• Journal of Ceramic Processing Research
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• v.19 no.5
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• pp.413-418
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• 2018

All-solid-state lithium batteries (ASSBs) using inorganic sulfide-based solid electrolytes are considered prospective alternatives to existing liquid electrolyte-based batteries owing to benefits such as non-flammability. However, it is difficult to form a favorable solid-solid interface among electrode constituents because all the constituents are solid particles. It is important to form an effective electron conduction network in composite cathode while increasing utilization of active materials and not blocking the lithium ion path, resulting in excellent cell performance. In this study, a mixture of fibrous VGCF and spherical nano-sized Super P was used to improve rate performance by fabricating valid conduction paths in composite cathodes. Then, composite cathodes of ASSBs containing 70% and 80% active materials ($LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$) were prepared by a solution-based process to achieve uniform dispersion of the electrode components in the slurry. We investigated the influence of binary carbon additives in the cathode of all-solid-state batteries to improve rate performance by constructing an effective electron conduction network.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.19-26
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• 2012

SEI (solid electrolyte interphase) layers are generated on a graphite negative electrode from three different electrolytes and low-temperature ($-30^{\circ}C$) charge/discharge performance of the graphite electrode is examined. The electrolytes are prepared by adding 2 wt% of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) into a standard electrolyte solution. The charge-discharge capacity of graphite electrode shows the following decreasing order; FEC-added one>standard>VC-added one. The polarization during a constant-current charging shows the reverse order. These observations illustrate that the SEI film resistance and charge transfer resistance differ according to the used additives. This feature has been confirmed by analyzing the chemical composition and thickness of three SEI layers. The SEI layer generated from the standard electrolyte is composed of polymeric carbon-oxygen species and the decomposition products ($Li_xPF_yO_z$) of lithium salt. The VC-derived surface film shows the largest resistance value even if the salt decomposition is not severe due to the presence of dense film comprising C-O species. The FEC-derived SEI layer shows the lowest resistance value as the C-O species are less populated and salt decomposition is not serious. In short, the FEC-added electrolyte generates the SEI layer of the smallest resistance to give the best low-temperature performance for the graphite negative electrode.

• Journal of the Korean Magnetics Society
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• v.15 no.3
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• pp.198-201
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• 2005

We investigated the effects of organic additives on the properties of nickel-copper thin films prepared by electroplating. Compared with thin films fabricated by pure electrolyte only, the films utilizing organic additives show different crystalline orientations. With no alteration of plating conditions simply adding the organic materials changed the composition of copper and nickel. The concentration of nickel could be varied to $65-95\%$ depending on the species and concentration of the additives. The change of material property has contributed to the increase or decrease of the magnetoresistance.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.310-310
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• 2010

Electronic and photovoltaic characteristics of two sensitizers (TA-BTD-CA and TA-BTD-St-CA), composed of a different $\pi$-conjugation in the linker group, have been investigated by theoretical and experimental methods. The electronic structure, transition dipole moment and oscillator strengths of two sensitizers have been scrutinized by using density functional theory (DFT) and time-dependent DFT (TD-DFT) method. The LUMO level and the oscillator strength of TA-BTD-St-CA was higher than that of TA-BTD-CA, which may facilitate the electron injection process as well as increase the absorption coefficient. The relative efficiencies of the electron injection from the excited sensitizer to nanocrystalline TiO2 and SnO2 films have also been investigated by nanosecond transient absorption spectroscopy. The relative electron injection efficiency of TA-BTD-St-CA exhibited similar injection efficiency for two different semiconductors. However, in the case of TA-BTD-CA sensitizer, electron injection into SnO2 was approximately three times larger than that into TiO2. This enhancement of electron injection of TA-BTD-CA for the SnO2 is due to the increment of the driving force caused by positive shift of conduction band of semiconductor, which was also confirmed from the investigation for the photovoltaic characteristics according to the electrolyte additive, such as LiI additive.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.133-136
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• 2007

We investigated the changes of the magnetic properties in electroplated Permalloy thin films by a few organic additives added to the plating electrolytes. Under identical electroplating conditions, the crystalline orientations and the surface roughness of the plated thin films were different from those prepared with a pure electrolyte. These property changes reduced the coercivity and increased the magnetoimpedance ratio (MIR) up to 20%.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.75.2-75.2
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• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.26-30
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• 2011

In order to improve the energy conversion efficiency of dye-sensitized solar cell (DSSC), the photoelectrode was manufactured by using $TiO_2$ and $WO_3$ on combination effects of two conduction bands. The smash procedure of $TiO_2$ and $WO_3$ was carried out by using a paint shaker to enlarge the contact area of semiconductor with dye and electrolyte. The energy conversion efficiency of prepared DSSC was improved about two times from current-voltage curve based on effects of $WO_3$ and smash. The mechanism was suggested that the conduction band of $WO_3$ worked for prohibiting the trapping effects of electrons in conduction band of $TiO_2$. This result is attributed to the prevention of electron recombination between electron in conduction band of $TiO_2$ with dye and electrolyte. Impedance results indicate the improved electron transport at interface of $TiO_2$/dye/electrolyte.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.723-733
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• 2016

Intensive researches have been focused on the 3-dimensional packaging technology using through silicon via (TSV) to overcome the limitation in Cu interconnection scaling. Void-free filling of TSV by the Cu electrodeposition is required for the fabrication of reliable electronic devices. It is generally known that sufficient inhibition on the top and the sidewall of TSV, accompanying the selective Cu deposition on the bottom, enables the void-free bottom-up filling. Organic additives contained in the electrolyte locally determine the deposition rate of Cu inside the TSV. Investigation on the additive chemistry is essential for understanding the filling mechanisms of TSV based on the effects of additives in the Cu electrodeposition process. In this review, we introduce various filling mechanisms suggested by analyzing the additives effect, research on the three-additive system containing new levelers synthesized to increase efficiency of the filling process, and methods to improve the filling performance by modifying the functional groups of the additives or deposition mode.

• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.390-396
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• 1985

The manganese was extracted from ferromanganese slag with 6N ammonium sulfate and purified with ammonium sulfide. The current efficiencies were substantially increased when small amounts of selenious acid is used as an additive. Stainless steel was used as cathodic electrode and lead (+1% Ag) as anodic electrode. The effects of several variables were investigated, and the optimum conditions were found to be; 40g/l Mn in electrolyte at pH 7.0 with 1$20g/l (NH_4)_2SO_4$, Cathode current density 60mA/cm$^2$, Current efficiency 90% and up at the temperature about $25^{\circ}C.$ The metal produced has been consistantly of high quality.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.48.1-48.1
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• 2010

Cu has been used for metallic interconnects in ULSI applications because of its lower resistivity according to the scaling down of semiconductor devices. The resistivity of Cu lines will affect the RC delay and will limit signal propagation in integrated circuits. In this study, we investigated the characteristics of electroplated Cu films according to the variation of concentration of organic additives. The plating electrolyte composed of $CuSO_4{\cdot}5H_2O$, $H_2SO_4$ and HCl, was fixed. The sheet resistance was measured with a four-point probe and the material properties were investigated with XRD (X-ray Diffraction), AFM (Atomic Force Microscope), FE-SEM (Field Emission Scanning Electron Microscope) and XPS (X-ray Photoelectron Spectroscopy). From these experimental results, we found that the organic additives play an important role in formation of Cu film with lower resistivity by EPD.