Cu ion regulates the stability and oxygen reduction kinetics of Co-based double perovskite as SOFC cathode

Enhancing the oxygen reduction catalytic activity and thermal compatibility of cathode materials under intermediate-temperature conditions remains pivotal for advancing the commercialization of solid oxide fuel cells (SOFCs). Therefore, this article regulates the crystal structure of NdBaCo 2 O 5+δ (NBC)-based double perovskite by Cu, replacing Co with a small amount of Cu ions to increase the oxygen vacancy content of the cathode material and reduce the thermal expansion coefficient (TEC) of NBC-based materials, to improve the electric catalytic activity and long-term stability of SOFC. The distribution of relaxation time results confirms that compared with NBC, NdBaCo 1.8 Cu 0.2 O 5+δ (NBCC2) can greatly enhance oxygen's dissociation and adsorption rates. As a symmetrical cell at 650 °C, the area-specific resistance (ASR) of NBCC2 is only 0.067 Ω cm −2 , which is about 40 % of NBC. As the cathode of SOFC, the maximum power density of the NBCC2-based cell reaches 0.67 W cm 2 , which is 1.58 times that of NBC, and Cu doping improves the long-term stability problem caused by the high TEC of Co-based materials. This study provides an effective solution for further enhancing the electrocatalytic activity of Co-based perovskite and addressing stability issues caused by high TEC. • Cu ions regulate the concentration of oxygen vacancies in Co-based perovskite. • Partially replacing Co with Cu promote the adsorption and dissociation rate of oxygen. • The ASR value of NBCC2 as a symmetrical cell at 650 °C is 0.067 Ω cm −2 . • NBCC2, as a SOFC cathode, has excellent power density and long-term stability.