Stability study on a novel micro structure configuration of cathode contact layer for solid oxide fuel cell stack

A novel structure layer of the cathode contact materials LaCo0.6Ni0.4O3−δ (LCN) containing fine particles layer and coarse particles layer is designed to compare with the conventional structure layer in the condition of thermal cycle from 200 °C to 750 °C. The thermal expansion measurements of LCN in different particle sizes are investigated to explore the strength matching about the thermal expansion coefficient (TEC) and sintering shrink between them and interconnect. For the novel structure of LCN layer, with a ferritic stainless steels SUS430 as the interconnect, the area specific resistance (ASR) of SUS430/LCN/SUS430 increase to 110 mΩ cm2 in 15 thermal cycles and remains stable in the following thermal cycles. The formation of the oxide scale on the surface of SUS430 which is negligible to the measured ASR depends on the oxygen partial pressure on the interface. With the novel structure of LCN as the cathode contact layer, the power density above 390 mW cm−2 is obtained at 750 °C at a current density of 500 mA cm−2 and the average degradation rate is 0.4% per cycle in the following thermal cycle test and the degradation tends to more stable with the times of thermal cycle increase.