• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.41-45
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• 2021

In this study, in order to secure the high reliability of the memristor, we adopted a patterned lithium filament seed layer as the main agent for resistive switching (RS) characteristic on the 30 nm thick ZrO₂ thin film at the device manufacturing stage. Lithium filament seed layer with a thickness of 5 nm and an area of 5 ㎛ × 5 ㎛ were formed on the ZrO₂ thin film, and various electrode areas were applied to investigate the effect of capacitance on filament type memristive behavior in the parallel memristive circuit of memristor and capacitor. The RS characteristics were measured in the samples before and after 250℃ post-annealing for lithium metal diffusion. In the case of conductive filaments formed by thermal diffusion (post-annealed sample), it was not available to control the filament by applying voltage, and the other hand, the as-deposited sample showed the reversible RS characteristics by the formation and rupture of filaments. Finally, via the comparison of the RS characteristics according to the electrode area, it was confirmed that capacitance is an important factor for the formation and rupture of filaments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.39-41
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• 2000

Carbon is an attractive candidate for use in eletrochemical supercapacitors that depend on charge storage in the electrode/eletorlyte international double layer. Property of an electrical double layer capacitor depend both on the technique used to prepare the electrode and on the current collector structure. The study is to research that $V_2O_5$-carbon (SP270) composite electrode for supercapacitor. The discharge capacitance of $V_2O_5$-SP270 (20wt%) in 1st and 35cyc1e was 14F/g and 8.5F/g at current density of $0.1mA/cm^2$. The discharge process of $V_2O_5$-SP270 (20wt%) composite electrode is larger than that others.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.246-247
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• 2005

본 연구에서는 활성탄소의 표면 작용기와 전해액, 결합제의 분해반응을 줄여서 내구성을 향상시키기 위해 $H_2$ 기체의 Spill-Over 현상을 이용하여 활성탄소 표면의 작용기를 치환시킨 시료를 사용하여 전극을 구성하였다. $H_2$기체로 활성탄소를 700$^{\circ}C$에서 열처리한 결과, 원소 분석기 (Elemental Analyzer)를 이용한 원소 분석 시에 산소의 비율이 1.4%로 활성탄소의 2.44%에 비해 감소함을 알 수 있었고, Carbon의 비율이 700$^{\circ}C$에서 94.3%로 증가함을 알 수 있었다. 또한, 활성탄소를 사용한 전극을 1.2M TEABF$_4$/Acetonitrile 전해액을 사용하여 커패시터를 구성 했을 때, 1kHz의 AC저항은 700$^{\circ}C$에서 열처리한 활성탄소가 0.58\Omega$로 활성탄소의 1.300에 비해 양호한 전기화학 특성을 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.296-296
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• 2013

Supercapacitor is a capacitor with extraordinarily high energy density, which basically consists of current collector, active material and electrolyte. Ruthenium oxide ($RuO_2$) is one of the most widely studied active materials due to its high specific capacitance and good electrical conductivity. In general, it is known that the coating of $RuO_2$ on nanoarchitectured current collector shows improved performance of energy storage device compared to the coating on the planar current collector. Especially, the surface structure with standing coaxial nanopillars are most desirable since it can provide direct paths for efficient charge transport along the axial paths of each nanopillars and the inter-nanopillar spacing allows easy access of electrolyte ions. However, well-known fabrication methods for metal or metal oxide nanopillars, such as the process using anodize aluminum oxide (AAO) templates, often require long and complicated nanoprocess.In this work, we developed relatively simple method fabricating indium tin oxide (ITO) nanopillars via sputtering. We also electrodeposited $RuO_2$ nanoparticles onto these ITO nanopillars and investigated its physical and electrochemical properties.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2022-2024
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• 2005

Electrical double-layer capacitor (EDLC) is an electrochemical energy storage device in which electric charges only accumulated by a pure electrostatic attraction force are stored on the electrolyte-electrode interface in a form of double layer and separated by the electrolyte. The composite was prepared by mixing nanosize $TiO_2$ and activated carbon through a means of ultrasonic vibration in ethanol solution for 30 min in various mass ratios of $AC:TiO_2$ to form activated carbone-semiconducting oxide composites. Either 1.0 M $LiClO_4/EC-DEC$ or $Et_4NBF_4$/EC-DEC was used as the electrolyte. It was found that with modification of $TiO_2$, the specific capacitance of activated carbon measured at $1mA/cm^2$ was increased from 40 to 50 F/g. This method is unique in comparison the conventional method because it uses semiconducting TiO2 other than electrochemically active materials such as $RuO_2$. The increase in specific capacitance could be attributed to the decrease in electric polarization, caused by the introduction of $RuO_2$.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.191-195
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• 2016

