상온 이온액을 이용한 고온 무수 PEMFC용 고정화 액막의 온도에 따른 이온전도도 거동

김범식,변용훈,박유인,이상학,이정민,구기갑 한국막학회 2006 멤브레인 Vol.16 No.4

이온전도도가 높은 상온 이온액을 이용하여 저온, 고온 상분리에 의한 multi-stage phase separation process로 새로운 고정화 이온액 전해질 막(supported ionic liquid electrolyte membranes, SILEMs)을 제조하였다. PVDF와 imidazolium계 이온액을 각각 분리막 소재와 전해액으로 사용하였다. 이온전도도 특성을 알아보기 위해 SILEMs을 LCR meter를 이용 해 30℃부터 130℃까지 실험하였다. 가습조건에서 cast Nafion 막의 이온전도도는 30℃부터 100℃까지는 직선적으로 증가하였으나 그 이후에는 감소하였다. 그러나 SILEMs의 경우 운전온도의 증가에 따라 이온전도도가 증가하였다. 또한 SILEMs의 이온전도도 거동은 가습과 관계없이 거의 같았다. SILEMs의 이온전도도는 30℃에서 2.7x10 -3 S/cm이었고 온도가 130℃까지 증가함에 따라 2.2x10 -2 S/cm까지 거의 직선적으로 증가하였다. SiO2를 이용하여 SILEMs의 물리적 성질에 대한 무기첨가제의 영향에 관하여 연구하였다. SILEMs에 SiO2의 첨가는 비록 약간의 이온전도도 감소는 있으나 SILEMs의 기계적 강도를 향상시킬 수 있었다. Novel SILEMs were prepared by multi-stage phase separation process combined by the low temperature phase separation (LTPS) and the high temperature phase separation (HTPS) using room temperature ionic liquids (RTILs) which have a high ionic conductivity. PVDF and imidazolium series ionic liquids were used as membrane material and electrolyte, respectively. To study the ion conducting properties, the SILEMs were tested using LCR meter at temperature controlled from 30 to 130℃. Under humid conditions, with increasing temperature from 30 to 100℃, the ion conductivity of the cast Nafion ® membrane increased linearly, but then started to decrease after 100℃. However, in the case of the SILEMs, with increasing operating temperature, the ion conductivity increased. Also, the ion conductivity behaviors of the SILEMs were almost same, regardless of humidity. The ion conductivity of the SILEMs was 2.7x10 -3 S/cm and increased almost linearly up to 2.2x10 -2 S/cm with increasing temperature to 130℃. The effects of an inorganic filler on the physical properties of the SILEMs were studied using the SiO2. The addition of SiO2 could improve the mechanical strength of the SILEMs, though the ionic conductivity was decreased slightly.

Observation of electrochemical characteristic of phosphoric acid doped PBI based high temperature PEMFC in the temperature range 120-160 °C

유성관,유동진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

High-temperature (90-200 °C) proton exchange membrane fuel cells (PEMFCs) have been considered the next generation of fuel cell because of their advantages over those operated at lower temperatures (usually below 80 °C). These advantages include: (1) faster electrochemical kinetics, (2) improved and simplified water management, (3) effective thermal management and (4) improved contamination tolerance. In this study, We prepared a single cell using a commercially MEA, and autonomously produced a single test station equipped with a reformer, and observed the performance and electrochemical characteristics of the single cell. Furthermore the effect of stoichiometry on the single cell electrochemical properties were investigated by electrochemical impedance spectroscopy(EIS) measurements. We conducted long-term experiments for 500 hours to observe the durability of single cells.

