Cell performance enhancement facilitated by mixed ionic and electronic conductor fiber for protonic ceramic fuel cells

This study examines the electrochemical properties of a fibrous composite cathode for protonic ceramic fuel cells (PCFC). Sm_0.5Sr_0.5CoO_3-δ (SSC) fibers having embedded BaCe_0.5Zr_0.35Y_0.15O_3-δ (BCZY) particles were fabricated using the electro-spinning process. The BCZY powders were prepared using the conventional citrate-nitrate method. It was subsequently mixed with an SSC solution comprising polyvinylpyrrolidone and aqueous metal nitrate. By electro-spinning the obtained mixture, continuous and longish fibers were obtained, yielding a fiber diameter of 150–200 nm after calcination. The calcined composite nanofibers were deposited via the electrostatic slurry spray deposition technique as a cathode layer on a half-cell comprising NiO and BCZY. According to the results of the single-cell measurement, the fibrous composite cathode exhibited much higher electrochemical properties than a typical nanocomposite cathode over the entire operating temperature range of 550–700 °C. Specifically, the polarization resistance of the fibrous composite cathodes was 0.186 Ω·cm² at 700 °C, lower than that of a typical nanocomposite cathode. In accordance with the impedance analysis, the maximum power density given by the I–V curve was 642 mW/cm² at 700 °C, which is regarded as reasonable performance for PCFCs.