Inorganic thermoelectric materials: A review

The binary skutterudite CoSb3 is a narrow bandgap semiconductor thermoelectric (TE) material with a relatively flat band structure and excellent electrical performance. However, thermal conductivity is very high because of the covalent bond between Co and Sb, resulting in a very low ZT value. Therefore, researchers have been trying to reduce its thermal conductivity by the different optimization methods. In addition, the synergistic optimization of the electrical and thermal transport parameters is also a key to improve the ZT value of CoSb3 material because the electrical and thermal transport parameters of TE materials are closely related to each other by the band structure and scattering mechanism. This review summarizes the main research progress in recent years to reduce the thermal conductivity of CoSb3-based materials at atomic-molecular scale and nano-mesoscopic scale. We also provide a simple summary of achievements made in recent studies on the non-equilibrium preparation technologies of CoSb3-based materials and synergistic optimization of the electrical and thermal transport parameters. In addition, the research progress of CoSb3-based TE devices in recent years is also briefly discussed.

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A review of CoSb3-based skutterudite thermoelectric materials

Progress and Perspective: Soft Thermoelectric Materials for Wearable and Internet-of-Things Applications

High thermoelectric figure of merit in mesostructured In0.25Co4Sb12 n-type skutterudite

The uniform dispersion of nanoparticles in bulk materials is one of the promising ways of enhancing thermoelectric properties through increased phonon scattering at the interfaces. The influence of...

https://pubs.acs.org/doi/pdf/10.1021/acsaem.9b01851

Enhanced Thermoelectric Properties of In-Filled Co4Sb12 with InSb Nanoinclusions

Thermoelectric generators (TEGs) offer a versatile solution to convert low-grade heat into useful electrical power. While reducing the length of the active thermoelectric legs provides an efficient strategy to increase the maximum output power density pmax, both the high electrical contact resistances and thermomechanical stresses are two central issues that have so far prevented a strong reduction in the volume of thermoelectric materials integrated. Here, it is demonstrated that these barriers can be lifted by using a nonconventional architecture of the legs which involves inserting thick metallic layers. Using skutterudites as a proof-of-principle, several single-couple and multi-couple TEGs with skutterudite layers of only 1 mm are fabricated, yielding record pmax ranging from 3.4 up to 7.6 W cm−2 under temperature differences varying between 450 and 630 K. The highest pmax achieved corresponds to a 60-fold increase per unit volume of skutterudites compared to 1 cm long legs. This work establishes thick metallic layers as a robust strategy through which high power density TEGs may be developed.

/pdf/high-power-density-thermoelectric-generators-with-3mq0zrlczq.pdf

High Power Density Thermoelectric Generators with Skutterudites

Mesostructured thermoelectric Co1−yMySb3 (M = Ni, Pd) skutterudites

Thermoelectric properties in double-filled Ce0.3InyFe1.5Co2.5Sb12 p-type skutterudites

The skutterudite materials belonging to the CoSb3 family are widely studied for thermoelectric applications. They are typically used under vacuum, but applications under oxidizing environments are increasingly considered. The addition of ytterbium is known to enhance the thermoelectric properties of CoSb3, but the corresponding impact on the oxidation behavior of the skutterudite material is barely explored. For that purpose, the present research describes the oxidation behavior of Yb0.2Co4Sb12 under a flow of air at 800 K for 15, 50, 100, and 1000 hours. The oxidation treatment induces the growth of a surface layer made of three oxides in various amounts as a function of the oxidation time. The spinel oxide CoSb2O4/CoO·Sb2O3 and CoSb2O6 are observed from 15 hours of oxidation, whereas Sb2O4 is formed only from 100 hours of treatment. To assess the impact of ytterbium, the oxidation behavior of Yb0.2Co4Sb12 is compared to that of CoSb3 oxidized in the same experimental conditions. The results show that the low amount of ytterbium promotes the oxidation reactions of the skutterudite material. Nonetheless, the impact on the degradation of the material remains acceptable to use Yb0.2Co4Sb12 for thermoelectric applications under oxidizing environments.

https://hal.archives-ouvertes.fr/hal-03409569/document

M. Benyahia

Papers

High thermoelectric figure of merit in mesostructured In0.25Co4Sb12 n-type skutterudite

High Power Density Thermoelectric Generators with Skutterudites

Mesostructured thermoelectric Co1−yMySb3 (M = Ni, Pd) skutterudites

Thermoelectric properties in double-filled Ce0.3InyFe1.5Co2.5Sb12 p-type skutterudites

Oxidation Behavior of the Skutterudite Material Yb0.2Co4Sb12