Preliminary exploration of key technique for the application of thermoelectric SnTe in mid-temperature power generation

As a kind of environment-friendly mid-temperature thermoelectric materials, SnTe-based alloy has been widely studied in recent years, but so far, the module catering to mid-temperature power generation based on it has not been developed. In this work, on the basis of Mn-Li co-doping to optimize thermoelectric properties, we preliminarily explored the key technique for the fabrication of SnTe-based modules. A composite barrier layer of 304 stainless steel and Sn with high thermal stability, high bonding strength and low contact resistivity is developed. Transient liquid phase bonding is innovatively applied to the connection of hot end and realizes low-temperature connection and high-temperature service, which overcomes the difficulty that the traditional AgCu-based solder is invalid due to the volatilization of SnTe. A module containing two couples of p-type Sn_0.88Mn_0.12Li_0.01Te and n-type Yb_0.25Co₄Sb₁₂ is fabricated and demonstrates a decent efficient of ∼5.4% and a high output power density of ∼1.9 W cm² under a nominal temperature gradient of 530 K. This work not only promotes the application of SnTe-based materials in the field of mid-temperature power generation, but also provides a new avenue for the fabrication of other thermoelectric modules.