• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.119-125
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• 2008

The FAS(Fluoroalkylsilane)/Nafion inorganic-organic composite electrolyte membrane was successfully fabricated through sol-gel method. The FAS having hydrophobic functional group and silanol ligands is impregnated in $Nafion^{(R)}$ membrane to reduce methanol crossover. The prepared FAS/Nafion inorganic-organic composite electrolyte membrane consist of the hydrophobic FAS-derived silicate nano-particles and $Nafion^{(R)}$ matrix showed decrease of methanol crossover and reduction of humidity dependence without large sacrifice of proton conductivity. The microstructural analysis of the composite membranes was performed using FESEM and FTIR. And the effect of the incorporation of the hydrophobic FAS-derived silicate nano-particles into $Nafion^{(R)}$ membrane was investigated via solvent uptake, membrane expansion rate, humidity dependency of proton conductivity and contact angle measurement.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.34-42
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• 2012

Gas diffusion layers (GDLs) of carbon composite type in polymer electrolyte fuel cells were prepared by simple and cheap manufacturing process. To obtain the carbon composite GDLs, carbon black with polymer binder was mixed in solvent, rolled to make sheet, and finally heat-treated at $340^{\circ}C$. The performance of fuel cell using composite GDLs was changed by PTFE content. The physical properties of composite GDLs for pore, conductivity and air permeability were analyzed to compare with the variation of fuel cell performance. The conductivity of composite GDLs was very similar to carbon paper as commercial GDL but pore properties and air flux were considerably different. The porosity, PTFE content and conductivity for composite GDLs did not have an influence on the cell performance much. The increase of pore diameter and air flux led to enhance cell performance.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.159-166
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• 2003

The preparation method for composite membranes of high temperature operation above $100^{\circ}C$ for Polymer Electrolyte Membrane Fuel Cells (PEMFCs ) was presented, using perfluorosulfonylfluoride Nafion resin and mordenite, in addition to the physical properties, proton conductivity and single cells performance for it. The composite membranes were fabricated via melting of Nafion resin with various mordenite content. As the increase of mordenite content, at high temperature range, proton conductivity of the composite membrane increased due to the late dehydration rate of existent water in the mordenite. Also, from the result of the current-voltage relationship for single cells under $130^{\circ}C$ operation condition, the composite membrane cell with l0 wt% mordenite content showed better performance than that of the others over the entire current density range. This result indicated that the existent water in the composite membrane with l0 wt% mordenite content was higher than that with the others, thereby maintains its conductivity. Based upon the results of experiments, therefore, a Nafion/mordenite composite membrane prepared by this work is thought to be a satisfactory polymer electrolyte membrane for PEMFC operation above $100^{\circ}C$.

• Composites Research
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• v.29 no.6
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• pp.395-400
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• 2016

Recently, many research groups have studied on the epoxy-based multifunctional electrolyte to develop the structural composite bearing high mechanical properties without sacrificing the ionic conductivity at the same time. The studies on the optimal content and material selection for structural electrolyte have been published, while its curing behavior has not much analyzed yet. In this study, epoxy-based structural electrolyte containing solid electrolyte was prepared by varying the curing temperature and time. In addition, the ionic conductivities and mechanical properties of specimens were measured. We also find out the optimal hardening condition where the epoxy domain enables to be hardened within the range of temperature at which the thermal decomposition of electrolyte does not occur. Finally, we propose the multifunctional structural electrolyte showing achievable electrical and mechanical properties (282 MPa and $9{\times}10^{-6}S/cm@25^{\circ}C$).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.62-67
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• 2007

Optimization of cathode properties for intermediate temperature-operating SOFC (IT-SOFC) is carried out by using composite-type electrode structure in this study. Composite cathode may lower cathode overpotential by enhancing mixed ionic-electronic conductivity. In this study, particularly, LSM/YSZ, LSF/YSZ, LSCF/CGO, and PSC/CGO were selected as cathode materials. LSM/YSZ composite cathode showed the best performance of about 0.9${\Omega}cm^2$ at $700^{\circ}C$. It is inferred that the resistance is mainly affected by the reactivity between cathode and electrolyte which can cause the formation of resistive phases. Area specific resistance (ASR) characteristics were not changed significantly with decreasing sintering temperature of cathode, because reaction sites were increased even with worse adhesion of cathode on electrolytes.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.101-106
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• 2016