Numerical study of thermal stresses in high-temperature proton exchange membrane fuel cell (HT-PEMFC)

Oh, K.,Chippar, P.,Ju, H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.6

The purpose of this work is to numerically examine the thermal stress distributions in a high-temperature proton exchange membrane fuel cell (HT-PEMFC) based on a phosphoric acid doped polybenzimidazole (PBI) membrane. A fluid structure interaction (FSI) method is adopted to simulate the expansion/compression that arises in various components of a membrane electrode assembly (MEA) during the HT-PEMFC assembly processes, as well as during cell operations. First, three-dimensional (3-D) finite element method (FEM) simulations are conducted to predict the cell deformation during cell clamping. Then, a nonisothermal computational fluid dynamic (CFD)-based HT-PEMFC model developed in a previous study [1] is applied to the deformed cell geometry to estimate the key species and temperature distributions inside the cell. Finally, the temperature distributions obtained from these CFD simulations are employed as the input load for 3-D FEM simulations. The present numerical study provides a fundamental understanding of the stress-temperature interaction during HT-PEMFC operations and demonstrates that the coupled FEM/CFD HT-PEMFC model presented in this paper can be used as a useful tool for optimizing HT-PEMFC clamping and operating conditions.

An experimental and simulation study of novel channel designs for open-cathode high-temperature polymer electrolyte membrane fuel cells

Thomas, S.,Bates, A.,Park, S.,Sahu, A.K.,Lee, S.C.,Son, B.R.,Kim, J.G.,Lee, D.H. Applied Science Publishers 2016 APPLIED ENERGY Vol.165 No.-

<P>A minimum balance of plant (BOP) is desired for an open-cathode high temperature polymer electrolyte membrane (HTPEM) fuel cell to ensure low parasitic losses and a compact design. The advantage of an open-cathode system is the elimination of the coolant plate and incorporation of a blower for oxidant and coolant supply, which reduces the overall size of the stack, power losses, and results in a lower system volume. In the present study, we present unique designs for an open-cathode system which offers uniform temperature distribution with a minimum temperature gradient and a uniform flow distribution through each cell. Design studies were carried out to increase power density. An experimental and simulation approach was carried out to design the novel open-cathode system. Two unique parallel serpentine flow designs were developed to yield a low pressure drop and uniform flow distribution, one without pins and another with pins. A five-cell stack was fabricated in the lab based on the new design. Performance and flow distribution studies revealed better performance, uniform flow distribution, and a reduced temperature gradient across the stack; improving overall system efficiency. (C) 2015 Elsevier Ltd. All rights reserved.</P>

5kW급 고온 고분자연료전지 스택 실증 연구

최민구,김민진,손영준,김승곤,김지홍,이성근,정재훈,이하늘 한국에너지학회 2019 한국에너지공학회 학술발표회 Vol.2019 No.10

Electrodeposition-fabricated PtCu-alloy cathode catalysts for high-temperature proton exchange membrane fuel cells

박현주,김경민,김호영,김동권,원용선,김수길 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.7

Pt electrocatalysts in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) containing phosphoric acid (PA)-doped polymer membranes are prone to poisoning by leaked PA. We performed a preliminary density functional theory (DFT) study to investigate the relationship between the electronic structure of Pt surfaces and their adsorption of PA. Excess charge on Pt was found to weaken its bonding with the oxygen in PA, thus presenting a strategy for the fabrication of PA-resistant catalyst materials. Consequently, PtCu-alloy catalysts with various compositions were prepared by electrodeposition. The morphologies and crystalline structures of the alloys were strongly dependent on alloy composition. Moreover, the Pt atoms in the PtCu-alloy catalysts were found to be in an electronrich state, similar to that of the excessively charged Pt simulated in the DFT study. As a result, the oxygen reduction reaction activities of the PtCu-alloy catalysts were superior to that of a Pt-only catalyst, regardless of the presence of PA. In the absence of PA, the higher activity of the PtCu-alloy catalysts was ascribable to conventional alloying effects, while the increased activity in the presence of PA was largely due to the enhanced resistance to PA poisoning. Therefore, PtCu-alloy catalysts easily prepared by electrodeposition were found to be strong candidate materials for HT-PEMFC electrodes.

