Evaluation of A-site deficient Sr_1−xSc_0.175Nb_0.025Co_0.8O_3−δ (x=0, 0.02, 0.05 and 0.1) perovskite cathodes for intermediate-temperature solid oxide fuel cells

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• 作者：Guihua Chen^a ; ¹ ; Jaka Sunarso^b ; ¹ ; Yong Wang^a ; ^c ; ^{wang_yong932@hotmail.com" class="auth_mail" title="E-mail the corresponding author} ; Changhua Ge^a ; Jianguo Yang^a ; Fengli Liang^d ; ^{fengli0912@nuaa.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：A. Powders ; solid state reaction ; E. Fuel cells ; E. Electrodes
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：15 August 2016
• 年：2016
• 卷：42
• 期：11
• 页码：12894-12900
• 全文大小：1911 K

文摘

This work strives to improve the performance of SrSc_0.175Nb_0.025Co_0.8O_3−δ (SSNC) cathode by introducing A-site cation deficiency up to 10 mol%. Three different Sr-deficient compositions, i.e., Sr_1−xSc_0.175Nb_0.025Co_0.8O_3−δ (S_1−xSNC, x=0.02, 0.05 and 0.1) including the non-deficient analogue, SSNC are prepared. Powder X-ray diffraction patterns indicate that the original cubic perovskite structure is retained. The thermal expansion coefficient between 50 °C and 900 °C increases progressively with increasing Sr deficiency, consistent with the “β-oxygen” release profiles trend. The electrical conductivities for SSNC, S_0.98SNC, S_0.95SNC and S_0.9SNC show a maximum-type profile against increasing temperature, i.e., semiconducting behavior followed by metallic behavior. Despite the consistent increase in the oxygen non-stoichiometry with increasing Sr deficiency, the oxygen reduction reaction performance increases in the order of SSNC, S_0.9SNC, S_0.98SNC and S_0.95SNC. That the highest oxygen reduction reaction (ORR) performance is demonstrated by S_0.95SNC indicates the trade-off between the increase in the concentration of oxygen vacancies and the formation of the phase impurities. At 650 °C, S_0.95SNC shows an area specific resistance of 0.017 Ω cm² (from symmetric cell test) and a peak power density of 1263 mW cm⁻² (from single fuel cell test on a Ni-Sm_0.2Ce_0.8O_1.9 (SDC) anode supported SDC electrolyte).