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-δ cathodes is Sr segregation on the surface. In this paper, the high-entropy (La0.2Nd0.2Gd0.2Sr0.2Ba0.2)Co0.2Fe0.8O3-δ(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 °C for 2 h. The orthorhombic perovskite phase is still stable when the HE-LSCF oxide precursor powders are calcined at 1250 °C for 2 h. At 700 °C，the specific polarization resistance (Rasp) of the pristine HE-LSCF and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathodes is 0.71Ωcm2 and 0.57Ωcm2, 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 °C, Rasp at 700 °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 segregates on the LSCF cathode surface after being aged, but Sr segregation on the HE-LSCF cathode surface is hindered. The research results show that HE- LSCF will be a potential cathode material for the intermediate temperature solid oxide fuel cells.