La2NiO4+δ與LaNiO3及La3Ni2O7-δ化合物皆屬於Ruddlesden-Popper(RP)相之一種Lan+1NinO2n+1 (n=1,2,3…),La2NiO4+δ具有離子及電子混合導電性化合物,是中溫固態氧化物燃料電池(IT-SOFC)陰極材料的新的研究方向,而鈣鈦礦結構的LaNiO3則有良好的電子傳導性。本研究以燃燒合成法製備LaNiO3、La2NiO4+δ化合物,利用高溫煆燒1200°C 6小時後使LaNiO3形成La3Ni2O7-δ, La3Ni2O7-δ之製備一般須經由高溫長時效性的處理,而我們利用燃燒法具有降低煆燒溫度的特性及LaNiO3高溫敏感性,使LaNiO3可在1200°C 6小時後形成La3Ni2O7-δ。甘胺酸燃燒法分別製備出La2NiO4+δ與LaNiO3之多孔電極,在以莫耳混合比例經由球磨混合煆燒後形成具有La3Ni2O7-δ及La2NiO4+δ相之複合陰極,探討隨著LaNiO3之添加在溫度1200°C 6 h所造成的La3Ni2O7-δ相會對於陰極顯微結構及電化學性能的變化及影響,結果發現於La2NiO4+δ中添加LaNiO3在燒結溫度1200°C下形成的La3Ni2O7-δ可提升其導電性質,隨著La3Ni2O7-δ含量的增加在600~800°C之間陰極導電率皆有明顯上升。此外,添加50 mol%LaNiO3複合陰極材料在1200°C燒附溫度於750°C量測有最低的極化阻抗,說明La3Ni2O7-δ不僅可改善陰極電子傳導性也可提升其電化學性能。La2NiO4+δ陰極塊材在1200°C 6小時透過TEM分析發現為正方晶系Tetragonal,與煆燒粉末之結構比較無任何變化。利用Rietveld精算可發現La2NiO4+δ 煆燒1000°C晶格體積有微量的縮小,但在晶格內NiO6八面體晶格有變長之現象。
La2NiO4+δ and LaNiO3 compounds are belong to Ruddlesden-Popper series Lan+1NinO3n+1(n=1,2,3…). La2NiO4+δ have ionic conductivity and and LaNiO3 is a highly conductive oxide with a perovskite type structure. These properties can applying for on materials as cathodes for IT-SOFCs. La2NiO4+δ and LaNiO3 are porous powders that apply for cathodes of powders were prepared by glycine nitrate process(GNP). The study purpose is La3Ni2O7-δ and La2NiO4+δ compound for the affect of micro-structure and electrochemical performance of composite cathode at calcined 1200°C. The effect of composition on the electrical performance of the composite electrodes was studied. The addition of LaNiO3 into La2NiO4+δ increased the electrical conductivities because of the more La3Ni2O7-δ phase in composite cathode sample is depend on the content of LaNiO3. when composite electrode containing 50 mol% LaNiO3 calcined at 1200°C exhibited the lowest polarization resistance at 750°C in air. The addition of LaNiO3 to La2NiO4+δ cathode reduced the polarization resistance and made the electrical conductivity increasing with temperature.