Viscous flow of Co-doped Gd_0.1Ce_0.9O_2-δ electrolytes for low-temperature densification of thin layers in metal-supported solid oxide fuel cells

A major challenge in the development of Metal-supported solid oxide fuel cells (MS-SOFCs) is achieving a fully densified electrolyte while staying within the temperature limits that the metal substrate can withstand. This study investigates the impact of Co doping on the sintering behavior of Gd_0.1Ce_0.9O_2-δ (GDC) and its application in MS-SOFCs. The study identifies the formation of a low-melting-point Co–Ce-Gd-O phase as a key factor that facilitates viscous flow. HRTEM results reveal slight Co aggregation at the grain boundaries, indicating that Co doping enhances intergranular element diffusion and particle sliding. This effect contributes to a significant reduction in the onset sintering temperature by over 300 °C. The 1CoGDC electrolyte exhibits high ionic conductivity of 1.01 × 10⁻² S cm⁻¹ at 550 °C, highlighting its advantages at intermedium-low temperature. Notably, the MS-SOFCs is fabricated through screen printing with 25 μm in thickness of 1CoGDC electrolyte at sintering temperature of 1050 °C. The MS-SOFCs exhibits an open circuit voltage of 0.90V at 650 °C and showed high power density of 502.44 mW cm⁻² under hydrogen as the anode fuel and flowing air at the cathode, the remarkable voltage clearly demonstrates the gas-tightness of the GDC electrolyte. Furthermore, the cell performance remained stable after 120 h long-term operation, demonstrating 1CoGDC electrolyte appear outstanding performance and potential application in MS-SOFCs.