• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.271-275
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• 2009

Five novel lithium polyelectrolyte-ionic liquid systems, using poly (lithium 2-acrylamido-2-methyl propanesulfonate; PAMPSLi) were prepared and their electrochemical properties were measured. The ionic conductivity of the PAMPSLi/1-ethyl-3-methylimidazolium tricyano methanide (emImTCM) system was exhibited high conductivity (1.28 $\times$ $10^{-3}$ $S/cm^{-1}$). The high conductivity and low viscosity of PAMPSLi/emImTCM system is due to the high flexibility of imidazolium cation and dissociation of lithium cation from the polymer chains. The PAMPSLi/N,N-dimethyl-N-propyl-Nbutylammonium tricyanomethanide ($N_{1134}TCM$) and PAMPSLi/N, N-dimethyl-N-propyl-N-butylammonium dicyanamide ($N_{1134}DCA$) systems showed fairly high conductivity (6.3 $\times$ $10^{-4}$ $S/cm^{-1}$, 6.0 $\times$ 10.4 S/cm.1). PAMPSLi/Trihexyl (tetradecyl) phosphonium bis (trifluoromethane sulfonyl) amide ($P_{66614}TFSA$) exhibited low conductivity (2.22 $\times$ $10^{-5}$ $Scm^{-1}$) and thermally stable over 400$^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.838-842
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• 2015

The Li-air battery is a promising candidate for the most energy-dense electrochemical power source because it has 5 to 10 times greater energy storage capacity than that of Li-ion batteries. However, the Li-air cell performance falls short of the theoretical estimate, primarily because the discharge terminates well before the pore volume of the air electrode is completely filled with lithium oxides. Therefore, the structure of carbon used in the air electrode is a critical factor that affects the performance of Li-air batteries. In a previous study, we reported a new class of carbon nanomaterial, named carbon nanoballs (CNBs), consisting of highly mesoporous spheres. Structural characterization revealed that the synthesized CNBs have excellent a meso-macro hierarchical pore structure, with an average diameter greater than 10 nm and a total pore volume more than $1.00cm^3g^{-1}$. In this study, CNBs are applied in an actual Li-air battery to evaluate the electrochemical performance. The formation mechanism and electrochemical performance of the CNBs are discussed in detail.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.25-34
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• 2017

Concurrent electrocatalysis and sensing of hydrazine, sulfite ions, and nitrite ions in a mixture were studied using electrodes modified by electrodeposited Au nanostructures (NSs). The ${\beta}$-cyclodextrin-mixed silicate sol-gel composite was drop-casted on the electrode surface and nucleation guided by ${\beta}$-cyclodextrin occurred, followed by the electrodeposition of Au NSs. The additive, ${\beta}$-cyclodextrin, played an evident role as a structure-directing agent; thus, small raspberry-like Au NSs were obtained. The modified electrodes were characterized by surface characterization techniques and electrochemical methods. The Au NSs-modified electrodes effciently electrocatalyzed the oxidation of toxic molecules such as hydrazine and sulfite and nitrite ions even in the absence of any other electron transfer mediator or enzyme immobilization. Well-resolved oxidation peaks along with decreased overpotentials were noticed during the electrooxidation process. The fabricated Au nanostructured electrode clearly distinguished the electrooxidation peaks of each of the three analytes from their mixture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.634-637
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• 1999

The amorphous vanadium oxide as a cathode material is very preferable for fabricating high performance micro-battery. The amorphous vanadium oxide cathode is preferred over the crystalline form because three times more lithium ions can be inserted into the amorphous cathode, thus making a battery that has a higher capacity. The electrochemical properties of sputtered films are strongly dependent on the oxygen partial pressure in the sputtering gas. The effect of different oxygen partial pressure on the electrochemical properties of vanadium oxide thin films formed by r.f. reactive sputtering deposition were investigated. The stoichiometry of the as-deposited films were investigated by Auger electro spectroscopy. X-ray diffraction and atomic force microscopy measurements were carried out to investigate structural properties and surface morphology, respectively. For high oxygen partial pressure(>30% ), the films were polycrystalline V$_2$O$_{5}$ while an amorphous vanadium oxide was obtained at the lower oxygen partial pressure(< 15%). Half-cell tests were conducted to investigate the electrochemical properties of the vanadium oxide film cathode. The cell capacity was about 60 $\mu$ Ah/$\textrm{cm}^2$ m after 200 cycle when oxygen partial pressure was 20%. These results suggested that the capacity of the thin film battery based on vanadium oxide cathode was strongly depends on crystallinity.y.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.5
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• pp.418-427
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• 2019

