One-step Synthesis of GDC-NiO-C Anode for IT SOFC with GNP Method

• Main Authors: Kuen-De Chen, 陳昆德
• Other Authors: Bing-Sheng Yu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/ym52y5

碩士 === 國立臺北科技大學 === 資源工程研究所 === 97 === CeO2 becomes a new choice for the anode and electrolyte materials for intermediate-temperature SOFC thanks to its substantial oxygen ionic conductivity in the intermediate temperature range of 600~800℃. As it takes a very high temperature and a long time to form a solid solution of GDC (gadolinia doped ceria) with solid state method, GNP (glycine nitrate process) was used as the major approach to synthesize GDC in this study. Furthermore, the Raman spectra of the GDC from GNP method showed distinct vibration modes of oxygen vacancies which were absent in the case of solid state method, indicating that it is more efficient to form GDC solid solution with GNP method, which only requires calcinations at 700℃ for 60 minutes. Moreover, it was observed that the lattice parameter increased with linear stability from 5.4053 Å to 5.4366 Å as Gd2O3 was doped into CeO2 up to 30mol%. The lattice parameter continued to rise to 5.4435 Å as the doping moved up to 40mol% while the previous stability was interrupted. On the other hand, we can synthesize GDC-NiO with one step GNP method to diminish the pollution and time cost thanks to the fairly low solubility of NiO-CeO2 system. Moreover, transmission electron microscopy can be used to observe the crystallinity before and after the addition of NiO. After dry press, calcination, and sintering, well-mixed, porous, and nano-sized GDC-NiO-C anode was synthesized with 47vol% porosity by adding cotton fiber into the precursor before combustion. The study further used BEI (backscattered electron image) to observe the NiO, CeO2, Gd2O3, and pore distribution, and conductive AFM (atomic force microscope) was used to help confirm the connection within the reduced anode substrate. When CuO was added into the anode substrate to prevent the carbon deposition with GNP method, graphite tube was observed to appear around anode powders after calcinations. Subsequent reduction, on the other hand, turned CuO+NiO into CuNi alloy, helping increase the conductivity and strength of the anode.