鐠、釓共摻雜之氧化鈰電解質於中溫固態氧化物燃料電池之研究

Abstract

本研究以Pechini法製備鐠、釓共摻雜的氧化鈰粉末，其化學式為Ce0.8Gd0.2-XPrXO2-δ(X=0.01-0.05) 作為中溫固態氧化物燃料電池(ITSOFC)的電解質。對所得粉末進行一系列性質探討，由粉末繞射儀結果說明，經煆燒700℃共摻镨、釓的氧化鈰有純相螢石結構和較釓摻雜氧化鈰（Ce0.8Gd0.2O2-δ）大的晶格常數。由Scherrer公式計算出的粒徑與從穿透式電子顯微鏡圖量測的粒徑大小一致。由掃描式電子顯微鏡圖和電解質相對密度計算可以說明镨摻雜有提高電解質密度的效果。镨、釓共摻雜的電解質材料的氧離子導電性與電解質相對密度和X射線光電子能譜O 1s譜圖中氧空位/晶格氧的的面積比率趨勢大致一致。其中Ce0.8Gd0.18Pr0.02O2-δ在700℃下有最高的氧離子導電性6.15 S/m 。以厚度20 μm的Ce0.8Gd0.18Pr0.02O2-δ作為電解質，La0.6Sr0.4Co0.2Fe0.8作為陰極，60％NiO - 40％Ce0.8Gd0.2O2-δ為陽極，利用共壓法製成陽極支撐的電池在700℃以160 mL/min的氫氣作為燃料和160 mL/min的氧氣作為氧化劑時，開路電壓為0.82 V，能量密度為0.739 W/cm2，其表現較以Ce0.8Gd0.2O2-δ為電解質的能量密度高 。

The Pr, Gd co-doped CeO2 powders with the chemical formula Ce0.8Gd0.2-XPrXO2 (X=0.01-0.05) were prepared by Pechini method and used as electrolyte material for intermediate temperature solid oxide fuel cell (ITSOFC). The XRD results showed that Pr, Gd co-doped CeO2 calcined at 700℃ had pure fluorite structure and slightly larger lattice parameters than Gd-doped CeO2 (Ce0.8Gd0.2O2-δ). The particle sizes calculated by Scherrer equation were in good agreement with those obtained from TEM images. The oxide ion conductivities of the co-doped materials were found to be directly proportional to the ratios of oxygen vacancies/lattice oxygen determined by the area ratios of O 1s XPS spectra. Among these co-doped materials, Ce0.8Gd0.18Pr0.02O2 gave the highest oxide ion conductivity (6.15 S/m at 700℃). The anode-supported single cell, fabricated by a simple co-pressing method using Ce0.8Gd0.18Pr0.02O2 of thickness of 20 μm as the electrolyte, La0.6Sr0.4Co0.2Fe0.8 as cathode, and 60%NiO-40%Ce0.8Gd0.2O2-δ as anode, gave a high power density of 0.739 W/cm2 and OCV of 0.82 V at 700℃ using 160 mL/min hydrogen as the fuel and 160 mL/min oxygen as the oxidant, and the single cell gave higher power density than that withCe0.8Gd0.2O2-δ as the electrolyte.