Activated carbon was synthesized from bamboo charcoal by KOH activation at various temperatures for electrochemical double layer capacitor applications. The micro-structural and surface properties of all the samples were characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption/desorption isotherm method. The electrochemical properties of the activated bamboo charcoal were examined by cyclic voltammetry in the potential window of -1.0 to 0.2 V in 6 M KOH electrolyte at different scan rates. An electrode made from the sample activated with 7.5 M KOH and heat treated at $750^{\circ}C$ for 3 h gave a maximum capacitance of 553 F/g at 1 mV/s and 450 F/g at 10mV/s.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.209-209
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• 2003

The adventages of Li alloys have attracted the attention of many research groups, many of which have investigated tin-based alloys [1-2], Despite interesting performances of these, the irreversible capacity loss systematically observed on the first cycle for these compounds is a main drawback for their use as anode materials in lithium ion cells. Not only Sn is efficient in forming alloys with Li, Si can also react with Li to form alloys with a high Li/Si ratio, like Li$\_$22/Si$\_$5/ at 400$^{\circ}C$. It corresponds to a capacity of 4200mAh/g. Electrochemical Li-Si reaction occurs between 0 and 0.3 V against Li/Li$\^$+/, so that high-energy density battery can be realized. Despite the high theoretical capacity of elements like Si, however, particles of the alloys crack and fragment due to the repeated alloying and do-alloying which occurs as cell are charged and discharged. The research groups of Muggins [3] and Besenhard [4] have proposed that the volume expansion due to the insertion of Li can be reduced in micro- and submicro-structured matrix alloys. For this reason, the research group of J.R. Dahn investigated Sn/Mo sequential sputter deposition to prepare nanocomposites [5]. In this study, we investigated the characterization and the electrochemical characteristics of sequentially sputtered Si/Mo multilayer for microbattery anode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.713-716
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• 2001

In many papers, the electrochemical analysis of LiMn$_2$O$_4$shows the transition results of Mn$^{3+}$ ion. Charge ordering is accompanied by simultaneous orbital ordering due to the Jahn-Teller effect in Mnl$^{3+}$ ions. To analyze the cycle performance of LiMn$_{2-x}$Cu$_{x}$ O$_4$as the cathode of 4 V class lithium secondary batteries, XRD, TGA analysis were conducted. Although the cycle performance of the LiMn$_{2-x}$Cu$_{x}$ O$_4$was improved from pure LiMn$_2$O$_4$, the discharge capacity was significantly lower than LiCoO$_2$. In this paper, We study the Electrochemical characterization and enhanced stability of Cu-doped spinels in the LiMn$_{2-x}$Cu$_{x}$ O$_4$upon initial cycling.l cycling.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.282-286
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• 2009

The synthesis and characterization of catalysts supported on multi-walled carbon nanotubes (CNTs). $Pt/Au/TiO_2$ is added to a CNTs(cabon nano tube) carbon support to improve the performance of a direct methanol fuel cell. XRD and SEM showed that uniform anatase $TiO_2$ and Pt/Au particles were about 200 nm and 20${\sim}$25 nm in diameter. The composite catalyst activities were measured by cyclic voltammetry (CV), demonstrating that it is more promising for use in fuel cells.

• Journal of the Korean institute of surface engineering
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• v.40 no.1
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• pp.16-22
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• 2007

Recently, mesoporous metallic materials are becoming more and more important in various applications like catalysts, electrochemical detectors, batteries, and fuel cells because of their high surface area. Among the various methods for manufacturing mesoporous structure, surfactant templating method followed by electroplating has been tried in this study. A mesoporous metallic film was prepared by electrodeposition from electroplating solution mixed with surfactant template. Nonionic type lyotropic liquid crystalline surfactant, Brij56, and nickel acetate based solution were selected as a template material and electroplating solution, respectively. To determine the content of surfactant forming a hexagonal column structure, the phase diagram of electroplating solution and surfactant mixture has been exploited by polarized optical microscopy equipped with heating and cooling stage. Nickel films were electroplated on Cu foil by stepwise potential input method to alleviate the concentration polarization occurred during the electroplating process. TEM and XRD analyses were performed to characterize the size and shape of mesostructures in manufactured nickel films, and electrochemical characterization was also carried out using cyclic voltammetry.

• Analytical Science and Technology
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• v.8 no.4
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• pp.583-590
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• 1995

Pitch-based mesophase carbon fibers prepared at different temperatures were heat-treated at temperatures lower than those of the preparation and the electrochemical Li doping/undoping characteristics were evaluated in relation to the data of IR, mass, etc. Presence of surface hydroxyls were confirmed by FTIR for lower temperature sample which showed poor anode characteristics. Upon oxidative heating, removal of surface hydroxyls took place, resulting in a remarkable improvement of the electrode characteristics. At the same time, surface roughening took place, which was confirmed by SEM and double layer capacity measurements. In situ mass spectra obesrved during the heat-treatments showed gas evolution of $H_2O$, CO, $CO_2$, $C_2H_4$, and/or $H_2$ depending on the conditions. These data together with those of weight loss and conductivity provided us a valuable information in regard to the evaluation of the electrochemical characteristics.