Optimizing the Reliability of Bi₂Te₃-Based Thermoelectric Generators with Asymmetric Structures under Large Temperature Difference

The thermoelectric (TE) recovery technology for industrial waste heat is crucial for improving energy utilization efficiency. Currently, commercial Bi2Te3-based thermoelectric generators (TEGs) show significant reliability issues when operating under large temperature differences (Th > 200 °C, ΔT > 150 °C). This is primarily due to the accumulation of interfacial thermal stress resulting from traditional rigid structural designs and material degradation at high temperatures. In this work, we improve two TEG structures: B-TEG (symmetrically modified with thermal conductive adhesive) and C-TEG (asymmetric design using arc-sprayed Zn/Al electrodes). Finite element simulations indicate that under thermal shock (from 100 °C to 250 °C), B-TEG can reduce interfacial stress by 78% compared to traditional rigidly bonded TEGs (A-TEG). Excellent stability was confirmed through 2000 thermal cycles and 1000 h of aging tests. The AC resistance (ACR) change rate of C-TEG is only 0.90%, outperforming B-TEG (1.28%) and A-TEG (which experienced 100% failure). Microstructural analysis (SEM/TEM) confirms that the arc-sprayed Ni layer forms an active NiBi3 phase at the interface, effectively suppressing crack propagation and interelement diffusion. The asymmetric design of C-TEG, combined with scalable arc spraying manufacturing, provides a robust solution for enhancing TEG reliability in extreme thermal environments.