Gd0.1Ce0.9O1.95/Er0.4Bi1.6O3 bilayered electrolytes fabricated by a simple colloidal route using nano-sized Er0.4Bi1.6O3 powders for high performance low temperature solid oxide fuel cells

Thin and dense bilayer electrolytes consisting of erbium stabilized bismuth oxide (ESB) and gadolinium-doped ceria (GDC) were fabricated on tape-cast porous Ni–GDC anode-supports using a scalable and cost-effective colloidal deposition process. Nano-sized ESB particles were successfully synthesized at temperatures as low as ∼500 °C using wet chemical co-precipitation. Due to the high sinterability of this powder, dense ESB layers were obtained at a sintering temperature of 800 °C. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis of a full button cell with an ESB/GDC bilayer sintered at 800 °C showed no visible interfacial diffusion between each layer. A systematic study on the sintering behavior of ESB revealed that at higher sintering temperatures, bismuth oxide can sublime or penetrate into the GDC sublayer. The effect of both the ESB layer and the GDC layer thickness on increasing open circuit potential (OCP) was demonstrated. The current–voltage measurement of the cell showed high power density (∼1.5 W cm−2) at 650 °C due to the increase in OCP and a significant reduction in area specific resistance when compared to solid oxide fuel cells (SOFCs) with a single GDC layer. These results demonstrate that ESB/GDC bilayer electrolytes have significant potential for high performance SOFCs at low operational temperature.

► We fabricate ceria/bismuth oxide bilayered electrolytes using a cost-effective colloidal process.
► Co-precipitated nano-sized ESB powder demonstrates increased sinterability.
► The effect of layer thickness in ESB/GDC bilayered electrolytes on the OCP.
► A SOFC with an ESB/GDC electrolyte yields a high performance of ∼1.5 W cm−2 at 650 °C.