Intrinsic Low Thermal Conductivity Research Articles

Promising thermoelectric performance in p-type AgBiSe2 doping with alkaline-earth metals

P-type AgBiSe2 is a promising thermoelectric material because of its intrinsic low lattice thermal conductivity and multiple valence band behavior. However, realizing high performance in p-type AgBiSe2 is challenging due to the doping bottleneck. In this work, the enhancement of thermoelectric performance for p-type AgBiSe2 has been successfully realized by adding an excess amount of Se and doping with alkaline-earth metals. We show that Ca or Mg doping at the Bi site effectively increases the room-temperature hole concentration and improves the electrical transport properties of p-type AgBiSe2. Combined with the intrinsic lower thermal conductivity, the maximum zT values of ∼0.74 and ∼0.63 at 448 K were achieved in AgBi0.98Ca0.02Se2 and AgBi0.98Mg0.02Se2, respectively. This work demonstrates a crucial strategy for improving the thermoelectric properties of p-type AgBiSe2-based materials.

Enhanced thermal conductivity and electrical insulation by patterned self-assembly of electrospun nanofibers

Low intrinsic thermal conductivity (TC) of polymer materials has severely limited their further applicability in electronic and electrical products. To enhance the TC, a strategy for constructing nanofiller-based thermal conductive networks by patterned self-assembly of electrospun nanofibers was first proposed in this paper. By selecting a regular metal mesh as the collector, the electrostatic field-induced directional deposition of nanofibers was achieved, thereby constructing interconnected heat transfer paths aligned in at least four directions. The in-plane TC of heat-pressed electrospun polyvinylidene fluoride (PVDF) nanofibers with 20 wt% loading of boron nitride nanosheets (BNNSs) can reach 7.27 W/(m·K). Electrical insulation of the PVDF/BNNS composites has also been confirmed, showing high volume resistivity and breakdown strength, which have increased by 460.0 % and 26.6 %, respectively, compared to pure PVDF. Finally, a double-layer composite film with waterproof and easy-cleaning characteristics was prepared for electronic device packaging. This simple and efficient preparation strategy for thermal conductive networks may bring new perspectives to thermal management applications.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

AbstractEpoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards.

High thermal conductivity in three-dimensional BN/epoxy composites by engineered favorable interfacial adhesion between BN sheets

Because of their excellent insulation performance and processing properties, polymers are widely used in electrical and electronic applications. However, their further applications are severely constrained by their extremely low intrinsic thermal conductivity. Boron nitride (BN), which has high thermal conductivity and ideal insulation properties, is commonly used as a filler for improving the thermal conductivity of polymers. However, the high chemical inertia of the surface of BN makes it difficult to achieve an interconnection of BN sheets when building a three-dimensional (3D) BN skeleton in a polymer. In this study, urea melt pore preparation (UMPP) was used to fabricate a 3D BN skeleton. Urea was infiltrated into the BN skeleton to minimize the interfacial thermal resistance among the BN flakes and to join BNs. When the volume of a BN is 10 %, the thermal conductivity of the BN/epoxy composites is 3.15 W/(m·K). When the BN volume is 80 %, the thermal conductivity of BN/epoxy can reach 13.65 W/(m·K), which is 6500 % of pure epoxy resin. Additionally, the skeleton exhibits a remarkable mechanical strength capable of supporting weights up to 50,000 times its own, which facilitates easier handling and operation. The electrical resistivity volume of the UMPP composite is as high as that of the pure epoxy, whereas the dielectric loss is lower than that of pure epoxy. This study provides a new method for reducing internal interface thermal resistance of a skeleton formed by thermal conductive fillers with high chemical inertia such as boron nitride.

