• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.502-507
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• 2007

The oxidation treatment of several carbon materials with a sodium chlorate and 70 wt.% of nitric acid, combined with heat treatment, were attempted to achieve an electrochemical active material with a larger capacitance. Among pitch, needle coke, calcinated needle coke and natural graphite, the structure of needle coke and calacinated needle coke were changed to the graphite oxide structure with the expansion of the inter-layer. On the other hand, the calcinated needle coke after oxidation and heating at $200^{\circ}C$ has exhibited largest capacitance per weight and volume of 29.5 F/g and 24.5 F/ml at the two-electrode system in the potential range of 0 to 2.5 V. The electrochemical performance of the calcinated needle coke was discussed with the phenomenon of the electric field activation and the formation of new pores between the expanded inter-layer at first charge.

• Journal of Electrochemical Science and Technology
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• 제10권1호
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• pp.55-60
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• 2019

Herein, the effect of counter anions on the formation of a solid electrolyte interphase (SEI) in a propylene carbonate (PC)-based electrolyte solution was investigated. Although the reversible capacities were different, reversible intercalation and de-intercalation of lithium ions occurred in the graphite negative electrode in the PC-based electrolyte solutions containing 1 M $LiClO_4$, $LiPF_6$, $LiBF_4$, and $LiCF_3SO_3$ at low temperature ($-15^{\circ}C$). This indicated that the surface films acted as an effective SEI to suppress further co-intercalation and decomposition reactions at low temperature. However, the SEIs formed at the low temperature were unstable in 1 M $LiPF_6$ and $LiBF_4/PC$ at room temperature ($25^{\circ}C$). On the other hand, increasing reversible capacity was confirmed in the case of $LiCF_3SO_3/PC$ at room temperature, because the SEI formed at the low temperature was still maintained. These results suggest that counter anions are an important factor to consider for the formation of effective SEIs in PC-based electrolyte solutions.

• 한국표면공학회지
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• 제28권2호
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• pp.83-91
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• 1995

A new method for preparation of thin nickel foam for Ni-MH battery was investigated. In this method, fine graphite powders of $1\mu\textrm{m}$～$2\mu\textrm{m}$ diameter were pasted into pores of thin polyurethane foam film in order to supply electric conducting seeds for nickel deposition by electroless plating reaction. After electroless plating, remaining polyurethane foam was removed chemically by organic solvent treatment and graphite particles also removed by ultrasonic cleaning. Porosity of formed nickel foam was about 85% During electroplating, porosity of the nickel foam decreased less than 5% up to $30\mu\textrm{m}$ coating thickness. And then it was electroplated and heat-treated to improve mechanical strength and ductility. Finally, thin nickel foam for Ni electrode of Ni-MH battery with 80% porosity and $350\mu\textrm{m}$～X$400\mu\textrm{m}$ thickness was obtained.

• 한국응용과학기술학회지
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• 제31권4호
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• pp.663-668
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• 2014

An in-vivo diagnosis of trace Mg(II) ion was performed using a low-cost and environment-friendly voltammetric method, using a graphite counter and reference electrodes and a fluorine-immobilized graphite working electrode, and clean deep seawater was used as an electrolyte solution. Under optimum conditions, the analytical working ranges attained microgram ranges, and a detection limit of $80.6ugL^{-1}$ was obtained using stripping voltammety with 60 sec accumulation time. Ex-vivo application was performed on fish liver and mice droppings. The developed techniques can be applicable to tumor cell analysis.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.97.2-97.2
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• 2012

This study examined the utility of two zwitterions, nitrile-functionalized zwitterions and a zwitterion without a nitrile group (MF-ZI), were used as additives along with 1 M $LiPF_6$ in ethylene carbonate (EC):diethylene carbonate (DEC) (3:7 V/V) (E-0) to form an electrolyte solution for use in lithium ion batteries comprising graphite and $LiCoO_2$ electrodes. The presence of NF-ZI (E-NF-ZI) in the electrolyte produced an ion conductivity comparable to that of E-0 and higher than that of an electrolyte containing MF-ZI (E-MF-ZI). Linear sweep voltammetry data revealed that the intensity of the E-NF-ZI reduction peak was lower than that of E-0. Furthermore, the successful formation of an SEI layer in the E-NF-ZI over graphite was confirmed by cyclic voltammetry data. These results were attributed to the adsorption of NF-ZI on the electrode surface, as verified by differential capacity measurements.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.472-477
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• 2014

