CALPHAD accelerated design of advanced full-Zintl thermoelectric device

Abstract

Since thermoelectric materials have different physical and chemical properties, the design of contact layers requires dedicated efforts, and the welding temperatures are distinctly different. Therefore, a general interface design and connection technology can greatly facilitate the development of thermoelectric devices. Herein, we proposed a screening strategy for the contact materials based on the calculation of phase diagram method, and Mg₂Ni has been identified as a matched contact layer for n-type Mg₃Sb₂-based materials. And this screening strategy can be effectively applied to other thermoelectric materials. By adopting the low-temperature sintering silver nanoparticles technology, the Zintl phase thermoelectric device can be fabricated at low temperature but operate at medium temperature. The single-leg n-type Mg_3.15Co_0.05SbBi_0.99Se_0.01 device achieves an efficiency of ~13.3%, and a high efficiency of ~11% at the temperature difference of 430 K has been realized for the Zintl phase thermoelectric device comprised together with p-type Yb_0.9Mg_0.9Zn_1.198Ag_0.002Sb₂. Additionally, the thermal aging and thermal cycle experiments proved the long-term reliability of the Mg₂Ni/Mg_3.15Co_0.05SbBi_0.99Se_0.01 interface and the nano-silver sintering joints. Our work paves an effective avenue for the development of advanced devices for thermoelectric power generation.

Based on the CALPHAD method, authors propose an effective screening strategy for thermoelectric contact materials, realizing a high efficiency of ~11% (at ∆T = 430 K) for the full-Zintl phase thermoelectric device.