The investigation of co-assembled high-performance (Ba, Sm/Sr)(Co, Zr)O3-δ composite perovskite cathodes for intermediate-temperature solid oxide fuel cell

Abstract

The cobalt-based perovskites are the most common solid oxide fuel cell (SOFC) cathode materials, which generally have the issues of thermal compatibility and performance at the reducing temperature. In this study, two Ba0.5(Sm/Sr)0.5Co0.8Zr0.2O3-δ (BSmCZ/BSrCZ) perovskite composites were synthesized using a smart co-assembled method, which were primarily composed of cubic doped-BaZrO3 and hexagonal doped-BaCoO3 perovskites. Both BSmCZ and BSrCZ composites exhibited more suited thermal expansion coefficient (12.8 × 10-6 and 13.9 × 10-6 K−1) to the electrolyte, nanostructure with extensive heterointerfaces and excellent cathode|electrolyte interfaces. Compared to BSrCZ composite, the BSmCZ composite possessed a relatively higher content (65 %) of activated oxygen species and higher electrical conductivity (70.7 S cm−1). The cells with two composite cathodes could achieve the remarkable maximum power density, especially for BSmCZ composite cathode of 2.00–1.11 W∙cm−2 at 800–650 °C. The electrochemical analysis revealed that the BSmCZ composite cathode demonstrated the enhanced surficial oxygen catalysis processes, which could benefit from the active oxygen species and heterointerface.