• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.365-372
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• 2024

As the energy density of lithium-ion batteries (LIBs) continues to increase, various separators are being developed to with the aim of improving the safety performance. Although poly(imide) (PI)-based separators are widely used, it is difficult to control their pore size and distribution, and this may further increase the risk associated. Herein, a melamine phosphonic acid (MP)-coated PI separator that can effectively control the pore structure of the substrate is suggested as a remedy. After the MP material is embedded into the PI separator with a simple one-step casting process, it effectively clogs the large pores of the PI separator, preventing the occurrence of internal short circuits during charging. It is anticipated that the MP material can also suppress rapid thermal runaway upon cycling due to its ability to reduce the internal temperature of the LIB cell caused by the desirable endothermic behavior around 300℃. According to experiments, the MP-coated PI separator not only decreases the thermal shrinkage rate better than commercial poly(ethylene) (PE) separators but also exhibits a desirable Gurley number (109.6 s/100 cc) and electrolyte uptake rate (240%), which is unique. The proposed separator is electrochemically stable in the range 0.0-5.0 V (vs. Li/Li⁺), which is the typical working potential of conventional electrode materials. In practice, the MP-coated PI separator exhibits stable cycling performance in a graphite-LiNi_0.83Co_0.10Mn_0.07O₂ full cell without an internal short circuit (retention: 90.3%).

• Composites Research
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• v.30 no.1
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• pp.46-51
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• 2017

Structural battery has been researched extensively to combine the functions of the battery and structure without gravimetric or volumetric increments compared to their individual components. The main idea is to employ carbon fabric as the reinforcement and electrode, glass fabric as the separator, and solid-state electrolyte which can transfer load. However, state-of-the-art solid-state electrolytes do not have sufficient load carrying functionality and exhibiting appropriate ion conductivity simultaneously. Therefore, in this research, a system which has both battery and load carrying capabilities using glass fabric separator and liquid electrolyte was devised and tested to investigate the potential and feasibility of this structural battery system and observe electric properties. It was observed that elongating separator decreased electrical behavior stability. A possible cause of this phenomenon was the elongated glass fabric separator inadequately preventing the penetration of small particles of the cathode material into the anode. This problem was verified additionally by using a commercial separator. The characteristic of the glass fabric and the interface between the electrode and glass fabric needed to be further studied for the realization of such a load carrying structural battery system.

• Journal of the Korean institute of surface engineering
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• v.31 no.1
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• pp.3-11
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• 1998

Molten Carbonate Fuel cell is a promising new type electric power generation system which can achieve high efficiency, lower matrrial cost and high operating temperature Making internal reforming possible. Although the development of the MCEC is progressing rapidly toward commercialization, two important tchological problems such as dissolution of NiO cathode and not corrosion of metallic separator plate must be resolved. Because MCFC is operated at $650^{\circ}C$ and the electrolyte is very corrosive, corrosion-resistance of separator plated against oxidation abd molten carbonate is required. Al-coating on separator material for corrosion-resistance was carried out by painting, thermal spraying. hot dipping and vacuum vapour deposition. The corrosion of Al-coated STS 316S and 316L in molten carbonate at $700^{\circ}C$was studied. Vacuum vapour deposition and thermal spraing for Al-coating on STS 310S and 316L were the most effective methods for protecting thestainless steel corrosion in molten carbonate.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.365-371
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• 2016

Cell performance of the Zn-Br redox flow battery (ZBRFB) using two different type's membrane (Nafion117 and SF-600) was evaluated at $20mA/cm^2$ of current density in 1M (mol/L) $ZnBr_2$ + 2M KCl + 0.3M EMPBr(1-ethyl-1-methyl pyrrolidinium bromide) electrolyte. The average energy efficiencies of ZBRFB were 74.9% and 74.7% for Nafion117 and SF-600, respectively. The electrolyte added the 1-ethyl-3-methylimidazolium dicyanamide (EMICA) as an additive was tested for the electrolyte in ZBRFB using SF-600 at $30mA/cm^2$ of current density. An average energy efficiency of the ZBRFB was 74.5% and 77.4% for the electrolyte non-added EMICA and added 1wt% of EMICA, respectively. ZBRFB using the electrolyte added EMICA was showed the higher performance than that using the electrolyte non-added EMICA.

