• Title/Summary/Keyword: Specific capacitance

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Effect of Hydrogen in Rapid Thermal Annealing on the Graphene-Zinc Oxide Electrode for Supercapacitor (슈퍼커패시터용 그래핀-산화아연 전극의 급속열처리에서 수소의 영향)

  • Jeong, Woo-Jun;Oh, Ye-Chan;Kim, Sang-Ho
    • Journal of the Korean institute of surface engineering
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    • v.52 no.3
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    • pp.123-129
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    • 2019
  • With recent demand for the renewable energy resources, we conducted a research on the energy conversion and storage device of supercapacitor. The hybrid graphene-zinc oxide(GZO) electrodes for the supercapacitors (SCs) were fabricated and investigated. To increase the electrical conductivity of the GZO electrode, the rapid thermal annealing(RTA) in $Ar/H_2$(10%) atmosphere was applied and the effect was examined by comparing it with RTA at Ar atmosphere. In Raman spectroscopy, the electrodes annealed at 400? in $Ar/H_2$ atmosphere showed a lower ratio of D/G peak than that of annealed at Ar atmosphere, and had a larger specific capacitance(Sc) in the cyclic voltammetry(CV), and a lower the equivalent series resistance(ESR) in the electrochemical impedance spectroscopy(EIS). The reason seems to come from the better mixing of the graphene and zinc oxide by the RTA in $Ar/H_2$(10%).

Fabrication of Porous Electrodes for Zinc-Ion Supercapacitors with Improved Energy Storage Performance (아연-이온 전기화학 커패시터의 에너지 저장 성능향상을 위한 다공성 전극 제조)

  • An, Geon-Hyoung
    • Korean Journal of Materials Research
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    • v.29 no.8
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    • pp.505-510
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    • 2019
  • Zn-ion supercapacitors (ZICs) show high energy densities with long cycling life for use in electronic devices. Porous Zn electrodes as anodes for ZICs are fabricated by chemical etching process using optimized conditions. The structures, morphologies, chemical bonding states, porous structure, and electrochemical behavior are examined. The optimized porous Zn electrode shows a root mean square of roughness of 173 nm and high surface area of $153{\mu}m^2$. As a result, ZIC using the optimized porous Zn electrode presents excellent electrochemical performance with high specific capacitance of $399F\;g^{-1}$ at current density of $0.5A\;g^{-1}$, high-rate performance ($79F\;g^{-1}$ at a current density of $10.0A\;g^{-1}$), and outstanding cycling stability (99 % after 1,500 cycles). The development of energy storage performance using synergistic effects of high roughness and high surface area is due to increased electroactive sites by surface functionalization of Zn electrode. Thus, our strategy will lead to a rational design and contribute to next-generation supercapacitors in the near future.

Preparation of Biomass Based Carbon for Electrochemical Energy Storage Application

  • Harshini Priyaa, V.S.;Saravanathamizhan, R.;Balasubramanian, N.
    • Journal of Electrochemical Science and Technology
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    • v.10 no.2
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    • pp.159-169
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    • 2019
  • The activated carbon materials were prepared from waste biomass by ultrasonic assisted chemical activation method (UCA), ultrasonic assisted physical activation method (UPA) and Manganese nitrogen doped carbon (Mn/N-C). The XRD result shows the turbostatic (fully disordered) structure. The cyclic voltammetry test was done at 50 mV/s using 1M sodium sulfate and the values of specific capacitance were found to be 93, 100 and 115 F/g for UCA, UPA and Mn/N-C respectively. The power density values for the samples UCA, UPA and Mn/N-C were found to be 46.04, 87.97 and 131.42 W/kg respectively. The electrochemical impedance spectroscopy was done at low frequency between 1 to 10 kHz. The Nyquist plot gives the resistant characteristics of the materials due to diffusional resistance at the electrode-electrolyte interface. The Energy Dispersive X-Ray Spectroscopyanalysis (EDAX) analysis showed that the percentage doping of nitrogen and manganese were 3.53 wt% and 9.44 wt% respectively. It is observed from the experiment Mn/N-C doped carbon show good physical and electrochemical properties.

Evaluation of Electrochemical Stability of Graphite Current Collector for Electric Double Layer Capacitor Based on Acid Electrolyte (산성 전해질 기반의 전기 이중층 커패시터용 흑연 집전체의 전기화학적 안정성 평가)

  • Park, Sijin;An, Geon-Hyoung
    • Korean Journal of Materials Research
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    • v.31 no.5
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    • pp.272-277
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    • 2021
  • Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g-1 at a current density of 0.1 A g-1, a superior high-rate performance (104 F g-1 at a current density of 20.0 A g-1), and a remarkable cycling stability of 98 % at a current density of 10.0 A g-1 after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.

