Evaluation of Ni–Ni 3Al(5 wt.%)–Al(3 wt.%) as an anode electrode for molten carbonate fuel cell. Part II: wetting ability and performance in unit cell operation

Abstract

In part I of this paper, the sintering and creep resistances of the five kinds of anode electrodes were compared and those of Ni–Ni 3Al(5)–Al(3) were even better than any other electrodes. In part II of this paper, the wetting abilities of the same five kinds of anode electrodes to the electrolyte and their performance in unit cell operation were investigated. Their contact angles, which indicate the wetting ability, were within the range between 77 and 84°. The contact angles of Al- and/or Ni 3Al-added electrodes such as Ni–Al(5), Ni–Ni 3Al(7) and Ni–Ni 3Al(5)–Al(3) were relatively lower than those of Cr-added electrodes. Although there was no evidence that the effect of Al and/or Ni 3Al addition to pure Ni could enhance the number of pores or improve their structure for more wetting ability, it could be clearly known that the component of Al and/or Ni 3Al in anode electrode could make the electrode be wetted by the electrolyte very well. In unit cell operation, the electric resistance of Ni–Al(5) and Ni–Ni 3Al(5)–Al(3) were relatively lower than those of any other electrodes. After 120 h operation of the unit cell, the cell performance and the endurance of Ni–Ni 3Al(5)–Al(3) were even better than those of any other electrodes. And also its thickness shrinkage and porosity changes after unit cell operation were the least in five kinds of electrodes. The performance of Ni–Ni 3Al(5)–Al(3) as anode seems to be caused by the synergy effect between the strengthening characteristics of Ni 3Al and electric conductivity of Al.