Composite cathode for IT-SOFC: Sr-doped lanthanum cuprate and Gd-doped ceria

Abstract

Composite cathodes were synthesized via a citrate combustion method followed by an organic precipitation method. The cathodes were of K(2)NiF(4)-type crystal structure with x wt.% Ce(0.9)Gd(0.1)O(1.95) (CGO)-(100 - x) wt. % La(1.96)Sr(0.04)CuO(4+delta) (LSC), where x=0, 10, 20 and 30. The individual structural phases of the composite cathodes were characterized using a third-generation synchrotron source beamline powder X-ray diffractometer (XRD). The porous grain morphology of the CGO-LSC cathode composite for a symmetrical half-cell was determined from cross-sectional scanning electron microscopy images and elemental line profiles. The composite cathode was made of 20 wt.% CGO-80 wt.% LSC (CL20-80) and was coated onto a Ce(0.9)Gd(0.1)O(1.95) electrolyte. It showed the lowest area specific resistance (ASR) of 0.07 Omega cm(2) at 750 degrees C. An electrolyte-supported (300 mu m thick) single-cell configuration of CL20-80/CGO/Ni-CGO attained a maximum power density of 626 mW cm(-2) at 700 degrees C. The unique composite composition of CL20-80 demonstrates enhanced electrochemical performance and good chemical compatibility with the CGO electrolyte, as compared with the pure LSC (CLO-100) cathode for IT-SOFCs. (C) 2010 Elsevier B.V. All rights reserved.