Impedance Studies of Heterogeneous BSCF-Ni-based Cathode Material at Intermediate Temperatures

Abstract

Intermediate-temperature solid oxide fuel cells (IT-SOFCs) offer a promising route to high-efficiency, low-emission energy conversion. However, the development of highly efficient IT-SOFCs is limited by the performance of their key components, particularly the cathode, for instance, Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF). Although the BSCF exhibits high oxygen-ion and electronic conductivity, it suffers from phase instability and thermal expansion mismatch. To overcome limitations and enhance material performance, this study focuses on incorporating nickel (Ni) into BCSF to form heterogeneous BSCF-Ni composites. Experimental studies demonstrate that a single cell using heterogeneous BSCF-Ni cathodes achieves a polarization resistance as low as 10.80 Ω cm², compared to 22.32 Ω cm² for homogeneous BSCF-Ni at 750 °C.  DRT peaks have shown that the heterogeneous BSCF-Ni enhances oxygen reduction and reduces polarization resistance, thereby improving overall cell performance. These advancements confirm that BSCF-Ni composites, enabled by doping and nanostructuring strategies, are highly promising cathode materials for durable, efficient IT-SOFC systems.