Long-Term Study of MIEC Cathodes for Intermediate Temperature Solid Oxide Fuel Cells

Abstract

The time-related change of anode supported single cell performance for intermediate temperature SOFC was evaluated continuously up to 700 hours of operation. For the first time, cathodic and anodic polarization losses were separated by high resolution impedance studies based on DRT analysis (distribution of relaxation times) followed by a CNLS fitting approach. The cathodic polarization resistance (15mΩcm2 at t = 11 h), by far the smallest part, could only be visualized in the relevant frequency range by well selected and adapted experimental parameters. Within 700h the cathode resistance increases by 400% (63mΩcm2 at t = 700 h) undergoing a nonlinear degradation rate which can not explained by microstructural changes but probably by compositional changes.