• Journal of the Korean Ceramic Society
• /
• 제43권9호
• /
• pp.588-593
• /
• 2006

Spinel phase $LiMn_2O_4$ is of great interest as cathode materials for lithium-ion batteries. In this study, SHS (Self propagating High-temperature Synthesis) method to synthesize spinel $LiMn_2O_4$ directly from lithium nitrate, manganese oxide, manganese and sodium chloride were investigated. The influence of Li/Mn ratio, the heat-treated condition of product have been explored. The resultant $LiMn_2O_4$ synthesized under the optimum synthesis conditions shows perfect spinel structure, uniform particle size and excellent electrochemical performances.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2000년도 하계학술대회 논문집 B
• /
• pp.772-774
• /
• 2000

The objective of a cathodic protection system (CP) is to protect the buried metallic structure against the corrosion caused by chemical reaction between the buried structure and the surrounding medium, such as soil. This paper presents a boundary element application to determine the optimal impressed current densities in a cathodic protection system. The potential within the electrolyte is described by the Laplace's equation with nonlinear boundary conditions which are enforced based on experimentally determined electrochemical polarization curves. The optimal impressed current densities are determined in order to minimize the power supply for protection. The solution is obtained by using the conjugate gradient method in which the governing equations and the protecting conditions are taken into account by the penalty function method. Numerical example are presented to demonstrate the practical applicability of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• 제45권3호
• /
• pp.374-379
• /
• 1996

Effects of reactant gas flow rates and starvation on phosphoric acid fuel cell performance were studied. As the reactant gas flow rates increased, the cell performance increased and then the cell maintained constant performance. The optimum flow rates of hydrogen, oxygen and air under galvanostatic condition of 150 mA/cm$_{2}$ are found to be 5cc/min cm$_{2}$ 5cc/min cm$_{2}$ and 15cc/min cm$_{2}$ at room temperature and 1 atm, respectively. Also the open circuit voltage of single cell decreased with increasing oxygen flow rate due probably to the decreased probably to the decreased oxygen pressure in the cathode side. Hydrogen and oxygen starvation resulted in voltage loss of about 5mV and 0-2mV, respectively. The voltage loss was independent of starvation time. These results were discussed from point of view of electrochemical reaction of the cell. (author). 9 refs., 8 figs.

• Journal of the Korean Society of Marine Environment & Safety
• /
• 제3권2호
• /
• pp.77-84
• /
• 1997

For the effective treatment of shipboard sewage continuously, a non-diaphragm electrolytic treatment device using DSA type insoluble electrode, Ti/IrO2, anode and H-C metal cathode, was studied. The most effective electrolytic conditions were obtained when cell clearance, 6mm, pH 5-6 and the concentration of seawater, more than 20% as batch test results. The COD removal rate was varied in logarithmic function, showed as C=Coe-KE and the required current was E = A/QCo [A.min/mgCOD]. When the COD removal effeciency was more than 90%, the electrolytic reaction constant was 0.02.

• Proceedings of the KSME Conference
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.3067-3072
• /
• 2008

A two-dimensional model for anode-supported IT-SOFCs is proposed in order to accurately consider the heat and mass transport processes with a fully-developed axial velocity profile in channel flow. A comprehensive micro model is employed to describe the electrochemical reaction in anode and cathode of SOFCs. This paper investigates the effects of operational parameters (inlet temperature, the amount of flow rate, and air flow rate) including flow configurations (co-flow and counter-flow) on the current density and temperature distributions in the IT-SOFCs.

• Journal of Powder Materials
• /
• 제26권4호
• /
• pp.340-344
• /
• 2019

Due to the rapid development of electricity, electronics, information communication, and biotechnology in recent years, studies are actively being conducted on nanopowders as it is required not only for high strengthening but also for high-function powder with electric, magnetic, and optical properties. Nonetheless, studies on nickel nanopowders are rare. In this study of the synthesis of nickel nanoparticles from $LiNiO_2$ (LNO), which is a cathode active material, we have synthesized the nanosized nickel powder by the liquid reduction process of $NiSO_4$ obtained through the leaching and purification of LNO. Moreover, we have studied the reduction reaction rate according to the temperature change of liquid phase reduction and the change of particle size as a function of NaOH addition amount using hydrazine monohydrate ($N_2H_4{\cdot}H_2O$) and NaOH.

