Bimodally integrated anode functional layer for lower temperature solid oxide fuel cells
Here we demonstrated a simple low-cost approach to dramatically increase the power density of solid oxide fuel cells (SOFCs) using an improved anode functional layer (AFL) structure. By infiltrating a very small amount (∼2 wt%) of Ni and Gd0.1Ce0.9O1.95(GDC) precursor solution into a submicron-sized, colloidally deposited AFL, a high power density cost-effective bimodally integrated AFL (BI-AFL) was produced. Microstructural analysis of this BI-AFL revealed that the superimposed ultra-fine features surrounding a submicron Ni–GDC particulate structure remained even after high temperature sintering. Applying this BI-AFL on an anode-supported SOFC yielded a maximum power density (MPD) of ∼1.2 W cm−2 at 600 °C, a ∼3× increase compared to SOFC without an AFL. Electrochemical impedance results showed a striking decrease in both ohmic and non-ohmic electrode area specific resistances (ASR) compared to SOFCs with either no AFL or a conventional AFL. The effect of the BI-AFL structure on improving SOFC performance was even greater at lower temperature. These results indicate that a network structure with bimodal particle size distribution in the AFL dramatically increased triple phase boundary (TPB) length and enhanced the interfacial contact between anode and electrolyte.