MICROSTRUCTURE, SINTERABILITY AND ELECTROCHEMICAL PROPERTIES OF A Sm-Sr-(Co,Fe,Ni)-O CATHODE SYSTEM FOR SOLID OXIDE FUEL CELLS

摘要

Samarium (Sm) is a rare earth material that shows promise for use in cathodes of intermediate temperature-operating solid oxide fuel cells (IT-SOFCs). Perovskite-structured oxide containing Sm has very attractive electrocatalytic properties, and spinel-structured oxide generally exhibits low thermal expansion, indicating its suitability for application as a SOFC cathode. In this paper, the characteristics of the various Sm-based oxide materials (Sm-Sr-(Co,Fe,Ni)-O) deposited on Sm_(0.2)Ce_(0.8)O_(1.9) (SDC) electrolyte pellets were investigated in terms of their microstructure, sinterability and electrochemical properties. The relationship between the composition and the sintering temperature was studied and discussed. Results show that the substitution of iron (Fe) and nickel (Ni) in Co-sites affects the sinterability, adhesion to the electrolyte and electrochemical activity, such that the different sintering temperatures for these compositions should be considered. The microstructure and sinterability of the cathodes were investigated using a scanning electron microscope (SEM). Area specific resistance (ASR) values for all cathode compositions were measured using AC electrochemical impedance spectroscopy (EIS).