On the oxygen vacancies optimization through Pr co-doping of ceria-based electrolytes for electrolyte-supported solid oxide fuel cells

Abstract

Praseodymium-doped ceria electrolyte powders are synthesized by a co-precipitation method using ammonium carbonate in little excess to fabricate a stable electrolytesupported solid oxide fuel cell able to operate in hydrogen conditions. Raman and X-ray Photoelectron Spectroscopy are employed for the electrolyte characterization to check the distribution of vacancies and the initial oxidation state of Pr that influences the transport mechanism under the real operation of SOFCs. The optimum Pr concentration in the electrolyte is found to be 6 mol% of Pr and 14 mol% of Gd (sample 6Pr). The electrolytesupported cells fabricated with this composition are sintered at 1250 degrees C for 3 h and tested in different gas conditions and operating temperatures, showing a maximum power density of 305.31 mW.cm-2 at 530.36 mA-cm-2 (750 degrees C) in wet hydrogen conditions. Compared to standard cells fabricated with a gadolinium-doped ceria electrolyte sintered at 1500 degrees C, the 6Pr has long term stability performances with a power density loss of 17% after 100 h of operation. The results demonstrate the eligible use of this electrolyte under real operating environments. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.