• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.115-120
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• 2000

All solid-state thin film micro-batteries consisting of lithium metal anode, an amorphous LiPON electrolyte and cathode of vanadium oxide have been fabricated and characterized, which were fabricated with cell structure of $Li/LiPON/V_2O_5Pt$. The effect of various oxygen partial pressure on the electrochemical properties of vanadium oxide thin films formed by d.c. reactive sputtering deposition were investigated. The vanadium oxide thin film with deposition condition of $20\%\;O_2/Ar$ ratio showed good cycling behavior. In in-siか process, the LiPON electrolyte was deposited on the $V_2O_5$ films without breaking vacuum by r.f. magnetron sputtering at room temperature. After deposition of the amorphous LiPON, the Li metal films were grown by a thermal evaporator in a dry room. The charge-discharge cycle measurements as a function of current density and voltage variation revealed that the $Li/LiPON/V_2O_5$ thin film had excellent rechargeable properly when current density was $7{\mu}A/cm^2$. and cut-off voltage was between 3.6 and 2.7V In practical experiment, a stopwatch ran on this $Li/LiPON/V_2O_5$ thin film micro-battery. This result means that thin film micro-battery fabricated by in-siか process is a promising for power source for electronic devices.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.1-6
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• 2002

Silver doped vanadium pentoxides with a doping ratio Ag/V ranging from 0.03 to 0.11 were synthesized by sol-gel process, and $Li/Ag_xV_2O_5$ cell was investigated by the electrochemical methods. It appears to be amorphous layered material and entangled fibrous textures has been grown to form anisotropic corrugated fibrils. NMR measurements revealed that several different kinds of $Li^+$ ions exist in the lithium intercalated xerogel electrodes and the average cell potential was about 3.0V vs. $Li/Li^+$. The cell capacity of the silver doped $Ag_xV_2O_5$ xerogel cathodes was more than 359 mAh/g at discharge current 10mA/g and cycle efficiency $94\%$ was achieved.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.211-216
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• 2010

$(NH_4)_{0.3}V_2O_5$ nanorods and $V_2O_5$ nanosheets have been synthesized by the reaction of $V_2O_5$ gel via homogeneous precipitation process employing urea and formic acid. The electrochemical and chemical characteristics of these nanomaterials have been investigated using TGA, SEM, FT-IR, XRD, and LSV. The interlayer distance of $(NH_4)_{0.3}V_2O_5$ was about $10.7{\AA}$, and that of $V_2O_5$ synthesized by using formic acid was $14.2{\AA}$. The surface morphology of $(NH_4)_{0.3}V_2O_5$ and $V_2O_5$ showed features that looked like nanorods and nanosheets, respectively. Specific capacity of $(NH_4)_{0.3}V_2O_5$ nanorods prepared at $95^{\circ}C$ was at least 280 mAh/g at 10 mA/g discharge rate.

• Journal of Electrochemical Science and Technology
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• v.7 no.4
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• pp.306-315
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• 2016

Amorphous vanadium titanates (aVTOs) are examined for use as a negative electrode in lithium-ion batteries. These amorphous mixed oxides are synthesized in nanosized particles (<100 nm) and flocculated to form secondary particles. The $V^{5+}$ ions in aVTO are found to occupy tetrahedral sites, whereas the $Ti^{4+}$ ions show fivefold coordination. Both are uniformly dispersed at the atomic scale in the amorphous oxide matrix, which has abundant structural defects. The first reversible capacity of an aVTO electrode ($295mAhg^{-1}$) is larger than that observed for a physically mixed electrode (1:2 $aV_2O_5$ | $aTiO_2$, $245mAhg^{-1}$). The discrepancy seems to be due to the unique four-coordinated $V^{5+}$ ions in aVTO, which either are more electron-accepting or generate more structural defects that serve as $Li^+$ storage sites. Coin-type Li/aVTO cells show a large irreversible capacity in the first cycle. When they are prepared under nitrogen (aVTO-N), the population of surface hydroxyl groups is greatly reduced. These groups irreversibly produce highly resistive inorganic compounds (LiOH and $Li_2O$), leading to increased irreversible capacity and electrode resistance. As a result, the material prepared under nitrogen shows higher Coulombic efficiency and rate capability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.304-304
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• 2006

Ternary tellurite glassy systems ($Li_2O-V_2O_5-TeO_2$) have been synthesised using Vanadium oxide as a network former and Lithium oxide as network modifier. The addition of a metal oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode materials for solid-state batteries. This glass-ceramics crystallized from the $Li_2O-V_2O_5-TeO_2$ system are particularly interesting, because they exhibit high conductivity (up to $5.63{\times}10^{-5}$ S/cm) at room temperature the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric DC conductivity result have been analyzed in terms of a small polaron-hopping model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.334-335
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• 2005

