Evolutionary Programming Based Approach for SOFC Cathode Characterization: A Case Study on Co-Free Mixed Conducting Perovskites

Abstract

Cobalt-free perovskites were investigated in this work, in order to find more economical and chemically stable materials to serve as cathodes for intermediate temperature solid oxide fuel cells. The electrochemical performance of Ba 0.5 Sr 0.5 Fe 0.91 Al 0.09 O 3-δ and Ba 0.5 Sr 0.5 Fe 0.8 Cu 0.2 O 3-δ with oxide ion conducting La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ and proton conducting Ba 0.5 Sr 0.5 Ce 0.6 Zr 0.2 Gd 0.1 Y 0.1 O 3-δ electrolytes was studied using nondestructive electrochemical impedance spectroscopy. The measured data was analyzed by impedance spectroscopy genetic programming (ISGP), which results in a unique model that requires no a-priori knowledge of the tested system. In-depth cathode operation mechanism is shown by finding the distribution function of relaxation times (DFRT) using ISGP. By monitoring the changes in the DFRT models at different temperatures, we are able to de-convolute the oxygen reduction reaction to its several polarization processes. Using our analysis approach, it is possible to gain additional information, which may be convoluted and therefore undetected in conventional impedance analysis.

Understanding of Oxygen Reduction Reaction on Perovskite-Type Ba0.5Sr0.5Fe0.91Al0.09O3-δ and Ba0.5Sr0.5Fe0.8Cu0.2O3-δ Using AC Impedance Spectroscopy Genetic Programming

“…DFRT plots (normalized by R pol ) at 600–825 °C of (a) BSFCu+LSGM, (b) BSFAl+LSGM, (c) BSFCu+BSCZGY, and (d) BSFAl+BSCZGY …”

“…Our approach is ideal for comparative studies, where a method to carefully screen different cathode and electrolyte assemblies is presented here, in order to find the optimal parameters of the systems in an objective and thorough manner. We further analyze and discuss the ORR performance of Co-free perovskite-type Ba 0.5 Sr 0.5 Fe 0.91 Al 0.09 O 3‑δ (BSFAl) and Ba 0.5 Sr 0.5 Fe 0.8 Cu 0.2 O 3‑δ (BSFCu) as IT-cathodes for LSGM and BSCZGY electrolytes in air, through combined electrochemical impedance spectroscopy and ISGP that were reported in conference proceedings. , …”

Oxygen Reduction Reaction Properties of Cobalt-Free Perovskites for SOFCs

“…Typically this value of capacitance is associated with charge transfer process between the electrode and electrolyte layer (13). Detailed analysis of the electrochemical performance of current symmetrical cells will further be investigated by impedance spectroscopy genetic programming (ISGP) (30). ORR performance of BSFCu-BSCZGY/BSCZGY/BSFCu-BSCZGY symmetrical is shown in Figure 4 c-d.…”