Effects of Gd_(0.8)Ce_(0.2)O_(1.9-δ) coating with different thickness on electrochemical performance and long-term stability of La_(0.8)Sr_(0.2)Co_(0.2)Fe_(0.8) O_(3-δ) cathode in SOFCs

摘要

The commercialization of Solid oxide fuel cells (SOFCs) has always been limited by the poor catalytic activity and the severe degradation of cathode in the intermediate and low operating temperature. Here we report a Gd0.8Ce0.2O1.9-delta (GDC) coated La0.8Sr0.2Co0.2Fe0.8O3-delta (LSCF) composite cathode material, which can significantly improve the electrochemical performance and durability of LSCF cathode. The effects of different GDC coating thickness on the electrochemical performance and long-term working stability of LSCF cathode are investigated, and the optimal coating thickness is established. The polarization impedance of GDC coated LSCF (LSCF@GDC) cathode with 9 nm of GDC coating is 0.08 U cm(2) at 800 degrees C, which is only one quarter of that of the raw LSCF cathode, and the degradation rate of constant current polarization with 100 mA cm(-2) is only 0.42%/100 h at 700 degrees C, which is far less than that of the raw LSCF cathode. The X-ray photoelectron spectroscopy (XPS) results show that the degree of Sr segregation decreases with the increase of the thickness of the coated GDC layer. The potential LSCF@GDC composite material is expected to increase the operability of SOFCs and accelerate its commercialization. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.