A new (La0.2Nd0.2Gd0.2Sr0.2Ba0.2)Co0.2Fe0.8O3-δ high-entropy oxide cathode for intermediate temperature solid oxide fuel cell

The main degradation mechanism of La0.6Sr0.4Co0.2Fe0.8O3-delta cathodes is Sr segregation on the surface. In this paper, the high-entropy (La0.2Nd0.2Gd0.2Sr0.2Ba0.2)Co0.2Fe0.8O3-delta(HE-LSCF) oxide with perovskite-type is designed to improve the cathode stability. The orthorhombic perovskite phase with the space group of Pbnm(62) is obtained when the HE-LSCF oxide precursor powders are calcined at 800 degrees C for 2 h. The orthorhombic perovskite phase is still stable when the HE-LSCF oxide precursor powders are calcined at 1250 degrees C for 2 h. At 700 degrees C,the specific polarization resistance (Rasp) of the pristine HE-LSCF and La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) cathodes is 0.71 omega cm2 and 0.57 omega cm2, respectively. The electrode process related to the oxygen dissociation and the interfacial charge transfer involving atomic oxygen is the rate-determining step of the oxygen reduction reaction in HE-LSCF cathodes. After being aged for 200 h at 800 degrees C, Rasp at 700 degrees C of the LSCF and HE-LSCF electrodes increases by 122.8% and 5.6%,respectively. The SEM, EDS and XPS results show that Sr segre-gates on the LSCF cathode surface after being aged, but Sr segregation on the HE-LSCF cathode surface is hin-dered. The research results show that HE-LSCF will be a potential cathode material for the intermediate temperature solid oxide fuel cells.