Direct ammonia-fueled solid oxide fuel cells: 3D-multiphysics modeling and experimental validation of the operation conditions on the cell performance

Ammonia is a promising carbon–neutral fuel for solid oxide fuel cells (SOFCs), but its direct use can cause degradation due to nitridation. Pre-cracking ammonia reduces this issue but increases system complexity and energy consumption. This study examines both direct and pre-cracked ammonia as fuels, focusing on cracking kinetics across various temperatures and flow rates (3.4 − 50 mL min⁻ 1 cm⁻2). A 3D multiphysics model is developed, incorporating mass transport, electrochemical reactions, and ammonia decomposition, and shows strong agreement with experimental data between 700 °C and 850 °C. Results indicate nearly complete ammonia decomposition (>99 %) above 700 °C, except at high flow rates, with additional cracking occurring outside the cell due to reactions with metallic components. At lower temperatures and higher flow rates, incomplete decomposition reduces performance and may lead to Ni nitridation. Although direct ammonia yields lower performance, efficiency improves with higher temperature and fuel utilization, highlighting the importance of optimizing operating conditions.