Hetero-Interfaces at Nanoscaled (La,Sr)CoO3-δ Thin-Film Cathodes Enhancing Oxygen Surface-Exchange Properties
Hetero-Interfaces at Nanoscaled (La,Sr)CoO3-δ Thin-Film Cathodes Enhancing Oxygen Surface-Exchange Properties
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DOI：
10.1149/2.017304jes
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发表时间：
2013-01-01
影响因子：
3.9
通讯作者：
Ivers-Tiffee, Ellen
中科院分区：
文献类型：
--
作者：
Hayd, Jan;Yokokawa, Harumi;Ivers-Tiffee, Ellen
在 400 至 600 摄氏度之间运行的微型固体氧化物燃料电池 (mu-SOFC) 需要定制的纳米级电解质和电极结构。先前提出了由金属有机沉积（MOD）衍生且具有纳米级微观结构的La0.6Sr0.4CoO3-delta（LSC）薄膜阴极，并表现出极低的面积比极化电阻（7 m Omega）。 cm(2) 在 600 摄氏度时增加至 1.9 Omega 。 cm(2)（400 摄氏度）。当然，纳米级的颗粒和孔隙至关重要，但这里首次提出了高性能的决定性因素。事实上，我们的 LSC 薄膜阴极表现出增强的氧表面交换性能，其 k* 值比（名义上）相同成分的块体高出 47 倍。 (La,Sr)(2)CoO4+/-delta 和 Co3O4 等第二相的存在导致了这种显着的改善，与 LSC 形成精细分散的异质界面。有趣的是，这些次生相在金属有机盐凝胶膜的低温分解过程中结晶出来。热力学计算表明，在有机物氧化过程中，必须存在低氧分压。在 La0.6Sr0.4CoO3-delta 中添加高达 10% 过量的 A 位（La、Sr）或 B 位（Co）的故意化学计量变化并没有带来进一步的有益效果。 (C) 2013 年电化学协会。 [DOI：10.1149/2.017304jes] 保留所有权利。
Miniature solid oxide fuel cells (mu-SOFCs) to be operated at temperatures between 400 and 600 degrees C require custom-tailored electrolyte and electrode structures on the nanoscale. La0.6Sr0.4CoO3-delta (LSC) thin-film cathodes derived by metal organic deposition (MOD) and with a nanoscaled microstructure were previously presented and exhibited an extremely low area specific polarization resistance of 7 m Omega . cm(2) at 600 degrees C, increasing to 1.9 Omega . cm(2) at 400 degrees C. Naturally, grains and pores at the nanoscale are essential, but the decisive aspect to high-performance is presented here for the first time. In fact, our LSC thin-film cathodes exhibit enhanced oxygen surface-exchange properties, with a k* value up to 47 times better than that of bulks of (nominally) equal composition. The presence of secondary phases such as (La,Sr)(2)CoO4+/-delta and Co3O4 leads to this significant improvement, forming finely dispersed hetero-interfaces with LSC. Interesting enough, these secondary phases crystallize out during a low-temperature decomposition of the metal organic sal-gel film. Thermodynamic calculations revealed that low oxygen partial pressures must prevail for this, which occur during the oxidation of the organics. Deliberate stoichiometry variations with up to 10 % A-site (La, Sr) or B-site (Co) excess added to La0.6Sr0.4CoO3-delta did not lead to further beneficial effects. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.017304jes] All rights reserved.