Among the lithium metal oxides for hybrid-capacity, $Li_4Ti_5O_{12}(LTO)$ is an emerging electrode material as zero-stain material in volume change during the with the charging and discharging processes. However, LTO has a limitation of low ionic and electronic conductivity. To enhance the ionic and electronic properties of $Li_4Ti_5O_{12}(LTO)$, we synthesized the spherical LTO/CNT composite by sol-gel process for hybrid capacitors. CNT interconnection networks between CNT-LTO particles enhanced electronic conductivity and electrochemical charging/discharging properties. All of the LTO samples was observed to show the spinel structure and spherical morphology with the diameter of $5{\sim}10{\mu}m$. Especially, spherical LTO/CNT composite of the CNT-3 wt% showed the enhanced capacity from 110 mAh/g to 140 mAh/g at 10 C.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.46-46
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• 2007

There has been rapid progress in the portable electronics industry. which has led to a great increase for a demand of portable, lightweight power sources. Lithium 2'nd batteries have met these demand. and many studies on the cahtod materials for the lithium 2,nd batteries have been reported during the last decade. Possible candidates for the cathode materials for lithium 2,nd batteries are $LiCoO_2$, $LiNiO_2$, and $LiMn_2O_4$. Currently $LiCoO_2$ is widely used. but $LiMn_2O_4$ is an excellent alternative material in view of its several advantages such a low cost as well as the wasy availability of raw materials and environmental benignity. In this study, find the most suitable synthesis method that satisfied high capacitor and stability cycle character, etc in Li-Mn oxide for 2'nd batteries. And also made an experiment on doping the $LiMn_2O_4$ spinel with a small amount of metal ions has a remarkable effect on the electrochemical properties and characterics of powder, BET, PSA, Porosity, etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.541-542
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• 2006

This work describes the effect of the number of roll pressing and the composition of carbon black on the electric and mechanical properties of carbon-PTFE electrode, in which composition is MSP 20 : carbon black : PTFE = 95-X : X : 5 wt.%. It was found that the best electric and mechanical properties were obtained for sheet electrode roll pressed about 15 times and for sheet electrode, in which composition is MSP 20 : carbon black : PTFE = 80 : 15 : 5 wt.%. These behaviors could be explained by the network structure of PTFE fibrils and conducting paths linked with carbon blacks, respectively. On the other hand, cell capacitor using the sheet electrode with 15 wt.% of carbon black attached on aluminum current collector with the electric conductive adhesive, in composition is carbon black : CMC = 70 : 30 wt.%, has exhibited the best rate capability between $0.5mA/cm^2{\sim}100mA/cm^2$ current density and the lowest ESR.

• Journal of Radiation Industry
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• v.9 no.1
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• pp.15-20
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• 2015

Carbon fiber has received much attention owing to its properties, including a large surface-to-volume ratio, chemical and thermal stability, high thermal and electrical conductivity, and high mechanical strengths. In particular, magnetic nanopowder dispersed carbon fiber has been attractive in technological applications such as the electrochemical capacitor and electromagnetic wave shielding. In this study, the nickel-oxide-nanoparticle dispersed polyacrylonitrile (PAN) fibers were prepared through an electrospinning method. Electron beam irradiation was carried out with a 2.5 MeV beam energy to stabilize the materials. The samples were then heat-treated for stabilization and carbonization. The nanofiber surface was analyzed using a field emission scanning electron microscope (FE-SEM). The crystal structures of the carbon matrix and nickel nanopowders were analysed using X-ray diffraction (XRD). In addition, the magnetic and electrical properties were analyzed using a vibrating sample magnetometer (VSM) and 4 point probe. As the irradiation dose increases, the density of the carbon fiber was increased. In addition, the electrical properties of the carbon fiber improved through electron beam irradiation. This is because the amorphous region of the carbon fiber decreases. This electron beam effect of PAN fibers containing nickel nanoparticles confirmed their potential as a high performance carbon material for various applications.

• Nano
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• v.13 no.11
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• pp.1850136.1-1850136.12
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• 2018

Three-dimensional (3D) mixed phases NiSe nanoparticles growing on the nickel foam were synthesized via a simple one-step hydrothermal method. A series of experiments were carried out to control the morphology by adjusting the amount of selenium in the synthetic reaction. Meanwhile, the as-prepared novel column-acicular structure NiSe exist three advantages including ideal electrical conductivity, high specific capacity and high cycling stability. It delivered a high capacitance of $10.8F\;cm^{-2}$ at a current density- of $5mA\;cm^{-2}$. An electrochemical capacitor device operating at 1.6 V was then constructed using NiSe/NF and activated carbon (AC) as positive and negative electrodes. Moreover, the device showed high energy density of $31W\;h\;kg^{-1}$ at a power density of $0.81kW\;kg^{-1}$, as well as good cycling stability (77% retention after 1500 cycles).