Great Enhancement in the Seebeck Coefficient of PEDOT:PSS by Polaron Level Splitting via π–π Overlapping with Nonpolar Small Aromatic Molecules

AbstractOrganic thermoelectric (TE) materials are regarded as the next‐generation TE materials because of their merits including low cost, high mechanical flexibility, and low intrinsic thermal conductivity. However, their Seebeck coefficient is usually quite low. Herein, a new strategy is demonstrated to greatly enhance the Seebeck coefficient of poly(3,4‐ethylenedioxy‐thiophene):poly(styrenesulfonate) (PEDOT:PSS), which is the most popular TE polymer, through polaron level splitting via π–π overlapping with nonpolar small aromatic molecules including anthracene, naphthalene, and pyrene. Although these aromatic molecules are neither oxidizing nor reducing agent, they can greatly enhance the Seebeck coefficient of PEDOT:PSS films pre‐treated with dimethyl sulfoxide, acid, or acid then base, while they do not lower the electrical conductivity too much. Through such a treatment with anthracene, the Seebeck coefficient can be up to 45.5 µV K−1, and the ZT value can be up to 0.27. The enhancement is ascribed to the splitting of the lower polaron energy level of PEDOT, which is induced by the π–π overlapping between the aromatic compounds and conjugated PEDOT. This can shift up the Fermi level, thereby enhancing the Seebeck coefficient.

Isovalent co-alloying contributes to considerable improvement in thermoelectric performance of BiSe bulks with weak anisotropy

BiSe with intrinsic low thermal conductivity has considered as a promising thermoelectric (TE) material at nearly room temperature. To improve its low thermoelectric figure of merit (zT), in this work, Sb and Te isovalent co-alloying was performed and significantly optimized its TE property with weakly anisotropic characteristic. After substituting Sb on Bi sites, the carrier concentration is suppressed by introduction of Sb Se site defects, which contributes to the increased absolute value of Seebeck coefficient (|S|). Further co-alloying Te on Se of the optimized composition Bi0.7Sb0.3Se, the carrier concentration increased without affecting the |S| due to the enhanced effective mass, which leads to a highest power factor of 12.8 μW/(cm·K2) at 423 K. As a result, a maximum zT of ∼0.54 is achieved for Bi0.7Sb0.3Se0.7Te0.3 along the pressing direction and the average zT (zTave) (from 300 K to 623 K) are drastically improved from 0.24 for pristine BiSe sample to 0.45. Moreover, an energy conversion efficiency ∼4.0% is achieved for a single leg TE device of Bi0.7Sb0.3Se0.7Te0.3when applied the temperature difference of 339 K, indicating the potential TE application.

Impact of mobility and effective mass on the thermoelectric performance of Ni doped Cu2Se

Cu2Se, a liquid-like thermoelectric material, has shown tremendous promise in recent years due to its strong electrical properties and intrinsic low thermal conductivity, which might be optimized for future applications by engineering the performance of Cu ions. In the present study, the thermoelectric features of hydrothermally grown Cu2Se are modified by tuning the presence of nickel in the crystalline matrix. The approach of modifying electronic band structures has been explored to optimize carrier transports by balancing the competitive relationship between carrier mobility and effective mass in order to discover improvements in thermoelectric materials beyond nanostructures. Its exceptional thermoelectric performance stems from ultrahigh carrier mobility over the whole working temperature range, which is achieved by effectively modifying the transport parameters through Ni doping. The inclusion of nickel in the Cu2Se lattice at either substitutional or interstitial sites has a substantial influence on its thermal and electrical transport properties. A band sharpening caused by the presence of Ni in the lattice of Cu2Se tailored the carrier's effective mass, resulting in increased carrier mobility without compromising the carrier concentration. A simultaneous enhancement in the carrier concentration and carrier mobility is achieved due to the presence of Ni in the interstitial sites. A maximum power factor of 614 µW/mK2 is observed for the sample doped at 1.5 wt% Ni at 573 K. The lattice distortion and point defects caused by Ni substitution generated additional phonon scattering centers, resulting in a substantial decrease in thermal conductivity. The sample doped with 2 wt% Ni shows a maximum ZT value of 0.535 at 573 K, which is around 3 times higher than that of pristine Cu2Se. These findings show that nickel is a novel efficient dopant that may significantly increase the thermoelectric performance of Cu2Se via defect and band engineering.

