• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.206-211
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• 2017

Carbon felt electrode for the vanadium redox-flow battery (VRFB) has been studied to see the effect of grephene oxide (GO) treatment on the surface of the carbon felt electrode. In this paper, surface of carbon felt electrodes were treated with various concentrations of grephene oxide. Electrochemical analysis, cyclic voltammetry (CV), was performed to investigate redox characteristics as electrode for VRFB. Also the effect of GO on the introduction of functional group on the surface of carbon felt electrodes were investigated using X-ray photoelectron spectroscopy (XPS), which discovered increase in the overall functional group content on the surface of carbon felts.

• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.180-185
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• 2019

The demands to improve the performance of the vanadium redox flow battery have attracted an intense research on modifying the carbon-based electrode. In this study, the surface of graphite felt was reformed, using cobalt oxide. The cobalt oxide was implanted into graphite felt during hydrothermal and two step heat treatments. The cobalt was deposited by hydrothermal method and the two step heat treatments made lots of holes on the graphite felt surface which is called as porous surface. The porous surface acts as an electrochemically active site for the cathodic reaction of vanadium redox flow battery. The reformed electrode shows the electrochemically improved performance compared with the pristine electrode.

• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.150-155
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• 2019

The carbon electrode was modified through manganese-catalyzed hydrogenation method for high energy density vanadium redox flow battery (VRFB). During the catalytic hydrogenation, the manganese oxide deposited at the surface of the carbon electrode stimulated the conversion reaction from carbon to methane gas. This reaction causes the penetration of the manganese and excavates a number of cavities at electrode surface, which increases the electrochemical activity by inducing additional electrochemically active site. The formation of the porous surface was confirmed by the scanning electron microscopy (SEM) images. Finally, the electrochemical performance test of the electrode with the porous surface showed lower polarization and high reversibility in the cathodic reaction compared to the conventional electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.448-451
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• 2004

Vanadium oxides have been widely used in a variety of technological applications such electrochromic devices as infrared detectors and are expected as a material suitable for gas sensing applications. Thin films of Vanadium oxide (VOx) have been deposited by r.f magnetron sputtering under different oxygen partial pressure ratios and substrate temperatures. Humidity-sensitive properties of resistive sensors having interdigitated electrode structure are characterized. Our sensors show good response to humidity over 20%RH to 80%RH. Vanadium oxide films deposited with 0% $O_2$ partial pressure at foot exhibit greater sensitivity to humidity change than others.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.10
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• pp.475-480
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• 2006

Vanadium oxide thin films (VOx) have been deposited by RF magnetron sputtering from $V_2O_5$ target under different oxygen partial pressure ratios(0%, 10%) and substrate temperatures$(27^{\circ}C,\;400^{\circ}C)$. Crystallographic structure and morphology of the films are studied by XRD and SEM. Humidity-sensing properties of resistive sensors having interdigitated electrode structure are characterized through electrical conduction measurements. The films deposited at room temperature are amorphous whereas the ones deposited above foot are polycrystalline. The sensors show good response to humidity over 20%RH to 80%RH. Vanadium oxide thin films deposited with $0%O_2$ partial pressure at $400^{\circ}C$ exhibit greater sensitivity to humidity change than others.

• Journal of the Korean Electrochemical Society
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• v.21 no.3
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• pp.55-60
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• 2018

The demand for LIBs with higher energy densities has increased continuously because the emergence of wider and more challenging applications including HEV and EV has became imperative. However, in the case of anode material, graphite is insufficient to meet this need. To meet such demand, several type of negative electrode materials like silicon, tin, SiO, and transition metal oxide have been investigated for the advanced lithium secondary batteries. Recently, lithium vanadium oxide, which has a layered structure, is assumed as one of the promising anode material as alternative of graphite. This material shows a high volumetric capacity, which is 1.5 times higher than that of graphite. However, relative low electrical conductivity and particle fracture, which results in the electrolyte decomposition and loss of electric contact between electrode, induce rapid capacity decay. In this report, we investigated the effect of electrolyte additive on the electrochemical characteristics of lithium vanadium oxide.