In this study, we prepared an ionic liquid composite solid polymer electrolyte (PEO-LiTFSI-$Pyr_{14}TFSI$) with poly(ethylen oxide), lithium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide by blending-cross linking process. Although the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte displayed a small peak at 4.4 V, it had high electrochemical oxidation stability up to 5.7 V. Ionic conductivity of the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte increased with increasing temperature from $10^{-6}S\;cm^{-1}$ at $30^{\circ}C$ to $10^{-4}S\;cm^{-1}$ at $70^{\circ}C$. To investigate the electrochemical properties, the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte assembled with $LiFePO_4$ cathode and Li-metal anode. At 0.1 C-rate, the cell delivered $40mAh\;g^{-1}$ for $30^{\circ}C$, $69.8mAh\;g^{-1}$ for $40^{\circ}C$ and $113mAh\;g^{-1}$ for $50^{\circ}C$, respectively. The PEO-LiTFSI-$Pyr_{14}TFSI$ solid polymer electrolyte exhibited good charge-discharge performance in Li/SPE/$LiFePO_4$ cells at $50^{\circ}C$.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.149-151
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• 2004

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.85-95
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• 2023

In recent years, solid-state Li metal batteries (SSLBs) have attracted significant attention as the next-generation batteries with high energy and power densities. However, uncontrolled dendrite growth and the resulting pulverization of Li during repeated plating/stripping processes must be addressed for practical applications. Herein, we report a plastic-crystal-based polymer/ceramic composite solid electrolyte (PCCE) to resolve these issues. To fabricate the one-side ceramic-incorporated PCCE (CI-PCCE) film, a mixed precursor solution comprising plastic-crystal-based polymer (succinonitrile, SN) with garnet-structured ceramic (Li₇La₃Zr₂O₁₂, LLZO) particles was infused into a thin cellulose membrane, which was used as a mechanical framework, and subsequently solidified by using UV-irradiation. The CI-PCCE exhibited good flexibility and a high room-temperature ionic conductivity of over 10^-3 S cm^-1. The Li symmetric cell assembled with CI-PCCE provided enhanced durability against Li dendrite penetration through the solid electrolyte (SE) layer than those with LLZO-free PCCEs and exhibited long-term cycling stability (over 200 h) for Li plating/stripping. The enhanced Li⁺ transference number and lower interfacial resistance of CI-PCCE indicate that the ceramic-polymer composite layer in contact with the Li anode enabled the uniform distribution of Li⁺ flux at the interface between the Li metal and CI-PCCE, thereby promoting uniform Li plating/stripping. Consequently, the Li//LiFePO₄ (LFP) full cell constructed with CI-PCCE demonstrated superior rate capability (~120 mAh g^-1 at 2 C) and stable cycle performance (80% after 100 cycles) than those with ceramic-free PCCE.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2529-2535
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• 2013

Sol-gel method was utilized to prepare SPEEK/PWA electrolyte composite membranes. TEOS was used as a precursor and phosphotungstic acid(PWA) as a catalyst for the sol-gel reaction. It was observed through FE-SEM analysis that the PWA and silica nanoparticles were uniformly dispersed into the polymer matrix. The water uptake of SPEEK/PWA/silica composite membranes was less affected by TEOS concentration at higher TEOS contents, while the water uptake decreased as TEOS concentration increased at lower TEOS contents. The proton conductivity of the composite membranes showed similar trend as the water uptake of the composite membranes. The methanol permeability of SPEEK/PWA/silica composite membranes decreased as TEOS concentration increased.

• Membrane Journal
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• v.32 no.6
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• pp.427-441
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• 2022

Polymer electrolyte membrane (PEM) serving as a separator that can prevent the permeation of unreacted fuels as well as an electrolyte that selectively transports protons from the anode to the cathode has been considered a key component of polymer electrolyte membrane fuel cell (PEMFC). The perfluorinated sulfonic acid-based PEMs, represented by Nafion®, have been commercialized in PEMFC systems due to their high proton conductivity and chemical stability. Nevertheless, these PEMs have several inherent drawbacks including high manufacturing costs by the complex synthetic processes and environmental problems caused by producing the toxic gases. Although numerous studies are underway to address these drawbacks including the development of sulfonated hydrocarbon polymer-based PEMs (SHP-PEMs), which can easily control the polymer structures, further improvement of PEM performances and durability is necessary for practical PEMFC applications. Therefore, this study focused on the various strategies for the development of SHP-PEMs with outstanding performance and durability by 1) introducing cross-linked structures, 2) incorporating organic/inorganic composites, and 3) fabricating reinforced-composite membranes using porous substrates.