A novel high-entropy cathode with the A2BO4-type structure for solid oxide fuel cells

For the first time, A2BO4 type high-entropy oxide is applied to SOFC cathode. In this paper, a (La0.2Pr0.2Nd0.2Sm0.2Gd0.2)2CuO4 high-entropy oxide (HE-LCO) is synthesized. The phase structure, DC conductivity, high-temperature thermal expansion and electrochemical performance of HE-LCO are studied in detail. HE-LCO crystallizes in tetragonal symmetry with space group I4/mmm. The thermal expansion coefficient of HE-LCO is 12.19 × 10−6 K−1 in the range of 100–800 °C, which is compatible with GDC electrolyte. The area-specific resistance (ASR) of HE-LCO cathode is 0.52 Ω cm2, and the peak power density of the anode support fuel cell attains 528 mW cm−2 at 700 °C. In addition, the dissociation of molecular oxygen on HE-LCO cathode is recognized to be the rate-limiting step of the ORR kinetics.