K and Mg Co-doped perovskite oxide for enhanced anode of direct ammonia protonic ceramic fuel cell

Ammonia (NH₃) is a promising fuel for protonic ceramic fuel cells (PCFCs) due to its favorable liquefaction conditions and high volumetric energy density. However, even state-of-the-art PCFC anodes show insufficient NH₃ decomposition activity at reduced temperatures, compromising PCFC power output and durability. In this study, we report a novel nickel-perovskite-type structured oxide cermet anode with an NH₃ decomposition activity that enables relatively high power output from direct NH₃-PCFCs at 600 °C. We co-dope K and Mg into a perovskite-type structured oxide to produce the Ba 0.95 K 0.05 (Zr 0.1 Ce 0.7 Y 0.1 Yb 0.1 ) 0.95 Mg 0.05 O 3- δ (BZCYYb-KMg) material, which facilitates the rate-limiting steps in NH₃ decomposition: hydrogen transport and nitrogen desorption. Consequently, our modified nickel-perovskite-type structured oxide cermet anode achieves 100% NH₃ conversion at 600 °C. When used as a PCFC anode, this material increased the power output of a PCFC using NH₃ fuel at 600 °C by 25% and lifetime by more than 15 times compared to PCFC containing the unmodified nickel-perovskite-type structured oxide cermet anode. • The K and Mg co-doped BZCYYb (BZCYYb-KMg) shows increased proton conductivity and facilitates N 2 desorption from the nickel cermet. • Ni + BZCYYb-KMg shows a 100% NH 3 conversion rate at 600 °C. • Ni + BZCYYb-KMg increases the power output of PCFCs by 25% when used as an anode at 600 °C relative to the unmodified anode. • The reversible reaction between Ni and NH 3 significantly changes the anode morphology.