A novel method for suppressing thermal stress in high-temperature thermoelectric modules

Thermoelectric (TE) module enabling direct conversion of thermal energy into electrical energy, is characterized by its static operation, maintenance-free nature, and high reliability. It serves as a critical core component in high-temperature waste heat recovery systems and radioisotope TE generators. Half-Heusler (HH) alloy, with its excellent mechanical properties and high-temperature stability, holds potential for application in such modules. To ensure long-term stable operation of HH TE module under high temperatures, the selection of an appropriate diffusion barrier layer is essential. However, the introduction of the barrier layer intensifies thermal stress, leading to cracks on the TE legs. To address the thermal stress issue, this study proposes a novel method of filling the gaps between TE legs (FGT-Method) for thermal stress suppression. Simulations demonstrate that this approach improves the thermal stress distribution within the TE legs, reducing the maximum thermal stress to less than 70 % of that without the filler. Aging tests on TE module reveal that modules fabricated using the FGT-Method maintain stable TE leg resistance during aging, with only a slight decline in output performance. The filler effectively mitigates the impact of thermal stress in high-temperature TE module. This study provides valuable insights for the fabrication of high-temperature TE module.