Highly Functional And Effective Ceramic Coatings For Solid Oxide Cell (SOC) Interconnects

국문 초록 (Abstract)

고체산화물 연료전지(SOFC)와 고체산화물 수전해전지(SOEC)의 주요한 부품인 금속 분리판은 단전지를 전기적으로 연결하고 인접한 전지에 공급되는 연료와 산소(공기)를 분리하는 역할을 한다. 일반적으로 표면 안정성을 개선하 고 산화극의 Cr 피독을 완화하기 위해 Ferrite 계 소재의 Fe-Cr 분리판 표면을 Spinel 계 전도성 산화물로 보호 코팅하여 사용한다. 본 논문에서는 효과적인 금속 분리판 보호 코팅 공정과 소재에 대한 연구를 통해 이러한 문제를 해결 하고자 한다. 먼저, 대표 보호 코팅 소재인 Mn-Co 스피넬을 신규 기법인 화학 적 보조 전착법(CAED)으로 제작하여 모수 조절을 통한 최적화 연구와 시험법 을 통해 전기적 성능과 내구성을 검증한다. 나아가, CAED 최적화 연구를 효과 적으로 활용하기 위해 막 접착력 향상과 장기 내구성 강화를 목적으로 Cu 전 기 도금 피막을 버퍼층으로 적용한 하이브리드 코팅 방법을 제안하고 성능 평 가를 통해 코팅 소재와 방법의 우수함을 입증한다. 후반부에는 이와 더불어 튜 브타입 및 세그먼트 타입 SOC용 세라믹 연결재 소재인 SLTM 페로브스카이트 코팅막의 효율적인 제작 방법도 제시한다. 주요단어(Key words) : 고체산화물셀, SOC 연결재, 금속 분리판, 보호 코팅, 도금, 화학보조 전기화학 코팅, 크롬피독 방지, 스피넬 산화층, 페로브스카이트

다국어 초록 (Multilingual Abstract)

High-temperature solid oxide cell (SOC) systems represent a significant approach to addressing global climate change, as they operate in reversible modes between solid oxide fuel cell (SOFC) and solid oxide water electrolyzer configurations. This versatility makes them an attractive option for the conversion and storage of renewable energy sources. However, high costs and limited lifespans are currently hindering the commercialization of SOCs. These challenges are in part related to the degradation of ferritic stainless steel interconnects as follows. One of the main challenges with ferritic stainless steel interconnects is the increase of electrical resistance due to the growth of chromia oxide scales, and the other one is poisoning of the SOFC cathode from Cr(VI) species vapor. This thesis investigates using protective spinel oxide coatings to alleviate these problems. It is widely accepted that coatings with a ceramic spinel base are highly effective in retarding the oxidation of ferritic stainless steel and providing low electrical resistivity. The first part of this thesis introduces a new method for applying an effective (Mn,Co)3O4 spinel protective coating, called Chemically Assisted Electrodeposition (CAED). A parametric study was conducted to identify the optimal conditions for the deposition of a (Mn,Co) 3O4 spinel coating on STS substrates in a more economical and efficient manner. The study employed a wet plating-based deposition method and involved the optimization of several key parameters. The results provide insights into the optimal conditions for effectively coating (Mn,Co) 3O4 spinel on STS substrates. Subsequently, the performance was validated through high-temperature and long-term tests. The further study proposed a two-step hybrid coating involving the deposition of a buffer layer by electroplating. This novel method enhances the durability and adhesion of the coating film. In addition, the final part presents innovative fabrication methods for ceramic interconnects used in non-planar SOCs. Key words : SOC(Solid Oxide Cells), SOC Interconnects, Metallic Interconnects, Protective Coating, Spinel Oxide, Cr Poisoning

목차 (Table of Contents)

• 1. Introduction
• 1.1. Research motivation
• 1.2. Thesis objectives
• 2. Literature review
• 2.1 SOC and global energy issues
• 2.2 SOFC
• 2.3 SOEC
• 2.4 SOC stacks
• 2.5. Interconnects
• 2.6. Technical challenges
• 2.7. Protective coatings for SOFC interconnects
• 2.7.1. Protective coatings materials
• 2.7.2. Protective layer deposition techniques
• 2.7.3. Drawbacks of coating techniques Interconnect
• 3. Parametric study for (Mn,Co)3O4 spinel prepared by CAED method for SOCs interconnects
• 3.1 Introduction
• 3.1.1. CAED technique for protective coating layer
• 3.2 Experimental
• 3.2.1. Preparation of coating layer
• 3.2.2. Characterization of coating film
• 3.2.3. Performance test
• 3.3. Results and discussion
• 3.3.1. Microstructure after coating preparation
• 3.3.2. Characterizations of optimized coating layer
• 3.3.3. Performance test
• 3.4. Conclusion
• 4. Investigation of a novel hybrid coating method of (Mn,Cu)3O4 spinel for high electrical conductivity and high durability SOFC metal interconnects protective film
• 4.1 Introduction
• 4.2 Experimental
• 4.2.1. Cu plating
• 4.2.2. CAED on Cu plating
• 4.2.3. Characterizations of coating layer
• 4.2.4 Performance test
• 4.3. Results and discussion
• 4.3.1. Microstructural analysis of Cu plating
• 4.3.2. Characterizations of coating layer
• 4.3.3. Performance test
• 4.4. Conclusion
• 5.Efficient and robust ceramic interconnects based on a mixed-cation perovskite for solid oxide fuel cells
• 5.1 Introduction
• 5.2 Experimental
• 5.2.1. Preparation of materials and IC films
• 5.2.2. Characterizations of materials and IC films
• 5.3. Results and discussion
• 5.3.1. Preparation of materials and IC films
• 5.3.2. Characterizations of coating layer
• 5.4. Conclusion
• 6.Summary and future recommendation