K and Mg Co-doped perovskite oxide for enhanced anode of direct ammonia protonic ceramic fuel cell
Desheng Feng, Tianjiu Zhu, Mengran Li, Vanessa K. Peterson, Hesamoddin Rabiee, Beibei Ma, Zhonghua Zhu
Abstract
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.