Characterization and optimization of Ln1.7Sr0.3CuO4 (Ln = La, Nd)-based cathodes for intermediate temperature solid oxide fuel cells

The Ln1.7Sr0.3CuO4 (Ln = Nd, La), i.e., NSCu and LSCu materials with perovskite-related structure were synthesized and evaluated as new cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). The crystal structure, thermal expansion, electrical conductivity and electrochemical performance of Ln1.7Sr0.3CuO4 cathodes have been investigated by X-ray diffraction, dilatometry, DC four-probe method, AC impedance and cyclic voltammetry (CV) techniques. The conductivity of NSCu and LSCu reached 106 S cm−1 and 125 S cm−1 at 800 °C. NSCu cathode exhibited much lower area specific resistances (ASR) than LSCu, e.g., the ASR values for NSCu cathode on Sm-doped ceria (SDC) electrolyte in air were 0.07 Ω cm2, 0.09 Ω cm2 and 0.24 Ω cm2 at 800 °C, 750 °C and 700 °C, while the corresponding values for LSCu were 0.11 Ω cm2, 0.21 Ω cm2 and 0.44 Ω cm2, respectively. To further optimize the electrochemical performance of the cathodes, a certain amount of Sm-doped ceria (SDC) electrolyte was introduced. The polarization resistance of NSCu-SDC30 and LSCu-SDC30 was 0.12 Ω cm2 and 0.18 Ω cm2 at 700 °C in air, nearly half of pure NSCu and LSCu, respectively.