Bi0.7Sr0.3(Fe, Ni)O3-δ perovskite covered by self-assembled dual-phase ferrites as high-performance cathode for intermediate-temperature solid oxide fuel cells

Bi1-xSrxFeO3-delta (BSFO), a novel Co-free perovskite with advantages of low thermal expansion coefficient and good catalytic activity, suffers from poor electronic conductivity and undesirable chromium-poisoning for the application in solid oxide fuel cells (SOFCs). In this paper, high performance Bi0.7Sr0.3(Fe, Ni)O3-delta cathodes modified by self-assembled dual-phase ferrites Bi2Fe4O9 and NiFe2O4 were fabricated by a simple Ni doping method. The comprehensive properties consisting of electronic conductivity, anti-chromium ability, and oxygen reduction reaction (ORR) activity all were dramatically enhanced. The electronic conductivity (2.32 S cm(-1) @700 degrees C) of Ni doped samples is about 1.8 times higher than that of BSFO (1.24 S cm(-1)@700 degrees C). The polarization resistance retains nearly no change under the Cr-treatment condition, which is mainly due to higher Cr2O3 adsorption energies by assembled dual-phase ferrites confirmed by the DFT calculation. The optimized polarization resistance (R-p) is 0.19 Omega cm(2) at 700 degrees C, only 25 % of that of BSFO (0.76 Omega cm(2) at 700 degrees C). The single cell with modified cathodes using wet H-2 as fuels shows a maximum power density (P-max) of 715.89 mW cm(-2) at 700 degrees C, and a stable output maintaining for 50 h without evident degradation.