Preparation and Performance of Grade-layer Composite Cathode for SOFCs

The cathode on Ce_(0.8)Sm_(0.2)O_(1.9) (SDC) electrolyte was fabricated by a spray method.The composite phases in these materials of Sm_(0.5)Sr_(0.5)CoO_3(SSC)-Ce_(0.8)Sm_(0.2)O_(1.9)(SDC) were proved by X- ray diffraction.The microstructure shows that cathode contacts well with electrolyte and there are many pores in the cathode.The results of thermal expansion and resistance measurements show that thermal expansion coefficient increases with the increasing of SSC,whereas the resistance decreases. The results of electrochemical measurement show that the grade-layer composite cathode has better performance than single-layer SSC cathode.