| 摘要: | 為改善陽極材料在長時間操作時所遭遇之電極與電解質間脫層、翹曲及陽極因使用混和氣體所造成積碳之問題，本研究提出使用合金觸媒(Ni1-xMx, M=Fe, Co)取代金屬鎳作為陽極之觸媒材料，開發高性能質子傳輸型固態氧化物燃料電池之陽極。質子傳導基材將使用甚具前景之BaCeO3系列，配比為Ba(Ce0.6Zr0.2Y0.2)O3，進行合金陽極之製備，並探討不同合金及比例的陽極特性及其對電池性能之影響。為了降低歐姆阻抗，提升電池性能，陽極支撐型固態氧化物燃料電池已成為未來之趨勢。但因陽極需具備多孔性以利氫氣擴散與進行氧化反應，故機械強度較弱。目前陽極支撐型固態氧化物燃料電池所遭遇之瓶頸為長時間操作下之穩定性不佳，其主因亦為多孔陽極所致，於長時間操作後，相較於電解質與陰極，易先產生質變(體積膨脹、相變化等不利於陽極材料之因素)。由於合金觸媒具備：(1)可降低氧化鎳與電解質粉末之間的不匹配性；(2)可增加觸媒催化活性；(3)抑制積碳現象產生；(4)高抗氧化性等優點。故本計畫將利用合金觸媒優異之材料特性取代金屬鎳作為陽極之觸媒材料，希望開發出具高電子/質子導性、高穩定性與良好氣體擴散通路之陽極材料。並嘗試利用聚焦離子束三維重構技術解析陽極合金材料三相點密度及分佈。本計畫首年將進行鎳鐵及鎳鈷合金材料之製備，並進行導電性、催化活性、熱膨脹係數與微結構等基本物理化學性能之綜合評估。次年將針對不同比例之鎳鐵及鎳鈷合金之系統，進行熱循環與混合氣體化學穩定性之測試，並優化陽極合金材料系統。第三年則將優化後之陽極合金材料系統進行陽極支撐型半電池製備與性能測試，並搭配交流阻抗分析儀釐清新型合金陽極與傳統陽極之差異，且進行長時間電池性能測試(燃料：氫氣與混合氣體)。亦會探討新型合金陽極測試前後之材料特性、微結構及機械性質之變化。 ;The aim of this project is to develop high performance anode materials for Proton conducting solid oxide fuel cell (P-SOFC). During practical operation, the anode material of a SOFC suffers from the delamination and warping between the metallic catalysts and the ceramic electrolyte. In addition, carbon may deposits on the electrode when using syngas. We propose a bimetallic alloy (Ni1-xMx; M=Fe, Co) to replace nickel (Ni) in the anode. Ba(Ce0.6Zr0.2Y0.2)O3 will be used as the protonic conductor. We will investigate the effects of different alloying ratios of the bimetallic alloy coupled with Ba(Ce0.6Zr0.2Y0.2)O3 perovskite ceramic structure on the cell performance. To reduce the ohmic resistance and improve the cell performance, the anode-supported cell (ASC) type has become an emphasis. Anode needs to be porous so that hydrogen can diffuse and facilitate oxidation reaction. The mechanical strength is therefore usually weak. At present, the bottleneck of ASC type P-SOFC is poor stability. The main reason for poor stability is due to the porous anode. Compared to electrolyte-supported cell (ESC) and cathode-supported cell (CSC), the anode of ASC is more prone to volume expansion and phase change. The alloy (Ni1-xMx) has several advantages over Ni alone. (1) Reduce the mismatch between nickel oxide (NiO) and ceramic electrolyte. (2) Increase the catalytic activity. (3) Inhibit the carbon deposition. (4) Higher oxidation resistance. Therefore, we will utilize these advantages of bimetallic alloy to develop high performance anode materials with high electron/proton conductivity, good stability and suitable gas transport channels. In addition, we will use FIB-SEM 3D reconstruction to analyze the density and distribution of three-phase boundary.In the first year, nickel-iron (NiFe) and nickel-cobalt (NiCo) alloy anode materials with various ratios will be synthesized. The physical and chemical properties (conductivity, catalytic activity, thermal expansion and microstructure) will be studied. In the second year, the thermal cycling and syngas chemical stabilities of NiFe and NiCo anode materials will be investigated. In the final year, the optimized anode alloy materials will be assembled to test the ASC half-cell performance, investigate the difference between alloy anode and traditional anode by AC impedance spectroscopy and study the long-term cell performance (fuel: hydrogen and syngas). In addition, we will also investigate the changes in the material properties, microstructure and mechanical properties of anode material before and after long-term cell performance test. |
