| 摘要: | 本研究使用甘胺酸-硝酸鹽燃燒合成法製備奈米級粒徑之鈣鈦礦結晶結構La0.6Sr0.4Co0.8Fe0.2O3 (LSCF)、La0.6-xSr0.4BaxCo0.8Fe0.2O3 (標示為x=0.13；LSB1CF、0.26；LSB2CF、0.39；LSB3CF)陰極粉末。經由調整LSCF前驅硝酸鹽水溶液之酸鹼值(pH值: 2、3、4、5)與甘胺酸-硝酸根比值(G/N比: 0.50、0.75、1.00、1.25)，觀察煆燒後粉末之結晶結構與表面形貌，並對其材料熱性質、電化學性質進行探討；再以最佳燃燒法合成參數(pH值、G/N比)進行LSBxCF之合成，並分析其電化學性質。最後評估LSCF作為陰極骨架、LSBxCF作為浸潤材料，將兩者經由浸潤法製成複合式陰極應用於質子傳導型固態氧化物燃料電池陰極之可行性。在LSCF實驗結果所示，LSCF1.00/、LSCF1.00/4、LSCF1.25/3與LSCF1.25/4等樣品為所有燃燒法合成參數中，結晶結構與表面形貌最符合作為SOFC陰極之結果，其中LSCF1.25/3由雷射粒徑分析其平均粒徑為300nm；由熱膨脹(TMA)之分析可發現LSCF1.25/3與電解質BCZY之熱膨脹係數最為相近；由四點式直流電量測導電度，LSCF1.00/4之導電度可達3690 S/cm；而LSBxCF之實驗結果，在熱重損失(TGA)分析中可發現， LSB2CF有最高之氧空缺變化量；其半電池之電子傳導阻抗與氧離子轉移阻抗分別為0.24 Ωcm2與0.30 Ωcm2。LSCF1.25/3作為陰極骨架、LSB2CF作為浸潤材料將兩者結合製成陰極進行極化曲線測試，在700°C時浸潤之陰極最高功率密度為39.5 mW/cm2，未浸潤之陰極最高功率密度為23.7 mW/cm2，效率提升將近66.67 %，而浸潤之陰極其極化阻抗為1.06 Ωcm2，未浸潤之陰極其極化阻抗為3.21 Ωcm2，阻抗降低約66.9 %。;In this study, the nanostructured perovskite La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) and La0.6-xSr0.4BaxCo0.8Fe0.2O3 (note as x=0.13; LSB1CF, 0.26; LSB2CF, 0.39; LSB3CF) prepared by the glycine-nitrate combustion synthesis method were considered as a potential candidate for use as cathode in solid oxide fuel cells (SOFC) operated at intermediate-temperature. In the present work, combustion synthesis method was investigated by adjusting the pH of LSCF nitrate solution (pH=2, 3, 4, 5) and ratio between glycine and nitrate (G/N=0.50, 0.75, 1.00, 1.25). The crystal structure and morphology of the powders after calcining were analyzed and also its thermal properties and electrochemical characteristic were discussed. The optimal combustion synthesis parameters (pH and G/N) were used to synthesize the LSBxCF. Then the crystal structure and electrochemical properties were investigated. Finally, the feasibility for using as cathode in P-SOFC though combining LSCF as cathode backbone and LSBxCF as infiltrating material together by infiltration to fabricate a composite cathode was evaluated. The results of LSCF analysis showed that LSCF1.00/3, LSCF1.00/4, LSCF1.25/3 and LSCF1.25/4 were the optimal parameters for combustion synthesis whose crystal structure and morphology were the most suitable as cathode for SOFC. Among all, LSCF1.25/3 was analyzed that its average particle size around 300nm. For the measurement of thermal expansion coefficient (TMA), the coefficient of LSCF1.25/3 was about 11.8 × 10-6 K-1 which was the closest to that of electrolyte BCZY. In the results of four-probe DC conductivity measurement, LSCF1.00/4 had the highest conductivity near 3690 S/cm@550°C. For the thermosgravimetric analysis of LSBxCF, the results showed that the weight loss of La0.34Sr0.4Ba0.26Co0.8Fe0.2O3 (LSB2CF) was the biggest which indicated that LSB2CF provided the highest amount of oxygen vacancies in LSBxCF. Also, the resistance of electron conductivity and oxygen ion transfer for half-cell of LSB2CF was 0.24 Ωcm2 and 0.30 Ωcm2 respectively. Then, results of performance tests for the cell used LSCF as cathode backbone and LSB2CF as infiltrating material showed that the maximum power density of infiltrated cell was 39.5 mW/cm2 and pristine was 23.7 mW/cm2. The power density enhanced about 66.67 %. The polarization resistance of infiltrated cell was 1.06 Ωcm2 and pristine was 3.21 Ωcm2. The resistance reduced about 66.9 %. |
