Development of Nano-Structured and Nano-Porous BSCF Cathode for Low Temperature Solid Oxide Fuel Cell Application

ABSTRACT

Nano-structured and nano-porous mixed ionic and electronic conducting Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–δ (BSCF) cathodes with an average grain size ∼500 nm and porosity ≤30% were processed from sol-gel method using metal organic precursors and calcined at 950°C for 5 h followed by sintering at 1000°C for 3 h. Crystallization of the powder was analyzed by X-ray diffraction and found to be dependent on calcination temperature. The calcined powder was compacted into circular discs and sintered between 1000° and 1100°C to achieve the desired porosity. Scanning electron microscopy showed porous BSCF structure, facilitating gas transfer and maximizing the number of active sites for oxygen reduction reaction at the cathode of a solid oxide fuel cell. BSCF powder was made into paste and screen printed on Ce_0.8Gd_0.2O_2–δ (GDC) electrolyte to form a symmetric cell. Thickness of the BSCF cathode film is around 4 µm. Area specific polarization resistance was measured in a broad range of temperature (300°-700°C) at the frequency range from 10 MHz to 0.1 Hz. Impedance measurements show that area-specific resistance for the symmetric cell with BSCF cathode is 1.74 Ω-cm² at 600°C. These results are impressive and demonstrate the potential of BSCF to be used as cathode material in new-generation SOFCs with GDC as the electrolyte.

GRAPHICAL ABSTRACT

Keywords:

• SOFC
• BSCF cathode
• MIEC
• Sol-gel
• Catalytic activity
• Impedance