The influence of NiO content on ceramic-based solid oxide fuel cell anodes

Solid oxide fuel cell (SOFC) anodes based on electronically conducting ceramics have potential advantages over conventional Ni-YSZ anodes, including better fuel flexibility, stability under redox cycling, and sulfur tolerance. Here we report small additions of NiO to anodes based on La_0.8Sr _0.2Cr_0.03V_0.03O₃ (LSCV) that also contained Ce_0.9Gd_0.1O_1.95 (GDC), and describe results for these electrodes in SOFCs with GDC electrolyte supports. Microstructural evaluation showed a porous anode that varied significantly with anode firing temperature. Metallic Ni was observed in the anodes after reduction by x-ray diffraction for ≥ 5 weight percent NiO. Cell performance with hydrogen was evaluated using current-voltage measurements and electrochemical impedance spectroscopy (EIS) - total polarization resistance values at open circuit were ∼ 0.1 ωcm² at 800°C for ≥ 2 weight percent NiO. The maximum power density of the SOFCs decreased sharply with decreasing NiO content from 5 to 0 weight%, however, little effect was observed from 5 to 20 weight% NiO.