Effect of Doping la/nd in pr Site and fe/cu in ni Site on Thermal Stability of the Pr2NiO4+δ as the Cathode of Intermediate Temperature Solid Oxide Fuel Cell

Behsam, Shadi | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51987 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Fagihi Sani, Mohammad Ali
  7. Abstract:
  8. Solid oxide fuel cells (SOFCs) are a route to highly efficient and clean power, which have been attracting interest due to the issues associated with the ever-increasing energy demand and pollution. However, their commercialization is hindered by the high operating temperatures (700-1000℃). One of the challenges faced by intermediate temperature solid oxide fuel cells (IT-SOFCs) with operating temperature in the range of 500-700℃ is the increased overpotentials of the components, especially cathode. Lanthanide nickelates (Ln2NiO4+δ, Ln = La,Pr,Nd) with mixed ionic and electronic conduction (MIEC) have already been introduced as promising IT-SOFC cathode materials. Among them, Pr2NiO4+δ offers the superior oxygen reduction performance, but suffers from thermodynamic instability at IT-SOFC operating temperatures. One of the approaches adopted to increase its stability is by doping it in Pr site, which often leads to the diminished electrochemical properties of the cathode. The degredation of the elechtrochemical properties can be compensated by doping in the Ni site. This study aims to investigate the effects of lanthanium/neodymium and copper/iron doping in Pr and Ni sites, respectively, on the thermodynamic stability of Pr2NiO4+δ . In this respect, Pr2-xAxNiO4+δ (A= La,Nd; x=0,0.5,1) and Pr1.9A0.1Ni0.75-yCu0.25FeyO4+δ (A = La,Nd; y=0.01,0.05) powders are synthesized with auto-combustion method, heated at 700 and 800℃ for 24 and 100h, and studied by X-ray diffraction. The results show that lanthanium is a better Pr-site dopant from the both stability and cathodic function viewpoints. Copper is one of the rare dopants that enhance both stability and cathodic function. However, iron facilitates the decomposition process and reduces the stability
  9. Keywords:
  10. Solid Oxide Fuel Cell (SOFC) ; Mixed Ionic and Electronic Conduction (MIEC) Materials ; Lanthanide Nickelates ; Thermodynamic Stability ; Praseodymium Nickelate ; High Temperature Fuel cell

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