本研究主要探討纖維(Fiber)結構運用於固態氧化物燃料電池(Solid Oxide Fuel Cell，SOFC)的纖維複合陰極。由於纖維具有更高的比表面積，可擴大有效的催化面積，使電極對氣體的催化能力提升，並利用交流阻抗分析儀來探討纖維複合陰極氧還原反應的極化損失，以及電化學反應，再搭配X-ray繞射分析儀分析晶體結構、掃描式顯微鏡來分析微觀結構。
利用靜電紡絲法(Electrospinning)製備釔穩定氧化鋯(8YSZ)纖維，藉由改變電紡的不同參數，如電場強度、高分子含量得到不同型貌的纖維。由實驗結果顯示，當電紡溶液的Polyvinyl pyrrolidone(PVP)含量為整體溶液的9.89 wt％、8YSZ離子濃度為15.04 wt％、電場強度為20 kV時，可得到直徑70 nm，且表面平滑連續的8YSZ纖維。
纖維具有高含量的高分子，因此利用熱重分析儀(Thermogravimetry Analysis，TGA)分析，發現當溫度為420℃時，就沒有重量的損失。並經由XRD分析得到燒結溫度超過1000℃，8YSZ纖維將有良好的成相性與結晶性，經由掃瞄式電子顯微鏡得知纖維直徑會隨著燒結溫度的增加而有所提升。
將製備的8YSZ纖維(電場20 kV、高分子濃度為9.89 wt％、8YSZ濃度為15.04 wt％)應用於固態氧化物燃料電池的陰極部份，8YSZ與La0.6Sr0.4Co0.2Fe0.8，(LSCF6428)粉末均勻混合後，配製成膠體後網印在8YSZ的電解質，並燒結不同溫度(1000、1050、1100、1150℃)。
經由掃瞄式電子顯微鏡觀察陰極微觀結構，得知隨著燒結溫度增加，電極的孔隙相對的減少，經由Sigmascan分析發現燒結溫度1000、1050、1100、1150℃的孔隙率分別為26.84％、32.31％、36.94％、44.32％，且由破斷面可看出明顯的孔隙梯度分佈，如此一來有助於氧氣進入電極參與反應。
利用AC交流阻抗分析不同燒結溫度之極化阻抗，當燒結溫度為1050℃時，有最小的極化阻抗(0.77 Ωcm2)，在阻抗值換算阿瑞尼士圖也顯示出纖維複合纖維擁有最小的活化能(1.11 eV)；鐵弗曲線也可看出在燒結溫度1050℃擁有最高的交換電流密度(141.46 mA/cm2)；極化曲線得知其曲線斜率最大，表示有好的氧氣還原反應，並與一般粉末的複合陰極比較後，發現運用纖維可提升電極之電化學反應。
最後量測一般複合陰極及纖維複合陰極單電池的發電效應，陽極使用傳統的Ni-8YSZ，燃料氣體使用40％H2，其功率密度分別為42.26 mW/cm2及46.66 mW/cm2，表示纖維取代粉末後可有效提升固態氧化物燃料電池有效能；另外，使用具高離子導的新型陽極(Ni-YMSZ)取代傳統陽極，並搭配纖維複合陰極，其功率密度提升至51.25 mW/cm2。

This research was focused on the electrospinning and cathode material, Investigation of electrospinning 8YSZ fiber and its application in SOFC composite cathode, fiber has appear several amazing characteristics such as very large surface area to volume ratio. Using fiber in the cathode to expand the effective catalysis area of cathode, and also improve dissolution ability of the electrode to oxygen. The cathode effect on polarization loss of cathode oxygen reduction reaction and electrical chemical reaction with electrochemical impedance spectroscopy. Tafel curve analysis was used to observe the performance of electrochemical reaction at the TPB’s and power density measurement was used to check the efficiency of the fuel cell.

8YSZ fibers were fabricated by electrospinning process which is a low cost production methode. Electrospinning was involved with many effective parameters. Viscosity of the solution and the applied voltage played a significant role to generate long and uniform size fibers. Electrospinning technique was adopted to produce 8YSZ fibers using PVP as solvent material. The best result is achieved with PVP concentration of 9.89 wt% and electric field of 20 kV to get smooth fibers. Fibers of average size of 70 nm were generated using electrospinning.

According to the statistics from Thermogravimetry Analysis(TGA), no weight loss above 600℃. Sintering temperature above 1000℃, 8YSZ fibers analyzed by XRD was Cubic phase. Scanning electron micrographs of the fibers sintered at various temperatures show increasing fiber size and length.

The mixture of 8YSZ fibers and La0.6Sr0.4Co0.2Fe0.8 powder(LSCF) at the ratio of 20:80 in weight percent were used to screen print on 8YSZ electrolyte. The bulks were sintered at different temperatures(1000, 1050, 1100 and 1150℃). Scanning electron micrographs of the cathode sintered at various temperatures show increasing fibers and LSCF grains size and decreasing porosity of cathode.

AC impedance analysis of electrolyte-supported half cell(LSCF-8YSZ fiber/8YSZ/Pt) , the least value of area specific resistance at sintering temperature of 1050℃, because this sintering temperature has more triple phase boundary(TPB) and the best porosity distribution. Moreover, the energy required to activate the electrochemical reaction is lower(1.11 eV) in the cathode sintered at 1050℃.

Exchange current density measured using Tafel curves and polarization curve(I vs.η curve) indicates that the electrochemical reaction is faster at sintering temperature of 1050℃.

Among the sintering temperature of LSCF-8YSZ fiber cathode, sintering temperature at 1050℃ performed the best because the cathode electrical impedance was quite low(0.77 Ωcm2) and the highest change current density(141.46 mA/cm2). Additionally the catalysis was significantly improved, due to the fastest Oxygen reduction reaction rate.

The efficiency of the single cell in converting the chemical energy in to electrical energy was estimated by measuring the power density using 40%H2+60N2(100 sccm) as fuel and air as oxidant. Using Ni-8YSZ as anode material, Ni-8YSZ/8YSZ/LSCF-8YSZ fibers single cell has shown the power density of 46.66 mW/cm2 at 800℃ which is much higher than Ni-8YSZ/8YSZ/LSCF-8YSZ powders. And to go though the single cell test with excellent ionic conductivity of the electrolyte materials Zr0.92Y0.155Mg0.005O2.0775(YMSZ) replaced 8YSZ powders of anode, Ni-YMSZ/8YSZ/LFCF-8YSZ fibers has shown higher power density of 51.26 mW/cm2 than traditional anode material.

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