Designing Perovskite Oxides for Solid Oxide Fuel Cells

Abstract

Perovskite-type oxides with the general formula ABO 3 have been widely studied and are utilized in a large range of applications due to their tremendous versatility. In particular, the high stability of the perovskite structure compared to other crystal arrangements and its ability, given the correct selection of A and B cations, to maintain a large oxygen vacancy concentration makes it a good candidate as electrode in solid oxide fuel cell (SOFC) applications. Utilizing this novel structure allows the engineering of advanced, effective electrolytes for such devices. This review details the development of current state-of-the-art perovskite-type oxides for solid oxide fuel cell (SOFC) applications.

Recent advances, practical challenges, and perspectives of intermediate temperature solid oxide fuel cell cathodes

“…6,7 The general formula of a perovskite can be written as ABO 3 , where A and B are cations with a coordination number of 12 and 6, respectively. 8 Alkaline, alkaline-earth and rare-earth metals can occupy larger A-sites while transition metals with smaller size can occupy B-sites. 8,9 Fig.…”

“…8 Alkaline, alkaline-earth and rare-earth metals can occupy larger A-sites while transition metals with smaller size can occupy B-sites. 8,9 Fig. 1a schematically shows an ideal cubic perovskite structure, however, due to the variation of ionic radius after cation substitutions, structural distortion changes the cubic lattice to tetragonal, orthorhombic, and rhombohedral, as demonstrated in Fig.…”

“…26,27,29 However, this composition is not an optimum cathode candidate in IT-SOFCs due to the inferior performance at lower operational temperature. 8,26…”

“…Based on the conducting mechanism and the pathways for the ORR, cathode materials can be categorized into two groups: (i) pure electronic conducting materials, and (ii) mixed ionic-electronic conductors (MIECs). 6,8,119,302,303 In the first group, after the oxygen molecule has been adsorbed and dissociates on the perovskite surface, it migrates to the TPBs through surface diffusion where oxide ions form and incorporate into the electrolyte by electron transfer. Fig.…”

Effects of sintering temperature on the structural and electrochemical properties of SrFe0.5Ti0.5O3‐δ perovskite cathode

“…The pure electronic cathode allows the oxygen‐reduction reaction to occur only at the triple‐phase boundary (TPB). However, the MIEC allowed the reaction to occur at the TPB and through the bulk path . For the intermediate SOFC (ITSOFC), the perovskite material La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3‐δ is commonly used to produce a cathode component .…”