• Journal of Hydrogen and New Energy
• /
• 제30권3호
• /
• pp.193-200
• /
• 2019

$RuO_2$, $PtO_2$, and various $(Ru,Pt)O_2$ colloidal solution were prepared using modified Watanabe method. Electrodes were manufactured by dipping of Ni mesh into the colloidal solution. Manufactured electrodes were characterized by XRD, SEM, and EDS. $(Ru,Pt)O_2$ electrodes showed $RuO_2$ crystal structure and high roughness. The hydrogen evolution reaction (HER) activities were evaluated by Linear Sweep Voltammetry. 1Ru2Pt electrode showed similar activity with commercial electrode, HER potentials are -0.9 V for both.

• Progress in Superconductivity and Cryogenics
• /
• 제8권4호
• /
• pp.19-21
• /
• 2006

Biaxially textured Ni was fabricated by electrodeposition process and delaminated from the biaxially textured cathode surface for further buffer layer deposition process. Those electrode posited Ni substrates showed well-developed biaxial texture and smooth surface. In order to improve the thermal stability of Ni substrates, Mn was alloyed by adding Mn precursor into the electrodeposition bath. Subsequently, $CeO_2$ buffer layers are deposited by MOD process to prevent interfacial reaction between superconductor and substrates. In particular, Bismuth oxide was added to $CeO_2$ to realize lower temperature processing of buffer layers. The microstructure and texture development of each layers have been investigated. Preliminary results shows that all electro/chemical process can be a candidate for cost effective route to YBCO coated conductor.

• Nuclear Engineering and Technology
• /
• 제56권3호
• /
• pp.1013-1021
• /
• 2024

A series of experiments were performed to produce a fuel source for a molten salt reactor (MSR) through pyroprocessing technology. A simulated LiCl-KCl-UCl₃-NdCl₃ salt system was prepared, and the U element was fully recovered using a liquid cadmium cathode (LCC) by applying a constant current. As a result, the salt was purified with an UCl₃ concentration lower than 100 ppm. Subsequently, the U/RE ingot was prepared by melting U and RE metals in Y₂O₃ crucible at 1473 K as a surrogate for RE-rich ingot product from pyroprocessing. The produced ingot was sliced and used as a working electrode in LiCl-KCl-LaCl₃ salt. Only RE elements were then anodically dissolved by applying potential at - 1.7 V versus Ag/AgCl reference electrode. The RE-removed ingot product was used to produce UCl₃ via the reaction with NH4Cl in a sealed reactor.

• Journal of the Korean Electrochemical Society
• /
• 제4권2호
• /
• pp.58-64
• /
• 2001

YSZ ($8mol\%$ yttria-stabilized zirconia)-modified LSM $(La_{0.85}Sr_{0.15}MnO_3)$ composite cathodes were fabricated by formation of YSZ film on triple phase boundary (TPB) of LSM/YSZ/gas. The YSZ coating film greatly enlarged electrochemical reaction sites from the increase of additional TPB. The composite cathode was formed on thin YSZ electrolyte (about 30 Um thickness) supported on an anode and then I-V characterization and AC impedance analyses were performed at temperature between $700^{\circ}C\;and\;800^{\circ}C$. As results of the impedance analysis on the cell at $800^{\circ}C$ with humidified hydrogen as the fuel and air as the oxidant, R1 around the frequency of 1000 Hz represents the anode Polarization. R2 around the frequency of 100Hz indicates the cathode polarization, and R3 below the frequency of 10 Hz is the resistance of gas phase diffusion through the anode. The cell with the composite cathode produced power density of $0.55\;W/cm^2\;and\;1W/cm^2$ at air and oxygen atmosphere, respectively. The I-V curve could be divided into two parts showing distinctive behavior. At low current density region (part I) the performance decreased steeply and at high current density region (part II) the performance decreased gradually. At the part I the performance decrease was especially resulted from the large cathode polarization, while at the part H the performance decrease related to the electrolyte polarization.