보고서 정보
주관연구기관 |
한국과학기술연구원 Korea Institute Of Science and Technology |
연구책임자 |
김병국
|
참여연구자 |
유지행
,
Tatsuya Kawada
,
이종숙
,
김영철
,
심준형
,
신동욱
,
박준영
,
송선주
|
보고서유형 | 2단계보고서 |
발행국가 | 대한민국 |
언어 |
한국어
|
발행년월 | 2015-08 |
과제시작연도 |
2014 |
주관부처 |
미래창조과학부 Ministry of Science, ICT and Future Planning |
등록번호 |
TRKO201600018391 |
과제고유번호 |
1711014449 |
사업명 |
첨단융합기술개발 |
DB 구축일자 |
2017-09-20
|
키워드 |
프로톤 전도체.연료전지.PCFC.전해질.전극.페로브스카이트.결함화학.전자이온 혼합 전도체.나노 복합체.proton conductor.fuel cell.PCFC.electrolyte.electrode.perovskite.defect chemistry.mixed electronic ionic conductor.nano-composite.
|
DOI |
https://doi.org/10.23000/TRKO201600018391 |
초록
▼
본 과제에서는 PCFC 핵심 기술 개발을 위하여, 주관기관에서는 소재, 공정 및 단전지 기술, 1세부기관은 다종수송현상 규명, 2세부기관은 나노박막공정, 3세부기관은 신규 전해질소재 개발에 대한 연구를 수행함. 주관기관은 전해질의 소결도, 전기전도도 및 화학적 안정성을 향상시키고, 고안정성 음극 지지체 제작 공정을 개발하였으며, 양극의 반응기구 규명 및 전극 활성을 향상시키고, 고기능성 단전지를 제조하였음. 1세부기관은 벌크 다종수송현상을 모니터할 수 있는 방법을 개발하였고, 분극 양상을 dynamic하게 모니터할 수 있는 측정시스
본 과제에서는 PCFC 핵심 기술 개발을 위하여, 주관기관에서는 소재, 공정 및 단전지 기술, 1세부기관은 다종수송현상 규명, 2세부기관은 나노박막공정, 3세부기관은 신규 전해질소재 개발에 대한 연구를 수행함. 주관기관은 전해질의 소결도, 전기전도도 및 화학적 안정성을 향상시키고, 고안정성 음극 지지체 제작 공정을 개발하였으며, 양극의 반응기구 규명 및 전극 활성을 향상시키고, 고기능성 단전지를 제조하였음. 1세부기관은 벌크 다종수송현상을 모니터할 수 있는 방법을 개발하였고, 분극 양상을 dynamic하게 모니터할 수 있는 측정시스템을 개발하였으며, 물리적인 메커니즘이 반영된 패러미터로 온도와 주파수에 따른 분극 양상을 전면적으로 기술할 수 있게 하였음. 2세부기관은 대표적인 프로톤 세라믹 물질인 BZY, BCY, BZCY의 박막전해질 및 전극 제조기법을 확보하고, 향상된 성능과 안정성을 도모한 연료전지 플랫폼 개발에 대한 연구를 수행함.
3세부기관은 PCFC용 전해질의 성능향상을 위한 신규 조성을 도출하고, 도핑물질, 미세구조 제어 및 다양한 합성 방법에 따른 특성 평가 연구를 진행하였음.
Abstract
▼
III. Results and Discussion
○ Hub
In this project, the research has been focused on searching for advanced electrolyte materials and enhancing their sinterability, electrical conductivity and chemical stability, fabricating porous cermet anode supports, understanding the cathode reaction m
III. Results and Discussion
○ Hub
In this project, the research has been focused on searching for advanced electrolyte materials and enhancing their sinterability, electrical conductivity and chemical stability, fabricating porous cermet anode supports, understanding the cathode reaction mechanisms and improving the catalytic activity, obtaining thermomechanical and thermochemical stability of new materials, and developing the fabrication techniques for high performance PCFCs. In electrolyte development, BZY and BCY were considered as candidate materials, and their materials characteristics were examined. This enabled developing BCZY that has the strengths of both BZY and BCY. In addition, its electrical, electrochemical and thermo-mechanical properties were optimized by controlling fabrication conditions, composition ratios and dopant ratios. In case of BZY electrolyte, the high sintering temperature causes various problems related to the evaporation of Ba and segregation of secondary phases. In this research, techniques were developed to suppress Ba evaporation and sintering aids such as Zn, Cu, NiO, eutectic phase were employed to lower the sintering temperature and overcome the challenges related to high sintering temperatures.
Moreover, the bi-layer electrolyte composed of BZY and BCY was developed. BZY, which has good stability in reducing atmosphere, was used on the anode side and BCY, which possesses high performance, was employed on the cathode side.
