Toughening Thermoelectric Materials: From Mechanisms to Applications

Abstract

With the tendency of thermoelectric semiconductor devices towards miniaturization, integration, and flexibility, there is an urgent need to develop high-performance thermoelectric materials. Compared with the continuously enhanced thermoelectric properties of thermoelectric materials, the understanding of toughening mechanisms lags behind. Recent advances in thermoelectric materials with novel crystal structures show intrinsic ductility. In addition, some promising toughening strategies provide new opportunities for further improving the mechanical strength and ductility of thermoelectric materials. The synergistic mechanisms between microstructure-mechanical performances are expected to show a large set of potential applications in flexible thermoelectric devices. This review explores enlightening research into recent intrinsically ductile thermoelectric materials and promising toughening strategies of thermoelectric materials to elucidate their applications in the field of flexible thermoelectric devices.

Low-Cost Magnesium-Based Thermoelectric Materials: Progress, Challenges, and Enhancements

“…Inorganic TE semiconductor materials are brittle due to the crystalline structure, which contains intrinsic ionic, covalent, and/or van der Waals bonds, allowing easy cleavage along the ab-plane. 67 As shown in Figure 3 a, we found that the Mg 2 Si 0.4 Sn 0.6 pellet were very easy to break after sintering if not controlled properly due to its low mechanical strength. TE materials are typically polycrystalline samples produced through melting or powder metallurgy methods, which inevitably contain a high concentration of defects or flaws, leading to reduced mechanical strength.…”

“…Inorganic TE semiconductor materials are brittle due to the crystalline structure, which contains intrinsic ionic, covalent, and/or van der Waals bonds, allowing easy cleavage along the ab-plane . As shown in Figure a, we found that the Mg 2 Si 0.4 Sn 0.6 pellet were very easy to break after sintering if not controlled properly due to its low mechanical strength.…”

High-Entropy Engineering in Thermoelectric Materials: A Review

“…The mechanical behavior of TE devices and materials depends largely on the microstructure, composition, phase purity, grain size, and phase stability at high temperatures. Recently, the incorporation of architected structures has been utilized to improve the toughening mechanisms of TE alloys [58,114,115]. However, more studies are required to draw constructive conclusions about high-entropy TE materials.…”

“…Mechanical properties play a crucial role in determining their lifespan, making them a highly sought-after technology. Conventional TE alloys' mechanical properties have been extensively studied and documented in the literature [57][58][59][60][61][62].…”

New Nanofibrous Structured CsAg5Te3 Exhibiting Ultralow Thermal Conductivity and High Figure of Merit

“…Thermoelectric (TE) materials can convert heat energy into electricity and vice versa. − Their conversion efficiency can be evaluated by the dimensionless figure of merit zT , given by zT = S 2 σ T /κ, where S , σ, T , and κ represent the Seebeck coefficient, electrical conductivity, absolute temperature, and thermal conductivity, respectively . The lattice contribution κ l and the electronic contribution κ e determine thermal conductivity.…”