Exceptionally Heavy Doping Boosts the Performance of Iron Silicide for Refractory Thermoelectrics

Abstract

Thermoelectric (TE) power generation is expected to be one of the most effective solutions to convert industrial exhaust heat to electricity for conserving fossil energy and reducing carbon emissions. However, its real application is obstructed decisively by the weakness of the service stability of state‐of‐the‐art TE materials at high temperatures in air. Refractory iron silicide (β‐FeSi2) used to be widely investigated as TE materials, but the low zT has restricted its practical application and even made it almost vanish from TE research in recent years. Here, guided by theoretical calculation, ultrahigh solubility of Ir on the Fe sites of β‐FeSi2 is successfully realized. Doping 16% Ir elicits multi‐valley electrical conduction and phonon‐electron scattering, doubling the previous zT record of β‐FeSi2 to ≈0.6 at 1000 K. The TE properties of the obtained β‐FeSi2 are practically unchanged after thermal aging in air at 1173 K. The new conceptual electrode‐less β‐FeSi2‐based refractory module demonstrates considerable power density and stable power generation when it is burned by a gas flame in air. These results mark a step toward developing practical TE power generation technology for the recovery of industrial waste heat.

A robust thermoelectric module based on MgAgSb/Mg3(Sb,Bi)2with a conversion efficiency of 8.5% and a maximum cooling of 72 K

“…5 Many good TE materials, such as FeSi 2 , SiGe, and half-Heusler compounds, have peak zT values of 0.6 to 1.5 between 900 K and 1200 K, but only 0.1 to 0.3 at room temperature. [6][7][8][9] Despite their exceptional robustness and applicability for industrial waste heat recovery, these materials are only suitable for heat sources with much higher temperatures, e.g. 4700 K. The application of TE devices around room temperature is still dominated by Bi 2 Te 3 for more than half a century.…”

Efficiency Measurement and Modeling of a High‐Performance Mg2(Si,Sn)‐Based Thermoelectric Generator

“…Finally, the use of the CPM calculations is found to be reliable and beneficial for the evaluation of the performance of this TEG and as a valuable tool to identify room for improvement. [29,41,44,[59][60][61][62][63][64]…”

“…Empty symbols indicate toxic compounds. Data were taken from other studies [29,41,44,[59][60][61][62][63][64].…”

Thermoelectric Modules: Key Issues in Architectural Design and Contact Optimization

“…[155] These devices possess U-shaped geometry (Figure 15B) and FeSi 2 at elevated temperature makes a metallic bonding between the n-and p-type materials. [156] In Cassini space exploration mission, NASA employed SiÀ Ge alloy in radioisotope thermoelectric generators. 572 unicouples were joined electrically in series and thermally in parallel to tap the decay heat of Pu-238 into electrical power.…”

“…Fabrication of directly bonded p‐ and n‐type materials were realized using polycrystalline FeSi 2 which facilitates the operation of the devices at high temperature and in oxidizing environment [155] . These devices possess U‐shaped geometry (Figure 15B) and FeSi 2 at elevated temperature makes a metallic bonding between the n‐ and p‐type materials [156] . In Cassini space exploration mission, NASA employed Si−Ge alloy in radioisotope thermoelectric generators.…”