Study On Preparation And Performance Of Low Temperature Metal Support Solid Oxide Fuel Cells

Solid oxide fuel cells directly convert the chemical energy in fuel into electric energy,has many advantages such as high efficiency,zero pollution,high degree of modularity,sustainable use.It is known as the most promising green energy technology in the 21st century.The traditional SOFC mostly uses metal-ceramic?Ni-YSZ?as the support body.The disadvantages such as high material cost,poor structural mechanical properties,difficulty in achieving mechanical processing seriously restrict the commercialization of SOFC.With the low temperature of SOFC and the rapid development of thin-film preparation technology,the preparation process of SOFC is continuously moving towards high efficiency and high level,and the choice of raw materials for battery supports is more broader.The use of metal materials as the support for the SOFC not only improves the electrical conductivity and thermal conductivity of the anode,but also enables the battery to be started quickly,and it is also beneficial to improve the structural strength of the SOFC and improve the mechanical processing performance.In this paper,Ni_0.7Fe_0.3 alloy support SOFC are successfully fabricated by tape casting-screen printing-sintering-in-situ reduction process with NiO and Fe₂O₃,with Ni-GDC as anode,GDC as electrolyte,LSM-BSCF as cathode.The mechanical properties of the Ni_0.7Fe_0.3 alloy support,thermal matching with the battery module,and redox properties were studied.The support body with 10wt.%and 2wt.%pore-forming agent was tested for fracture strength using a coaxial ring force method.The fracture toughness of the battery was tested using the double twist method.The results showed that the fracture strength of the sintered support body was?33.41±0.55?MPa and?36.77±0.59?MPa,the fracture toughness was?8.75±0.41?MPa·m^1/2 and?9.64±0.37?MPa·m^1/2,and the fracture strength of the support after reductionwas?29.81±0.50?MPa and?32.61±0.60?MPa,fracture toughness was?11.05±0.34?MPa·m^1/2 and?13.21±0.4?MPa·m^1/2.The average CET of the Ni_0.7Fe_0.3 alloy support at the temperature of 400⁹00?was 14.8×10^-6 K^-1.It had good heat-matching performance with the anode?Ni-GDC?and electrolyte?GDC?of the battery,which was beneficial to the improvement battery structure stability.Electrochemical analysis of SOFC supported by Ni_0.7Fe_0.3 alloy showed that the maximum power density of the battery at 650?was 0.567 W·cm^-2 with wet H₂ as fuel.The analysis of corresponding impedance spectrum showed that the main factor of restricting the battery performance was polarization resistance;In the discharge test with a current density of400 mA·cm^-2,the battery operated stably for 60 h and the decay rate was about 0.63 mV·h^-1..After the MS-SOFC had 5 cycles of redox and three thermal cycles,the change of open circuit voltage was tiny,while the battery's maximum power density dropped much.