Slowing down the heat in thermoelectrics

Abstract

Heat transport has various applications in solid materials. In particular, the thermoelectric technology provides an alternative approach to traditional methods for waste heat recovery and solid‐state refrigeration by enabling direct and reversible conversion between heat and electricity. For enhancing the thermoelectric performance of the materials, attempts must be made to slow down the heat transport by minimizing their thermal conductivity (κ). In this study, a continuously developing heat transport model is reviewed first. Theoretical models for predicting the lattice thermal conductivity (κlat) of materials are summarized, which are significant for the rapid screening of thermoelectric materials with low κlat. Moreover, typical strategies, including the introduction of extrinsic phonon scattering centers with multidimensions and internal physical mechanisms of materials with intrinsically low κlat, for slowing down the heat transport are outlined. Extrinsic defect centers with multidimensions substantially scatter various‐frequency phonons; the intrinsically low κlat in materials with various crystal structures can be attributed to the strong anharmonicity resulting from weak chemical bonding, resonant bonding, low‐lying optical modes, liquid‐like sublattices, off‐center atoms, and complex crystal structures. This review provides an overall understanding of heat transport in thermoelectric materials and proposes effective approaches for slowing down the heat transport to depress κlat for the enhancement of thermoelectric performance.

PbmBi2S3+m Homologous Series with Low Thermal Conductivity Prepared by the Solution-Based Method as Promising Thermoelectric Materials

“…15 It is noteworthy that the lattice thermal conductivities κ Lat of both PbBi 2 S 4 and Pb 3 Bi 2 S 6 in this work are much lower than that of their "binary components" reported in the literature studies, such as PbS 13,28 and Bi 2 S 3 . 30 Furthermore, the lattice thermal conductivity κ Lat of PbBi 2 S 4 in this work reaches 0.4−0.5 W•m −1 • K −1 over a wide temperature range, which is nearly comparable to that of the advanced thermoelectric materials, 31 (m = 0, 1, 3) can be calculated by a combination of electrical and thermal transport properties using the formula zT = α 2 σT/κ total , as illustrated in Figure 9A. Thanks to a large power factor PF combined with a low thermal conductivity κ total , the zT of PbBi 2 S 4 increases with increasing temperature and finally reaches a maximum of 0.46 at 800 K. The zT value of PbBi 2 S 4 is more than twice that of Pb 3 Bi 2 S 6 (zT = 0.20 at 800 K).…”

“…It is noteworthy that the lattice thermal conductivities κ Lat of both PbBi 2 S 4 and Pb 3 Bi 2 S 6 in this work are much lower than that of their “binary components” reported in the literature studies, such as PbS , and Bi 2 S 3 . Furthermore, the lattice thermal conductivity κ Lat of PbBi 2 S 4 in this work reaches 0.4–0.5 W·m –1 ·K –1 over a wide temperature range, which is nearly comparable to that of the advanced thermoelectric materials, such as K-doped PbTe 0.7 S 0.3 (∼0.35 W·m –1 ·K –1 at 923 K) and Sn 0.83 Mn 0.17 Te (∼0.5 W·m –1 ·K –1 ).…”

Power generation and thermoelectric cooling enabled by momentum and energy multiband alignments

“…T hermoelectric materials are regarded as potential materials in energy technology because they can enable direct and reversible conversion between heat and electricity. Their applications include waste heat recovery and electronic refrigeration (1)(2)(3). The performance of a thermoelectric material is determined by the dimensionless figure of merit ZT, defined as ZT = (S 2 s/k)⋅T, where S, s, k, and T represent the Seebeck coefficient, electrical conductivity, thermal conductivity [i.e., the sum of the electronic (k ele ) and lattice (k lat ) thermal conductivities], and temperature in kelvin (4,5), respectively.…”

An Update Review on N-Type Layered Oxyselenide Thermoelectric Materials

“…where, C v and v a represent the specific heat capacity per unit volume and average sound speed, respectively. A highly intense phonon scattering process and decrease of κ lat in Ta-doped Bi 2 O 2 Se can be seen from monotonically reduced l ph from~11.9 Å for Bi 2 O 2 Se to~9.9 Å for Bi 1.90 Ta 0.10 O 2 Se, which mainly results from that Ta substitution introduces multi-scale lattice defects, including the enormous defects, grain boundaries, and phase interfaces [68,77].…”