Advanced Symmetric Solid Oxide Fuel Cell with an Infiltrated K 2 NiF 4 -Type La 2 NiO 4 Electrode

Advanced symmetric solid oxide fuel cells (SOFCs) with a reducible electrode were proposed. Specifically, La 2 NiO 4 + La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3−δ (LSGM) [or Sm 0.2 Ce 0.8 O 1.9 (SDC)] composite electrodes were successfully fabricated by an infiltration method and tested for power generation. X-ray diffraction (XRD) results demonstrated there was no noticeable phase reaction between infiltrated La 2 NiO 4 and LSGM (or SDC) scaffold, and scanning electron microscopy (SEM) analysis indicated that the La 2 NiO 4 phase formed as nanoparticles that decorated the surface of the scaffold. Different from conventional symmetric SOFCs, the electrode material La 2 NiO 4 of current cells was reduced under an anode atmosphere to form metallic nickel as a high active catalyst for fuel oxidation. After the reduction, the electrode morphology and geometric integrity were maintained for the infiltrated electrode. For thick electrolyte-supported symmetric SOFCs with infiltrated La 2 NiO 4 electrodes, an attractive maximum power density of ∼550 mW cm –2 was achieved at 800 °C operating on hydrogen fuel, significantly higher than similar cells with stable perovskite oxide electrodes, as reported in the literature. It suggested that the unreduced and reduced La 2 NiO 4 performed well as a cathode for the oxygen reduction reaction and as an anode for fuel electro-oxidation, respectively. In addition, a favorable operating stability was demonstrated for a symmetric SOFC with an infiltrated La 2 NiO 4 electrode. It provides a new way for developing cost-effective SOFCs with huge application opportunities.