Sub-second sintering process for La6Sr4Co2Fe8O3-δ-gadolinium doped ceria composite cathode via a flash light irradiation method for intermediate temperature-solid oxide fuel cells

Abstract

A solid oxide fuel cell (SOFC) requires an elevated operating temperature to achieve high oxygen ion conductivity and the oxygen reduction reaction (ORR). However, at high operating temperatures above 800 °C, performance deteriorates due to the chemical reaction of the electrode and electrolyte materials at the interface. Therefore, it is necessary to lower the operating temperature to the intermediate temperature regime while maintaining the high oxygen reduction reaction kinetics. One approach is adopting the composite cathode material such as La6Sr4Co2Fe8O3-δ-gadolinium doped ceria (LSCF-GDC). However, the high temperature in the fabrication process results in non-conduction material of strontium zirconate (SrZrO3, SZO) layers at the cathode/electrolyte interface, which blocks oxygen ion conduction and degrades the fuel cell performance. By utilizing the novel flash light sintering process, which can be completed in a few seconds, high temperature fabrication issues are solved. The surface microstructure and thickness of the composite electrode are inspected using a scanning electron microscope (FE-SEM). The secondary phase generation and chemical reaction are analyzed using XRD (X-ray diffraction), SEM-EDS, and TEM-EDS. The anode supported LSCF-GDC cathode cells are measured from 600 °C to 750 °C. The maximum power density at 750 °C of the novel flash light sintered LSCF-GDC composite cathode cell is 727.4 mW/cm2. In addition to the utilization of high performing cathode structure, the flash light sintering process dramatically reduces the process time and suppresses the side reaction at the cathode/electrolyte interface.