Electrochemical performance of La1.6Sr0.4NiO4–Ag composite cathodes for intermediate-temperature solid oxide fuel cells

La1.6Sr0.4NiO4–Ag (LSN–Ag) composite cathodes are prepared and characterized by XRD and SEM, respectively. The electrochemical properties of the composite cathodes are investigated using AC impedance and DC polarization methods from 500 to 700 °C under different oxygen partial pressures. The polarization resistance (Rp) decreases with the increase of Ag content in the composite electrode. The addition of 5 vol.% Ag in LSN results in the lowest Rp of 0.21 Ω cm2 at 700 °C in air. Oxygen partial pressure dependence study indicates that the charge transfer process is the reaction rate limiting step, while the diffusion process has no sensitive to the Ag loading. LSN–5Ag cathode exhibits the lowest overpotential of about 32 mV at a current density of 144 mA cm−2 at 700 °C in air.

Figure optionsDownload as PowerPoint slideResearch highlights▶ LSN-5Ag composite cathode gave the lowest polarization resistance value of 0.21 Ω cm2 at 700 °C. ▶ The charge transfer process is the reaction rate limiting step for LSN-5Ag composite cathode. ▶ The electrochemical performance of LSN-5Ag for the oxygen reduction reaction was superior to the LSN. ▶ The impregnated silver enhances the oxygen reduction performance of LSN.