Synthesis of Activated Carbon from a Bio Waste (Flower of Shorea Robusta) Using Different Activating Agents and Its Application as Supercapacitor Electrode

  • Ghosh, Souvik;Samanta, Prakas;Murmu, Naresh Chandra;Kim, Nam Hoon;Kuila, Tapas
    • Composites Research
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    • v.35 no.1
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    • pp.1-7
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    • 2022
  • The activated carbon is a very good choice for using as supercapacitor electrode materials. Herein, the flower of Shorea robusta, a bio-waste material was successfully used to synthesize the activated carbons for application as supercapacitor electrode materials. The activated carbon was synthesized through chemical activation process followed by thermal treatment at 700℃ in presence of N2 atmosphere using KOH, ZnCl2 and H3PO4 as the activating agents. The physicochemical analyses demonstrate that the obtained activated carbons are graphitic in nature and the degree of disorder of the graphitic carbons is changed with the activating agents. The activated carbon obtained from Shorea robusta flower (ACSF-K) electrode shows the specific capacitance of ~610 F g-1 at 2 A g-1 current density, which is higher than ACSF-Z (560 F g-1) and ACSF-H (470 F g-1) electrode material under the identical current density. The synthesized graphitic carbons also demonstrated good rate capability and high electrochemical stability as supercapacitor electrode.

Facile Electrodeposition Technique for the Fabrication of MoP Cathode for Supercapacitor Application

  • Samanta, Prakas;Ghosh, Souvik;Murmu, Naresh Chandra;Lee, Joong Hee;Kuila, Tapas
    • Composites Research
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    • v.34 no.6
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    • pp.345-349
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    • 2021
  • The continued environmental pollution caused by fossil fuel consumption has prompted researchers around the world to develop environmentally friendly energy technologies. Electrochemical energy storage is the significant area of research in this development process, and the research significance of supercapacitors in this field is increasing. Herein, a simple electrodeposition synthetic route was explored to develop the MoP layered cathode material. The layered structure provided a highly ion-accessible surface for smooth and faster ion adsorption/desorption. After Fe was doped into MoP, the morphology of MoP changes and the electrochemical performance was significantly improved. Specific capacitance value of the binder-free FeMoP electrode was found to be 269 F g-1 at 2 A g-1 current density in 6 M aqueous KOH electrolyte. After adding Fe to MoP, an additional redox contribution was observed in the redox conversion from Fe3+ to Fe2+ redox pair, and the charge transfer kinetics of MoP was effectively improved. This research can provide guidance for the development of supercapacitor electrode materials through simple electrodeposition technology.

Optimizing the Performance of Three-Dimensional Nitrogen-Doped Graphene Supercapacitors by Regulating the Nitrogen Doping Concentration

  • Zhaoyang Han;Sang-Hee Son
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.36 no.4
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    • pp.376-384
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    • 2023
  • Nitrogen-doped graphene was synthesized by a hydrothermal method using graphene oxide (GO) as the raw material, urea as the reducing agent and nitrogen as the dopant. The morphology, structure, composition and electrochemical properties of the samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption analysis, electrical conductivity and electrochemical tests. The results show that urea can effectively reduce GO and achieve nitrogen doping under the hydrothermal conditions. By adjusting the mass ratio of raw materials to dopants, the graphene with different nitrogen doping contents can be obtained; the nitrogen content range is from 5.28~6.08% (atomic fraction percentage).When the ratio of dopant to urea is 1:30, the nitrogen doping content reaches a maximum of 6.08%.The supercapacitor performance test shows that the nitrogen content prepared by the ratio of 6.08% is the best at 0.1 A·g-1. The specific capacitance is 95.2 F·g-1.

