NdBaMn₂O_5+δ layered perovskite as an active cathode material for solid oxide fuel cells

A layered perovskite, NdBaMn₂O_5+δ (NBMO), was synthesized by solid state reaction method in air. Rietveld analysis of X-Ray Diffraction (XRD) data showed the material crystallizing in orthorhombic symmetry (Pmmm space group). Scanning electron microscopy (SEM) was used to check the morphology and, the analysis of the micrographs exhibited a porous structure with in-situ growth of nanoparticles. Electrochemical Impedance Spectroscopy (EIS) measurements from 600 °C to 800 °Cshows the highest conductivity value of 1.17 × 10⁻¹ S/cm obtained at 800 °C with low activation energy (E_a) of 0.3 eV in air. In 5% H₂/Ar gas mixture, the conductivity and activation energy values were 1.97 × 10−2 S/cm and 0.4 eV, respectively at 800 °C. The DC conductivity measurements also showed that this material is highly conductive in air with a conductivity value of 0.75 S/cm at 850 °C. Dual chamber fuel cell measurements on Ni-YSZ/YSZ/NBMO cell using 5% H₂/Ar as fuel (from 700 °C to 800 °C) showed a maximum power density of 0.202 W/cm² at 800 °C. The relatively high conductivity of the material in air and low activation energy makes it a potential candidate as cathode for solid oxide fuel cells.