Significant Enhancement of Thermoelectric Figure of Merit in BiSbTe‐Based Composites by Incorporating Carbon Microfiber

Abstract

Bismuth telluride‐based materials are already being commercially developed for thermoelectric (TE) cooling devices and power generators. However, the relatively low efficiency, which is characterized by a TE figure of merit, zT, is the main obstacle to more widespread application. Significant advances in the TE performance have been made through boundary engineering via embedding nanoinclusions or nanoscale grains. Herein, an effective approach to greatly enhance the TE performance of p‐type BiSbTe material by incorporating carbon microfibers is reported. A high zT of 1.4 at 375 K and high average zT of 1.25 for temperatures in the range of 300 to 500 K is achieved in the BiSbTe/carbon microfiber (BST/CF) composite materials. Their superior TE performance originates from the low thermal conductivity and the relatively high power factor. A TE unicouple device based on the p‐type BST/CF composite material and the commercially available n‐type bismuth telluride‐based material shows a huge cooling temperature drop in the operating temperature range of 299–375 K, and is greatly superior to the unicouple device made of both commercial p‐type and n‐type bismuth telluride‐based material. The materials demonstrate a high average zT and excellent mechanical properties and are strong candidates for practical applications.

Electronic Topological Transition as a Route to Improve Thermoelectric Performance in Bi0.5Sb1.5Te3

“…To better highlight the advantages, we have compared our result with the representative p‐type Bi 0.5 Sb 1.5 Te 3 materials are shown in Figure 6b. [ 8,20,22,25–27,54–56 ] Clearly, the zT value of our Bi 0.5 Sb 1.5 Te 3 material at 300 K outperforms almost all the best reported materials and is comparable even to the best reported by Kim et al. [ 20 ] The pressure‐driven ETT turns out to be an effective way to tune the electronic structure for the improved TE properties while maintaining the same crystal structure.…”

“…b) The comparison of our obtained peak zT at room temperature with the other high‐ zT p‐type Bi 0.5 Sb 1.5 Te 3 materials. [ 8,20 ] [ 22,25–27 ] [ 54–56 ]…”

Recent Progress in Multiphase Thermoelectric Materials

“…The impedance mismatch between the PbTe and PbS rich phases in (Pb 0.95 Sn 0.05 Te) 1−x (PbS) x samples led to an inhibition of the heat flow, with the lattice thermal conductivity reaching 0.4 W•m −1 •K −1 for the sample with 8% PbS, an 80% reduction in the reported values for the bulk material [169]. In general, phonon scattering has proven to be an effective strategy to reduce the lattice thermal conductivity in multiphase lead telluride-based materials [170][171][172][173] and bismuth telluride-based [174][175][176] materials. For instance, nano-engineered multiphase PbTe-x% InSb compounds showed an exceptionally low minimum lattice thermal conductivity of ~0.3 W•m −1 •K −1 at ~770 K for 4% InSb and consequently a zT value of ~1.83 at 770 K [177].…”

Microstructure and thermoelectric properties of the medium-entropy block-textured BiSbTe1.5Se1.5 alloy

“…To texture the alloy being studied, spark plasma sintering (SPS) was applied. The SPS method is often applied to prepare various Bi 2 Te 3 -based materials with improved and governed thermoelectric properties [19,20,22,31,32].…”