Ni-10Sc1CeSZ and Ni-YSZ Anode Supported Microtubular SOFCs. Electrochemical Characterization and Aging experiments.

摘要

This work describes the manufacture and characterization of anode supported microtubular SOFC′s (Solid Oxide Fuel Cells) and analyses the effect of substitution of the YSZ by the ScSZ. The cells consist on Ni-YSZ or Ni-10Sc1CeSZ anode tubes of 400μm wall-thickness and 2,4mm inner diameter, 10Sc1CeSZ electrolyte of 15-20μm thickness and LSM-YSZ composite as cathode. The microtubular anode supporting tubes are prepared by cold isostatic pressing. The deposition of thin layers of electrolyte and cathode are made by spray coating and dip coating respectively. The cells were electrochemically characterized with polarization curves and complex impedance measurements using 97 and 4.85% of H2, humidified at 3% as fuel gas in the anodic compartment and air in the cathodic one, at temperatures between 600-850oC. The results of complex impedance measurements show area specific resistances of 1 to 0.53 Ωcm~2 at temperatures between 750-850oC with polarization of 200mA·cm-2 and diluted hydrogen. The I-V measurements show maximum power densities of 0.5 and 0.65 W·cm~(-2) at temperatures between 800 and 850oC using 97% H2 humidified at 3%. A fast degradation of the electrical performance of Ni-10Sc1CeSZ/10Sc1CeSZ/LSM-YSZ microtubular cell is observed when operated above 850oC. The degradation results in an increase of the cell electrical resistance of about 50% after only 30min operation at 850oC and 97%H2- 3%H2O. The 10Sc1CeSZ phase transformation and the Ce~(4+)→Ce~_(3+) conversion during operation are studied using the Raman spectroscopy technique.