Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ- Sm_0.2Ce_0.8O_1.9) and Schottky barrier

Perovskite Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) is synthesized via a chemical co-precipitation technique for a low temperature solid oxide fuel cell (LTSOFC) (300–600 °C) and electrolyte-layer free fuel cell (EFFC) in a comprehensive study. The EFFC with a homogeneous mixture of samarium doped ceria (SDC): BSCF (60%:40% by weight) which is rather similar to the cathode (SDC: BSCF in 50%:50% by weight) used for a three layer SOFC demonstrates peak power densities up to 655 mW/cm², while a three layer (anode/electrolyte/cathode) SOFC has reached only 425 mW/cm² at 550 °C. Chemical phase, crystal structure and morphology of the as-prepared sample are characterized by X-ray diffraction and field emission scanning electron microscopy coupled with energy dispersive spectroscopy. The electrochemical performances of 3-layer SOFC and EFFC are studied by electrochemical impedance spectroscopy (EIS). As-prepared BSCF has exhibited a maximum conductivity above 300 S/cm at 550 °C. High performance of the EFFC device corresponds to a balanced combination between ionic and electronic (holes) conduction characteristic. The Schottky barrier prevents the EFFC from the electronic short circuiting problem which also enhances power output. The results provide a new way to produce highly effective cathode materials for LTSOFC and semiconductor designs for EFFC functions using a semiconducting-ionic material.