• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.152-161
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• 2023

Vanadium redox flow batteries (VRFBs) have been considered one of promising power sources for large scale energy storage systems (ESS) because of their excellent cycle performance and good safety. However, VRFBs still have a few challenging issues, such as poor Coulombic efficiency due to vanadium crossover between catholyte and anolyte, although recent efforts have shown promise in electrochemical performance. Herein, the vanadium complexes with various glyme ligands have been examined as active materials to suppress vanadium crossover between catholyte and anolyte, thus improving the Coulombic efficiency of VRFBs. The conventional Nafion membrane has a channel size of ca. 10 Å, whereas vanadium cation species are small compared to the Nafion membrane channel. For this reason, vanadium cations can permeate through the Nafion membrane, resulting in significant vanadium crossover during cycling, although the Nafion membrane is a kind of ion-selective membrane. In this regard, various glyme additives, such as 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), and tetraethylene glycol dimethyl ether (tetraglyme) have been examined as complexing agents for vanadium cations to increase the size of vanadium-ligand complexes in electrolytes. Since the size of vanadium-glyme complexes is proportional to the chain length of glymes, the vanadium permeability of the Nafion membrane decreases with increasing the chain length of glymes. As a result, the vanadium complexes with tetraglyme shows the excellent electrochemical performance of VRFBs, such as stable capacity retention (90.4% after 100 cycles) and high Coulombic efficiency (98.2% over 100 cycles).

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.168-172
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• 2013

This work presents the effects of binders on the electrochemical performance of Si-C composites as the anode of lithium ion batteries. PAI (polyamide-imide) was used as an organic binder, and PAN (polyacrylonitrile), PAA (polyacrylic acid) and CMC + SBR (carboxymethyl cellulose + styrene-butadiene rubber) were used as aqueous binders. As a result, stabilization time for the cell with a Si-C composite anode synthesized using aqueous binders became shorter than an organic binder. Particularly in the case of the cell using PAA binder, better performance was observed in terms of adhesion strength, initial efficiency, the volume expansion ratio, Coulombic efficiency, and capacity retention.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1226-1229
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• 2004

Supercapacitors, also known as electrochemical capacitors, are being extensively studied due to an increasing demand for energy-storage systems. These devices offer many advantages over conventional secondary batteries, which include the ability of fast charge propagation, long cycle-life and better storage efficiency. That is to say supercapacitor bridges the gap between conventional capacitors and batteries. A new type electric double layer capacitor (EDLC) also called supercapacitors. Recently, supercapacitors concerns about their high power density and energy density. So we experiment with EDLC by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. The electrode for supercapacitor was prepared by synthesis of DAAQ covered CNFs. CNFs could be covered with very thin DAAQ oligomer from the results of CV, XRD, DSC, SEM images, and TEM images. Dissolved electrode active material in NMP solution has been drop-coated on carbon plate. Its electrochemical characteristics were investigated by cyclic voltammograms. And compared with different electrolyte of aqueous type. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors with respect to specific capacity and scan rate dependency.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.137-144
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• 2015

The present paper deals with the extractive separation and selective recovery of nickel and lithium from the sulfate leachate of cathode scrap generated during the manufacture of LIBs. The conditions for extraction, scrubbing and stripping of nickel from lithium were optimized with an aqueous feed containing $2.54kg{\cdot}m^{-3}$ Ni and $4.82kg{\cdot}m^{-3}$ Li using PC-88A. Over 99.6% nickel was extracted with $0.15kmol{\cdot}m^{-3}$ PC-88A in two counter-current stages at O/A=1 and pH=6.5. Effective scrubbing Li from loaded organic was systematically studied with a dilute $Na_2CO_3$ solution ($0.10kmol{\cdot}m^{-3}$). The McCabe-Thiele diagram suggests two counter-current scrubbing stages are required at O/A=2/3 to yield lithium-scrubbing efficiency of 99.6%. The proposed process showed advantages of simplicity, and high purity (99.9%) nickel sulfate recovery along with lithium to ensure the complete recycling of the waste from LIBs manufacturing process.

• Journal of Electrochemical Science and Technology
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• v.9 no.2
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• pp.85-92
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• 2018

Olivine structure of $LiFePO_4$ (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of $Li^+$ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M $Li_2SO_4$. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM $Li_2SO_4$ solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that $Li^+$ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of $Li_2SO_4$ solution was increased, the current increased. The flow rate peaked at $4.8{\mu}L/30s$ in 1.0 mM $Li_2SO_4$ solution and then decreased. When the EOP was tested continuously in 1.0 mM $Li_2SO_4$ solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.141-141
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• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.801-804
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• 2002

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. Both of amorphous cobalt oxide and manganese dioxide were prepared by sol-gel process reported in our previous work. Nanostructured supramolecular oligomer of 1,5-diaminoanthraquinone(DAAQ) coated metal oxides were successfully prepared by electrochemical oxidation from an acidic non-aqueous medium. We established process parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured metal oxide electrodes using controlled solution chemistry. $CoO_2$ and $MnO_2$-based composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.370-374
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• 2009

Adsorption characteristics of glass fibers, obtained from the spent lithium primary batteries recycling process, were investigated for the removal of Acid Red 27 dye from aqueous solution. The batch data clearly showed that increasing the initial sorptive concentration apparently enhanced the amount adsorbed and the uptake process followed the pseudo-second order rate model. The equilibrium adsorption data at different initial sorptive concentrations were fitted well to Freundlich and Langmuir adsorption isotherms. Moreover, the increase in temperature, favored the uptake of dye on this solid, indicated the process was endothermic in nature. Further, using the temperature dependence sorption data obtained at different temperatures was used to estimate various thermodynamic parameters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.7-10
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• 2001

Orthorhombic type $LiCo_{x}Mn_{1-x}O_{2}$(0 ${\times}$ 0.14) oxides have been synthesized by hydrothermal treatment of $(Co_{x}Mn_{1-x})_{3}O_{4}$ precursors and LiOH aqueous solution at $170^{\circ}C$. As-synthesized powders showed well-ordered ${\beta}-NaMnO_{2}$ structures, and the products were single crystalline particle oxides from TEM observations. The particle size decreased with increasing the amount of Co substituent. Much more improved capacity upon 100 cyclings was clearly seen in orthorhombic $LiCo_{0.1}Mn_{0.9}O_{2}$, comparing to orthorhombic $LiMnO_2$.

• Electrical & Electronic Materials
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• v.14 no.12
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• pp.7-10
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• 2001

Orthorhombic type LiCo$_{x}$Mn$_{1-x}$ O$_2$(0$\leq$x$\leq$0.14) oxides have been synthesized by hydrothermal treatment of (Co$_{x}$Mn$_{1-x}$ )$_3$O$_4$precursors and LiOH aqueous solution at 17$0^{\circ}C$. As-synthesized powders showed well-ordered $\beta$-MaMnO$_2$structures, and the products were single crystalline particle oxides from TEM observations. The particle size decreased with increasing the amount of Co substituent. Much more improved capacity upon 100 cyclings was clearly seen in orthorhombic LiCo$_{0.1}$Mn$_{0.9}$O$_2$, comparing to orthorhombic LiMnO$_2$./TEX>.EX>.