本實驗主要在探討以Ni-YSZ奈米纖維改質之陶金陽極的製備與特性研究:以YSZ奈米纖維為骨架，浸鍍Ni(NO3)2•6H2O水溶液製備的陶金陽極，探討其不同參數製程所造成極化行為的原因。且在YSZ 奈米纖維電紡絲製備的影響參數與特性進行討論與研究。
本實驗所用之YSZ奈米纖維以電紡絲製備，為一種低成本多產量之製程方式，電紡絲牽涉到諸多影響因素，其中又以溶液黏度與外加電場為絕對因素，實驗結果顯示，在PVP濃度11.32wt% (乙醇重×25wt%) YSZ紡絲黏度為334 cps，電場為20 KV，下可紡出直徑均勻約40nm的YSZ纖維。而為搭配應用在SOFC的陽極上，必需預煆燒550℃/2h移除高分子，在1300℃/1h下與電解質燒結以達好的結晶性與燒結性。
為了解Ni(NO3)2•6H2O水溶液含浸YSZ奈米纖維的行為，以0.34M、0.68M、以及3M的濃度進行含浸測試其NiO分佈情形，以3M濃度較恰當，可達到NiO連續相的效果。另外，溶液pH值也影響Ni+之附著，YSZ擔體的IEP(isoelectric point)值為4.8，鍍液pH值必須高於4.8才利於陽離子(Ni+)的附著，本實驗鍍液pH值為5.4。
本實驗之Ni-YSZ奈米纖維陽極，控制兩個變因，一為不同鍍液濃度，另一變因為加入25 wt%的YSZ粉末，變成[75 wt%YSZ纖維+ 25 wt%YSZ粉末]混合擔體，總共三種陶金陽極組成分別為
(1)YSZ纖維乾式含浸濃度0.68M之硝酸鎳水溶液，以縮寫F0.68M表示。(2)2YSZ纖維乾式含浸濃度3M之硝酸鎳水溶液，以縮寫F3M表示。(3)75 wt% YSZ纖維 + 25 wt% YSZ粉末混合擔體濕式含浸3M之硝酸鎳水溶液，以FP3M表示。
由SEM觀察其微觀發現以濃度0.68M硝酸鎳水溶液含浸所得的NiO含量太少未達連續相，不足以將反應所得的電子傳導至外部迴路。而以較高濃度3M硝酸鎳水溶液所得之NiO已達連續相，但是經交流阻抗分析後發現，單純以YSZ纖維做擔體的陽極F3M在電荷轉移(charge transfer)上遭受很大的阻抗，而混合擔體的FP3M並未有此現象。再搭配SEM微觀之後推論電荷轉移阻抗很大的原因為
YSZ纖維與電解質之間的孔隙率太大，接合過少，造成在陽極/電解質界面處O2-的傳導路徑太少，因此遭遇到很大的電荷轉移阻抗，使得整體反應變差。反觀混合擔體的FP3M電荷轉移及整體阻抗皆較小許多。
塔弗曲線藉由過電位與電流密度的關係，在低電流部份通過電極的電流與活化過電位成線性關係。800℃下活化過電位
ηF0.68M >ηF3M ηFP3M。高電流部份可觀察限制電流密度，為降低濃度極化的指標。在相同的濃度過電位下(1.23V)，FP3M的反應電流最大，FP3M有最大的發電電流。
三種陶金陽極(半電池量測)的功率密度在800℃下以雙氣室(two chambers)，通以燃料5%H2，量測結果為F0.68M:17.6mW/cm2，F3M:23.5mW/cm2，FP3M:28.9mW/cm2。
結果顯示FP3M的半電池發電功率較另兩者佳，表示以硝酸鎳含浸YSZ纖維為陽極，與YSZ為電解質以及以氧化物為陰極的單電池而言，FP3M的製程可得較好的發電功率。

Processing and characterization of Ni-YSZ cermet anode powders replaced with Ni-YSZ nanofibers developed by impregnation method is mainly investigated in this thesis. The processing and characterization of electrospinning of YSZ fibers were also discussed.
In this experiment, YSZ nanofibers were fabricated by electrospinning process which is a low cost and plenty production method. Electrospinning was involved with many effective parameters in which viscosity of the solution and applied electric field are the absolute parameters.
The better result is achieved with PVP concentration of 11.32wt% (alcohol×25wt%), viscosity of the solution of 334cps, electric field of 20kV and YSZ fibers with diameter of 40nm. In order to combine nanofiber with SOFC anode, YSZ fibers are calcined at 550℃/2h to remove the polymer and final sintered at 1300℃/1h for good crystallinity and sinterability.
To understand the behavior of YSZ nanofibers and to check the distribution of NiO, the fibers are impregnated with Ni(NO3)2•6H2O solution of concentrations 0.34M, 0.68M and 3M. The concentration of 3M is found to be appropriate to get continue phase of NiO. Besides, the pH of the solution is also observed to effect the adhesion of Ni+. For better adhesion of Ni+, the PH of impregnating solution should be higher than IPE (isoelectric point)(4.8) of YSZ. Therefore in the present study, the PH of impregnating solution is taken as 5.4.
In the present study, anode made of Ni-YSZ nanofiber is controlled by two parameters, in which first one is changing the concentration of impregnating solution and the second one is adding 25 wt% YSZ powder to YSZ nanofibers to become [75 wt%YSZ fiber + 25 wt%YSZ powder] mixed composition. Three different compositions used to prepare anode are as follows:
(1) YSZ fiber dry impregnated by 0.68M nickel nitrate solution, denoted as F0.68M.
(2) YSZ fiber dry impregnated by 3M nickel nitrate solution, denoted as
F3M.
(3) The mixture of 75 wt% YSZ fiber + 25 wt% YSZ powder which is wet impregnated by 3M nickel nitrate solution, denoted as FP3M.
From the microstructure of NiO distribution in anode impregnated by 0.68M nickel nitrate solution, it was found that the content of NiO is too less to form the continue phase and hence can’t conduct the electrons to the outer circuit. The higher concentration of nickel nitrate solution(3M) was found to form the better continue phase. But after analyzing through AC impedance, it was found that pure YSZ fibers support F3M anode suffer to huge impedance for charge transfer. In comparison with mixed YSZ support, FP3M anode does not suffer to the above phenomenon. Combining the microstructure and impedance analysis, it reveals that the cause for huge impedance for charge transfer is due to high porosity of YSZ fibers and week adhesion between electrode and electrolyte. Moreover, the conducting path is too small at the anode/electrolyte interface and hence suffered to huge impedance for charge transfer and makes the reaction poor. In contrary to the mixed support anode, the impedance for charge transfer is less in FP3M.
Tafel curve indicates the linearity between the current passing through the anode and the activation overpotential. At 800℃, the activation overpotential sequence is found to be ηF0.68M > ηF3M ηFP3M. In the region of higher currents, we are able measure the limiting current density which is an indicator of the concentration overpotential. At the same concentration overpotential (1.23V), the reaction current of FP3M is the largest indicating that FP3M can generate larger currents.
The power densities measured for the three semi-cells at 800℃ are
F0.68M:17.6mW/cm2，F3M:23.5mW/cm2，FP3M:28.9mW/cm2. It is found that the performance of semi-cell with FP3M anode is better than other two cells, indicating the use of FP3M made of YSZ fiber by impregnation method as an anode in the fabrication of single cell with 8YSZ as electrolyte and cathode made of oxides for better performance.

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