| Solid oxide fuel cells (SOFCs) are solid-state electrochemical power generation device, it was concerned with some outstanding advantages such as efficient, clean, fuel adaptability, simple structure, stable operation and so on, and its application prospect were widely. But its high operating temperature lead to many problems, for example, interfacial diffusion of electrolyte and electrode, thermal expansion mismatch etc., reducing the efficiency and service life of SOFCs. Anode-supported SOFC structure was commonly used to improve that problem, the thickness of anode supporter was larger than electrolyte and cathode, so the electrochemical and physical properties of SOFC were decided by chemical composition and porous structure of anode to a great extent. For high-quality anode, it was extremely important to ensure a high electrochemical activity, high electrical conductivity and high mechanical strength, pore structure. One commonly method was adding pore-former to optimize anode microstructure, effective, sample and easy. But the types, particle size distribution and additive amount of pore-forming agent were particularly critical.This paper mainly analyzed and explored the following three aspects:explored the dependence of Bi2O3content on low-temperature sintering properties of NiO/YSZ(Y2O3stabilized ZrO2) without pore-former. Studied the influence of pore-forming agent on porous structure and properties of NiO/YSZ. Prepared YSZ electrolyte membrane by sol-gel method in one step.Bi2O3doping significantly improved the sintering performance of NiO/YSZ, and the best matching point of Bi2O3content and sintering temperature are:6wt%Bi2O3and1250℃. Under this point, linear shrinkage was19.12%, relative density reached93.41%, open porosity was3.28%, no internal crack propagation and surface cracks existed in the sample. Flexural strength reached71.96MPa, thermal shock was better than the sample which contains0wt%Bi2O3sintered in1400℃. This paper selected soluble starch, graphite and activated carbon as pore-forming agent. It is found that the more pore-forming agent is added, the larger the open porosity is. the smaller particle size of pore-forming agent is, the lower open porosity is. Pore-forming efficiency is decreasing from activated carbon, soluble starch to graphite. When the content of pore-forming agent was10wt%, the open porosity of activated carbon, soluble starch and graphite reached33.25%,27.03%and23.92%respectively. The open porosity of three pore-former after reduction increased about13%, all reached more than35%, meeting the demand of anode material applied in SOFC. Among the three pore-forming agents, porous structure of activated carbon was the best, the pores were mainly rod-shaped, distributed uniformly, crossed each other, connected well, and gas transmission efficiency of anode was higher. Compared NiO/YSZ ceramic without Bi2O3sintered in1400℃, we found that the bending strength of NiO/YSZ ceramic containing6wt%Bi2O3sintered in1250℃were basically the same, but resistance shock increased. Adding pore-former reduced the bending strength, but increased the resistance shock. When10wt%activated carbon was added, the bending strength reached24.91MPa, the cycle times of thermal shock reached12.Sol-gel method was used for preparing dense YSZ membrane on Si substrate, transparent spin-coating sol was prepared using Y(NO3)3-6H2O and ZrOCl2·8H2O as raw material, ethylene glycol monomethyl as solvent. The as-synthesized YSZ membrane was dense, homogeneous and no pinholes, cracks and other defects after sintering at1000℃. A1.3μm dense YSZ film could be deposited by single coating at2000rpm for30s. Electrolyte films and anode-supporter pre-sintered at1000℃matched better. Preparing YSZ film on Si substrate used the sol prepared with smaller concentration component, Preparing YSZ film on anode-supporter used the sol prepared with larger concentration component. |
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