本論文實驗量測棋盤式(pin-type)雙極板尺寸效應對固態氧化物燃料電池(solid oxide full cell, SOFC)性能之影響。採用單電池堆配合不同流道尺寸設計的Crofer-22-APU雙極板，藉此探討雙極板流道尺寸效應對電池性能及其物理化學反應機制和劣化程度的影響。量測方法有二，含單電池堆電壓-電流密度之極化曲線量測與電化學阻抗頻譜量測，所探討的尺寸參數包含：(1)雙極板格狀凸出物(pin)寬度與流道寬度之和(Wpitch = Wpin + Wchannel)和(2)Wpin與Wpitch 的比值( f = Wpin/Wpitch)。結果顯示，在相同實驗操作條件下，電池輸出功率密度會隨Wpitch值減少而增加，這是因為當Wpitch值減少時，電池反應氣體較易擴散至pin下方多孔性電極，進而減少電池濃度損失；相反地，電池輸出功率密度卻會隨f值減少而減少，這是由於當Wpin值小於3 mm時，濃度損失幾乎不會隨f 值減少而變化，但卻會使雙極板與電極間的接觸電阻大幅增加，進而使歐姆損失大幅增加。當單電池堆在負載電壓下(0.8 V、0.6 V)，我們發現極化阻抗可被大幅度地減少，而歐姆阻抗則幾乎沒有變化。綜合而論，在電池堆實際操作條件下，如何設計棋盤式流道尺寸使電池堆具有較低之歐姆阻抗為設計之首要，故我們找到優化流道尺寸為Wpitch = 4 mm和f = 0.66。此研究結果應有助於提升棋盤式SOFC電池性能及壽命。 This study aims to investigate the size effect of pin-type interconnectors on the performance of solid oxide fuel cell (SOFC). Using the SOFC single-cell stacks, we apply Crofer-22-APU pin-type interconnectors with various sizes to investigate the size effect on the cell performance and its corresponding physical and chemical reaction mechanisms as well as the related cell degradation. Two different measurements are carried out, including the voltage-current density polarization curves (PC) and the electrochemical impedance spectroscopy (EIS), which the key parameters for the study of the size effect are the interconnect pin width (Wpin), the channel width (Wchannel), the pitch width (Wpitch = Wpin+Wchannel), and a fraction ratio between Wpin and Wpitch (f = Wpin/Wpitch). Results show that the cell power density increases as values of Wpitch decrease, by which all other experimental conditions are kept constant. This power increase is because the reactants are more easier to diffuse into the porous electrode under the bottom of the pin when decreasing Wpitch, and thus the cell concentration losses can be reduced. On the other hand, the cell power density decreases with decreasing f. This is because when Wpin is smaller than 3 mm, the decrease of f has little influences on the concentration losses, but it has strong influence on the contact resistances between the interconnector and the electrode so that a significant increase of the ohmic losses is found. We found that the polarization resistance decreases under the load voltages (0.8 V and 0.6 V), while the ohmic resistance remains almost unchanged. Finally, a combination of Wpitch = 4 mm and f = 0.66 is proposed to obtain a better cell performance. These results should be useful for the improvement of cell performance and longevity of pin-type planar SOFCs.
