Advanced design strategies for highly efficient and durable anodes in direct ammonia solid oxide fuel cells

Ammonia is increasingly considered a promising zero-carbon hydrogen energy carrier owing to its favorable properties for storage, transport, and distribution. The direct utilization of ammonia in solid oxide fuel cells (SOFCs) has the potential to offer a highly efficient power source with high energy density. However, the poor stability and low catalytic activity of conventional Ni-based anodes for ammonia utilization significantly limit the performance and application of ammonia SOFCs. Here, we report the development of a new anode composed of exsolved nanoparticles from an Sr(Ti, Fe, Ru)O3-delta (STFR) perovskite structure and a catalytic iron layer (STFR + Fe), which considerably enhances activity and durability for ammonia utilization. The La0.8Sr0.2Ga0.8Mg0.2O3-delta electrolyte-supported cell with an STFR + Fe anode shows peak power densities of 1.25 W/cm(2) at 800 degrees C and 0.76 W/cm(2) at 700 degrees C with NH3 as fuel. These power densities surpass 85% of those achieved using H-2 as fuel and are significantly higher than those of cells with an Ni-Ce0.9Gd0.1O2-delta (Ni-GDC) anode (0.38 W/cm(2) at 700 degrees C). Additionally, the STFR-Fe anode demonstrates exceptional stability when operating at a constant voltage of 0.75 V at 800 degrees C. The current density of the cell exhibits a marginal decrease from 1.33 A/cm(2) to 1.32 A/cm(2) after 120 h of testing, corresponding to a degradation rate of 0.006%/h, which is substantially lower than that of the Ni-GDC cell (degradation rate 0.283%/h). This degradation rate is the lowest ever reported, highlighting the superior stability of the STFR + Fe anode system.