High thermoelectric properties realized in polycrystalline (Ag, Ga) Co-doped SnSe via two-steps point defects modulation

Tin selenide materials have attracted much attention due to the intrinsic low thermal conductivity. However, the further application of SnSe materials is limited due to the poor electrical conductivity. Herein, a two-step doping process is employed on p-type polycrystalline SnSe materials to enhance the thermoelectric properties. It is found that the Sn0·98Ag0.01Ga0.01Se sample achieves a high ZT value of 1.53 at 823 K and a quite competitive ZTave value of 1.04 from 673 to 823 K. This is attributed to the associations of point defects, AgSn′, GaSn·, and Ga0, and nano-precipitates, SnGa4Se7, Ag9GaSe6 and AgGa1+δ. In those defects, AgSn′ acts as an accepter, which can conduce to enhancing the hole carrier concentration. Ga element doping astonishingly play dual-roles, in that it both faultlessly maintains the electrical transport properties and effectively decreases the thermal conductivity through the associations with the point defects, GaSn·, and Ga0, and nano-precipitates, SnGa4Se7, Ag9GaSe6 and AgGa1+δ. The method paves the way for achieving high thermoelectric properties in SnSe materials by the point defects engineering and nano-precipitates.

N-Type Thermoelectric AgBiPbS3 with Nanoprecipitates and Low Thermal Conductivity.

Thermoelectric sulfide materials are of particular interest due to the earth-abundant and cost-effective nature of sulfur. Here, we report a new n-type degenerate semiconductor sulfide, AgBiPbS3, which adopts a Fm3̅m structure with a narrow band gap of ∼0.32 eV. Despite the homogeneous distribution of elements at the scale of micrometer, Ag2S nanoprecipitates with dimensions of several nanometers were detected throughout the matrix. AgBiPbS3 exhibits a low room-temperature lattice thermal conductivity of 0.88 W m-1 K-1, owing to the intrinsic low lattice thermal conductivity of Ag2S and the effective scattering of phonons at nanoprecipitate boundaries. Moreover, compared to AgBiS2, AgBiPbS3 demonstrates a significantly improved weighted mobility of >16 cm2 V-1 s-1 at 300 K, leading to an enhanced PF of 1.6 μW cm-1 K-2 at 300 K. The superior electrical transport in AgBiPbS3 can be attributed to the high valley degeneracy of the L point (the conduction band minimum), which is contributed by the Pb s and Pb p orbitals. Further, Ga doping is found to be effective in modulating the Fermi levels of AgBiPbS3, leading to further enhancement of PF with a PFave of 2.7 μW cm-1 K-2 in the temperature range of 300-823 K. Consequently, a relatively high ZTave of 0.22 and a peak ZT of ∼0.4 at 823 K have been achieved in 3% Ga-doped AgBiPbS3, highlighting the potential of AgBiPbS3 as an n-type thermoelectric sulfide.

Realizing high thermoelectric performance in CeCl3-doped n-type SnSe polycrystals

SnSe is a promising thermoelectric material because of its intrinsic low lattice thermal conductivity. However, the inferior electrical transport properties restrict the thermoelectric performance of n-type SnSe polycrystals especially at lower temperature range. In this work, an effective strategy to enhance the performance of n-type SnSe polycrystals by CeCl3 doping is reported. CeCl3 doping increased both the carrier concentration and electrical conductivity. The high weighted mobility contributed to the high power factor over the whole temperature range. Combined with the reduced thermal conductivity, a peak zT of ∼1.3 at 823 K was obtained in SnSe0.92+1 mol% CeCl3 with an average zT of ∼0.36 in the temperature range of 300–773 K. This work suggests that CeCl3 doping is an effective way to optimize the thermoelectric properties of n-type SnSe polycrystals.

Room temperature high thermoelectric performance of Bi-based full-Heusler compounds CsxRb[formula omitted]Bi with strong anharmonicity

