Improved Durability of High-Performance Intermediate-Temperature Solid Oxide Fuel Cells with a Ba-Doped La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ Cathode

Abstract

As a device for direct conversion of chemical energy into electrical energy, the solid oxide fuel cell (SOFC) contributes positively to the sustainable development strategy. However, the commercialization of fuel cells is still impeded by severe cathode degradation caused by its limited stability at operating temperatures and being prone to Cr-poisoning from Cr-containing alloy interconnectors commonly used in these cells. This paper reports the development of a high-durability Ba-doped LSCF(La0.6Sr0.4Co0.2Fe0.8O3−δ) cathode material under realistic fuel cell operating conditions in the presence of the Cr alloy. In particular, when tested in a symmetrical cell constructed of Ba-doped LSCF, the polarization resistance of the cell remains very low at 0.06 Ω cm2 after being tested at 800 °C for 120 h exposed to Cr in 3% humidified air. In contrast, for the undoped LSCF under the same testing conditions, the polarization resistance of the cell increases ∼10 times from 0.22 Ω cm2 of the pristine cell to 2.18 Ω cm2 after Cr-exposure testing. Furthermore, when tested in an anode-supported complete cell as a cathode under typical SOFC operation conditions at 750 °C, the cell with the Ba-doped LSCF cathode displays significantly low degradation rates of 0.00056% h–1 (without Cr) and 0.00310% h–1 (with Cr); both are much lower than that of the cell using the undoped LSCF cathode (0.00124% h–1 without Cr and 0.01082% h–1 with Cr). This enhanced durability and Cr-tolerance exhibited by the Ba-doped LSCF cathode stem from its higher crystal structure stability and improved chemical resistance compared to undoped LSCF.