Structure Optimization and Multi-frequency Phonon Scattering Boosting Thermoelectrics in Self-Doped CoSb₃-Based Skutterudites

Abstract

The utilization of thermoelectric devices that directly convert waste heat to electricity is an effective approach to alleviate the global energy crisis. However, the low efficiency of thermoelectric materials has puzzled the widespread applications. The CoSb 3based skutterudites are favored by device integration due to the excellent thermal stability, while the development of pristine CoSb 3 materials is limited by the ultra-high thermal conductivity and the poor Seebeck coefficient. In this work, we demonstrate that both structural improvement and strong phonon interaction are realized simultaneously in Infilled CoSb 3 coordinated with excessive Sb. The extra Sb compensates the deficiency on the Sb 4 ring, improving the Seebeck coefficient, and cooperates with In to further advance the carrier concentration. Therefore, the structure optimization and chemical potential regulation maximize the electrical properties. Thermally, the residual InSb nanoparticles and partial In/Sb-alloying, along with vibration of In in voids, jointly shorten the multifrequency phonon relaxation time, leading to a dramatic decline in the lattice thermal conductivity. As a result, a maximum zT max of ∼1.27 at 650 K and an average zT avg of ∼0.9 from 300 to 750 K was obtained in In 1.4 Co 4 Sb 12 + 8%Sb, respectively. Our findings provide valuable guidance for the selection of CoSb 3 -based skutterudite dopants to achieve high-performance thermoelectric materials.

Preparing filled CoSb3 skutterudites at 500 °C by a self-reduction sol–gel route

“…[7][8][9] The typical synthesis methods require high temperature or high pressure. For example, the melting-annealing method requires a temperature of 1323 K, 10,11 while the high pressure method requires a pressure of at least 65 mPa. [12][13][14] These methods require high energy consumption and complex equipment for support, which limit the application of CoSb 3.…”

First Principle Investigations on Structural, Mechanical, Electronic, And Thermoelectric Properties of XCoP (XTi, Zr, Hf) Half Heusler Alloys for Energy Recovery Application

“…The best TE material is thought to have a high Seebeck coefficient, high electrical conductivity, and low thermal conductivity, where all three factors are reliant on one another. Till date, by considering the cost effectiveness, ease of material design and high figure of merit, different types of thermoelectric materials have been analyzed including Skutterudites, [4] Tetrahedrites, [5] Zintl Phases, [6] Clathrates, [7] Tellurides, [8] Sulphides, [9] Selenides, [10] Metal Chalcogenides, [11] Heusler Alloys (HA) etc. [12] The first principle calculations are very useful to discover highly efficient new thermoelectric materials.…”