氧化铈纳米晶浸渍430L复合阳极的形貌控制及电化学性能研究

The novel metal-supported solid oxide fuel cells (MS-SOFCs) use porous alloys to support thin functional anode-electrolyte-cathode layers, and have gained increasing interest due to advantages over the common all-ceramic counterparts, including excellent structural robustness and stability, high tolerance toward rapid thermal cycling, easy stack assembling as well as low materials cost. Main barriers for the advancement of MS-SOFCs include nickel coarsening and metallic interdiffusion between the nickel anodes and the supporting alloys. This proposal is aimed at developing low-temperature metal-supported SOFCs based upon thin scandia-stabilized zirconia (SSZ) electrolytes. In particular, tri-layers of “porous 430L | dense SSZ | porous SSZ” will first be produced by laminating and co-firing three tape-cast green tapes. Nano-scale SmBa0.5Sr0.5Co2O5+δ (SBSCO) oxides will be selected as the cathode catalysts and impregnated into the porous SSZ scaffolds. Ceria nanocrystals with tunable sizes, well-defined crystal planes and specific shapes will be hydrothermally synthesized, and colloidally impregnated into the porous 430L scaffolds to produce Nano-CeO2@430L composite anodes. The detailed mechanisms for H2 or CO oxidation in the anodes will be explored using electrochemical impedance spectroscopy. Quantitative microscopy, spectroscopy, diffraction, as well as chemisorption and physisorption techniques will be used to characterize the microscopic features of the Nano-CeO2@430L composite anodes, such as pore structure, local chemistry, surface area, pore volume, pore size distribution, and adsorptive properties. The primary objective here is (1) correlate the electrochemical performances of the composite anodes with their three-dimensional pore structures, bulk transport of ionic and electronic defects, morphology, surface structures and catalytic properties of the ceria nano-scale catalysts. (2) optimize the composition, morphology and microstructure of the Nano-CeO2@430L composite anodes. (3) deliver low temperature metal-supported SOFCs that provide stable and high power densities at 400-600°C.

针对金属支撑固体氧化物燃料电池存在的阳极镍颗粒团聚和金属原子界面扩散等问题，本项目拟发展基于氧化钪稳定氧化锆(SSZ)薄膜电解质的低温金属支撑电池，采用“流延-层压-共烧结”技术制备“多孔430L|致密SSZ|多孔SSZ”基体，采用溶液浸渍技术在多孔SSZ内沉积阴极催化剂，采用水热法合成不同尺寸、形貌与暴露晶面的氧化铈纳米晶，并通过悬浮液浸渍技术沉积于多孔430L的孔内壁，形成Nano-CeO2@430L复合阳极，研究电池在400-600°C下的放电特性及稳定性。利用高温原位XRD和程序升温还原(TPR)研究H2、CO与氧化铈纳米晶的相互作用；构造对称阳极电池，采用交流阻抗谱研究H2、CO等燃料的电化学氧化过程。本项目将阐明氧化铈纳米晶的组成、尺寸、形貌与晶面、表面催化性质对复合阳极的电化学性能的影响，揭示电化学性能的稳定性与微结构演变之间的联系，为高强度和高性能阳极的设计提供实验依据。

课题采用水热法合成特定形貌的氧化铈基纳米晶，并通过悬浮液浸渍技术沉积于多孔骨架内壁，研究电池在400-600°C下的放电特性及稳定性。其中研究不同元素（钐、钆、镨、镍）对氧化铈纳米棒表面氧空位的影响，并考察其作为阳极材料的氢气氧化动力学过程。成功制备了Ce0.9Ni0.1O2-δ作为阳极催化剂的单电池，在600℃下的最大功率密度为820mW/cm-2，为高性能阳极的设计提供实验依据。