Temperature Equalization Design and Performance Optimization of Embedded High-Conductivity Thermal Bridges in Direct Ammonia Solid Oxide Fuel Cells

Direct ammonia solid oxide fuel cells (DA-SOFCs) are a promising carbon-free power generation technology, yet their large-scale application is limited by severe temperature nonuniformity and thermomechanical stresses caused by the coexistence of endothermic ammonia decomposition and exothermic electrochemical reactions at the anode. To gain a deeper understanding of the multiphysics field distribution within the cell, a three-dimensional coupled multiphysics numerical model of the direct ammonia fuel cell was developed and validated. The numerical simulation results reveal a temperature difference exceeding 70 °C between the inlet and outlet, as well as stress concentrations exceeding 200 MPa during high-current operation of the ammonia fuel cell. These factors pose a significant threat to the cell’s lifespan and stability. An integrated direct ammonia solid oxide fuel cell model incorporating high-conductivity thermal bridges was proposed to optimize the internal temperature distribution and alleviate stress concentrations. By embedding thermal bridges within the interconnect, the pronounced temperature gradients induced by the coexistence of endothermic ammonia decomposition and exothermic electrochemical reactions were effectively mitigated. Numerical results show that the thermal bridges reduce the inlet–outlet temperature difference by more than 50 °C, enhance current density by 5% and 14% at 700 °C and 750 °C, respectively, and decrease the average stress by over 10 MPa. Furthermore, a comparative analysis of different thermal bridge configurations indicates that the layout with ten thermal bridges achieves a more favorable stress distribution than those with four or six bridges. Overall, the proposed thermal bridge design offers a synergistic improvement in electrochemical performance and thermomechanical reliability, providing an effective pathway for the integrated design and scalable deployment of high-power DA-SOFC systems.