Recent Achievement of Degradation Analyses in Japanese National Project: High Efficiency and Dynamic Operation Effects on the Durability of SOFC Stacks

To achieve high efficiency of 65% LHV in the solid oxide fuel cells (SOFCs), the fuel utilization should increase to the level of over 80%, which is 10-15% higher fuel utilization (Uf) than the standard condition, and severe degradation can occur at the component materials. When the current density is controlled in the stack level, there might be the distribution of fuel utilization in the cells due to the distribution of fuel gas, water vapor pressures, and temperatures. So far, many studies were examined on the clarification of degradation mechanism under fuel cell operation. In this report, recent achievements of the Japanese national projects (NEDO projects) are presented, especially on the rapid evaluation methods for degradation (2018-2019) and most recent “Development of advanced evaluation and analysis technologies for the durability of Solid Oxide Fuel Cells stacks (2020-)”. Especially, the anode durability was discussed with different kinds of cell-stack geometry at high fuel utilization. The degradation mechanism and fuel utilizations are compared at the planer and flat tubular type cell-stacks. We discussed the microstructure change and stability of the Ni-YSZ cermet anode at high Uf and current density conditions.