• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.117-122
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• 2005

Electron Beam Physical Vapor Deposition (EB-PVD) is a typical technology for thermal barrier coating with Yttria Stabilized Zirconia (YSZ) on aero gas turbine engine. In this study EB-PVD method was used to fabricate dense YSZ film on NiO-YSZ as a electrolyte of Solid Oxide Fuel Cell (SOFC). Dense YSZ films of -10 $\mu$m thickness showed nano surface structure depending on deposition temperature. Electrical conductivities of YSZ film and electric power density of the single cell were evaluated after screen- printing $LaSrCoO_3$ as a cathode.

• Resources Recycling
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• v.10 no.6
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• pp.9-14
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• 2001

A sulfuric acid leaching of $LiCoO_2$as cathodic active materials of lithium ion secondary batteries was investigated in terms of reaction variables. In the absence of a reducing agent, the extraction of cobalt was less than 40% in 2 M sulfuric acid at $75^{\circ}C$ instead of that of lithium could be almost 100% in the same conditions. To improve the Co extraction, hydrogen peroxide was used as a reducing agent in the range 2~20 vol%. When over 10vo1% hydrogen peroxide was added, the extractions of both metals were improved to about 95%. It seems to be due to the reduction of Co(III) to Co(II) that can be readily dissolved. The extractions of Co and Li were increased with increasing $H_2$$SO_4$concentration and temperature, and amount of hydrogen peroxide and with decreasing of pulp density. The optimum leaching conditions were determined at $2 M H_2$$SO_4$concentration, $75^{\circ}C$ operating temperature, 100 g/L. initial pulp density, 20 vol% $H_2$$O_2$addition and 30 min.

• Resources Recycling
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• v.20 no.2
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• pp.67-73
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• 2011

In this study, for recovery of renewable noble metal from used stack of fuel cell, synthesis of platinum nano particle is established through effect of platinum solution concentration, pH value, reducing agent and dispersing agent at a volume ratio of 1 mM $H_2PtCl_6$:10 mM $NaBH_4$:8 mM Cl4TABr = 1:0.4:0.4(vol.%), pH4, $50^{\circ}C$, 160 rpm and 10min. Less than 5 nm platinum particles were synthesized using Pt leaching solution from used MEA of stack under same condition of method using simulated Pt solution. The characteristics of synthesized nano particles was illustrated by XPS analysis as the reduction of platinum ions into platinum metals(zero-valent).

• Resources Recycling
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• v.20 no.4
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• pp.65-70
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• 2011

Environmental friendly leaching process for the recovery of cobalt and lithium from the $LiCoO_2$ was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant and hydrogen peroxide, reaction time and temperature as well as the pulp density were tested to obtain the most effective conditions for the leaching of cobalt and lithium. The results showed that the latic acid was the most effective leaching reagent for cobalt and lithium among the organic acids and was reached about 99.9% of leaching percentage respectively. With the increase of the concentration of citric acid, hydrogen peroxide and temperature, the leaching rate of cobalt and lithium increased. But the increase of pulp density decreased the leaching rate of cobalt and lithium.

• Plant Journal
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• v.15 no.2
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• pp.42-45
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• 2019

The molten carbonate fuel cell has a high temperature of waste heat and can constitute a bottoming cycle to increase the efficiency. Previous study used a bottoming cycle as steam turbine cycle. In this study, we are going to replace the bottoming cycle with a supercritical carbon dioxide power cycle. The system power was compared to consider replacing the bottoming cycle. As a result, the power of the supercritical carbon dioxide power cycle at the present development stage is lower than that of the steam turbine cycle, but theoretically, the power can be larger than the steam turbine cycle. If the supercritical carbon dioxide power cycle improves the isentropic efficiency of the turbine by 89%, the isentropic efficiency of the compressor by 83%, and the effectiveness of the recuperator by 0.9, the power can be same to the steam turbine cycle.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.4
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• pp.303-311
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• 2019

Reversible solid oxide fuel cell (RSOFC) has become a prospective device for energy storage and hydrogen production. Many studies have been conducted around the world focusing on system efficiency improvement and realization. The system should have not only high efficiency but also a certain level of simplicity for stable operation. External waste steam utilization was proved to remarkably increase the efficiency at solid oxide electrolysis system. In this study, RSOFC system coupled with waste steam was proposed and optimized in term of simplicity and efficiency. Ejector for fuel recirculation is selected due to its simple design and high stability. Three system configurations using ejector for fuel recirculation were investigated for performance of design condition. In parametric study, the system efficiencies at different current density were analyzed. The system configurations were simulated using validated lumped model in EBSILON(R) program. The system components, balance of plants, were designed to work in both electrolysis and fuel cell modes, and their off-design characteristics were taken into account. The base case calculation shows that, the system with suction pump results in slightly lower efficiency but stack can be operated more stable with same inlet pressure of fuel and air electrode.

• Resources Recycling
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• v.26 no.3
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• pp.79-91
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• 2017

The core of Hydrogen Fuel Cell Vehicles (FCV) is polymer solid fuel cell (PEFC), and the core material that generates electrochemical electricity in the cell is platinum catalyst. Platinum is localized in South Africa and Russia, and the world production of Pt is about 178 tons per year, which is expensive and recycled. At present, the amount of Pt used in PEFC is $0.2{\sim}0.1mg/cm^2$. In order to reduce the price of the battery and increase the FCV supply, the target is to reduce the amount of Pt used to $0.05{\sim}0.03mg/cm^2$. $Pt-Pd/Al_2O_3$, Pt/C, Pt/GCB, Pt/Au/C, PtCo/C, PtPd/C, etc. by using polyol method using nano Pt, improved Cu-UPD/Pt substitution method and nano-capsule method, Have been researched and developed, and there have been reported techniques for improving the activity of Pt catalysts and stabilizing them. This paper investigates the production technology of nano-Pt and nano-Pt catalysts, recycling of spent Pt catalysts and application trends of Pt catalysts.

• Clean Technology
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• v.30 no.2
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• pp.105-112
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• 2024

Globally, the demand for electric vehicles has surged due to greenhouse gas regulations related to climate change, leading to an increase in the production of used batteries as a consequence of the battery life issue. This study aims to selectively leach and recover valuable metal lithium from the cathode material of spent LFP (LiFePO₄) batteries among lithium-ion batteries. Generally, the use of inorganic acids results in the emission of toxic gases or the generation of large quantities of wastewater, causing environmental issues. To address this, research is being conducted to leach lithium using organic acids and other leaching agents. In this study, selective leaching was performed using the organic acid methane sulfonic acid (MSA, CH₃SO₃H). Experiments were conducted to determine the optimal conditions for selectively leaching lithium by varying the MSA concentration, pulp density, and hydrogen peroxide dosage. The results of this study showed that lithium was leached at approximately 100%, while iron and phosphorus components were leached at about 1%, verifying the leaching efficiency and the leaching rates of the main components under different variables.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.50-52
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• 2004

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.291-297
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• 2004

For the while, food wastes have been mainly gathered in a trash place in outskirt of Seoul to bury under the ground. Recently the residents near the area strongly refused to fetch those food wastes to their area because of the terribly bad smell. According to the statistic, the food wastes have around $30\%$ portion of total living wastes, which are more than other countries. Most of the food wastes have been simply buried or incinerated without deep consideration of resource recovery view. Such burying or incineration makes problem to the residents' life condition. So the first is to reduce as much as possible and the rest should be controlled to reuse as resources.