Influence of the ratio between Ni and BaCe0.9Y0.1O3−δ on microstructural and electrical properties of proton conducting Ni–BaCe0.9Y0.1O3−δ anodes

Cermet anode substrates Ni–BaCe0.9Y0.1O3−δ (Ni–BCY10) with varied ratios between Ni and BCY10 were prepared. BCY10 powders were prepared by the citrate–nitrate auto-combustion method and anode substrates were prepared by the method of evaporation and decomposition of solutions and suspensions. Sintered anode substrates were reduced and their properties were examined before and after reduction as a function of the ratio between Ni and BCY10. Microstructural properties of the pellets were investigated using X-ray diffraction analysis and field emission scanning electron microscopy. The influence of the Ni:BCY10 ratio on the microstructure of conducting paths through ceramic and metal parts was discussed. Impedance spectroscopy measurements were used for evaluation of electrical properties of the anode pellets. The high conductivity values of reduced anodes confirmed percolation through Ni particles even for an anode with a reduced amount of nickel. Fuel cell tests were carried out in order to examine the influence of the Ni:BCY10 ratio on fuel cell performance and to compare characteristics of cermet anodes with platinum electrodes. The ratio between Ni and BCY10 did have a slight influence on the power output of fuel cells. Fuel cells with a cermet anode demonstrated a higher power output compared to fuel cells with a platinum electrode.

Research highlights▶ The influence of ratio between Ni and BaCe0.9Y0.1O3−δ on the microstructural and electrical properties of anode substrates was investigated. ▶ Changing of Ni:BCY10 ratio has a significant influence on the microstructure of conducting pathways in anode substrates, but the electrical characterization showed comparable activation energies of samples before and after reduction. ▶ Percolation through Ni particles properly took place even though the amount of Ni is decreased. This was confirmed by high conductivity values (σ* > 40 S cm−1) of all samples after reduction. ▶ Fuel cell tests showed very small decreasing (less than 5%) in the maximum power output between fuel cells with the highest and the lowest amount of nickel in anode composition. ▶ The anode with 40 wt.% of nickel could be used for fabrication of anode supported PCFC without any significant deterioration of the performances. ▶ Fuel cells with composite anode substrates showed higher maximum power output comparing to the fuel cell with platinum anode.