• Journal of the Korean Electrochemical Society
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• v.20 no.2
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• pp.41-48
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• 2017

Herein, we have fabricated an ultrathin aluminum oxide ($Al_2O_3$) coated PP separator by using a RF sputter deposition process. Approximately 20 nm thickness coating layer on the bare PP separator was formed at the power of 55 W for 2 minutes without thermal damage. Whereas only permeability of the coated separator was degraded slightly, other properties such as thermal stability, uptake amount of liquid electrolyte, and ionic conductivity were improved comparing to the bare PP separator. As a result, an only 20-nm-thick $Al_2O_3$ coating layer could improve the rate capability compared with a bare PP separator under a high current density.

• Journal of the Korean Electrochemical Society
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• v.20 no.3
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• pp.49-54
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• 2017

We develop a ceramic composite separator prepared by coating $ZrO_2$ nanoparticles with a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer on a polyvinyl alcohol (PVA) mechanical support prepared by electrospinning technique to improve thermal properties. The gurley number of the ceramic composite separator shows much lower value than that of a PE separator even though it possesses the polymeric coating layer with ceramic nanoparticles. In addition, the proposed sample shows higher electrolyte uptake than PE separator, leading to enhancing the ionic conductivity of the proposed sample and, by extension, the rate discharge properties of lithium ion batteries. Thermal stability of the ceramic composite separator is dramatically improved without any degradation in electrochemical performance compared to the performance of conventional PE separators.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.581-584
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• 2001

For the first time, a totally solid state electric double layer capacitor has been fabricated using an alkaline polymer electrolyte and an activated carbon powder as electrode material. The polymer electrolyte serves both as separator as well as electrode binder. The capacitor has a three-layer structure; electrode-electrolyte-electrode. A cyclic voltammetry and constant current discharge have been used for the determination of the electro chemical performance of capacitors.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.293-298
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• 2016

A hydrogel electrolyte consisting of 6 M KOH aqueous solution, potassium polyacrylate (PAAK, 3 wt.%), and a hydrophilic silica OX50 (1 wt.%) was prepared to use as an electrolyte medium coated on a Scimat separator of activated carbon supercapacitor. The silica particle distributed homogeneously on surface pores of the separator to increase ionic conductivity and electrochemical stability of the hydrogel electrolyte. The silica addition also involved superior specific capacitance even at higher scan rates due to decrease in interfacial resistance between hydrogel electrolyte and activated carbon electrode.

• Polymer(Korea)
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• v.37 no.1
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• pp.22-27
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• 2013

In this study, we prepared separators with improved thermal stability by coating microporous polyethylene (PE) film for lithium secondary battery using poly(meta-phenylene isophthalamide) (Nomex). The mechanical and thermal properties of prepared separators were evaluated by thermal stability test and TMA as a function of the Nomex concentration and coating parameters. The corresponding coated PE separator showed better thermal and mechanical properties than the original PE separator. Electrochemical properties were also assessed by ionic conductivity, cyclic voltammetry and charge/discharge cycle.

• Journal of Hydrogen and New Energy
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• v.24 no.1
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• pp.84-90
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• 2013

The hydrogen or oxygen gas producted by electrolysis become many bubbles in the electrolyte, but exact data on the behavior of these bubbles in the separator of an electrolysis stack didn't become known. In this study, the flow visualization experiment on the behavior of bubbles in the flow pattern of the array type separator is performed by using of a visible alkaline electrolysis stack and a stereoscopic microscope. As the results, a fine size bubbles adhered to the surface of the flow pattern grow to large sized bubbles until each bubble's buoyance is lager than the sum of external force and weight. And then the large bubbles flow into the upper area of the separator. Bubbles adhered to the surface of the vertical flow pattern grow quickly than them adhered to the surface of the horizontal flow pattern. Also, he electrolysis efficiency is declined because many multi-size bubbles occupied the wide volume in the flow pattern.