| 摘要: | 本研究透過在以燃燒合成法製作之鈣鈦礦結構La0.6-xSr0.4Co0.2Fe0.8O3陰極材料中摻雜鉍，形成La0.6-xSr0.4BixCo0.2Fe0.8O3-δ(X=0、0.1、0.2、0.3、0.4、0.5；分別標示為LSB1CF、LSB2CF、LSB3CF、LSB4CF、LSB5CF) ，以探討其作為質子傳導型固態燃料電池陰極材料的可行性。燃燒過程中經由調整LSCF前驅硝酸鹽水溶液之酸鹼值(pH值: 1、2、3、4)與甘胺酸-硝酸根比值(G/N比: 0.75、1.00、1.25、1.50)，觀察經1000 °C、2 h煆燒後粉末之結晶結構，再以最佳燃燒法合成參數(G/N比、pH值)進行LSBxCF之合成，並分析其電化學性質。在LSCF實驗結果所示，在LSCF1.25/3、LSCF1.25/4、LSCF1.50/3與LSCF1.50/4等樣品中，LSCF1.50/3為所有燃燒法合成參數中結晶結構最符合作為SOFC陰極之結果，故以此參數作為後續LSBxCF合成之燃燒參數。經X光晶體繞射分析LSBxCF陰極粉末可發現，因摻雜離子半徑較小之Bi3+進入A-site，所以出現整體特徵峰的 2θ 有變大之趨勢，並且在LSB4CF、LSB5CF中出現些微雜項，其餘之參數接並未出現雜項。由四點式直流電量測導電度，LSCF雖隨著Bi的摻雜會導致電子導電度下降，但同時質子導電度會從原本無法導通質子，而隨Bi摻雜量上升而有些微提升。LSB3CF之單電池在800°C時擁有最高功率密度358.4 mW cm-2，比LSCF單電池140.6 mW cm-2高了155%，以及最低極化阻抗0.09 Ω cm2，比LSCF單電池降低25%；並且分別在700°C和600°C下皆具有最高功率密度183.5 mW cm-2、134.3 mW cm-2。
本研究結果可知，LSB3CF陰極材料可有效提升質子在陰極中之傳導，在800 ℃操作溫度之電化學性能表現良好具有最高功率密度358.4 mW/cm2，並且在700°C及600°C下皆有最佳之電化學性能表現。
;In this study, the perovskite structure La0.6-xSr0.4Co0.2Fe0.8O3 cathode material made by the combustion synthesis method was doped with bismuth to form La0.6-xSr0.4BixCo0.2Fe0.8O3-δ(X=0 , 0.1, 0.2, 0.3, 0.4, 0.5; respectively marked as LSB1CF, LSB2CF, LSB3CF, LSB4CF) to explore its feasibility as a proton-conducting solid fuel cell cathode material. During the combustion process, the pH value (pH value: 1, 2, 3, 4) and the ratio of glycine-nitrate (G/N ratio: 0.75, 1.00, 1.25, 1.50) of the LSCF precursor nitrate aqueous solution were adjusted to observe After sintering at 1000°C for 2h, the crystalline structure of the powder is then synthesized with the best combustion method synthesis parameters (G/N ratio, pH value), and its electrochemical properties are analyzed. According to the LSCF experimental results, in the samples of LSCF 1.25/3, LSCF 1.25/4, LSCF 1.50/3 and LSCF 1.50/4, LSCF 1.50/3 is the most crystalline structure among all the combustion synthesis parameters. It conforms to the result of SOFC cathode, so this parameter is used as the combustion parameter for subsequent LSBxCF synthesis. Through X-ray crystal diffraction analysis of LSBxCF cathode powder, it can be found that the 2θ of the overall characteristic peak tends to become larger due to the smaller Bi3+ doped ion radius entering the A-site, and there are some minor miscellaneous items in LSB4CF and LSB5CF. The other parameter connections did not appear miscellaneous. The conductivity is measured by the four-point direct current electric quantity, LSCF will cause the electronic conductivity to decrease with the doping of Bi, but at the same time, the proton conductivity will never be able to conduct protons, and will slightly increase with the increase of the doping amount.. The LSB3CF single cell has the highest power density of 358.4 mW cm-2 at 800°C, which is 155% higher than the LSCF single cell 140.6 mW cm-2, and the lowest polarization impedance of 0.09 Ω cm2, which is 25% lower than the LSCF single cell; And it has the highest power density of 183.5 mW cm-2 and 134.3 mW cm-2 at 700°C and 600°C, respectively. The results of this study show that the LSB3CF cathode material can effectively enhance the conduction of protons in the cathode, and the electrochemical performance is good at the operating temperature of 800 ℃. It has the highest power density of 358.4 mW/cm2, and it has the highest power density at 700°C and 600°C. The best electrochemical performance. |
