Alloying engineering for thermoelectric performance enhancement in p-type skutterudites with synergistic carrier concentration optimization and thermal conductivity reduction

Abstract

The enhancements in thermoelectric (TE) performances of p-type skutterudites are usually limited due to the relatively low Seebeck coefficients owing to the higher carrier concentration and more impurity phases induced by inherent structural instability of a Fe-based skutterudite. As shown in this study, alloying engineering of Ni doping at Fe sites in a p-type CeFe 3.8 Co 0.2 Sb 12 skutterudite can not only reduce the impurity phases with high thermal conductivity but also regulate the carrier concentration, and thus significantly increase the Seebeck coefficient. The thermal conductivity was largely suppressed due to the enhanced point defect phonon scattering and decreased hole concentration. As a result, a TE figure of merit ZT of the CeFe 3.5 Ni 0.3 Co 0.2 Sb 12 sample reached 0.8, which is approximately 50% higher than that of a Ni-free sample. Appropriate Ni doping can maintain a high ZT at a high temperature by controlling the reduction in a band gap. Therefore, a high average ZT close to 0.8 at 650-800 K for CeFe 3.5 Ni 0.3 Co 0.2 Sb 12 was obtained, which was comparable to or even higher than those of the reported Ce-filled Fe-based skutterudites due to the synergistic optimization of electrical and thermal performances. This study provides a strategy to synergistically optimize electrical-thermal performances of the p-type skutterudites by alloying engineering.

High-performance flexible p-type Ce-filled Fe3CoSb12 skutterudite thin film for medium-to-high-temperature applications

“…Ce has been proven to be an excellent candidate filler for skutterudite due to its outstanding performance and low cost in bulk materials. Therefore, the synergistic control of Ce-filling and Fe-substitution for Co aims to regulate the p-type thermoelectric performance of the pristine CoSb 3 38 , 39 , 42 – 47 . To validate this concept, first-principles calculations were performed in this work.…”

Optimizing Thermoelectric Performance of Tellurium via Doping with Antimony and Selenium

“…The efficacy of TE devices in converting heat into electricity is primarily influenced by the dimensionless figure of merit, denoted as ZT = S 2 T/ρκ, where S, ρ, and T represent the Seebeck coefficient, electrical resistivity, and absolute temperature, respectively. Additionally, κ is the total thermal conductivity, comprising both electronic (κ e ) and phonon (κ ph ) thermal conductivities [6][7][8][9]. The optimization of ZT is constrained by the significant trade-off correlation observed between S, ρ, and κ as predicted by the Boltzmann transport theories and the Wiedemann-Franz relationship [10].…”