A medium-entropy perovskite oxide La0.7Sr0.3Co0.25Fe0.25Ni0.25Mn0.25O3-δ as intermediate temperature solid oxide fuel cells cathode material

Abstract

In this study, we report a novel medium-entropy perovskite oxide of La0.7Sr0.3Co0.25Fe0.25Ni0.25Mn0.25O3-δ (LSCFNM73) with high constitutive entropy (Sconfig) as the cathode material of intermediate temperature solid oxide fuel cells (IT-SOFCs). The intrinsic properties of phase structure, electrical conductivity, thermal expansion and oxygen adsorption capacity of La1-xSrxCo0.25Fe0.25Ni0.25Mn0.25O3-δ (LSCFNM, x = 0, 0.1, 0.2, 0.3) oxides are evaluated in detail. The LSCFNM73 oxide exhibits the maximum electrical conductivity of 464 S cm−1 at 800 °C and a relatively lower thermal expansion coefficient (TEC) of 15.34 × 10−6 K−1, which is selected as the propriate cathode composition. The B-site of LSCFNM73 contains four elements which can increase the configuration entropy. Additionally, NiO-Yttria stabilized zirconia (YSZ) supported fuel cell is fabricated by tape casting, hot pressing-lamination, co-sintering and screen printing technologies. The fuel cell demonstrates a maximum power density of 1088 mW cm2 at 800 °C, and excellent stability at 750 °C under 0.75V in 120 h and 10 times thermal cycling between 750 °C and 400 °C. Therefore, the medium-entropy LSCFNM73 oxide can be applied in IT-SOFCs as a competitive cathode material.