Controlling cation migration and inter-diffusion across cathode/interlayer/electrolyte interfaces of solid oxide fuel cells: A review

• Published in: Ceramics international 2021-03, Vol.47 (5), p.5839-5869
• Main Authors: Khan, Muhammad Zubair, Song, Rak-Hyun, Mehran, Muhammad Taqi, Lee, Seung-Bok, Lim, Tak-Hyoung
• Format: Article
• Language: English
• Subjects: Cathode; Cations migration; Degradation; Interdiffusion; Interface; Secondary phase; Solid oxide fuel cell
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2020.11.002

Solid oxide fuel cells (SOFCs) have attracted great interest as an alternative potential way to become the most efficient and cleanest electrochemical energy conversion system. The commercialization of SOFC technology is hindered by the degradation of component materials. The durable and high performing cathode materials is of immense importance in the durability improvement of SOFCs. Cobaltite type perovskite-based oxides have shown remarkable results but cation migration and formation of the insulating phases within and near the interface between cathode and electrolyte is often observed, which impacts greatly on the electrochemical performance and durability. Therefore, the reaction barrier layer (interlayer) typically made of doped ceria is required between cathode and electrolyte. The stability of this layer due to cations cross-migration between cathode and electrolyte and interdiffusion with electrolyte during fabrication and operation is presently one of the foremost issues (motivation) in the SOFC industry. The chemical and structural disparity associated with the cations migration and interdiffusion could affect the stability and functionality of different layers of SOFC. Understanding the formation of secondary phases and their evolution during the operating lifespan is thought-provoking because of the complexity of the system and the occurrence of numerous other processes simultaneously. In this review paper, the recent progress and advancement in this extent are presented, emphasizing the key driving forces, kinetics, analysis techniques at the micro- and nano-scale levels, and cations migration in extensively studied perovskite-based materials. An insightful understanding of the interdiffusion phenomenon taking place in the cathode/electrolyte/interlayer of SOFCs and control measures are then highlighted which is important to achieve the rational design of highly efficient SOFC with outstanding stable performance.