Bismuth-based compounds have been identified as a class of promising candidates for the realization of high-performance thermoelectrics, derived from their exceptional electrical conductivity and intrinsic low lattice thermal conductivity κL. Here, we employed first-principles calculations, self-consistent phonon theory, and compressive sensing technique in conjunction with the Boltzmann transport equation to investigate the anharmonic thermoelectric properties of full-heusler bismuth compounds CsxRb3−xBi. As the Cs content increases, the κL of CsxRb3−xBi decreases due to impurity scattering effects, and then increases. Among them, at 300 K, Rb3Bi has the largest κL of 0.69 Wm−1K−1, while Cs2RbBi has the smallest κL of 0.45 Wm−1K−1, both of which are lower than the κL of traditional bismuth-based thermoelectric materials. The ultralow κL originates from the strong lattice anharmonicity. In addition, the coexistence of high dispersion and flat band edges leads to high thermoelectric power factor at optimal doping concentration. As a result, the largest thermoelectric figure of merit ZT values of 2.59 (4.19) at 300 (500) K were obtained for CsRb2Bi at optimal hole doping level. These findings suggest that CsxRb3−xBi compounds are superior for thermal management and thermoelectric applications.

Thermally Conductive and Electrically Insulating Epoxy Composites Filled with Network-like Alumina In Situ Coated Graphene.

With the rapid development of the electronics industry, there is a growing demand for packaging materials that possess both high thermal conductivity (TC) and low electrical conductivity (EC). However, traditional insulating fillers such as boron nitride, aluminum nitride, and alumina (Al2O3) have relatively low intrinsic TC. When graphene, which exhibits both superhigh TC and EC, is used as a filler to fill epoxy resin, the TC of blends can be much higher than that of blends containing more traditional fillers. However, the high EC of graphene limits its application in cases where electrical insulation is required. To address this challenge, a method for coating graphene sheets with an in situ grown Al2O3 layer has been proposed for the fabrication of epoxy-based composites with both high TC and low EC. In the presence of a cationic surfactant, a dense Al2O3 layer with a network structure can be formed on the surface of graphene sheets. When the total content of Al2O3 and graphene mixed filler reached 30 wt%, the TC of the epoxy composite reached 0.97 W m-1 K-1, while the EC remained above 1011 Ω·cm. Finite element simulations accurately predicted TC and EC values in accordance with experimental results. This material, with its combination of high TC and good insulation properties, exhibits excellent potential for microelectronic packaging applications.

Lamellar Wood Sponge with Vertically Aligned Channels for Highly Efficient and Salt-Resistant Solar Desalination.

Solar-assisted interfacial evaporation is a promising approach for purifying and desalinating water. As a sustainable biomass material, wood has attracted increasing interest as an innovative substrate for solar desalination, owing to its intrinsic porous structure, high hydrophilicity, and low thermal conductivity. However, developing wood-based solar evaporators with high evaporation rates and excellent salt resistance still remains a significant challenge, owing to the absence of large pores with high interconnectivity in natural wood. Herein, by converting the honeycombed structure of natural wood into a lamellar architecture via structural engineering, we develop a flexible wood sponge with vertically aligned channels for efficient and salt-resistant solar desalination after surface coating with carbon nanotubes (CNTs). The special lamellar structure with an interlayer distance of 50-300 μm provides the wood sponge with faster water transport, lower thermal conductivity, and water evaporation enthalpy, thus achieving higher evaporation performances in comparison with the cellular structure of natural wood. Noteworthy, the vertically aligned channels of the wood sponge facilitate sufficient fluid convection and diffusion and enable efficient salt exchanges between the heating interface and the underlying bulk water, thus preventing salt accumulation on the surface. Benefiting from the distinctive lamellar structure, the developed wood-sponge evaporator exhibits exceptional salt resistance even in a hypersaline brine (20 wt %) during continuous 7-day desalination under 1 sun irradiation, with a high evaporation rate (1.38-1.43 kg m-2 h-1), outperforming most previously reported wood-based evaporators. The lamellar wood sponge may provide a promising strategy for desalinating high-salinity brines in an efficient manner.

