Grain boundary conduction behaviors of ultra-fine grained CeO2/BaCeO3 based electrolytes

• Published in: Ceramics international Vol. 48; no. 17; pp. 25314 - 25321
• Main Authors: Ding, Hao, Wu, Tong, Zhao, Shikai, Sun, Haibin, Li, Jiao, Guo, Xue, Wang, Peng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2022
• Subjects: CeO2/BaCeO3; Conduction behaviors; Electrolytes; Grain boundary; Solid oxide fuel cells; Electrolytes; Solid oxide fuel cells; Conduction behaviors; CeO2/BaCeO3; Grain boundary
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2022.05.204

CeO2/BaCeO3 based electrolytes, mixtures of oxygen ion and proton conductors, are promising in the application of solid oxide fuel cells (SOFCs). However, their grain boundary conduction behaviors are still unclear. Herein, Sm, Bi co-doping CeO2/BaCeO3 electrolytes (80 wt% Ce0.8Sm0.1Bi0·1O2-δ - 20 wt% BaCe0.8Sm0.1Bi0·1O3-δ, BiSDC-BCSBi) with ultra-fine grained (110–220 nm) and micron (1–1.8 μm) structures were prepared. In the ultra-fine grained structure, specific grain-boundary conductivities measured at 350 °C and 400 °C are 1–2 orders of magnitude higher than micron structures, thus resulting in dramatically enhanced electrical performances, which can be attributed to two aspects. One is the decrease of space charge potential Δφ(0) (0.165 V for ultrafine-fine grained ones, 0.396 V for micron ones). The other is the dilution of impurities (the impurity blocking term ω/dg is 0.94 for ultrafine-fine grained ones, and 0.53 for micron ones). In the ultra-fine grained electrolytes, no extra electronic conduction is introduced, and the ion migration number of O2− is higher than that of H+.