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PEMFC 고분자막의 화학적 내구성 평가를 위한 Fenton 반응 조건에 관한 연구
오소형 ( Sohyeong Oh ),박지상 ( Jisang Park ),정성기 ( Sunggi Jung ),정지홍 ( Jihong Jeong ),박권필 ( Kwonpil Park ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1
The Fenton reaction is often used to evaluate the chemical durability of polymer membranes of Proton Exchange Membrane Fuel Cells (PEMFC). However, due to the violent reaction between hydrogen peroxide and iron ions, it is difficult to compare experimental data because of low reproducibility. In this study, we tried to find the reaction conditions to improve the reproducibility of the durability test of the membrane by the Fenton reaction. The hydrogen peroxide concentration was fixed at 30%, the iron ion concentration, temperature, stirring speed, and sample size were varied, and the fluorine ion concentration of the Nafion polymer membrane deteriorated by radicals was measured. When the iron ion concentration was increased or the membrane sample size was increased, and the reaction temperature was increased to 80℃, the experimental deviation increased, so an iron ion concentration of 10 ppm, a temperature of 70℃, and a sample size of 0.5 cm<sup>2</sup> were suitable.
PEMFC Cathode 산소 조건에서 전극 촉매 내구성 평가
오소형 ( Sohyeong Oh ),임대현 ( Daehyeon Lim ),박권필 ( Kwonpil Park ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1
In this study, we tried to develop a method of accelerated degradation of the electrode by simply using a electronic loader without using a potentiostat to evaluate the durability of the electrode catalyst. To this end, the durability of the electrode was evaluated by repeating the stepwise voltage change using the self-generated voltage by introducing oxygen without introducing nitrogen into the cathode. For accurate electrode durability evaluation, that is, in order not to deteriorate the polymer membrane, the high voltage was lowered to 0.9 V in stepwise voltage change and the relative humidity was 100% to suppress degradation of the polymer membrane due to radicals. After 30,000 cycles (50 hours) of voltage change, the electrode active area decreased by 41.4%. It was confirmed that the electrode was deteriorated, but the polymer membrane was not deteriorated, that there was no increase in hydrogen permeability, no decrease in membrane thickness, and no increase in HFR(High Frequency Resistance).
고분자 전해질 연료전지의 전해질 막 두께가 내구성과 성능에 미치는 영향
황병찬 ( Byungchan Hwang ),이혜리 ( Hyeri Lee ),박권필 ( Kwonpil Park ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.4
The polymer membrane of proton exchange membrane fuel cell (PEMFC) has a great influence on PEMFC performance and durability. In this study, hydrogen permeability, fluorine emission rate (FER), lifetime, and performance of Nafion membranes with different thicknesses were measured to investigate the effect of thickness of polymer membrane on performance and durability. The relationship between membrane thickness and lifetime was obtained from the relationships between hydrogen permeability and membrane thickness, hydrogen permeability and FER, FER and lifetime. As the membrane became thicker, the hydrogen permeability and FER decreased and the lifetime increased. On the other hand, the performance decreased with increasing membrane resistance. The membrane thickness range satisfying both performance and durability was 25 to 28 μm.
PEMFC 고분자막 내구 평가를 위한 Fenton 반응에서 과산화수소 농도 변화에 관한 연구
오소형 ( Sohyung Oh ),김정재 ( Jeongjae Kim ),이대웅 ( Daewoong Lee ),박권필 ( Kwonpil Park ) 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.3
Fenton reaction is widely used as a out of cell method for evaluating the membrane electrochemical durability of Proton Exchange Fuel Cell (PEMFC). In this study, we investigated the factors affecting the Fenton reaction. In order to estimate the degree of the reaction, it is necessary to analyze the radicals as a product in the Fenton reaction. However, since the radicals are difficult to analyze, the degree of the reaction was measured by analyzing the concentration of hydrogen peroxide. The activation energy was calculated from the rate of hydrogen peroxide change with temperature. The activation energy was 24.9 kJ/mol at 180 min. The Fenton reaction rate was affected by the iron ion concentration. At 80 ℃, 200 rpm, and Fe<sup>2+</sup> 80 ppm, the concentration of hydrogen peroxide was decreased more than 20% even for 1 hour, which shows that frequent solution replacement increases the membrane degradation rate.
