• Title/Summary/Keyword: Specific capacitance

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Analysis of Interfacial Layer between Alumina and Silica/Silicon Substrate (알루미나와 실리카/실리콘 기판의 계면 분석)

  • 최일상;김영철;장영철
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2002.05a
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    • pp.252-254
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    • 2002
  • Metal oxides with high dielectric constants have the potential to expend scaling of transistor gate capacitance beyond that of ultrathin silicon dioxide. However, during deposition of most metal oxides on silicon, an interfacial region of SiOx is formed and limits the specific capacitance of the gate structure. We deposisted aluminum oxide and examined the composition of the interfacial layer by employing high-resolution X-ray photoelectron spectroscopy and X-ray reflectivity. We find that the interfacial region is not pure SiO$_2$, but is composed of a complex depth-dependent ternary oxide of $AlSi_xO_y$ and the pure SiO$_2$.

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Graphene Oxide based Metal ion Hybrid Supercapacitor (산화그라핀 및 금속 이온 결합체를 이용한 슈퍼커패시터 특성 연구)

  • Jung, Youngmo;Jun, Seong Chan
    • Transactions of the Society of Information Storage Systems
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    • v.9 no.1
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    • pp.22-27
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    • 2013
  • In this paper we are presenting a architecture of Co ion decorated graphene oxide as an electrode for supercapacitor application. Graphene oxide, which is exfoliated by oxidant from graphite, is the material for solving the problem of mass production and coating on the surface of working electrode. The $Co^{2+}$ ions are coated by using layer by layer(LBL) method on graphene oxide foam. The metal ion decorated graphene oxide shows enhanced capacitance performance when tested as supercapacitor electrode, showing the specific capacitance of $827Fg^{-1}$.

Naphthalene Derivative Supported Activated Carbon Composite Electrode with Enhanced Capacitance and Potential Window

  • Hu, Mengyang;Park, Jeong Ho;Lee, Kwang Se;Ko, Jang Myoun
    • Journal of Electrochemical Science and Technology
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    • v.10 no.2
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    • pp.99-103
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    • 2019
  • A derivative of 1,4-Naphthoquinone coded HBU671 was synthesized and used in addition to activated carbon as composite electrode for supercapacitor application. From the electrochemical properties analysis, a specific capacitance of about $300F\;g^{-1}$ exhibited almost two times of that of activated carbon at a scan rate of $100mV\;s^{-1}$ and a potential window of - 0.2 - 1V. This improvement is due to the inherent redox reaction in HBU671. Cycle test also proved that this composite is still stable even after 1000 cycle within the applied potential window and it is highly recommended for practical application.

Nano-Morphology Design of Nickel Cobalt Hydroxide on Nickel Foam for High-Performance Energy Storage Devices (고성능 에너지 저장 소자를 위한 니켈 구조체에 담지된 니켈 코발트 수산화물의 나노 형상 제어)

  • Shin, Dong-Yo;Yoon, Jongcheon;Ha, Cheol Woo
    • Korean Journal of Materials Research
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    • v.31 no.12
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    • pp.710-718
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    • 2021
  • Recently, due to high theoretical capacitance and excellent ion diffusion rate caused by the 2D layered crystal structure, transition metal hydroxides (TMHs) have generated considerable attention as active materials in supercapacitors (or electrochemical capacitors). However, TMHs should be designed using morphological or structural modification if they are to be used as active materials in supercapacitors, because they have insulation properties that induce low charge transfer rate. This study aims to modify the morphological structure for high cycling stability and fast charge storage kinetics of TMHs through the use of nickel cobalt hydroxide [NiCo(OH)2] decorated on nickel foam. Among the samples used, needle-like NiCo(OH)2 decorated on nickel foam offers a high specific capacitance (1110.9 F/g at current density of 0.5 A/g) with good rate capability (1110.9 - 746.7 F/g at current densities of 0.5 - 10.0 A/g). Moreover, at a high current density (10.0 A/g), a remarkable capacitance (713.8 F/g) and capacitance retention of 95.6% after 5000 cycles are noted. These results are attributed to high charge storage sites of needle-like NiCo(OH)2 and uniformly grown NiCo(OH)2 on nickel foam surface.

