Optimizing ammonia-fueled planar SOFCs for low-temperature operation: Multiphysics simulation and performance sensitivity analysis

Ammonia, a carbon-neutral compound and one of the largest chemical products globally, has emerged as a promising clean energy source for ships, offering advantages in terms of both economic viability and safety compared to hydrogen. However, using ammonia as a fuel in solid oxide fuel cells (SOFCs) poses challenges due to the high operating temperatures, which cause thermal stress and reduce the lifespan of the cells. Lowering the operating temperature to increase cell lifespan leads to decreased reaction rates, increased electrolyte losses, and anodic nickel-based nitridation, all of which negatively impact cell performance. To address these issues, this study employs a comprehensive evaluation and enhancement analysis of low-temperature ammonia-fuelled planar SOFCs using a multi-physics model. The results show that when the operating temperature is reduced from 800 degrees C to 700 degrees C, the thermal stress at the entrance and exit sides of the electrolyte layer, where the maximum thermal stress occurs, decreases by 12.62 % and 14.37 %, respectively. The average concentration of ammonia at the anode increases by 56.57 %, and the range of ammonia-nickel interaction at the electrode-fuel channel interface expands, leading to an enhancement of nickel-based nitridation. To mitigate this power density loss and improve cell lifespan, two methods are explored: reducing electrolyte thickness and using gadolinium-doped ceria (GDC) as the electrolyte material. Both approaches significantly reduce ohmic losses resulting from temperature reduction, resulting in a remarkable improvement of 65.61 % and 77.25 % respectively in the output performance of SOFCs.