A Study on Improvement of Performance and Durability based on the 5kW High-Temperature PEMFC Stack Demonstration

Min-goo CHOI(최민구),Minjin KIM(김민진),Young-Jun SOHN(손영준),Seung-Gon KIM(김승곤),Ji-Hong KIM(김지홍),Sungkun LEE(이성근),Jae-Hoon JEONG(정재훈),Haneul LEE(이하늘) 한국신재생에너지학회 2019 한국신재생에너지학회 학술대회논문집 Vol.2019 No.11

Numerical analysis of a high-temperature proton exchange membrane fuel cell under humidified operation with stepwise reactant supply

Kim, H.S.,Jeon, S.W.,Cha, D.,Kim, Y. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.31

<P>Dynamic response is a very important issue in a vehicle powered by a proton exchange membrane fuel cell (PEMFC) due to its frequent load change. In this study, three-dimensional transient simulation was conducted to investigate the dynamic response of a high temperature PEMFC. A stepwise change in the cell voltage was conducted to simulate the sudden load change during vehicle operation. After the load change, the oxygen concentration, ionic conductivity, and local current density were analyzed, and the water transport through the membrane electrode assembly (MEA) was also evaluated to determine the characteristics of overshoot and settling time. The result showed that the overshoot was mainly due to the pre-existing excessive oxygen. At the humidified condition, the overshoot increased with increasing relative humidity due to higher ionic conductivity and electrochemical reaction rate. In addition, a stepwise mass flow control strategy for the reactants decreased the overshoot and settling time by decreasing the amount of oversupplied oxygen immediately after the load change. The settling time for the stepwise mass flow control was approximately 30% lower than that for the constant mass flow rate control. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</P>

건물용 연료전지 발전 고온 PEMFC 기술 현황 및 전망

조장호 ( Jang Ho Jo ) 한국공업화학회 2011 공업화학전망 Vol.14 No.2

최근 시장 진입기에 들어선 연료전지는 가격과 신뢰성 문제로 도전받고 있다. 이러한 상황에 대한 해결책으로 주목 받기 시작한 기술이 바로 고온 PEMFC이다. 이 기술은 전해질 막의 프로톤 전도 메커니즘이 물에 의존하지 않아 가습기가 필요 없고, 높은 운전 온도로 인해 CO에 대한 내성이 강해 단순한 시스템 구성이 가능하여, 연료전지의 가격과 신뢰도를 크게 향상시킬 수 있을 것으로 기대되고 있다. 본 고에서는 이러한 고온 PEMFC의 기술적 특징을 자세히 살펴보고, 국내외 기술 현황 및 그 전망에 대해 살펴보고자 한다.

X+-β”-aluminas /Nafion (X = H3O, NH4) hybrid membranes for high-temperature PEMFCs

Seok-Jun Kim,Hee-Min Kim,Jung-Rim Haw,Seung-Gyun Kim,Min-Ho Jang,유영태,임성기 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.2

Hybrid membranes as an electrolyte for high-temperature proton exchange membrane fuel cells (PEMFCs) were prepared from a Nafion polymer matrix with NH4 + /H3O+-β”-aluminas as an inorganic filler that has fast proton conductivity. The membranes, containing 5-20 wt% of filler, were obtained with a fairly uniform thickness of about 80 μm. The properties of the hybrid membranes - such as thermal stability, water uptake, proton conductivity, methanol crossover, and proton selectivity - were measured in the 25-120℃ temperature range and compared to those of Nafion®. The hybrid membranes became more thermally stable, showing a mere 2 wt% of water loss at 120℃; they also had advantages over Nafion® in terms of water uptake, methanol crossover, and selectivity. The proton conductivities of the hybrid membranes generally lowered compared to Nafion®; however, they were maintained sufficiently for an electrolyte, representing 1.6 × 10−1 and 1.8 × 10−1 S/cm at 100 and 120℃ in the H3O+-β”-aluminas/Nafion® hybrid membrane, respectively.