Effect of chemical reaction on the thermal resistances of nickel/yttria- stablized zirconia interfaces in hydrogen environment

JL Zhou and LH Zhang and HR Sun and J Zhang and Z Zhong, JOURNAL OF POWER SOURCES, 506, 230264 (2021).

DOI: 10.1016/j.jpowsour.2021.230264

The thermal stress caused by the interfacial thermal resistance (ITR) between Ni and yttria-stabilized zirconia (YSZ) is one of the major factors causing the destruction of solid oxide fuel cells (SOFCs). However, the complicated chemical reactions occurring in this Ni/YSZ interface make it difficult to study the ITR of Ni/YSZ interface by conventional simulations and experiments. By using the state of art reactive molecular dynamics simulations together with the modification of two-temperature model, ITRs of three typical Ni/YSZ interfaces under hydrogen-free condition and in hydrogen environment are investigated in this paper. The accuracy of the present simulation methods is verified by the transient thermoreflectance experiments. Our simulation results indicate that among different Ni/YSZ interface structures, the Ni100/YSZ100 interface possesses the largest ITR. Moreover, the ITR of Ni/YSZ interfaces is found to increase significantly as the temperature grows from room temperature to the working temperature of SOFCs. In hydrogen environment, a great enhancement is observed in the ITR of Ni/YSZ interfaces after chemical reaction, which becomes more significant as the hydrogen concentration increases. The enhanced ITR observed after chemical reaction mainly originates from the breaking of chemical bonds at Ni/YSZ interfaces and also the enhanced phonon mismatch between Ni and YSZ.

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