Decoupling Anode Elementary Kinetics of Internal Cracking Ammonia-Fed Solid Oxide Fuel Cells toward Enhanced and Durable Performance

Internal cracking of ammonia as a fuel for solid oxide fuel cells (SOFCs) is an attractive option for ammonia-to-power systems, mitigating the kinetic limitations of ammonia conversion at anodes. The composite structure at the anode includes a cracking catalyst, a supporting layer, and triple phase boundary, involving complex coupled reaction processes and leading to an unclear understanding of the detailed reaction mechanism. Herein, elementary reaction modeling combined with experiments was employed to investigate the effect of elementary species, reaction partition, and catalyst properties and decouple the working principle in anode catalyst layer (ACL) modified NH3-SOFCs. The results demonstrate that the ACL dramatically boosts the ammonia decomposition reaction (ADR) rate at the anode by 102–103 times, leading to a significant increase in H(Ni) coverage (∼99.7%) and thus accelerating the charge transfer reaction (CTR) rate and NH3-SOFCs performance. The ACL effectively segregates the ADR and CTR regions at the anode, which not only promotes the ADR kinetics but also mitigates anode degradation. Moreover, beyond electrical conductivity, optimizing the ADR activity and fuel diffusion ability of the ACL is more critical for improving the NH3-SOFCs performance. Our work provides insights into the kinetics in ACL-modified NH3-SOFCs for improving their performance through optimization.