In such case, BZY experiences compressive stress during sintering, which facilitates densification and significantly lowers the sintering temperatures. In electrode development, various materials and manufacturing techniques were evaluated, and a number of analysis techniques were developed to clarify the reaction mechanisms. The activity and stability of the electrodes were investigated using electrical conductivity relaxation, impedance spectroscopy, SIMS, in-situ XAS, and TGA, and the reaction mechanism of proton and electrode materials via kinetics studies. Based on this information, optimized composite cathode was selected. Using the knowledge obtained on the electrode and electrolyte, high performance PCFC was fabricated, and the maximum power density of 830mW/cm2 at 600oC was obtained.
○ Spoke 1
The systems for experimental studies are the representative perovskite proton conductors as BZY, BCY, SCYb and lanthan niobates with Sr, Ca dopants (LSN, LCN). High temperature van der Pauw method was developed and applied to a BZY20 disk sample densely prepared by reactive sintering with NiO. AC conductivity relaxation was applied on SCYb, BZY15, BCY5, BCY15. A new impedance spectroscopy employing complex dielectric functions in parallel circuits was developed to describe competently strongly frequency dispersive behavior of BZY15 and LSN. The giant grain boundary impedance was ascribed to the mixed conduction effect due to the selective blocking of protons at grain boundaries in BZY15 and to the Schottky barrier in LSN. Various proton conductors were examined at different oxygen activity and humidity as a function of temperature. A new impedance spectroscopy allows the direct and objective examination of the raw data in AC Arrhenius plots, admittance/capacitance Bode plots for the effects of the composition, atmosphere, sintering aids, and processing methods. The dynamic monitoring is also applied to model PCFCs of a Pt/BCY/Pt configuration. The humidity effects on I-V and the corresponding impedance were investigated.
Atomistic simulations were performed for the defect mobility, concentration, formation energy in bulk, grain boundary, and electrodes for the macroscale phenomena of conduction, diffusion, grain boundary resistance, and PCFC performance.
○ Spoke 2
Highly dense thin film electrolytes and porous electrodes optimized for thin electrolyte were successfully developed using PLD and ESSD techniques in a thickness range of ~μm.
Multi-layered hybrid electrolytes based on representative protonic ceramics, BCY, BZY and BCZY, were developed as electrolytes of free-standing micro PCFCs, and a novel electrolyte form with improved electrochemical performance and chemical stability was suggested in this research. For the successful fabrication and adoption of thin protonic ceramic electrolytes, novel electrodes with gradient and multi-layered structure were developed in this research. A various of novel protonic ceramic electrodes with bi-material gradient, single material gradient pore-, multi-layered thin film-, core-shell structures were developed for performance enhancement. High performance thin film PCFCs, the main objective in this research, were successfully fabricated with a chemically stable protonic ceramic material through microstructural and electrochemical optimization process. From the results in the current research, several ways to enhance performance and stability of PCFCs were suggested in relation of fuel cell structures and functional layers.
○ Spoke 3
Yttria doped barium zirconate (BZY) is chosen for the development of electrolytes in this study given its high bulk proton conductivity and phase stability against CO2. In order to improve sinterability of BZY, nanopowder synthesis techniques such as combustion, hydrothermal, and co-precipitation method were used, and sintering aids (such as CuO, NiO, ZnO, etc) were added. BZY and carbonates were mixed to enhance densification and proton conductivity.
Under various gas atmospheres, composite BZY/carbonate electrolytes have 1-2 orders in magnitude higher proton conductivity than pure BZY. The ionic conductivity of hybrid conductor was enhanced by mixing of proton-conducting electrolyte materials which have difference characteristics.
The effect of various dopants on the electrical conductivity was analyzed and the conductivity is found be in Mg > Ca > Sr > Ba order, both in unhumidified and humid air atmospheres. The variation in conductivity with different dopant cations is explained by dopant solubility and polarizability of the dopant cation. The durability test of ceria-based single cell was investigated by failure mode and effect analysis (FMEA) method. The optimum operating logics of fuel cells, which have slow kinetics of degradation rate, were developed by performance recovery phenomena in FMEA method.
Furthermore, appropriate FMEA method for PCFC was researched by our group and that was based on the results of ceria-based SOFC.
목차 Contents
- 표지 ... 1제 출 문 ... 2보고서 요약서 ... 3요 약 문 ... 4SUMMARY ... 12CONTENTS ... 21목차 ... 22제 1 장 연구개발과제의 개요 ... 23 제 1 절 연구개발의 경제적·산업적 중요성 ... 23 제 2 절 연구개발의 필요성 ... 24 제 3 절 연구개발의 목표 및 내용 ... 27제 2 장 국내외 기술 개발 현황 ... 38 제 1 절 해외 기술 개발 현황 ... 38 제 2 절 국내 연구개발 현황 ... 60제 3 장 연구개발수행 내용 및 결과 ... 63제 4 장 목표달성도 및 관련분야에의 기여도 ... 65 제 1 절 목표달성도 ... 65 제 2 절 관련분야에의 기여도 ... 73제 5 장 연구개발결과의 활용계획 ... 75제 6 장 연구개발과정에서 수집한 해외과학기술정보 ... 77제 7 장 참고문헌 ... 79끝페이지 ... 81
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