• Composites Research
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• 제37권3호
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• pp.190-196
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• 2024

분리판은 바나듐 레독스 흐름전지(VRFB) 스택 내 셀의 전기적 통로 및 구조적 지지 역할 수행하는 매우 중요한 부품 중 하나이다. 흑연 소재는 전기 전도성이 뛰어나 분리판에 주로 사용되지만, 셀 스택에서 전극과 분리판 사이에 높은 계면 접촉 저항(ICR)이 발생하여 VRFB의 성능에 심각한 제한이 존재한다. 본 연구에서는 ICR의 한계를 해결할 수 있는 일체형 전극-분리판 조립체를 개발하는 것을 목표로 하였다. 일체형 조립체는 핫 프레스 방법을 활용하여 열가소성 및 열경화성 폴리머와 단일 탄소 펠트를 사용하여 제작하였다. 실험 결과, 일체형 조립체가 연속적인 전기 경로로 인해 감소된 전체 저항을 나타냄을 확인하였다. 또한, 충/방전 셀 테스트 결과에서 일체형 조립체는 향상된 셀 성능을 보여주었다. 따라서 개발된 일체형 전극-분리판 조립체는 기존의 분리판 및 전극 조립체를 대체할 수 있을 것으로 판단된다.

• 전기화학회지
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• 제22권3호
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• pp.122-127
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• 2019

유기이차전지가 가지고 있는 전극 내 낮은 접합력과 높은 계면저항의 단점을 해결하기 위하여 본 연구에서는 흑연 코팅 처리된 집전체를 사용하여 lithium terephthalate (LTA)전지의 전기화학적 특성 변화를 분석하였다. LTA 음극 활물질은 산의 이온 치환반응에 의하여 불순물 없이 합성되어 졌다. 막대 형태의 LTA 활물질로 제작된 전극과 흑연 코팅 처리된 집전체와의 접합특성은 SEM 단면과 EIS를 통하여 확인하였다. 흑연 코팅된 집전체를 사용한 LTA전지의 계면저항은 현저히 감소되었다. 순수한 금속 집전체 LTA 전지와 흑연 코팅 처리된 금속 기판 LTA 전지는 0.1C의 두 번째 사이클에서 107.6 mAh/g와 148.8 mAh/g의 방전 용량을 보인다. 흑연 코팅된 집전체를 사용한 LTA 전지는 순수한 LTA 전지에 비하여 우수한 수명 특성과 높은 방전 용량, 그리고 높은 고율 특성을 가진다.

• 한국재료학회지
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• 제9권10호
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• pp.1012-1017
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• 1999

Si 도핑된 n-$\textrm{In}_{0.17}\textrm{Ga}_{0.83}\textrm{N}$($1.63\times10^{19}\textrm{cm}^{-3}$)에 W을 이용하여 낮은 접촉저항을 갖는 Ohmic 접촉을 형성시켰다. 열처리 온도를 증가시킴에 따라 비접촉 저항이 낮아졌으며, 가장 낮은 비접촉 저항은 $950^{\circ}C$의 질소분위기 하에서 90초간 열처리 해줌으로써 $2.75\times10^{-8}\Omega\textrm{cm}^{-3}$의 낮은 비접촉 저항값을 얻었다. 열처리 온도증가에 따른 $\textrm{In}_{0.17}\textrm{Ga}_{0.83}\textrm{N}$와 W의 계면반응과 W의 표면은 XRD와 SeM을 이용하여 분석하였다. XRD 분석을 통하여 W과 $\textrm{In}_{0.17}\textrm{Ga}_{0.83}\textrm{N}$이 반응하여 계면에 $\beta$-$W_2N$ 상을 형성시킴을 확인할 수 있었다. SEM 분석결과 W 표면은 $850^{\circ}C$의 높은 열처리온도에서도 안정한 상태를 유지하였다. W과 InGaN의 Ohmic 접촉에 있어 비접촉 저항은 열처리 온도를 증가시킴에 따라 낮아지게 되는 온도 의존성을 갖는데 이에 대한 가능한 기구를 제시하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.153-156
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• 2005

Nondestructive sensing of electrospun PYDF web and multi-wall carbon nanotube (MWCNT)/epoxy composites were investigated using electro-micromechanical technique. Electrospinning is a technique used to produce micron to submicron diameter polymeric fibers. Electrospun PVDF web was also evaluated for the sensing properties by micromechanical test and by measurement electrical resistance. CNT composite was especially prepared for high volume contents, 50 vol% of reinforcement. Electrical contact resistivity on humidity sensing was a good indicator for monitoring as for multifunctional applications. Work of adhesion using contact angle measurement was studied to correlate acid-base surface energy between carbon fiber and CNF composites, and will study furher for interfacial adhesion force by micromechanical test.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.63-64
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• 2006

The solid state dye-sensitized solar cells (DSSCs) employing polymer electrolytes show high overall energy conversion efficiency as high as 4.5 % at 1 sun conditions. The improved efficiency may be primarily due to the enlarged interfacial contact area between the electrolyte and dyes in addition to the increased ionic conductivity, which were done by utilizing liquid oligomers, followed by in situ self-solidification, to form the solid DSSCs: "Oligomer Approach". The effect of the charge transfer resistance at the counter electrode side on the efficiency has also been investigated.

