The Stability Of Ni-YSZ Anode In Solid Oxide Fuel Cells

Solid Oxide Fuel Cell(SOFC)is a new type of power generation device,which has the advantages of all-solid-state operation,safer and more reliable use,pollution-free products and high energy conversion efficiency,it has broad application prospects.The Ni-based anode of SOFC has many advantages,such as good catalytic activity for hydrogen,hydrocarbon and other fuels,and high electronic conductivity.Currently,Ni-YSZ is composed of metal Ni and yttria stabilized zirconia(YSZ)Metal-ceramic composite anode materials have been applied in practice.However,when the SOFC is actually used,the long-term operating stability of the Ni-based anode under certain working conditions is still an important issue that deserves attention.In this paper mainly studies the performance evolution of Ni-YSZ anode-supported batteries during startup and long-term operation,analyzes the effects of temperature,current density,and water pressure on the performance of Ni-YSZ anode during long-term operation,and explores the non-steady-state environment for Ni-YSZ.The influence of anode and cell operation,study the influence of reducing conditions on Ni-YSZ anode,combined with relaxation time distribution(DRT)technique for impedance spectroscopy analysis,and carry out the mechanism analysis of Ni-YSZ decline process.First,the company produced Ni-YSZ as the anode support,a dense YSZ membrane as the electrolyte,Gd0.1Ce0.9O1.95(GDC)as the cathode buffer layer,and La0.6Sr0.4Co0.2Fe0.8O3(LSCF)as the cathode,the Ni-YSZ | YSZ | GDC | LSCF full cell is packaged and tested.The discharge curves,chronopotential curves and AC impedance spectroscopy at different operating temperatures(750 ?,800 ?,850 ?)were tested separately.The influence of temperature on their performance during long-term operation was studied,and the mechanism analysis was conducted.The electrochemical performance during long-term discharge at different current densities was tested,and the effect of current density on its stability was explored.The microstructure of the Ni-YSZ anode after long-term operation of the anode in a 20% water pressure environment was explored.Studies have shown that when operating at higher temperatures,the cell output performance is higher,but the decline in long-term operation is faster;when the current density is greater,the output voltage is lower;the microstructure will change when operated in an environment containing 20% water Poor,because the higher the water pressure will lead to coarser Ni migration and Ni loss.Secondly,the influence on the performance of Ni-YSZ anode in an unsteady state was investigated.A four-wire system was used to measure the resistance of the Ni-YSZ anode sample in a reducing atmosphere;BET specific surface area and pore size tests were carried out on the reduced Ni-YSZ anode to investigate the effect of the Ni-YSZ anode on multiple temperature changes and multiple redox cycles.The impact of its conductivity.The effect of different reduction processes on the performance of Ni-YSZ was studied,the DC performance at different flow rates and different reduction temperatures was studied,and the effect of different reduction temperatures on the long-term operation of Ni-YSZ was investigated.The results of the study show that under an unstable environment(repeated changes in temperature and multiple redoxes)will cause a significant decline in cell performance;the reduction rate is faster and the anode performance is better at larger hydrogen flow rates;reduction at 700 ? The performance is better than 800 ?.Finally,the relaxation time distribution(DRT)data analysis of the Ni-YSZ anode impedance spectrum was carried out,the multi-peak fitting was performed on the DRT data,and the peak area was obtained to obtain the polarization impedance of each reaction zone.Through the calculation of the characteristic frequency and the impedance The difference analysis obtains the polarization impedance of the anode electrochemical reaction zone,and analyzes the change of the polarization impedance.Study the impedance spectroscopy at different temperatures and different voltages and analyze the differences.