Structural, mechanical and electrical properties of NiO - GDC20 composite anodes for low or intermediate temperature solid oxide fuel cells

Abstract

Nano Composites NiO and 20 mol% gadolinium doped ceria (GDC20) were synthesized as X (NiO) +1-X (Ce0.8 Gd0.2 O2-δ) where (X = 40& 45 wt. %) for intermediate or low temperature operating solid oxide fuel cells (SOFC). For composite anode materials, NiO and GDC20 nano powders were mechanically mixed and calcined from 600 °C to 750 °C. Samples were pelletized and sintered at 1300°C. Systematic study of structure, purity, phase and structural parameters of anode samples were carried out by XRD and SEM. Mechanical strength of anode composites were estimated by Vickers micro-hardness and observed that microhardness of composites are varying from 9.37 GPa to 11.25GPa. Electrical properties D.C conductivity and A.C conductivity of anode composites were computed using four probe method and impedance analyser respectively. The A.C conductivity and their activation energies of the anode samples (compositions X = 40 & 45 wt. %) were computed from RT to 500°C with the impedance spectrosopy data and the conductivities are found 2.95 x 10−3 S/cm and 7.53 x 10−2 S/cm respectively at 500°C (frequency 1.33 MHz). The activation energies of A.C conductivity have observed that decrease with increase in frequencies.