PEMFC의 고분자막에서 지지체가 고분자전해질 막 성능 및 전기화학적 내구성에 미치는 영향
오소형 ( Sohyung Oh ),임대현 ( Dae Hyun Lim ),이대웅 ( Daewoong Lee ),박권필 ( Kwonpil Park ) 한국화학공학회 2020 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.58 No.4
To increase the mechanical durability of the proton exchange membrane fuel cells, a reinforced membrane in which a support is placed in the polymer membrane is used. The support mainly uses e-PTFE, which is hydrophobic and does not transfer ions, which may cause performance degradation. In this study, we investigated the effect of e-PTFE support on PEMFC performance and electrochemical durability. In this study, the reinforced membrane with the support was compared with the single membrane (non-reinforced membrane). Due to the hydrophobicity of the support, the water diffusion coefficient of the reinforced membrane was lower than that of the single membrane. The reinforced membrane had a lower water diffusion coefficient, resulting in higher HFR, which is the membrane migration resistance of ions, than that of a single membrane. Due to the low hydrogen permeability of the support, the OCV of the reinforced membrane was higher than that of the single membrane. The support was shown to reduce the hydrogen permeability, thereby reducing the rate of radical generation, thereby improving the electrochemical durability of the reinforced membrane.
PEMFC 고분자 막의 Short 저항 및 Shorting에 관한 연구
오소형 ( Sohyeong Oh ),권종혁 ( Jonghyeok Gwon ),임대현 ( Daehyeon Lim ),박권필 ( Kwonpil Park ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1
The shorting resistance (SR) of the PEMFC(Proton Exchange Membrane Fuel Cell) polymer membrane is an important indicator of the durability of the membrane. When SR decreases, shorting current (SC) increases, reducing durability and performance. When SR becomes less than about 0.1 kΩ?cm<sup>2</sup>, shorting occurs, the temperature rises rapidly, and MEA(Membrane Electrode Assembly) is burned to end stack operation. In order to prevent shorting, we need to control the SR, so the conditions affecting the SR were studied. There were differences in the SR measurement methods, and the SR measurement method, which improved the DOE(Department of Energy) and NEDO(New Energy and Industrial Technology Development Organization) method, was presented. It was confirmed that the SR decreases as the relative humidity, temperature and cell compression pressure increase. In the final stage of the accelerated durability evaluation process of the polymer membrane, SR rapidly decreased to less than 0.1 kΩ·cm<sup>2</sup>, and the hydrogen permeability became higher than 15 mA/cm<sup>2</sup>. After dismantling the MEA, SEM(Scanning Electron Microscope) analysis showed that a lot of platinum was distributed inside the membrane.
PEMFC 고분자막의 어닐링 온도가 내구성에 미치는 영향
이미화 ( Mihwa Lee ),오소형 ( Sohyeong Oh ),박유준 ( Yujun Park ),유동근 ( Donggeun Yoo ),박권필 ( Kwonpil Park ) 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.1
In the membrane forming process of a proton exchange membrane fuel cell (PEMFC), drying and annealing heat treatment processes are required for performance and durability. In this study, the optimal annealing temperature for improving the durability of the polymer membrane was studied. It was annealed in the temperature range of 125~175 ℃, and thermal stability and hydrogen permeability were measured as basic data of durability at each annealing temperature. The electrochemical durability was analyzed by Fenton reaction and open circuit voltage (OCV) holding. The annealing temperature of 165 ℃ was the optimal temperature in terms of thermal stability and hydrogen permeability. In the Fenton reaction, the fluorine emission rate of the membrane annealed at 165 ℃ was the lowest, and the lifespan of the membrane annealed at 165 ℃ was the longest in the OCV holding experiment, confirming that 165 ℃ was the optimal temperature for the durability of the polymer membrane.
고분자전해질 연료전지의 전극 열화 과정에서 고분자막에 석출된 백금에 관한 연구
오소형 ( Sohyeong Oh ),권혜진 ( Hyejin Gwon ),유동근 ( Donggeun Yoo ),박권필 ( Kwonpil Park ) 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.2
The study on electrode degradation of Proton Exchange Membrane Fuel Cell (PEMFC) was mainly studied on the particle growth and active area reduction of Pt on the electrode. The degradation of the electrode catalyst Pt in contact with the membrane affects the deterioration of the polymer membrane, but there are not many studies related to this. In this study, the phenomenon of the deposition of deteriorated Pt inside the polymer membrane during the accelerated electrode catalyst degradation test and its effects were studied. The voltage change (0.6 V ↔ 0.9 V) was repeated up to 30,000 cycles to accelerate the platinum degradation rate. When the voltage change cycle was repeated while oxygen was introduced into the cathode, the amount of Pt deposited inside the film was larger than when nitrogen was introduced. As the number of voltage change cycles increased, the amount of Pt deposited inside the membrane increased, and Pt dissolved in the cathode moved toward the anode, showing a uniform distribution throughout the membrane at 20,000 cycles. In the process of the accelerated electrode catalyst degradation test, the hydrogen crossover current density of the membrane did not change, and it was confirmed that the deposited Pt did not affect the durability of the membrane.