A voltammetric investigation of Au assay was conducted at a low cost, using Nafion and DNA immobilized on a graphite Pencil working electrode (NDP) with a black lead counter and reference. The following optimal parameters were found: 0.4 V amplitude, 500 Hz frequency, -0.7 V initial potential, and 0.015 V increment potential. These optimal conditions were also applied to sand obtained from the river site. The aforementioned technique is simpler and less costly compared to the common voltammetry and spectrophotometric methods.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.279-285
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• 2008

CNC (Carbon Nano Colloid) was used as an additive to the positive electrode to improve the discharge performance of sealed lead-acid batteries, The cathode active material ($PbO_2$) has a relatively low utility of less than 60 % compared with other kind of batteries, such as Ni-MH and Lithium ion, In this study, to overcome the above-mentioned problem we investigated the effects of CNC addition on the enhancement of electrical connection with not-utilized $PbO_2$ and resultantly electrical conductivity of electrode, We examined low rate discharge capacities, high rate discharge capacities and internal resistances of the batteries containing various amounts of CNC. From these results, we found out that the addition of CNC into the positive electrode made a significant improvement in high rate discharge capacity, We also suggested the optimum content of CNC material in positive electrode.

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.234-238
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• 2005

Glucose oxidase was immobilized on the carboxylated multi-wall carbon nanotubes (MWNT-COOHs) in the presence of a coulping reagent, 1-ethy1-3-(3-dimethylaminopropy1) carbodiimide. Significant amounts of glucose oxidase were also immobilized on MWNT-COOHs without the coupling reagent. Various conditions for the immobilization of glucose oxidase were optimized. Optimal pH for the maximal activity of the immobilized glucose oxidase shifted to 7 from the optimal pH of 6 for the maximal activity of free enzyme due to the carboxy1 groups on the surface of MWNT-COOHs. An electrode of graphite rod with a diameter of 6 mm was fabricated using the immobilized glucose oxidase. The cyclic voltammetry study of the enzyme electrode revealed that the oxidation of glucose and subsequent transfer of electrons from the oxidation of glucose to the electrode were possible by the immobilized glucose oxidase without a mediator, implying that the enzyme electrode can be utilized for the development of biofuel cells.

• Bulletin of the Korean Chemical Society
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• 제24권7호
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• pp.948-952
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• 2003

New approach for the determination of Ag(I) ion was performed by using a carbon paste electrode (CPE) containing N,N'-Diphenyl oxamide (DPO) with anodic stripping voltammetry. The CMEs have been prepared by making carbon paste mixtures containing an appropriate amount of DPO salt coated onto graphite particles to analyze trace metal ions via complexation followed by stripping voltammetry. Various experimental parameters affecting the response, such as pH, deposition time, temperature, and electrode composition, were carefully optimized. Using differential pulse anodic stripping voltammetry, the logarithmic linear response range for the Ag(I) ion was 1.0 × $10^{-7}$ - 5.0 × $10^{-9}$ M at the deposition time of 10 min, with the detection limit was 7.0 × $10^{-10}$ M. The detection limit adopted from anodic stripping differential pulse voltammetry was 7.0 × $10^{-10}$ M for silver and the relative standard deviation was ± 3.2% at a 5.0 × $10^{-8}$ M of Ag(I) ion (n = 7). The proposed electrode shows a very good selectivity for Ag(I) in a standard solution containing several metals at optimized conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1184-1187
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• 2003

Electrochemical capacitors are becoming attractive energy storage systems particularly for applications involving high power requirements such as hybrid systems consisting of batteries and electrochemical capacitors for electric vehicle propulsion. A new type electric double layer capacitor (EDLC) was constructed by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. Carbonaceous materials are found in variety forms such as graphite, diamond, carbon fibers etc. While all the carbon nanofibers include impurities such as amorphous carbon, nanoparticles, catalytic metals and incompletely grown carbons. We have eliminated of Ni particles and some carbonaceous particles in nitric acid. Nitric acid treated CNFs could be covered with very thin DAAQ oligomer from the results of CV and TG analyses and SEM images. DAAQ oligomer film exhibited a specific capacity as 45-50 Ah/kg in 4M $H_2SO_4$. We established Process Parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured CNFs electrodes using controlled solution chemistry. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.