CALPHAD accelerated design of advanced full-Zintl thermoelectric device

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 Mg3.15Co0.05SbBi0.99Se0.01 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 Yb0.9Mg0.9Zn1.198Ag0.002Sb2. Additionally, the thermal aging and thermal cycle experiments proved the long-term reliability of the Mg2Ni/Mg3.15Co0.05SbBi0.99Se0.01 interface and the nano-silver sintering joints. Our work paves an effective avenue for the development of advanced devices for thermoelectric power generation.

SEM images and EDS line scanning results for Mg2Ni/ Mg3.15Co0.05SbBi0.99Se0.01junction.Characterizations of Mg2Ni contact materials.(a) SEM image of sintered Mg2Ni bulk and (b) XRD patterns of bulk and powders.The calculated phase diagram.(a) The isothermal section at 773 K of the Ni-Mg-Sb ternary phase diagram.Calculated vertical section of (b) Ni-Mg3Sb2 and (c
The calculated phase diagram in this work and the experimental results.The isothermal sections of (a) Mg-Sb-Fe ternary phase diagram at 673 K and (d) Pb-Te-Fe ternary phase diagram at 773 K. Calculated vertical sections of (b) 70Fe30Sb-Mg3Sb2 and (e) 70Fe30Te-PbTe.Surface morphology and measured contact resistivity (ρc) of (c) 70Fe30Sb/Mg3Sb2 and (f) 70Fe30Te/PbTe junctions.
Design and characterization of the thermoelectric contact structures.Thermal expansion behavior of (a) Fe-Sb alloys and p-type Mg3Sb2 material, and (d) Fe-Te alloys and p-type PbTe material.SEM images and EDS mapping results of (b) 70Fe30Sb/Mg3Sb2 junctions and (e) 70Fe30Te/PbTe junctions after 800 hours aging.Corresponding changes in ρc of (c) 70Fe30Sb/Mg3Sb2 junctions and (f) 70Fe30Te/PbTe junctions with different aging time.Measured properties of n-Zintl single-leg module.Currentdependent (a) output voltage, (b) output power, (c) heat flow, and (d) efficiency for the single-leg device under different temperature gradients.
Simulated properties of the n-Zintl single-leg module.Currentdependent (a) output voltage, (b) output power, (c) heat flow, and (d) efficiency for the single-leg device under different temperature gradients.
Thermal aging test results for n-Zintl single-leg module.Showing changes in (a) output voltage, (b)output power, (c) heat flow, and (d) conversion efficiency as a function of the aging time.
Comparison of thermoelectric performance [69-85] and simulated conversion efficiency of p-type TE materials.(a) zT and (b) finite-element-simulated maximum efficiency of 18 different p-type TE candidates.Simulated properties of the p-Zintl single-leg module.Currentdependent (a) output voltage, (b) output power, (c) heat flow, and (d) efficiency for the single-leg device under different temperature gradients.
Measured properties of p-Zintl single-leg module.Currentdependent (a) output voltage, (b) output power, (c) heat flow, and (d) efficiency for the single-leg device under different temperature gradients.