Scandium-doped PrBaCo_2?xSc_xO_6?¦Ä oxides as cathode material for intermediate-temperature solid oxide fuel cells

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• 作者：Xiangnan Li ; Xuening Jiang ; Hongxia Xu ; Qiuli Xu ; Lei Jiang ; Yuchao Shi ; Qingyu Zhang
• 关键词：Cathode ; Sc3+ doping ; Oxygen content ; Structure ; Thermal expansion ; Performance
• 刊名：International Journal of Hydrogen Energy
• 出版年：2013
• 出版时间：10 September, 2013
• 年：2013
• 卷：38
• 期：27
• 页码：12035-12042
• 全文大小：1837 K

文摘

Scandium-doped PrBaCo_2?xSc_xO_6?¦Ä(PBCS-x, x?=?0.00-1.00) oxides have been evaluated as cathode materials of intermediate-temperature solid oxide fuel cells (IT-SOFCs) with respect to phase structure, oxygen content, thermal expansion behavior and electrical and electrochemical properties. The XRD results have demonstrated a phase transition in PBCS-x due to Sc³⁺ doping from tetragonal double-layered perovskite structure at x?=?0.00-0.20, bi-phase mixtures at x?=?0.30-0.40, to cubic perovskite structure at x?=?0.50-0.90. The oxygen contents (6-¦Ä) and average valences of cobalt ions in PBCS-x decrease with the higher Sc³⁺ content and increasing temperatures in air. Sc³⁺ doping has also led to decreased thermal expansion coefficients, lowered electrical conductivities and enhanced electrochemical reaction activities for PBCS-x characterized by decreased area-specific resistances (ASRs) and smaller reaction activation energies. Among the studied samples, the PBCS-0.50 oxide with Sc³⁺-doping content of x?=?0.50 exhibits the best electrochemical performance on Ce_0.9Gd_0.1O_1.95 electrolyte. Its ASR values range from 0.123?¦¸?cm² at 600?¡ãC to 0.022?¦¸?cm² at 750?¡ãC, which are much lower than the related cathode materials. These results have demonstrated that the PBCS-0.50 oxide is a promising cathode material for IT-SOFCs.