Tuning Cu-Content La_1-xSr_xNi_1-yCu_yO_3-δ with Strontium Doping as Cobalt-Free Cathode Materials for High-Performance...

Cu-content La_1-xSr_xNi_1-yCu_yO_3-δ perovskites with A-site strontium doping have been tuned as cobalt-free cathode materials for high-performance anode-supported SOFCs, working at an intermediate-temperature range. All obtained oxides belong to the R-3c trigonal system, and phase transitions from the R-3c space group to a Pm-3m simple perovskite have been observed by HT-XRD studies. The substitution of lanthanum with strontium lowers the phase transition temperature, while increasing the thermal expansion coefficient (TEC) and oxygen non-stoichiometry δ of the studied materials. The thermal expansion is anisotropic, and TEC values are similar to commonly used solid electrolytes (e.g., 14.1 × 10^-6 K^-1 for La_0.95Sr_0.05Ni_0.5Cu_0.5O_3-δ). The oxygen content of investigated compounds has been determined as a function of temperature. All studied materials are chemically compatible with GDC-10 but react with LSGM and 8YSZ electrolytes. The anode-supported SOFC with a La_0.95Sr_0.05Ni_0.5Cu_0.5O_3-δ cathode presents an excellent power density of 445 mW·cm^-2 at 650 °C in humidified H₂. The results indicate that La_1-xSr_xNi_1-yCu_yO_3-δ perovskites with strontium doping at the A-site can be qualified as promising cathode candidates for anode-supported SOFCs, yielding promising electrochemical performance in the intermediate-temperature range.