Ternary tellurite glassy systems ($Li_2O-V_2O_5-P_2O_5$) have been synthesised using Vanadium oxide as a network former and Lithium oxide as network modifier. The addition of a metal? oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode' materials for solid-state batteries. This glass-ceramics crystallized from the $Li_2O-V_2O_5-P_2O_5$ system are particularly interesting, because they exhibit high conductivity (up to $5.95\times10^{-4}$ S/cm) at room temperature. the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric D.C conductivity result have been analyzed in terms of a small polaron-hopping model.

• Journal of the Korean Electrochemical Society
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• v.3 no.4
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• pp.219-223
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• 2000

All-solid state lithium rechargeable thin film batteries were fabricated with the configuration of$Cu_{0.5}V_2O_5/Lipon/Li$ using sequential thin film techniques. Copper vanadium oxide thin films and Lipon thin films were prepared by DC reactive dual source magnetron sputtering and RF magnetron sputtering, respectively. According to XRD analysis, we found out that copper vanadium oxide thin films were amorphous. The electrochemical behaviour of them was examined in half cell system using EC : DMC(1:1 in IM $LiPF_5$) liquid electrolyte. The ionic conductivity of Lipon thin film was $1.02\times10^{-6}S/cm$ at $25^{\circ}C$ and $Cu_{0.5}V_2O_5/Lipon/Li$ cell showed that the discharge capacity was about $50{\mu}Ah/cm^2{\mu}m$ beyond 500cyc1es.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.28-32
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• 2009

Most portable mobile devices employ rechargeable lithium-ion batteries. This lithium-ion battery usually suffers from the possibility of explosion due to heat generation from surrounding atmosphere or internal deficiency during charging or at overuse. To solve these problems, most rechargeable batteries have a built-in protection circuit module (PCM). The resistance of a properly processed $VO_2$ critical temperature sensor (CTS) is changed dramatically at a critical temperature of around $68^{\circ}C$, which can replace some bi-metal, NTC, or PTC sensors embedded in PCM. Such $VO_2$ CTS consumes a very small current at the level of natural discharge. Experimental results showed that this CTS could be applied to a PCM as the PCM could protect the battery while keeping its power consumption at minimum.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.139-142
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• 2016

β-AgVO₃ nanorods have been successfully synthesized using a soft chemistry route followed by heat treatment. They were characterized by X-ray diffraction and field emission scanning electron microscopy, and their electrochemical properties were investigated using cyclic voltammetry, impedance spectra, and charge-discharge tests. The results showed that the smooth-surfaced nanorods are very uniform and well dispersed, with diameters of ~100-200 nm and lengths of the order of several macrometers. The nanorods deliver a maximum specific discharge capacity of 275 mAh g^-1 at 30 mA g^-1. They also demonstrated good rate capability with a discharge capacity at the 100^th cycle of 51 mAh g^-1.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.532-538
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• 1998

Emerald ($3BeO{\cdot}Al_2O_3{\cdot}6SiO_2:Cr^{3+}$) single crystal was grown by temperature gradient reflux method with using Korean natural beryl. The flux of lithium-molibudenium-vanadium oxide system was made by means of mixing the 2 sort of flux which were differently melted $Mo_3-Li_2O$ and $V_2O_5-Li_2O$ each other. The optimum composition of flux was 3 mole ratio of molibudenium. vanadium oxides to lithium oxide ($(MoO_3+V_2O_5)/Li_2O$), flux additives were substituted more less then 0.2 mole% of $K_2O$ or $Na_2O$ to the $Li_2O$ amount. The melting concentration of mixing beryl material was 3~10% content to the flux, that of $Cr_2O_3$ color dopant was 1% to the beryl amount. In the crystal growing apparatus with temperature gradient in the 3 zone furnace which was separated into the block of melt, growth and return, the solution have got to circulate continuously between $1100^{\circ}C$ and $1000^{\circ}C$ in steady state. When thermal fluctuation was treated to during 2 hrs once on a day at 950~$1000^{\circ}C$ in growth zone, the supersaturation solution was maintained, controled and emerald single crystal can be grown large crystal which was prevented from the nucleation of microcrystallite. The preferencial growth direction of hexagonal columnar emerald single crystal was the c(0001) plane of botton side and vertical to the m(1010) plane of post side.