銅基材料在固態燃料電池陽極端導電性、溫度感測及催化性質之研究

Abstract

燃料電池在使用碳氫燃料時，陽極的碳沉積和催化能力是兩個非常重要的研究項目。在最近的研究報告指出，鎳基陽極(NiO/YSZ)會與碳氫燃料反應，產生嚴重的碳沉積。故在本實驗中使用氧化銅來取代氧化鎳，以改善此現象。以固相法合成三種含銅、鎳及氧化鋯之陽極粉末。實驗中測試陽極催化前後滲透率，以證明樣品的積碳程度。半銅半鎳鋯(C50N50Z)陽極片在甲烷中具有良好的催化性質，且積碳速率較慢。在650 oC中溫燃料電池操作溫度下，C50N50Z的導電性為1503 Scm-1，可以將銅的高導電及溫度感測與催化功能結合，進行下面四種銅、銅鎳、銅基合金及鎳線(Cu, Cu11Ni, Cu-38Zn, Cu9Ni6Sn, Ni)之室溫及高溫導電性測試。銅在650 oC下的導電性最優，足以作為電流收集的材料。由上述線材製作的五種熱電偶在 200 oC~650 oC進行長時間 (>100小時) 測試，檢視熱電位的靈敏度及飄移量的要求，Cu-Cu11Ni, Cu-Cu9Ni6Sn和Cu-Ni三種熱電偶可在中溫型固態燃料電池中做為溫度感測器。因此，在燃料電池陽極端，銅基材料可以同時具有催化、溫度感測以及當作電流收集層等三種功能。

Carbon deposition and catalytic ability of anodes are two important issues when using hydro-carbon fuels for solid oxide fuel cells. Nickel based anode (NiO/YSZ) shows a serious carbon deposition reported in recent research. Therefore, CuO is added to replace the NiO. In this study, three anode powders (100%Ni with 8YSZ, 50%Cu-50%Ni with 8YSZ and 100%Cu with 8YSZ) are prepared by powder mixing in well-dispersed slurry. A new approach to verify the effects of carbon deposition by measuring the permeability of the anodes are used in this study. C50N50Z shows a good catalytic ability and low coking rate for CH4. The conductivity of C50N50Z is 1503 Scm-1 at 650 oC. Another two functions of copper can be combined with this anode. Four copper-based metal and nickel wires (Cu, Cu11Ni, Cu-38Zn, Cu9Ni6Sn, Ni) are tested for their electric conductivity at room to high temperature. Due to a high electric conductivity, Cu is good enough to apply as a material for current collector. Five different thermocouples made from above wires are also aging in air for more than 100 h at 200 oC~650 oC. Because of sensibility and less drift (<5%) of thermopotential at 200 oC to 650 oC, three thermocouples Cu-Cu11Ni, Cu-Cu9Ni6Sn and Cu-Ni are suitable for intermediate-temperature SOFC as temperature sensors. Thus, triple function of Cu-based materials can be applied on anode side of SOFCs.