Chemically Stable Perovskites as Cathode Materials for Solid Oxide Fuel Cells: La‐Doped Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ

Abstract

Ba0.5Sr0.5Co0.8Fe0.2O(3-δ) (BSCF) has won tremendous attention as a cathode material for intermediate-temperature solid-oxide fuel cells (IT-SOFC) on the basis of its fast oxygen-ion transport properties. Nevertheless, wide application of BSCF is impeded by its phase instabilities at intermediate temperature. Here we report on a chemically stable SOFC cathode material, La0.5Ba0.25Sr0.25Co0.8Fe0.2O(3-δ) (LBSCF), prepared by strategic approaches using the Goldschmidt tolerance factor. The tolerance factors of LBSCF and BSCF indicate that the structure of the former has a smaller deformation of cubic symmetry than that of the latter. The electrical property and electrochemical performance of LBSCF are improved compared with those of BSCF. LBSCF also shows excellent chemical stability under air, a CO2-containg atmosphere, and low oxygen partial pressure while BSCF decomposed under the same conditions. Together with this excellent stability, LBSCF shows a power density of 0.81 W cm(-2) after 100 h, whereas 25 % degradation for BSCF is observed after 100 h.

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

“…[ 194,198,199 ] In particular, a wide variety of composite oxides derived from the fi rst three perovskite-type parent oxides have been extensively studied since the catalytic activity of these materials are determined primarily by the B-site cations while Ni-, Co-, and Fe-based oxides show good catalytic activity for ORR. [200][201][202] Fe-Doped LaNiO 3 Metal Oxides : The LaNiO 3 parent oxide itself possessed a competitive electrical conductivity up to 100 S cm −1 . [ 203 ] However, its phase stability was relatively poor at high temperature, for example, it was reported that LaNiO 3 decomposed to La 2 NiO 4 phase with K 2 NiF 4 -type lattice structure and NiO at elevated temperature.…”

The effect of calcium doping on the improvement of performance and durability in a layered perovskite cathode for intermediate-temperature solid oxide fuel cells

“…[1][2][3][4] Notwithstanding these bene-ts, the high operating temperature leads to a number of problems, including high cost, electrode sintering, interface reactions between cell components, and material compatibility challenges. [1][2][3][4] Notwithstanding these bene-ts, the high operating temperature leads to a number of problems, including high cost, electrode sintering, interface reactions between cell components, and material compatibility challenges.…”

Triple‐Conducting Layered Perovskites as Cathode Materials for Proton‐Conducting Solid Oxide Fuel Cells

“…The material is a very unique mixed ion conductor: it contains both protonic defects and oxide ion vacancies and allows rapid transport of both, resulting in high ionic conductivity (~0.01 S cm À1 in a humidified O 2 atmosphere). [25][26][27] On the contrary, for the reaction of protons and oxygen ions in H + -SOFC systems, oxygen ions should diffuse from the surface of MIECs to the interface between the proton conducting electrolyte and the MIEC cathode (Table 1, step 3). [9,24] Generally, mixed ionic (O 2À ) and electronic conductors (MIECs) have been selected as the cathode material for O 2Àconducting SOFC systems because of their excellent catalytic activities for the oxygen reduction reaction (ORR) through extension of the electrochemically active sites to the entire surface of the cathode.…”