Mechanisms of performance degradation induced by thermal cycling in solid oxide fuel cell stacks with flat-tube anode-supported cells based on double-sided cathodes

Abstract

In this work, the degradation in output power of a stack with flat-tube anode-supported cells based on double-sided cathodes and its mechanism are studied. After 102 thermal cycles, the OCV keeps about 1.1 V and remains stable, showing that the one-cell stack exhibits a good sealing performance. During the first 100 thermal cycles, when the temperature ranges from 750 to 200 °C with a heating/cooling rate of 3 °Cmin−1, the stack degradation mainly occurs during the first 34 thermal cycles, and the degradation rate is ~0.89%/cycle. During the 101th and 102nd thermal cycles, an additional loading force is applied on the cathode side of the stack at room temperature, and the results shows that the output power at 750 °C increases and finally exceeds the initial output. As a result, the primary cause for degradation induced by thermal cycling is believed to originate from the weak interface between the cathode and the interconnect, resulting in an increase in ohmic resistance. The stack degradation can therefore be recovered by a secondary loading force on the cathode side.