A-site deficient semiconductor electrolyte Sr_1- Co FeO_3- for low-temperature (450-550 °C) solid oxide fuel cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Fast ionic conduction at low temperatures is crucial for efficient solid oxide fuel cells (SOFCs).
• Developing advanced electrolyte materials is key to improving the performance of low-temperature SOFCs (LT-SOFCs).

Purpose of the Study:

• To investigate A-site deficient Sr$_{1-x}$Co$_x$FeO$_{3- ext{δ}}$ as a novel electrolyte for LT-SOFCs.
• To evaluate the impact of cobalt doping on the electrochemical properties and ionic conductivity of the proposed electrolyte.

Main Methods:

• Fabrication and characterization of Sr$_{1-x}$Co$_x$FeO$_{3- ext{δ}}$ electrolytes with varying cobalt content.
• Assembly and testing of LT-SOFC devices using the developed electrolytes.
• Electrochemical performance analysis, including power density and open-circuit voltage (OCV) measurements.
• Analysis of ionic conductivity, energy bandgap, and oxygen vacancy concentration using techniques like XPS.

Main Results:

• A fuel cell utilizing Sr$_{0.7}$Co$_{0.3}$FeO$_{3- ext{δ}}$ achieved a peak power density of 771 mW cm$^{-2}$ at 550 °C.
• Cobalt doping significantly enhanced ionic conductivity to over 0.1 S cm$^{-1}$ at 550 °C.
• Optimized cobalt doping improved charge transport, increased oxygen vacancies, and resulted in a high OCV of 1.05 V, indicating efficient device operation.

Conclusions:

• Sr$_{0.7}$Co$_{0.3}$FeO$_{3- ext{δ}}$ is a highly promising electrolyte material for LT-SOFC applications.
• Cobalt doping effectively tunes the energy band structure and enhances oxide ion transport, boosting overall fuel cell performance.
• The study demonstrates the potential of A-site deficient perovskite oxides for advanced energy conversion devices.