Effects of Ti doping on the electrochemical performance of (La0.75Sr0.25)(Mn0.5Cr0.5)O3-δ anode for solid oxide fuel cells

Abstract

Single phase La 0.75 Sr 0.25 Mn 0.5 Cr 0.5-x Ti x O 3-δ (LSCMT, 0 ≤ x ≤ 0.3) perovskites were investigated as possible anode material for solid oxide fuel cells with yttria stabilized zirconia (YSZ) electrolyte. LSCMT samples were synthesized by solid state reaction method and sintered at 1500°C in air. Rietveld refinement of X-ray powder diffraction data show that the LSCMT materials crystallize in the rhombohedral symmetry with R3C space group. The cell parameters of the sample with 10 at.% of Ti (x = 0.1) were: a = b = 5.5125(4) Å; c = 13.3397(6) Å; α = 90°; β = 90°; γ = 120°. The scanning electron microscopy analyses confirmed the presence of sufficient porosity (about 35%). Symmetrical LSCMT|YSZ|LSCMT cell configurations with different Ti-doping (x = 0.1, 0.2 and 0.3) and good interface without delamination between the two materials, even after reduction process, were also prepared. Ti doping was very effective in reducing the interfacial polarization resistance with the lowest value of 0.22Ω·cm 2 and conductivity of 0.23 S/cm in 5% H 2 /Ar at 800°C. The obtained results suggest that Ti doping can substantially improve electrochemical performance of (La 0.75 Sr 0.25 )(Mn 0.5 Cr 0.5 )O 3-δ ceramics.