- 學位論文
La2NiO4+δ-LaNiO3複合陰極應用於中溫型固態氧化物燃料電池之研究
Properties and performance of La2NiO4+δ-LaNiO3 composite cathodes for intermediate temperature solid oxide fuel cells
摘要
本研究以固態合成法製備具類鈣鈦礦結構之陰極粉末，於陰極材料La2NiO4中添加不同重量比之LaNiO3形成La2NiO4-LaNiO3複合陰極，探討其物性及化學穩定性，期望開發出室溫至800°C其熱膨脹係數14 × 10-6 /K以下，導電率達100 S/cm以上，並符合陰極各項基本要求之最佳材料。結果顯示於La2NiO4中添加LaNiO3在燒結溫度1200°C下並不會發生反應生成新的相，並可大幅提升其導電性質，其中添加50 wt.%之樣品在600°C操作溫度下導電率可達156 S/cm，優於相關文獻上鎳酸鑭系化合物之最高導電率。此外，添加40 wt.%之LaNiO3複合陰極材料在燒附溫度1150°C下於750°C量測有最低的極化阻抗，顯示添加LaNiO3不僅可改善其電子傳導性也可提升其電化學性能，而其熱膨脹係數與電解質Ce0.8Sm0.2O1.9 (SDC20)之差異度皆在15%以下，說明La2NiO4-LaNiO3複合陰極為極有潛力之陰極材料應用於中溫型固態氧化物燃料電池。 本研究之複合陰極材料與電解質SDC20具有良好之化學穩定性，熱處理溫度達1000°C時並無兩者反應生成之二次相產生。
並列摘要
Composite cathodes of La2NiO4+δ-LaNiO3 were prepared for application in intermediate temperature solid oxide fuel cells (IT-SOFCs). La2NiO4+δ and LaNiO3 powders were synthesized by solid state reaction. The effect of composition on the electrical performance of the composite electrodes was studied. The addition of LaNiO3 into La2NiO4+δ increased the electrical conductivity remarkably. The composite cathodes with 50 wt.% LaNiO3 exhibited the highest electrical conductivity of 156 S/cm at 600°C in air. The composite electrode containing 40 wt.% LaNiO3 calcined at 1150°C exhibited the lowest polarization resistance at 700°C in air. The addition of LaNiO3 to La2NiO4+δ cathode reduced the polarization resistance and caused the electrical conductivity to increase with temperature. The corresponding electrical conductivity and thermal expansion mismatch with Ce0.8Sm0.2O1.9 (SDC20) basically satisfied the requirement for cathode material. Controlling the content of LaNiO3 in composite cathode can properly take advantage of LaNiO3 and La2NiO4+δ to achieve better electrical performance and La2NiO4+δ-LaNiO3 is a prospective cathode material for application in intermediate temperature solid oxide fuel cells. All the samples showed high chemical compatibility with electrolyte SDC20, even under the 1000°C thermal treatment.