• 에너지공학
• /
• 제2권2호
• /
• pp.194-199
• /
• 1993

인산형 연료전지에서 cathode 및 anode 전극의 반응 면적을 넓혀 전극성능을 향상시키고자 전극 촉매층에 가스 확산로를 도입하였다. 촉매층의 제작은 기체확산로로 이용하고자 제조된, 촉매가 담지되어 있지 않은 PTFE/carbon과 10w/o의 촉매가 담지된 Pt/carbon을 혼합 비율을 달리하면서 촉매 분말법으로 제작하였다. PTFE를 60w/o 담지한 PTFE(60 w/o)/carbon 분말과 Pt(10 w/o)/carbon분말을 7 : 3의 비율로 혼합하여 제조된 전극이 가장 우수한 성능을 보였다. 이들 조성을 변화시키면서 전극의 다공성과 전극성능을 비교 검토하여 본 결과 전극성능은 기체 확산로로 이용되는 macro pore와 전해질의 침투로 이용되는 micro pore 모두가 많이 형성됨에 따라 향상되었음을 알 수 있었다. 이때 전극에 담지된 백금 촉매의 양은 0.2mg/$\textrm{cm}^2$이었으며 PTFE함량은 42w/o이었다. 작동온도 15$0^{\circ}C$, 단자전압 0.7 V에서 전류밀도는 220 ㎃/$\textrm{cm}^2$이었다.

• 공업화학
• /
• 제10권5호
• /
• pp.652-659
• /
• 1999

메탄을 연료로 한 직접 내부개질형 용융탄산염 연료전지의 anode전극위치에 따른 개질 촉매의 피독 현상을 규명하였다. 수증기-탄소 비를 2.5로 고정시킨 후 운전전압 0.75 V, 전류밀도 $140mA/cm^2$을 유지하면서 24시간 운전중인 연료전지를 정지시키고 anode전극 내, 가스흐름 방향으로 입구, 중간 및 출구 부분에 충전된 촉매를 채취하여 탄소와 전해질 성분인 리튬과 칼륨의 피독 정도를 분석하였고 운전시간 100시간 후, 같은 방법으로 촉매를 분석하였다. 그 결과, 운전시간 24시간 경과 후 촉매의 리튬과 칼륨의 피독량은 입구부에서 0.27 wt%, 중간부에서 0.23 wt% 출구부에서 1.59 wt%로 출구부에 충전된 촉매 피독량이 제일 높았지만 100시간 경과 후 촉매의 피독량은 입구부에서 가장 높았다. 이러한 결과는 직접 내부개질형 연료전지의 성능 모사를 통한 전극 내 위치별 반응속도와 이에 따른 촉매의 역할로 설명이 가능하였다. 전지의 성능 모사 결과 전극 내 메탄-수증기 개질 반응은 입구 부분 30%까지 초기 메탄 유입량의 90%가 반응하여 이 부분에 충전된 촉매가 가장 많이 사용되고 전극반응도 가장 활발하게 일어나 입구부 촉매의 탄소와 전해질 피독량이 높았고 운전 시간에 따른 피독 정도가 가장 빨랐다. 전극 내 출구부는 가장 높은 온도분포를 보이고 있어 상대적으로 전해질 증발이 많아져 운전 초기부터 촉매의 전해질 피독이 빠르게 일어나지만 개질 반응과 전극 반응은 상대적으로 적게 진행되어 촉매의 피독 속도는 크지 않았다.

• Bulletin of the Korean Chemical Society
• /
• 제33권8호
• /
• pp.2539-2545
• /
• 2012

In the present study, we suggest a new way to reactivate performance of direct formic acid fuel cell (DFAFC) and explain its mechanism by employing electrochemical analyses like chronoamperometry (CA) and cyclic voltammogram (CV). For the evaluation of DFAFC performance, palladium (Pd) and platinum (Pt) are used as anode and cathode catalysts, respectively, and are applied to a Nafion membrane by catalyst-coated membrane spraying. After long DFAFC operation performed at 0.2 and 0.4 V and then CV test, DFAFC performance is better than its initial performance. It is attributed to dissolution of anode Pd into $Pd^{2+}$. By characterizations like TEM, Z-potential, CV and electrochemical impedance spectroscopy, it is evaluated that such dissolved $Pd^{2+}$ ions lead to (1) increase in the electrochemically active surface by reduction in Pd particle size and its improved redistribution and (2) increment in the total oxidation charge by fast reaction rate of the Pd dissolution reaction.