Synthesis and Electrochemical Characterization of Porous Co3O4/RuO2 Composite (다공성 Co3O4/RuO2 복합체 합성 및 전기화학적 특성)

  • Lim, Hye-Min;Ryu, Kwang-Sun
    • Korean Journal of Materials Research
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    • v.22 no.3
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    • pp.118-122
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    • 2012
  • We synthesized porous $Co_3O_4/RuO_2$ composite using the soft template method. Cetyl trimethyl ammonium bromide (CTAB) was used to make micell as a cation surfactant. The precipitation of cobalt ion and ruthenium ion for making porosity in particles was induced by $OH^-$ ion. The porous $Co_3O_4/RuO_2$ composite was completely synthesiszed after anealing until $250^{\circ}C$ at $3^{\circ}C$/min. From the XRD ananysis, we were able to determine that the porous $Co_3O_4$/RuO2 composite was comprised of nanoparticles with low crystallinity. The shape or structure of the porous $Co_3O_4/RuO_2$ composite was studied by FE-SEM and FE-TEM. The size of the porous $Co_3O_4/RuO_2$ composite was 20~40 nm. From the FE-TEM, we were able to determine that porous cavities were formed in the composite particles. The electrochemical performance of the porous $Co_3O_4/RuO_2$ composite was measured by CV and charge-discharge methods. The specific capacitances, determined through cyclic voltammetry (CV) measurement, were ~51, ~47, ~42, and ~33 F/g at 5, 10, 20, and 50 mV/sec scan rates, respectively. The specific capacitance through charge-discharge measurement was ~63 F/g in the range of 0.0~1.0 V cutoff voltage and 50 mAh/g current density.

Enhancement of Electrochemical and Mechanical Properties of 3D Graphene Nanostructures by Dopamine-coating (도파민 코팅을 이용한 3차원 그래핀 나노 구조체의 전기화학적/기계적 특성 향상 연구)

  • Lee, Guk Hwan;Luan, Van Hoang;Han, Jong Hun;Kang, Hyun Wook;Lee, Wonoh
    • Composites Research
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    • v.32 no.6
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    • pp.388-394
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    • 2019
  • Inherited the excellent electrical and mechanical properties based on the low dimensional structure of graphene, three-dimensional graphene nanostructures have gathered great attention as electrochemical energy storage electrodes owing to their high porosity and large specific surface area. Also, having the catecholamine structure, dopamine has been regarded as a multifunctional material to possess high affinity to various organic/inorganic materials and to modify a hydrophobic surface to a hydrophilic one. In this work, through coating dopamine on the three-dimensional graphene nanostructure, we tried to increase the specific capacitance by enhancing the wettability with electrolyte and to improve the mechanical compressive property by strengthening the nano-architecture. As a result, the dopamine-coated nanostructure exhibited significant improvement on the specific capacitance (51.5% increase) and compressive stress (59.6% increase).

Characteristics of high energy density hybrid capacitor using metal oxide electrode (금속산화물 전극을 사용한 고 에너지밀도 하이브리드 커패시터 특성)

  • Yoon, Hong-Jin;Shin, Yoon-Sung;Lee, Jong-Dae
    • Journal of the Korean Applied Science and Technology
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    • v.28 no.3
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    • pp.329-334
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    • 2011
  • The electrochemical performances of an asymmetric hybrid capacitor were investigated using $LiFePO_4$ as the positive electrode and active carbon fibers(ACF) as the negative electrode. The electrochemical behaviors of a nonaqueous hybrid capacitor were characterized by constant current charge/discharge test. The specific capacitance using $LiFePO_4$/ACF electrode turned out to be $0.87F/cm^2$ and the unit cell showed excellent cycling performance. This hybrid capacitor was able to deliver a specific energy as high as 178 Wh/kg at a specific power of 1,068 W/kg.

