Investigation of in Situ Co-assembled Sr(Co,Zr)O3-δ-Based Perovskite Nanocomposite Cathode for Intermediate-Temperature Solid Oxide Fuel Cells

Exploring cathode materials with fast oxygen reduction reaction (ORR) kinetics is crucial to intermediate-temperature solid oxide fuel cells (SOFCs). Herein, a highly active perovskite nanocomposite with a nominal composition of SrCo0.8Zr0.2O3-delta is developed. The two perovskite phases of cubic SrZr0.8Co0.2O3-delta (SZC, Pm (3) over barm, 30 wt %) and hexagonal SrCo(0.9)Z(r0.1)O(3-delta) (SCZ, R (3) over bar cH, 70 wt %) can be in situ co-assembled at the nanoscale for well-connected nanoparticles (50-100 nm) and congenital compatibility. The SZC-SCZ nanocomposite can exhibit the active surface oxygen species and a matchable thermal expansion coefficient (15.3 x 10(-6)K(-1)) with Ce0.8Gd0.2O1.9 (13.5 x 10(-6) K-1) electrolyte. When applied to the anode-supported SOFC, SZC-SCZ nanocomposite cathode cell shows superior power densities of 1.48-0.41 W cm(-2) at 750-550 degrees C to single cubic SZC cathode cell (0.24-0.06 W cm(-2)) and typical hexagonal SrCoO3-delta cathode cell (1.25-0.32 W cm(-2)). The distribution of relaxation times analysis reveals that the oxygen adsorption and dissociation process of SZC-SCZ nanocomposite cathode is significantly enhanced, of which the polarization resistances (0.07-0.22 Omega cm(2)) are 0.70-0.43 times those of SrCoO3-delta cathode. This benefits from the nanostructure for an extensive heterointerface and surface, and the synergistic interaction of components can contribute to enhancing oxygen catalysis. Thus, this work explores a promising SZC-SCZ nanocomposite cathode for enhancing ORR activity and cell performance at lower operating temperatures.