HE Shuai, ZOU Yuanfeng, JIANG Sanping
(Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory,
Foshan 528216, Guangdong, China)

Abstract: Electrode/electrolyte interface plays a critical role in determining the performance and durability of solid state devices, such as high temperature solid oxide fuel cells (SOFCs). Different from that in aqueous electrolyte cells, the interface between porous electrode and dense electrolyte is generally not continuous and typically shows the characteristics of solid-to-solid (StS) contact. Such StS contact is of critical role in surface segregation polarization, electrode/electrolyte interfaces and interphase reactivity of electrodes of SOFCs. This is particularly true for the cobaltite based perovskite materials, due to their high mixed ionic and electronic conductivity and high activity as cathodes for O2 reduction reaction of SOFCs. However, the studies of such fundamental issues are largely limited by the high activity of cobaltite-based perovskites with yttria-stabilized zirconia (YSZ) based electrolyte during the high temperature electrode/cell sintering stages. Recently,direct assembly techniques were developed to study the electrode/electrolyte interface formation and reactions under SOFC operating conditions, which avoids the detrimental issues associated with the conventional high temperature sintering. This article is aimed to briefly review the advances in the fundamental understanding and intrinsic relationship between the polarization, surface segregation and interface formation under SOFC operation conditions on electronic conducting La_0.8Sr_0.2MnO₃ and mixed ionic and electronic conducting La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ perovskite model electrodes and YSZ and gadolinium-doped ceria (GDC) electrolytes. The fundamental understanding of the electrode/electrolyte interface has general and significant implications for the development of high performance and durable SOFCs.
Key words: solid oxide fuel cells; cathode; electrode/electrolyte interface; surface segregation; polarization