Preparation and Performance Degradation of Plasma-Sprayed Gadolinium-Doped Ceria Electrolyte for Metal-Supported SOFCs

Abstract

Gadolinium-doped ceria (GDC) is a promising electrolyte for metal-supported solid oxide fuel cells (MS-SOFCs) due to its high ionic conductivity at intermediate temperatures (500-700 °C). However, the extremely high sintering and densification temperature required for GDC electrolytes limits their practical application. Low-pressure plasma spraying (LPPS) offers a potential solution by enabling the preparation of dense GDC coatings without the need for sintering. This study explores the relationship between spraying distance, coating microstructure, and cell performance and elucidates the deposition mechanism and performance degradation of GDC-based MS-SOFCs. Results show that spraying distance significantly affects coating microstructure and cell performance. At shorter distances, perpendicular cracks dominate, while parallel cracks increase with distance. Increasing the spraying distance from 250 to 300 mm reduces the cell open circuit voltage (OCV) from 0.896 to 0.876 V and the maximum power density (MPD) from 176 to 135 mW/cm² at 600 °C. After 100 h of degradation testing for 275 mm-cell, the OCV decreases from 0.885 to 0.86 V and MPD drops from 151 to 82 mW/cm². However, impedance spectroscopy analysis reveals that only 5% of the reduction in power density is attributed to the GDC electrolyte. These findings highlight the potential of LPPS as a viable technique for preparing dense GDC electrolyte for MS-SOFC.