 publications

(93 reference statements)

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“…However, the impedance angles of both devices are relatively stable from 10 mHz to 100 Hz, which are, −60.3° ( R 2 = 0.561) and −58.2° ( R 2 = 0.862) for the positive and negative electrode based devices, respectively. Nonetheless, despite the deviation from ideal capacitor behavior, devices with similar responses were shown to be favorable for non dc applications such as ac line filtering ,− and low-frequency oscillators. , Then, as the frequency is increased, the impedance angles tend quickly toward a resistive behavior as shown in Figure b. An angle of −45° at which the magnitude of resistance and reactance are equal is found to be at the frequencies of 1820 and 1157 Hz for the positive and negative electrode based devices, respectively.…”

Section: Materials Characterizationmentioning

confidence: 96%

Bipolar Exfoliation and in Situ Deposition of High-Quality Graphene for Supercapacitor Application

Khakpour

Baboukani

Allagui

et al. 2019

ACS Appl. Energy Mater.

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Developing a reliable, simple, cost-efficient, and eco-friendly method for scale-up production of highquality graphene-based materials is essential for the broad applications of graphene. In this study, bipolar electrochemistry concept is utilized to design a single-step and controllable process for simultaneously exfoliating a graphite source and depositing both graphene oxide and reduced graphene oxide layers on conductive substrates. The electrochemical analysis carried out on symmetric cells revealed an areal capacitance of 1.932 mF cm −2 for the high-quality reduced graphene oxide deposited on the negative feeding electrode, and 0.404 mF cm −2 for the graphene oxide deposited on the positive feeding electrode at a scan rate of 2 mV s −1 . The devices also showed high stability for periodic and repeated constant current charging/discharging cycles which is suitable for energy storage in supercapacitors. In the frequency domain, cutoff frequencies of 1820 and 1157 Hz at −45°impedance phase angle were obtained for the positive and negative feeding electrode-based devices, respectively, which is a promising characteristic for alternating current filtering applications.

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Section: Materials Characterizationmentioning

confidence: 96%

Bipolar Exfoliation and in Situ Deposition of High-Quality Graphene for Supercapacitor Application

Khakpour

Baboukani

Allagui

et al. 2019

ACS Appl. Energy Mater.

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“…The slight distortion at 2000 mV s −1 scan rate and non-straight sides at reversed scan points are related to the increased internal resistance of the devices. 39 The capacitive behavior of these devices is also revealed by the quasi-symmetric voltage-time profiles under different values of constant current charging/discharging as shown in Figs. 2a−2c.…”

Section: Resultsmentioning

confidence: 98%

Frequency-Dependent Effective Capacitance of Supercapacitors Using Electrospun Cobalt-Carbon Composite Nanofibers

Abdelkareem

Allagui

Said

et al. 2019

J. Electrochem. Soc.

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Mixing carbon-based materials with pseudocapacitive material is a widely used strategy to prepare high-energy, high-power supercapacitors. However, phase separation is inevitable after extended charging/discharging which leads to the degradation of performance metrics of the device. Here, we prepare in a single step cobalt-incorporated carbon nanofibers (CNF) by electrospinning homogeneous solutions of polyacrylonitrile (PAN) with cobalt acetate at different nominal proportions (1:0 to 1:1), and investigate their stability and capacitive behavior in symmetric supercapacitors. The electrochemical analyzes demonstrated up to an order of magnitude increase in the effective capacitive with increasing the cobalt content at both close-to-dc frequencies and at around 50/60 Hz power line frequencies. The maximum capacitance is recorded for a nominal cobalt acetate-to-PAN ratio of 0.9 (e.g. 29, 27, 22 and 10 mF at 0.01. 0.1, 1 and 100 Hz respectively; both electrodes are loaded with 1 mg cm −2 of active material each). All devices showed also an outstanding capacitance retention exceeding 99% for 10000 cycles at 1 mA and 5 mA charging/discharging rates each. The improved energy storage capabilities are attributed to both the increased electrical conductivity and high pyridinic nitrogen content which was revealed from the material characterization results using XRD, FE-SEM/TEM, and XPS.

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“…[1][2][3][4] These wearable powered electronics can be usually sorted as active components and passive components. [1][2][3][4] These wearable powered electronics can be usually sorted as active components and passive components.…”

Section: Introductionmentioning

confidence: 99%

All Fiber Based Electrochemical Capacitor towards Wearable AC Line Filters with Outstanding Rate Capability

et al. 2019

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Due to their high spatial utilization, excellent flexibility and good adaptability, fiber-shaped devices have promising potential for applications in wearable electronics. However, the fiberization process of the component with alternate current (AC) line filtering function is still far from being satisfactory, since it is difficult to arrange an ordered structure in a fiber shape in large-scale manufacturing. This leads to a slow frequency response. Herein, a weavable fiber-shaped electrochemical capacitor (SC) for AC line filtering is made of reduced graphene oxide (rGO) fibers with a highly oriented porous structure by wet-spinning method. The highly consistent orientations of the rich pores greatly improve the ionic accessible sites, ion mobility and the electron transport pathways. As a result, the all-fiber-based SC revealing a high rate performance (500 V s À 1 ) and a fast frequency response (RC time constant~0.241 ms, phase angle~À 80°) is successfully applied to filter � 1.5 V AC to 1.04 V direct current (DC). Notably, the highly flexible SC exhibits an outstanding consistency during the performance test at bending and folding states. This work shows a potential substitution for aluminium electrolytic capacitors (AEC) towards wearable electronic.

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Band‐Pass Filter and Relaxation Oscillator using Electric Double‐Layer Capacitor

Cited by 9 publications

References 49 publications

Bipolar Exfoliation and in Situ Deposition of High-Quality Graphene for Supercapacitor Application

Bipolar Exfoliation and in Situ Deposition of High-Quality Graphene for Supercapacitor Application

Frequency-Dependent Effective Capacitance of Supercapacitors Using Electrospun Cobalt-Carbon Composite Nanofibers

All Fiber Based Electrochemical Capacitor towards Wearable AC Line Filters with Outstanding Rate Capability

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