• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.406-414
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• 2021

Electrochemical devices are constructed for continuous syngas (CO + H₂) production with controlled selectivity between CO₂ and proton reduction reactions. The ratio of CO to H₂, or the faradaic efficiency toward CO generation, was mechanically manipulated by adjusting the space volume between the cathode and the polymer gas separator in the device. In particular, the area added between the cathode and the ion-conducting polymer using 0.5 M KHCO₃ catholyte regulated the solution acidity and proton reduction kinetics in the flow cell. The faradaic efficiency of CO production was controlled as a function of the distance between the polymer separator and cathode in addition to that manipulated by the electrode potential. Further, the electrochemical CO₂ reduction device using Au NPs presented a stable operation for more than 23 h at different H₂:CO production levels, demonstrating the functional stability of the flow cell utilizing the mechanical variable as an important operational factor.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.46.5-46
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• 2001

Electrostrictive polymer is deformed by electric force generated by electric field built by high voltage. When high voltage is applied to the electrostrictive polymer film in which the electrodes such as conductive grease or carbon powder are installed, it expands in the direction of area. Because electrostrictive polymer is incompressible and electric force is applied to it in the direction of thickness. Electrostrictive polymer film in which electrodes are installed, functions as a parallel-plate capacitor. Therefore anode and cathode charges are piled up or both electrodes and there exists attractive force that functions as pressure in the direction of thickness. So the thickness of electrostrictive polymer becomes thicker ...

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.110-116
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• 2011

Ru black was used for cathode catalyst in polymer electrolyte membrane fuel cell which showed low performance at the initial test. However, it was observed that the performance of Ru black cathode was dramatically enhanced after certain kind of experiment compared with initial one. It might be due to an electrochemical treatment in which a voltage was applied to the Ru cathode for constant period time. When a constant potential of 0.1 V was applied to Ru cathode for 30 min, the fuel cell performance of Ru cathode showed the best results. In order to investigate the effect of electrochemical treatment on the performance enhancement, the characteristics of electrochemically treated Ru black was compared with that of Ru black which was reduced under $H_2$ atmosphere. From XRD results, it was turned out that Ru black was not completely converted to metallic Ru by electrochemical treatment, but it is sufficient to be one of reasons for the performance enhancement. According to the results of CO stripping voltammetry, it was observed that some Ru was removed from Ru electrode by electrochemical treatment which might have a bad effect on the fuel cell performance. The removal of some Ru from as-received Ru black by electrochemical treatment is also another reason for the enhancement of fuel cell performance.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.333-338
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• 2021

The durability of the PEMFC stack for large commercial vehicles should be more than 5 times that for passenger vehicles. If the Chemical Accelerated Stress Test (AST) of PEMFC(Proton Exchange Membrane Fuel Cells) membrane for passenger cars is applied as it is for large commercial vehicles, there is a problem that the AST time becomes more than 2,500 hours. In order to shorten the AST time of DOE (Department of Energy), the chemical durability of the polymer membrane was evaluated using oxygen instead of air as a cathode gas. In this study, Nafion XL was used as a polymer membrane to evaluate accelerated durability under OCV, 90?, RH 30%, H₂/(air or oxygen) conditions. Among the DOE membrane durability target criteria, the decrease rate of short resistance was the fastest. By using oxygen instead of air, the degradation rate of the polymer membrane was accelerated while being less affected by electrode deterioration, reducing the polymer membrane durability evaluation time to less than half.

• Journal of Powder Materials
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• v.27 no.1
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• pp.63-71
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• 2020

It is necessary to fabricate uniformly dispersed nanoscale catalyst materials with high activity and long-term stability for polymer electrolyte membrane fuel cells with excellent electrochemical characteristics of the oxygen reduction reaction and hydrogen oxidation reaction. Platinum is known as the best noble metal catalyst for polymer electrolyte membrane fuel cells because of its excellent catalytic activity. However, given that Pt is expensive, considerable efforts have been made to reduce the amount of Pt loading for both anode and cathode catalysts. Meanwhile, the atomic layer deposition (ALD) method shows excellent uniformity and precise particle size controllability over the three-dimensional structure. The research progress on noble metal ALD, such as Pt, Ru, Pd, and various metal alloys, is presented in this review. ALD technology enables the development of polymer electrolyte membrane fuel cells with excellent reactivity and durability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.768-772
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• 1998

The new type polymer electrolyte composed of polymethyl methacrylate(PMMA) - polyethy leneoxide(PEO) contain $LiClO_4$ -EC/PC was developed for the weightless and long or life time of lithium polymer batery system with using polyaniline electrode. the gel type electrolytes were prepared by PMMA with PEO at different lithium salts in the glove box. The minimum thickness of PMMA-PEO gel electrolyte for the slim type is about(400~450$\mu\textrm{m}$. These gel electrolyte showed good compatibility with lithium electrode. The test cell Li/polymer electrolyte/polyaniline solid state cell which was prepared by different lithium salt was researched by electrochemical technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.273-276
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• 1996

Polyphenylenediamine(PPD) film was prepared with dimethylsulfoxide after the synthesis of PPD by chemical polymerization. The molecular structure of conductive polymer synthesized were discussed by using SEM, FT-IR, NMR. The electrical conductivity measurements were carried out at room temperature. The electrical conductivity which was obtained from electrical instrument was 1.98${\times}$10$\^$-2/ S/cm at ambient temperature.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.1-4
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• 1999

A lithium ion battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key factor of the secondary battery system, that has been obtained during the process of the development of a polymer type lithium battery. As a successful result of the solid polymer electrolyte. The ionic conductivity of the solid polymer electrolyte, which is composed of polyacrylonitrile and $LiClO_4\;with\; Al_2O_3$ dissolved as the supporting electrolyte, has been confirmed to be $2.3\times10^{-4} S/cm$ at room temperature.

• 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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.8
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• pp.604-612
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• 2009

Water management has been recognized as a crucial factor for achieving better performance and stability in polymer electrolyte membrane fuel cells (PEMFCs). Proper water management should provide favorable water conditions, including the local humidity, membrane water content, and liquid water saturation in PEMFCs, thereby leading to more uniform electrochemical reaction and current generation. In this study, computational fluid dynamics (CFD) simulation was conducted to investigate the effects of the cathode relative humidity (RH) on the performance of a 3 by $3\;cm^2$ PEMFC with serpentine flow fields. The CFD results showed that the best performance of the PEMFC was obtained for the cathode RH of 80%, but the performance variation was small for the cathode RH range of $60{\sim}100%$. However, the loss of the PEMFC performance was significant when the cathode RH was reduced below 40%. The reason for such performance variation was investigated through the detailed inspection of ohmic loss, activation and concentration overpotential, and water and current distributions.