Gadolinia-doped ceria mixed with alkali carbonates for SOFC applications: II – An electrochemical insight

Ionic transport mechanism of La0.9Sr0.1Ga0.8Mg0.2O2.85-(Li/Na)2CO3 composite electrolyte for low temperature SOFCs

“…The process increased the proportion of CO 3 2À with the combination of CO 2 /O 2À and separation [20], the results could be also explained by the former conclusion that the conductivity and transition temperature enhanced with the increasing of the content of carbonate. As we could see that the composite electrolyte transition temperature in air condition is 450 C, among those in carbon dioxide, nitrogen, and oxygen atmospheres, which could be explained by the fact that air is a mixture gas.…”

“…As can be seen wet gas (hydrogen, oxygen, carbon dioxide and air) could lower transition temperature in low temperature (450 C), the possible explanation for the decrease of transition temperature was that humidified gas enabled some formation of hydroxides from (Li/ Na) 2 CO 3 with lower melting point than carbonates (NaOH: 381 C, LiOH: 471 C). If hydroxides were formed, the melting of hydroxides would allow a higher mobility of the ions involved in the conduction mechanism [20].…”

“…Carbonate/doped ceria composite electrolyte shows enhanced properties compared to pure doped ceria [8], such as high ionic conductivity, improved stability and low electron conductivity at low temperatures (400e600 C), which has been considered promising electrolyte for using in low temperature solid oxide fuel cells (LT-SOFCs), with ionic conductivities as high as 0.01e0.1 S cm À1 achieved at 400e600 C [9,10]. Such LT-SOFCs could be achieved a power density of 900 mW cm À2 at 550 C with hydrogen and air as fuel and oxidant, respectively [11].…”

Effect of carbonates addition on Ce0.80Gd0.20O1.90 (GDC) nanorods prepared by wet chemical route for LT-SOFCs

“…Conductivity has decreased slightly at 35 wt% of the carbonate. The composition, 0.7GDC/0.3LNCO (GDC/30LNCO) shows the maximum conductivity, 2.74 Â 10 À1 S-cm À1 at 500 C. This value is higher than the previously reported results for other compositions at the same temperature [9,19]. The activation energy for conduction, E a has been determined by fitting the conductivity data to Arrhenius equation (Eq.…”

“…This is evidenced by the facts that water has generated on both the sides of the electrolyte [7,8]. It has been demonstrated that the interface provides a long channel for transport of the ions and leads to an enhanced conductivity [9]. The interface density and the contact area between the two phases are the parameters considered in order to enhance the electrical conductivity [4].…”