• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3233-3237
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• 2010

A $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode was modified by coating with Li-La-Ti-O, and the effect of the coating thickness on their electrochemical properties was studied. The thickness of the coating on the surface of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ was increased by increasing the wt % of the coating material. The rate capability of the Li-La-Ti-O-coated electrode was superior to that of the pristine sample. 1- and 2-wt %-coated samples showed considerable improvement in capacity retention at high C rates. However, the rate capability of a 5-wt %-coated sample decreased. All the coated samples showed a high discharge capacity and slightly improved cyclic performance under a high cut-off voltage (4.8 V) condition. Results of a storage test confirmed that the Li-La-Ti-O coating layer was effective in suppressing the dissolution of the transition metals as it offered protection from the attack of the acidic electrolyte. In particular, the 2- and 5-wt %-coated samples showed a better protection effect than the 1-wt %-coated sample.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.330-330
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• 2008

$Fe_2O_3$ added Pb$(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3-PbZrO_3 $ (PNN-PT-PZ) ceramics were produced in order to use them as a bimoph acturator for energy harvesting. Especially, the 0.25 wt% $Fe_2O_3$ added 0.4PNN-0.357PT-0.243PZ, having the composition of morphotropic phase boundary, showed good piezoelectric properties of $d_{33}$ of 810 pC/N, $k_p$ of 77% and $Q_m$ of 55 along with a high Curie temperature of $210^{\circ}C$. A bimorph actuator, composed of the two piezoelectric layers bonded together with a phosphorous bronze layer as a central metallic electrode, was successfully fabricated. The bimorph actuator, vibrated with a 1.3 mm amplitude at 68 Hz, produced high electric power of approximately 60 mW.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1794-1796
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• 2000

Oxides of the form $Mn_{3}O_4$-$Co_{3}O_4$-NiO present properties that make them useful as multilayer chip NTC thermistor for mobile communication telephone. When $Mn_{2}Ni_{x}CO_{1-x}O_4$ composition with the X = 0.12$\sim$0.24 at sintered temperature 1250$^{\circ}C$, resistivity and B-constant were 300$\sim$450[${\Omega}-cm$] and 3250$\sim$3450, respectively. Multilayer chip NTC(Negative Temperature Coefficient) resistor were fabricated with 4 layer by a conventional multilayer capacitor techniques, using 100 pd paste as internal electrode and $Mn_{2}Ni_{0.20}CO_{0.8}O_4$ composition as NTC materials. In particular, resistance change ratio (${\Delta}R$), the important factor for reliability, varied within $\pm$3%, indicating the compositions of multilayer chip NTC thermistor products could be available for mobile communication telephone.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2584-2588
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• 2009

The effect of $LaF_3$ coating on the structural and electrochemical properties of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_{2}$ cathodes was investigated using XRD, SEM, TEM, and a cycler. The coating layer consisted of nano-sized particles attached nonuniformly to the surface of pristine powder. Despite the surface coating treatment, phase difference by $LaF_3$ coating was not detected. The discharge capacities of coated electrodes were a little lower than that of pristine sample at a 1 C rate. However, as the C rate increases, the capacity retention of the coated sample becomes obviously superior to that of the pristine sample. The cyclic performances of the electrodes in the voltage range of 4.8 $\sim$ 3.0 V were also improved by the surface coating. Such enhancement is attributed to the presence of the $LaF_3$ coating layer, which effectively suppressd the reaction between electrodes and electrolytes on the surface of the $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_{2}$ electrode.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.217-221
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• 2015

Developing a metallization that has low cost and high efficiency is essential in solar-cell industries, to replace expensive silver-based metallization. Ni/Cu two-step metallization is one way to reduce the cost of solar cells, because the price of copper is about 100 times less than that of silver. Alkaline electroless plating was used for depositing nickel seed layers on the front electrode area. Prior to the nickel deposition process, 2% HF solution was used to remove native oxide, which disturbs uniform nickel plating. In the subsequent step, a nickel sintering process was carried out in $N_2$ gas atmosphere; however, copper was plated by light-induced plating (LIP). Plated nickel has different properties under different bath conditions because nickel electroless plating is a completely chemical process. In this paper, plating bath conditions such as pH and temperature were varied, and the metal layer's structure was analyzed to investigate the adhesion of Ni/Cu metallization. Average adhesion values in the range of 0.2-0.49 N/mm were achieved for samples with no nickel sintering process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.68-74
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• 2018

