Investigate the symmetrical electrode material based on Pr and Ni doping SmBaFe2O5+δ for its electrochemical and stability performance for solid oxide cell

Abstract

Symmetrical solid oxide cell (SSOC) that uses the same electrode material for both oxygen electrode and fuel electrode can simplify the preparation process and enhance the durability of the cell. In this study, the Pr and Ni doped SmBaFe₂O_5+δ (SBF), Sm_0.9Pr_0.1BaFe₂O_5+δ (SPBF91) and Sm_0.9Pr_0.1BaFe_1.6Ni_0.4O_5+δ (SPBFN) as symmetrical electrodes for SSOC are successfully prepared, and their properties are investigated. First principles calculation indicates that the oxygen vacancy formation energy of SPBF91 (2.24 eV), SPBFN (1.76 eV) is lower than that of SBF (2.49 eV). In addition, the doping of Pr and Ni significantly reduces the band center energy of Fe-3d and O-2p in SPBFN, which is conducive to oxygen ion and charge transfer. At 800 °C, the polarization resistance of SPBFN are 0.025 Ωcm², and 0.11 Ωcm² in air and H₂, respectively. At 800 °C, using H₂, CH₃OH, and wet C₃H₈ as fuel, the maximum power density (MPD) of fuel cell with SPBFN as a symmetrical electrode reaches 850, 651 and 648 mWcm⁻², respectively. The FeNi alloy is observed on the SPBFN surface at fuel electrode side. The FeNi alloy on SPBFN surface significantly improves the output performance and stability of symmetrical electrode. Furthermore, the solid oxide electrolysis cell (SOEC) with PBSFN as a symmetrical electrode exhibits good stability during a 200 h test when electrolyzing H₂-50%H₂O and electrolysis CO₂.