• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.47-55
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• 2020

Highly loaded LiCoO₂ positive electrodes are prepared to construct high-energy density lithium-ion batteries, their electrochemical performances are evaluated. For the standard electrode, a loading of about 2.2 mAh/㎠ is used, and for a high-loading electrode, an electrode is manufactured with a loading level of about 4.4 mAh/㎠. The content of carbon black as electronic conducting additive, and the porosity of the electrode are configured differently to compare the effects of electron conduction and ionic conduction in the highly loaded LiCoO₂ electrode. It is expected that the electrochemical performance is improved as the amount of the carbon black increases, but the specific capacity of the LiCoO₂ electrode containing 7.5 weight% carbon black is rather reduced. When the conductive material is excessively provided, an increase of electrode thickness by the low content of the LiCoO₂ active material in the same loading level of the electrode is predicted as a cause of polarization growth. When the electrode porosity increases, the path of ionic transport can be extended, but the electron conduction within the electrode is disadvantageous because the contact between the active material and the carbon black particles decreases. As the electrode porosity is lowered through the sufficient calendaring of the electrode, the electrochemical performance is improved because of the better contact between particles in the electrode and the reduced electrode thickness. In the electrode design for the high-loading, it is very important to construct the path of electron conduction as well as the ion transfer and to reduce the electrode thickness.

• Journal of the Korean Electrochemical Society
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• v.24 no.2
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• pp.28-33
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• 2021

Many researchers have increased the loading level of electrodes to improve the energy density of secondary batteries. In this study, high-loading NCM523 (LiNi_0.5Co_0.2Mn_0.3O₂) positive electrode is manufactured using a polytetrafluoroethylene (PTFE) binder, not the conventional polyvinylidene fluoride (PVdF) binder, which has been commonly used in lithium-ion batteries. Through the kneading process using PTFE suspension, not the conventional slurry process using PVdF solution in N-methyl-2-pyrrolidinone (NMP), thick electrodes with high loading are easily manufactured. When the PTFE and PVdF-based electrodes are prepared at a loading level of 5.0 mAh/cm², respectively, the PTFE-based electrode shows better cycle performance and rate capability than those of PVdF-based electrodes. The electrode manufactured by the kneading process using a PTFE binder has high electrode porosity due to insufficient roll-press, but the porosity can be lowered by high temperature roll-press over 120℃. However, there is no significant difference in cycle performance according to the roll press temperature. In addition, the cycle performance of the high loading electrode is slightly improved by increasing the content of the conductive material. Overall, the PTFE binder can improve the performance of the high loading electrode, but additional solutions will be needed.

• Journal of the Korean Electrochemical Society
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• v.27 no.1
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• pp.40-46
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• 2024

Among the electrode manufacturing processes for lithium-ion batteries, the drying process is crucial for production speed and process cost. Particularly, as the loading level of the electrode increases to enhance the energy density of the battery, optimizing process conditions for electrode drying becomes more critical. In this study, we compared the drying time and electrochemical performance of the positive electrode prepared at different drying temperatures. LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) was used as the active material and manufactured under various drying temperature conditions ranging from 120 ℃ to 210 ℃ at loading levels of 2.5 and 4.5 mAh cm^-2. The physical and electrochemical properties of the electrodes were compared. As the loading level of the electrode increases, the drying time of the electrode also increases, but this time can be reduced by increasing the drying temperature. The drying temperature used in manufacturing the NCM622 positive electrode does not significantly affect the electrochemical performance but drying above 210 ℃ resulted in an increase in the volume resistivity of the electrode and a decrease in electrochemical performance. Accordingly, in the manufacture of high-loading electrodes, the drying temperature was increased to 190 ℃ to shorten the electrode manufacturing time without a loss of performance.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.95.2-95.2
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• 2011

In order to achieve high performance and low cost for commercial applications, the development of membrane electrode assemblies (MEA), in which the electrochemical reactions actually occur, must be optimized. Expensive platinum is currently used as an electrochemical catalyst due to its high activity. Although various platinum alloys and non-platinum catalysts are under development, their stabilities and catalytic activities, especially in terms of the oxygen reduction (ORR), render them currently unsuitable for practical use. Therefore, it is important to decrease platinum loading by optimizing the catalysts and electrode microstructure. In this study, we prepared several different MEAs (non-uniform Nafion$^{(R)}$ ionomer loading electrode) which have dual catalyst layers to find the optimal Nafion$^{(R)}$ ionomer distribution in the electrodes. We changed Nafion$^{(R)}$ ionomer content in the layers to find the ideal composition of the binder and Pt/C in the electrode. For MEAs with various ionomer contents in the anodes and cathodes, the electrochemical activity (activation overpotential) and the mass transport properties (concentration overpotential) were analyzed and correlated with the single cell performance. The dual catalyst layers MEA showed higher cell performance than uniformly fabricated MEA, especially at the high current density region.