All transparent UV photodetector based on ZnO was fabricated with structure of NiO/ZnO/$SnO_2$/ITO by using RF and DC magnetron sputtering system. ZnO was deposited with 4 inch ZnO target (purity 99.99%) for a quality film. In order to build p-n junction up, p-type NiO was formed on n-type ZnO by using reactive sputtering method. The indium tin oxide (ITO) which is transparent conducting oxide (TCO) was applied as a transparent electrode for transporting electrons. To improve the UV photodetector performance, a functional $SnO_2$ layer was selected as an electron transporting and hole blocking layer, which actively controls the carrier movement, between ZnO and ITO. The photodetector (NiO/ZnO/$SnO_2$/ITO) shows transmittance over 50% as similar as the transmittance of a general device (NiO/ZnO/ITO) due to the high transmittance of $SnO_2$ for broad wavelengths. The functional $SnO_2$ layer for band alignment effectively enhances the photo-current to be $15{\mu}A{\cdot}cm^{-2}$ (from $7{\mu}A{\cdot}cm^{-2}$ of without $SnO_2$) with the quick photo-responses of rise time (0.83 ms) and fall time (15.14 ms). We demonstrated the all transparent UV photodetector based on ZnO and suggest the route for effective designs to enhance performance for transparent photoelectric applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.64-70
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• 2006

In this study, the $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ mixed cathode electrodes were prepared and their electrochemical performances were measured in a high cut-off voltage. As the content of $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ increased in a mixed cathode, the reversible specific capacity and cycleability of the electrode enhanced, but the rate capability was deteriorated. On the contrary the rate capability of the cathode enhanced, but the reversible specific capacity and cycleability were deteriorated, increasing the content of $LiCoO_2$ in the mixed cathode. The cell of $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ ($50:50 wt\%$) mixed cathode delivered a discharge capacity of ca. 168 mAh/g at a 0.2 C rate. The capacity of the cell decreased with the current rate and a useful capacity of ca. 152 mAh/g was obtained at a 2.0 C rate. However, the cell showed very stable cycleability: the discharge capacity of the cell after 20th charge/discharge cycling maintains ca. 163 mAh/g.

• Journal of the Korean Ceramic Society
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• v.44 no.10
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• pp.589-595
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• 2007

Physical properties of sputtered YSZ thin film electrolytes on anode thin film by spray pyrolisis has been investigated to realize the porous electrode and dense electrolyte multilayer structure for micro solid oxide fuel cells. It is shown that for better crystallinity and density, YSZ need to be deposited at an elevated temperature. However, if pure NiO anode was used for high temperature deposition, massive defects such as spalling and delamination were induced due to high thermal expansion mismatch. By changing anode to NiOCGO composite, defects were significantly reduced even at high deposition temperature. Further research on realization of full cells by processing hybridization and cell performance characterization will be performed in near future.

• Corrosion Science and Technology
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• v.11 no.6
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• pp.275-279
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• 2012

Ni-W alloy deposits have lately attracted the interest as an alternative surface treatment method for hard chromium electrodeposits because of higher wear resistance, hardness at high temperature, and corrosion resistance. This study deals with influences of process variables, such as electodeposition current density, plating temperature and pH, on the internal stress of Ni-W nanocrystalline deposits. The internal stress was increased with increasing the applied current density. With increasing applied current density, the grain size of the deposit decreases and concentration of hydrogen in the deposit increases. The subsequent release of the hydrogen results in shrinkage of the deposit and the introduction of tensile stress in the deposit. Consequently, for layers deposited at high current density, cracking occurs readily owing to high tensile stress value. By increasing the temperature of the electrodeposition from $60^{\circ}C$ to $80^{\circ}C$, the internal stress was decreased. It seems that an increase in the number of active ions overcoming the activation energy at elevated temperature caused a decline in the concentration polarization and surface diffusion. It decreased the level of hydrogen absorption due to the lessened hydrogen evolution reaction. Therefore, the lower level of hydrogen absorption degenerated the hydride on the surface of the electrode, resulting in the reduction of the internal stress of the deposits. By increasing the pH of the electrodeposition from 5.6 to 6.8, the internal stress in the deposits were slightly decreased. It is considered that the decrease in internal stess of deposits was due to supply of W complex compound in cathode surface, and hydrogen ion resulted from decrease of activity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2014-2018
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• 2016

Transparent, conductive electrode films, showing the particular characteristics of good conductivity and high transparency, are of considerable research interest because of their potential for use in opto-electronic applications, such as smart window, photovoltaic cells and flat panel displays. Multilayer transparent electrodes, having a much lower electrical resistance than widely-used transparent conducting oxide electrodes, were prepared by using RF/DC magnetron sputtering system. The multilayer structure consisted of three layers, [NiInZnO(NIZO)/Ag/NIZO]. The optical and electrical properties of the multilayered NIZO/Ag/NIZO structure were investigated in relation to the thickness of each layer. The optical and electrical characteristics of multilayer structures have been investigated as a function of the Ag and NIZO film thickness. High-quality transparent conductive films have been obtained, with sheet resistance of $9.8{\Omega}/sq$ for Ag film thickness of 8 nm. Also the multilayer films of inserted Ag 8 nm thickness showed a high optical transmittance above 93% in the visible range. The electrical and optical properties of the new multilayer films were mainly dependent on the thickness of Ag insertion layer.