Studies on Electrical Double Layer Capacitor Based on Mesoporous Activated Carbon

  • Meigen, Deng;Yihong, Feng;Bangchao, Yang
    • Carbon letters
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    • v.6 no.2
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    • pp.86-88
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    • 2005
  • Mesoporous activated carbon (AC) was prepared from aged petroleum coke through chemical activation. The AC has a specific surface area of 1733 $m^2/g$ and a mean pore diameter of 2.37 nm. The volume fraction of 2 to 4nm pores is 56.74%. At a current density of 10 mA/$cm^2$, a specific capacitance of 240 F/g is achieved representing the use factor of the surface area of 69.2%. And the electrical double layer capacitor (EDLC) based on the AC shows an excellent power performance. This result suggests that the presence of high fraction of mesopores can effectively increase the adsorption efficiency of the specific surface area of the AC and enhance the power performance of EDLC based on the efficient surface area of the AC.

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Preparation and Electrochemical Properties of PANI/TiO2 Composites for Supercapacitor Electrodes (수퍼커패시터 전극을 위한 폴리아닐린/TiO2 복합체의 제조 및 전기화학적 성질)

  • Park, Sukeun;Kim, Kwang Man;Lee, Young-Gi;Jung, Yongju;Kim, Seok
    • Korean Chemical Engineering Research
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    • v.50 no.1
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    • pp.50-54
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    • 2012
  • In this study, PANI and PANI/$TiO_2$ composites were prepared as electrode materials for a supercapacitor application. Cyclic voltammetry (CV) was performed to investigate the supercapacity properties of these electrodes in an electrolyte solution of 6 M KOH. The PANI/$TiO_2$ composites were polymerized by amount of various ratios through a simple in-situ method. The morphological properties of composites were analyzed by SEM and TEM method. The crystallinity of the composite and $TiO_2$ particle size were identified using X-ray diffraction (XRD). In the electrochemical test, The electrode containing 10 wt% $TiO_2$ content against aniline units showed the highest specific capacitance (626 $Fg^{-1}$) and delivered a capacitance of 286 $Fg^{-1}$ reversibly at a 100 $mVs^{-1}$ rate. According to the surface morphology, the increased capacitance was related to the fact that nano-sized $TiO_2$ particles (~6.5 nm) were uniformly connected for easy charge transfer and an enhanced surface area for capacitance reaction of $TiO_2$ itself.

Preparation of Heated Tobacco Biomass-derived Carbon Material for Supercapacitor Application (궐련형 담배 바이오매스 기반의 슈퍼커패시터용 탄소의 제조 및 응용)

  • Kim, Jiwon;Jekal, Suk;Kim, Dong Hyun;Yoon, Chang-Min
    • Journal of the Korea Organic Resources Recycling Association
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    • v.30 no.2
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    • pp.5-15
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    • 2022
  • In this study, heated tobacco biomass was prepared as an active material for supercapacitor device. Retrieved tobacco leaf from the heated tobacco was carbonized at various temperature(800/850/950℃). Carbonized tobacco leaf material synthesized at 850℃ exhibited the highest C/O ratio, indicating the finest carbon quality. In addition, polypyrrole was coated onto the carbonized leaf material for increasing the electrochemical performance via low-temperature polymerization method. As-synthesized carbonized leaf material at 850℃(CTL-850)-based electrode and polypyrrole-coated carbonized leaf material(CTL-850/PPy)-based electrode displayed outstanding specific capacitances of 100.2 and 155.3F g-1 at 1 A g-1 with opertaing window of -1.0V and 1.0V. Asymmetric supercapacitor device, assembled with CTL-850 as the negative electrode and CTL-850/PPy as the positive electrode, manifested specific capacitance of 31.1F g-1(@1 A g-1) with widened operating voltage window of 2.0V. Moreover, as-prepared asymmetric supercapacitor device was able to lighten up the RED Led (1.8V), suggesting the high capacitance and extension of operating voltage window. The result of this research may help to pave the new possibility toward preparing the effective energy storage device material recycling the biomass.