• Journal of the Korean Electrochemical Society
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• v.20 no.4
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• pp.61-66
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• 2017

The cycle performance of Ti-Si alloy anode material for Li-ion batteries has been investigated as a function of loading level of electrode using a nodule type of substrate, in which the current collector of flat foil is also used for comparison. The Ti-Si alloy powders are prepared by mechanical alloying method. The electrodes with the nodule type of current collector exhibit enhanced cycling performance compared to those using the flat foil because the alloy particles are more strongly adhered to substrate and the stress caused by lithiation and delithiation reaction can be effectively relaxed by nodule-type morphology. It appears, however, that the cycle performance is critically dependent on the loading level of electrode, even when the nodule type of current collector is applied. With high loading level, cracks are initiated at surface of electrode due to a steep stress gradient through the electrode thickness during cycling, leading to capacity fading.

• Journal of Electrochemical Science and Technology
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• v.14 no.4
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• pp.320-325
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• 2023

In Li-ion batteries, a thick electrode is advantageous for lowering the inactive current collector portion and obtaining a high energy density. One of the critical failure mechanisms of thick electrodes is inhomogeneous lithiation and delithiation owing to the axial location of the electrode. In this study, it was confirmed that the top layer of the composite electrode contributes more to the charging step owing to the high ionic transport from the electrolyte. A high-loading multilayered electrode containing LiFePO₄ (LFP) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) was developed to overcome the inhomogeneous electrochemical reactions in the electrode. The electrode laminated with LFP on the top and NCM811 on the bottom showed superior cyclability compared to the electrode having the reverse stacking order or thoroughly mixed. This improvement is attributed to the structural and interfacial stability of LFP on top of the thick electrode in an electrochemically harsh environment.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.171-175
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• 1999

Novel process for high power catalyst electrode for PEM fuel cell has been developed. MEA having this catalyst electrode showed $0.5W/cm^2\;with\;0.2mg/cm^2$ of Pt loading at aunospheric humid hydrogen and oxygen condition. In this process, platinized carbon and plain carbon powders were coated with ionomer (Nafion) and hydrophobic polymer (PTFE), respectively and it could maximize two roles of catalyst electrode, l.e., reaction and gas supplying component. Those polarization characteristics proved the improved performance by reducing potential drop especially in the concentration polarization region.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.2
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• pp.125-133
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• 2012

Nafion ionomer located in electrode helps to increase the platinum utilization and proton conductivity. To achieve higher performance in PEMFCs, it is important an optimum Nafion content in the electrode. As the platinum loading and fabricated method depend on the optimum Nafion content. In this study, we have examined the interrelationship between platinum loading and Nafion content fabricated by decal transfer method. For electrodes with 0.25 and 0.4 mg/$cm^2$ Pt loading, best performance was obtained at 25 wt.% Nafion ionomer loading. It is also found that MEA with 0.25 mg/$cm^2$ Pt, the optimum Nafion content appears differently at low and high current density.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.340-344
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• 2008

Electro-flotation (EF) was applied to a sequencing batch reactor process (SBR) in order to enhance solids-liquid separation. Solids-liquid separation was good enough in the SBR coupled with EF (EF-SBR) and it was possible to maintain the concentration of mixed liquor suspended solids (MLSS) high in the EF-SBR. Under moderate organic loading condition (COD loading rate: 6 g/day), control SBR (C-SBR) showed similar treatment efficiencies with the EF-SBR. Under high organic loading condition (COD loading rate: 9.6 g/day), the solids-liquid separation in the C-SBR was deteriorated due to proliferation of filamentous bulking organisms at high F/M ratio. However, the EF-SBR was operated stably and with the high MLSS concentration (above 4,000 mg/L) regardless of the organic loading conditions during overall operating period leading to the satisfactory effluent quality. Gas production rate of the electrodes was gradually decreased because of anodic corrosion and scale build-up at the surface of cathode. However it could be partially overcome by use of corrosion-proof electrode material (SUS-316 L) and by periodic current switching between the electrodes.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.3
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• pp.43-48
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• 2002

In this study, high performance electrode catalyst was developed in fabrication of membrane electrode assembly for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). The I-V characteristics were measured to evaluate the influence of Nafion solution and Pt loading amount in the catalyst composition. The electrode characteristics were also investigated with respect to temperature change. The electrode performance was optimized at Nafion 5 wt% and 0.5 mg Pt/$\textrm{cm}^2$ content. The increase in the concentration of Nafion solution resulted in the decrease in electrode performance. At $80^{\circ}C$ of unit cell, I-V characteristics excelled those obtained at lower temperature. There was no difference in performance at low current density, but the improvement of voltage value in higher temperature could be found at high current density.