An efficient multi-layer TEG with thermal-electrical interfaces for Mars rover RTGs

The radioisotope is the most promising power supply technology for Mars exploration and the thermoelectric generator (TEG) is the key component that convert the heat from isotope decay into electrical energy. However, the crucial drawback of current TEGs is the low conversion efficiency due to the limited operating temperature range for thermoelectric (TE) materials. In this work, a multi-layer TEG consists of high-, mid- and low-temperature TE materials is formulated with optimal operating conditions for each layer to improve the conversion efficiency. A two-scale contact model is established to clarify the thermal-electrical interfacial effects between multiple layers. In the roughness-scale, the thermal and electrical contact resistances under interfacial Martian atmosphere clearance are numerically calculated and compared with the vacuum, Earth's atmosphere, and silver-epoxy adhesive ones, the influence of pressure and temperature are clarified and the numerical results are experimentally validated. In the TEG-scale, the contact effect is equivalent to an additional layer and considered in the structural optimization with the objective of maximum gravimetric power density under typical isotope decay heat conditions. A typical TEG is fabricated and the numerical model is validated by the experimental measured voltage. The optimal TEG for Martian environment is finally obtained with conversion efficiency of 8.444%.