Structural and Electrical Properties of Nickel Hydroxide Electrode Prepared by Hydrothermal Synthesis on Nickel Foam (니켈 폼(Ni foam)에 수열 합성법으로 제조한 수산화니켈(Ni(OH)2) 전극의 구조적 및 전기적 특성)

  • Hyunjin Cha;Seokhee Lee;Jeonghwan Park;Young-Guk Son;Donghyun Hwang
    • Journal of the Korean institute of surface engineering
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    • v.56 no.5
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    • pp.320-327
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    • 2023
  • In this study, the nickel hydroxide (Ni(OH)2) electrode for supercapacitor was prepared via hydrothermal method. Based on the nickel (Ni) foam, the electrode does not require any additional binder material or post-processing. Nickel nitrate (Ni(NO3)2) and hexamethylenetetramine (C6H12N4) were used for synthesis, and the synthesis condition was 12 hours at 80 ℃. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) were used to analyze the structural characteristics of the electrode, and it shown that the nickel hydroxide was successfully prepared after only the one-step hydrothermal synthesis. The electrochemical properties were analyzed through the half-cell test. The prepared electrode shown a pair of oxidation/reduction peaks, indicating that the driving method included the redox reaction on the electrode surface. After the charge/discharge test, the specific capacitance was calculated as the value of 438 F/g at 3 A/g.

Preparation of Polymer Gel Electrolyte for EDLCs using P(VdF-co-HFP)/PVP (P(VdF-co-HFP)/PVP를 이용한 EDLC용 고분자 겔 전해질의 제조)

  • Jung, Hyun-Chul;Jang, In-Young;Kang, An-Soo
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.243-249
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    • 2006
  • Porous polymer gel electrolytes (PGEs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix and polyvinylpyrolidone (PVP) as a pore-forming agent were prepared and electrochemical properties were investigated for an electric double layer capacitor (EDLC) in order to increase a permeability of an electrolyte into the PGE. Propylene carbonate (PC) and ethylene carbonate (EC) as plasticizers, and tetraethylammonium tetrafluoroborate ($TEABF_4$) as a supporting salt for the PGE were used. EDLC unit cells were assembled with the PGE and electrode comprising BP-20 and MSP-20 as activated carbon powders, Super P as a conducting agent, and P(VdF-co-HFP)/PVP as a mixed binder. Ion conductivity of PGEs increased with an increased PVP content and was the best at 7 wt% PVP, whereas electrochemical characteristics such as AC-ESR of unit cell were better in 3 wt%. And electrochemical characteristics of the unit cell with PGE were the best at a 33 : 33 weight ratio of PC to EC. Specific capacitance of a mixed plasticizer system of PE and EC was higher than that of pure PC. Ion conductivity of PGEs with a film thickness of $20{\mu}m$ was higher, but electrochemical characteristics of unit cells were higher for a $50{\mu}m$ membrane thickness. Also, the unit cell has shown the highest capacitance of 31.41 F/g and more stable electrochemical performance when PGE and electrode were hot pressed. Consequently, the optimum composition ratio of PGE for EDLCs was 23 : 66 : 11 wt% such as P(VdF-co-HFP) : PVP = 20 : 3 wt% and PC : EC = 44 : 22 wt%. In this case, $3.17{\times}10^{-3}S/cm$ of ion conductivity was achieved at the $50{\mu}m$ thickness of PGE for EDLCs. And the electrochemical characteristics of unit cells were $2.69{\Omega}$ of DC-ESR, 28 F/g of specific capacitance, and 100% of coulombic efficiency.

Characterization of manganese oxide supercapacitors using carbon cloth (Carbon Cloth을 이용한 이산화망간 슈퍼커패시터 특성 연구)

  • Lee, Seung Jin;Kim, Chihoon;Ji, Taeksoo
    • Journal of Digital Contents Society
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    • v.18 no.6
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    • pp.1199-1205
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    • 2017
  • Global energy consumption is rapidly increasing yearly due to drastic industrial advances, requiring the development of new energy storage devices. For this reason, supercapacitors with fast charge-discharge, long life cycle and high power density is getting attention, and have been considered as one of the potential energy storage systems. In this research, we developed a supercapacitor that consists of amorphous manganese oxide($MnO_2$) electrodes deposited onto carbon cloth substrates using the hydrothermal method. The Fe-doped amorphous $MnO_2$ samples were characterized by X-ray diffraction(XRD), Energy Dispersive X-ray spectroscopy(EDX), as well as scanning electron microscopy(SEM). The electrochemical analysis of the prepared samples were performed using cyclic voltammetry and galvanostatic charge-discharge measurements in 1M $Na_2SO_4$ electrolyte. The test results demonstrate that the supercapacitor based on the Fe-doped amorphous $MnO_2$ electrodes has a specific capacitance as high as 163F/g at 1A/g current density, and good cycling stability of 87.34% capacitance retention up to 1000 cycles.