Exner Jörg, Pöpke Hendrik, Fuchs Franz-Martin, Kita Jaroslaw, Moos Ralf
Department of Functional Materials, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
SOFC Department, Kerafol Keramische Folien GmbH, Koppe-Platz 1, 92676 Eschenbach, Germany.
Materials (Basel). 2018 Oct 23;11(11):2072. doi: 10.3390/ma11112072.
Solid oxide fuel cells need a diffusion barrier layer to protect the zirconia-based electrolyte if a cobalt-containing cathode material like lanthanum strontium cobalt ferrite (LSCF) is used. This protective layer must prevent the direct contact and interdiffusion of both components while still retaining the oxygen ion transport. Gadolinium-doped ceria (GDC) meets these requirements. However, for a favorable cell performance, oxide ion conducting films that are thin yet dense are required. Films with a thickness in the sub-micrometer to micrometer range were produced by the dry room temperature spray-coating technique, aerosol deposition. Since commercially available GDC powders are usually optimized for the sintering of screen printed films or pressed bulk samples, their particle morphology is nanocrystalline with a high surface area that is not suitable for aerosol deposition. Therefore, different thermal and mechanical powder pretreatment procedures were investigated and linked to the morphology and integrity of the sprayed films. Only if a suitable pretreatment was conducted, dense and well-adhering GDC films were deposited. Otherwise, low-strength films were formed. The ionic conductivity of the resulting dense films was characterized by impedance spectroscopy between 300 °C and 1000 °C upon heating and cooling. A mild annealing occurred up to 900 °C during first heating that slightly increased the electric conductivity of GDC films formed by aerosol deposition.
如果使用诸如镧锶钴铁氧体（LSCF）之类的含钴阴极材料，固体氧化物燃料电池需要一个扩散阻挡层来保护基于氧化锆的电解质。该保护层必须防止两种组分直接接触和相互扩散，同时仍保持氧离子传输。钆掺杂二氧化铈（GDC）满足这些要求。然而，为了获得良好的电池性能，需要制备薄而致密的氧化物离子导电薄膜。通过干室温喷涂技术——气溶胶沉积法制备了厚度在亚微米到微米范围内的薄膜。由于市售的GDC粉末通常是针对丝网印刷薄膜或压制块状样品的烧结进行优化的，其颗粒形态为具有高表面积的纳米晶体，不适合气溶胶沉积。因此，研究了不同的热和机械粉末预处理程序，并将其与喷涂薄膜的形态和完整性联系起来。只有进行适当的预处理，才能沉积致密且附着力良好的GDC薄膜。否则，会形成强度低的薄膜。通过在300℃至1000℃之间加热和冷却时的阻抗谱对所得致密薄膜的离子电导率进行了表征。在第一次加热至900℃期间发生了温和的退火，这略微提高了通过气溶胶沉积形成的GDC薄膜的电导率。