• Journal of the Korean institute of surface engineering
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• v.30 no.2
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• pp.121-127
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• 1997

Vanadium tungsten oxide thin films were formed by RF magnetron sputtering and the effects of tungsten addition on the crystallinity and on the electrochemical behavior were investigated. X-ray analysis revealed that amorphized films could be obtained by tungase addition. In order to investigate the electrochemical behavior of the vanadium tungsten oxide films, electrochemical insertion and extraction of lithium were out in 1m $LiCIO_4$-PC-DME electrolyte using litium metal as a counter electrode. When the tungsten was added to the $V_2O_5$ films, cycling reversibility was considerably improved. Electrochemical test showed the cell capacity of about $70\mu\;Ah/\textrm{cm}^2-\mu\textrm{m}$ when the amount of additive tungseten reached 30 atomic percent. No appreciable degradation of the cell capacity could be observed after hundred cycles of insertion and extration od Li.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.225-230
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• 1987

The redox properties of 2-mercaptopyridine N-oxide (mpno) and its oxovanadium complex, $VO (mpno)_2$ have been studied by the use of polarography and cyclic voltammetry. The radical anion of mpno is generated in acetone and is adsorbed to the electrode to form an adsorption wave at -0.21 V vs Ag/AgCl electrode. The normal wave appeared at -0.50 V is attributed to the formation of radical anion. The $VO (mpno)_2$ exhibits one oxidation wave at +0.57 V, and two reduction waves at -1.07 V and -1.76 V vs. Ag/AgCl electrode; the oxidation is fully reversible one-electron process ($VO (mpno)_2\;{\leftrightarrow}\;VO(mpno)_2^+ + e).$ The reduction wave at -1.07 V is quasireversible and is arised from the formation of $VO (mpno)_2^-.$ The second reduction wave at -1.76 V is irreversible and this reduction process consists of two one-electron steps. The sulfur containing ligands seem to enhance the stability of lower oxidation state of vanadium while the oxygen or nitrogen donor of the ligands stabilize the higher oxidation state of vanadium when comparisons are made among several oxovanadium complexes.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.523-528
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• 1998

The electrochemical characteristics of $V_2O_5$ as working electrode were studied in the cell (1-butene+$O_2$, $V_2O_5{\mid}YSZ{\mid}Ag$, $O_2$) with a YSZ solid electrolyte. The sintering of Ag as a counter electrode was occurred after calcination, and the structure which has the pores of over $3{\mu}m$ was achieved. In particular, the peak of (010) plane of the working electrode on the XRD spectrum which is responsible for selective oxidation appeared after calcination. The major product of 1-butene oxidation over $V_2O_5$ was butadiene. The technique of SEP (solid electrolyte potentiometry) was used to monitor the chemical potential of chemical species adsorbed on the working electrode. Over a wide range of gas compositions of 1-butene and oxygen, open circuit voltage (OCV) exhibited the mixed potential of surface oxygen activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.239.2-239.2
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• 2016

Numerous studies and approaches have been performed for solar cells to improve their photoelectric conversion efficiencies. Among them, the study for electrode containing transparent conducting oxide (TCO) layers is one of issues as well as for the cell structure based on band theory. In this study, we focused on an interfacial layer between p-type silicon and indium tin oxide (ITO) well-known as TCO materials. According to current-voltage characteristics for the sample with the interfacial layers, the improvement of band alignment between p-type silicon and ITO was observed, and their ohmic properties were enhanced in the proper condition of deposition. To investigate cause of this improvement, spectroscopic ellipsometry and ultraviolet photoelectron spectroscopy were utilized. Using these techniques, band alignment and defect in the band gap were examined. The major materials of the interfacial layer are vanadium oxide and tungsten oxide, which are notable as a hole transfer layer in the organic solar cells. Finally, the interfacial layer was applied to silicon solar cells to see the actual behavior of carriers in the solar cells. In the case of vanadium oxide, we found 10% of improvement of photoelectric conversion efficiencies, compared to solar cells without interfacial layers.