• 한국표면공학회지
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• 제48권3호
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• pp.87-92
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• 2015

Carbon thin films were deposited on STS 316L sheets by inductively coupled plasma enhanced magnetron sputtering with or without substrate bias voltage. Typical Raman spectrum for amorphous diamond-like carbon (DLC) was obtained, and the interfacial contact resistance (ICR) was measured to show its conductive nature. The electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion mechanism of the carbon coating under the polymer electrolyte membrane fuel cell (PEMFC) condition. According to the pore-corrosion mechanism, the electrolyte penetrates the carbon coating through the pores and reacts with the substrate. As the substrate corrosion proceeds, the pore enlargement occurs and the surface area of the substrate exposed to the electrolyte. Applicability of the carbon coating for the PEMFC bipolar plate was evaluated by potentiodynamic polarization experiments. Finally, an adhesion problem was briefly considered.

• 한국재료학회지
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• 제20권4호
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• pp.187-193
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• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

• Composites Research
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• 제30권2호
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• pp.138-144
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• 2017

탄소나노튜브(CNT)를 이용하여 신율이 뛰어난 p-DCPD를 지로 사용하여 손상감지용 고분자 필름 센서를 연구하였다. CNT를 수지에 혼합시킬 경우 중합을 방해하여 1차 개환만 진행되었다. CNT 농도에 따른 정적접 촉각을 측정하여 계면의 젖음성을 측정하였다. 높은 신율을 가지는 p-DCPD에 CNT를 혼합시킴으로써 전도성을 확보하였고, CNT 농도에 따른 인장강도 및 전기저항 분산도 평가를 실시하였을 경우 0.5 wt% CNT/p-DCPD 조건이 최적의 조건임을 확인하였다. CNT/p-DCPD 센서의 내구성을 평가하기 위해 동적 피로 실험을 실시하여 인장응력에 따른 전기저항 변화를 평가하였다. 초기 3회 사이클 동안은 전기저항 변화도와 응력간의 결과가 유사한 경향을 나타내었다. CNT/p-DCPD 센서의 활용을 위해 에폭시 기지 표면에 센서를 붙이고 기지 재료의 파괴거동을 확인하였다. 기지 파괴가 발생되기 전에 CNT/p-DCPD 센서의 전기저항 점핑 신호를 관찰할 수 있었다. 이는 기지재료에 발생된 균열에 의해 CNT/p-DCPD 센서와 기지간의 접착 파괴로 발생된 신호이며, 이러한 신호를 이용하여 기지재료의 균열 및 파괴를 예측해 볼 수 있었다.

• 한국표면공학회지
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• 제44권5호
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• pp.173-178
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• 2011

Separator of stack in polymer electrolyte membrane fuel cell (PEMFC) is high cost and heavy. If we make it low cost and lighter, it will have a great ripple. In this study, low carbon steel is used as base metal of separator because the cost of low carbon steel is very cheaper commercial metal material than stainless steels, which is widely used as separator. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon steel needs to be surface treated. We made Chromium electroplated layer of $5{\mu}m$, $10{\mu}m$ thickness on the surface of low carbon steel and it was nitrided for 2 hours at $1000^{\circ}C$ in a furnace with 100 torr nitrogen gas pressure. Cross-sectional and surface microstructures of surface treated low carbon steel are investigated using SEM. And crystal structures are investigated by XRD. Interfacial contact resistance and corrosion tests were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1 N $H_2SO_4$ + 2 ppm $F^-$ solution at $80^{\circ}C$. Throughout this research, we try to know that low carbon steel can be replaced stainless steel in separator of PEMFC.

• 한국도로학회논문집
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• 제8권2호
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• pp.13-22
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• 2006

Surface fog coating methods to porous pavements with a polymer, that contains MMA as a main ingredient, are being widely used in Japan and called 'Top-Coat Processes'. They have lots of effects such as to prevention of the pavement void choking, improvement of the water permeability of the pavements and so on. The purpose of this research is to show the characterization of the polymer to optimize the functions of the polymer fog-coat methods. This study focused on the difference of 'wetting' by water among polymers used for the fog coatings, and calculation the surface free energy from the water contact angle on each material. At the end, the water permeability test were conducted using porous asphalt mixtures that were coated with several kinds of polymers. The permeability was also measured on the specimens that were forcibly choked by muddy water and the resistance to choking was compared. It is concluded that the reduction of the surface free energy between water and a polymer improves the life of the permeability functions of porous pavements. Improvement of water permeation capacity and void-blocking controlling effects can be quantitatively evaluated using the interfacial tension ($\gamma$sl) with water for the coating material (high-viscosity asphalt and hardening resin binder). Consequently, the smaller the $\gamma$sl of the coating material the higher the water permeation capacity and void-blocking controlling effects of the porous asphalt pavements.