• 한국수소및신에너지학회논문집
• /
• 제27권4호
• /
• pp.341-348
• /
• 2016

The experiments related on structure and water electrolysis performance of HALE UAV stack were conducted in this study. Anode catalyst $IrRuO_2$ was prepared by Adam's fusion methods as 2~3 nm nano sized particles, and the cathode catalyst was used as commercial product of Premetek. The MEA (membrane electrode assembly) was manufactured by decal methods, anode and anode catalytic layers were prepared by electro-spray. HALE stack was composed of 5 multi-cells as $0.2Nm^3/hr$ hydrogen production rate with hydrogen pressure as 10 bar. The water electrolysis performance was investigated at atmospheric pressure and temperature of $55^{\circ}C$. Best performance of HALE UAV stack was recorded as cell voltage efficiency as 86%.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.402.1-402.1
• /
• 2016

The performance of solid oxide fuel cells (SOFCs) is directly related to the electrocatalytic activity of composite electrodes in which triple phase boundaries (TPBs) of metallic catalyst, oxygen ion conducting support, and gas should be three-dimensionally maximized. The distribution morphology of catalytic nanoparticle dispersed on external surfaces is of key importance for maximized TPBs. Herein in situ grown nickel nanoparticle onto the surface of fluorite oxide is demonstrated employing gadolium-nickel co-doped ceria ($Gd0.2-xNixCe0.8O2-{\delta}$, GNDC) by reductive annealing. GNDC powders were synthesized via a Pechini-type sol-gel process while maximum doping ratio of Ni into the cerium oxide was defined by X-ray diffraction. Subsequently, NiO-GNDC composite were screen printed on the both sides of yttrium-stabilized zirconia (YSZ) pellet to fabricate the symmetrical half cells. Electrochemical impedance spectroscopy (EIS) showed that the polarization resistance was decreased when it was compared to conventional Ni-GDC anode and this effect became greater at lower temperature. Ex situ microstructural analysis using scanning electron microscopy after the reductive annealing exhibited the exsolution of Ni nanoparticles on the fluorite phases. The influence of Ni contents in GNDC on polarization characteristics of anodes were examined by EIS under H2/H2O atmosphere. Finally, the addition of optimized GNDC into the anode functional layer (AFL) dramatically enhanced cell performance of anode-supported coin cells.

• Advances in Energy Research
• /
• 제2권1호
• /
• pp.21-31
• /
• 2014

The use of a microporous membrane along with Au/C catalyst for direct glycerol alkaline fuel cell was investigated. In comparison with Nafion 112, the microporous Celgard 3401 membrane provides a better cell performance due to the lower ionic resistance as confirmed by impedance spectra. The single cell using Au/C as anode catalyst prepared by using PVA protection techniques provided a higher maximum power density than the single cell with commercial PtRu/C at $18.65mW\;cm^{-2}$ The short-term current decay studies show a better stability of Au/C single cell. The higher activity of Au/C over PtRu/C was owing to the lower activation loss of Awe. The magnitude of current decay indicates a low problem of glycerol crossover from anode to cathode side. The similar performance of single cell with and without humudification at cathode points out an adequate transport of water through the microporous membrane.

• 한국수소및신에너지학회논문집
• /
• 제32권5호
• /
• pp.401-409
• /
• 2021

The combination of different concentrations of ZnSO₄ in acidic solution as electrolyte in Zn-air batteries was investigated by Zn symmetrical cell test, half-cell and full cell tests. Using 1 M ZnSO₄ + 0.05 M H₂SO₄ as electrolyte and MnO₂ as air cathode catalyst with Zn foil anode, this combination had a satisfactory performance with balance of electrochemical activity and stability. Its electrochemical activity was matched to or even better than the PtRu catalyst in different current density. And its cycle life was improved (more than 100 cycles stable) by suppressing the growth of zinc dendrites on anode obviously. This electrolyte overcame the shortcomings of alkaline electrolyte that are easy to react with CO₂ in the air, severely growth of Zn dendrites caused by uneven plating/stripping of Zn.

• Journal of Electrochemical Science and Technology
• /
• 제14권3호
• /
• pp.283-292
• /
• 2023

Currently, spray coating has attracted interest in the mass production of anode catalyst layers for proton exchange membrane water electrolysis (PEMWE). The solvent in the spray ink is a critical factor for the catalyst dispersion in ink, the microstructure of the catalyst layer, and the PEMWE performance. Herein, various pure organic solvents were examined as a substitute for conventional isopropanol-deionized water (IPA-DIW) mixture for ink solvent. Among the polar solvents that exhibited better IrO₂ dispersion over nonpolar solvents, 2-butanol (2-BuOH) was selected as a suitable candidate. The PEMWE single cells were fabricated using 2-BuOH at various ionomer contents, spray nozzle types, and drying temperatures, and their performance was compared to the cells fabricated using a conventional IPA-DIW mixture. The PEMWE single cells with 2-BuOH solvent showed good performances comparable to the conventional IPA-DIW mixture case and highly durable performances under accelerated degradation tests.

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2002년도 연료전지심포지움 2002논문집
• /
• pp.183-188
• /
• 2002

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2002년도 연료전지심포지움 2002논문집
• /
• pp.287-292
• /
• 2002