Roles of concentration-dependent Cu doping behaviors on the thermoelectric properties of n-type Mg3Sb1.5Bi0.5

Large Seebeck coefficients induced by high degeneracy of conduction band minimum, and low intrinsic lattice thermal conductivity originated from large lattice vibrational anharmonicity render Mg3Sb2 as a promising n-type thermoelectric material. Herein, we demonstrated unique concentration-dependent occupation behaviors of Cu in Mg3.4Sb1.5Bi0.49Te0.01 matrix, evidenced by structural characterization and transport property measurements. It is found that Cu atoms prefer to enter the interstitial lattice sites in Mg3Sb2 host with low doping level (Mg3.4Sb1.5Bi0.49Te0.01 + x% Cu, x < 0.3%), acting as donors for providing additional electrons without deteriorating the carrier mobility. When x is larger than 0.3%, the excessive Cu atoms are inclined to substitute Mg atoms, yielding acceptors to decrease the electron concentration. As a result, the electrical conductivity of the Mg3.4Sb1.5Bi0.49Te0.01 + 0.3% Cu sample reaches 2.3 × 104 S/m at 300 K, increasing by 300% compared with that of the pristine sample. The figure of merit zT values in the whole measured temperature range are significantly improved by the synergetic improvement of power factor and reduction of thermal conductivity. An average zT ∼1.07 from 323 K to 773 K has been achieved for the Mg3.4Sb1.5Bi0.49Te0.01 + 0.3% Cu sample, which is about 30% higher than that of the Mg3.4Sb1.5Bi0.49Te0.01 sample.

Enhanced Thermoelectric Transport Properties of n -Type SnSe2 Polycrystalline Alloys by Te Doping

SnSe2, a layered posttransition metal chalcogenide, has attracted attention as a high-efficiency thermoelectric material owing to the intrinsic low thermal conductivity. Herein, a series of Sn S e 1 − x T e x 2 ( x = 0 , 0.025, 0.0375, 0.075, 0.1, and 0.125) samples was synthesized to examine the influence of Te doping on electrical, thermal, and thermoelectric properties of n -type SnSe2 alloys. Interestingly, carrier concentration and mobility were simultaneously increased for x = 0.025 and 0.0375. Therefore, electrical conductivity is increased for x = 0.025 and 0.0375 compared to that for the pristine sample, resulting in power factor increase to 0.25 mW/mK2 for x = 0.025 by 12% at 790 K. However, reductions in the electrical conductivity were observed for the samples with x &gt; 0.0375 due to the decrease in carrier mobility for x &gt; 0.0375 , resulting in the decrease of power factor. The lattice thermal conductivity slightly reduced for the doped samples owing to point defects of Te and vacancies originating from Te doping. Consequently, the thermoelectric figure of merit ( z T ) was increased to 0.45 and 0.49 for Sn(Se1.975Te0.025)2 ( x = 0.025 ) and Sn(Se1.9625Te0.0375)2 ( x = 0.0375 ) samples at 790 K, respectively, which was enhanced by 40% and 53% compared to that for undoped SnSe2. The enhanced electrical transport properties were validated by weighted mobility, density-of-state effective mass, and quality factor, and the reduction of the lattice thermal conductivity is analyzed by the Debye-Callaway model.

Re‐Doped p‐Type Thermoelectric SnSe Polycrystals with Enhanced Power Factor and High ZT &gt; 2

AbstractThermoelectric technology enables the direct interconversion between heat and electricity. SnSe has received increasing interest as a new promising thermoelectric compound due to its exceptionally high performance reported in crystals. SnSe possesses intrinsic low thermal conductivity as a congenital advantage for thermoelectric, but high thermoelectric performance can be hardly achieved due to the difficulty to realize efficient doping to raise its low carrier concentration to an optimal level. In this work, it is found that a series of rare earth elements are effective dopants for SnSe, which can greatly improve the electrical transport properties of p‐type polycrystalline SnSe. In particular, the remarkable enhancement in electrical conductivity and power factor is achieved by Na/Er co‐doping at 873 K. The lattice thermal conductivity is reduced due to the presence of abundant defects (dislocations, stacking faults, and twin boundaries). Consequently, a peak thermoelectric figure of merit ZT (2.1) as well as a high average ZT (0.77) are achieved in polycrystalline SnSe.

Record High Power Factor and Low Thermal Conductivity in Amorphous/PbTe/Amorphous Multiple Quantum Wells

AbstractQuantum well (QW) superlattice is one of the proposals to improve the thermoelectric properties and provide a rich platform for the next generation of thermoelectric device. Previous QW have two main challenges that need to be addressed: i) decrease the electron tunneling across the layers in the semiconductor‐based multiple QWs (MQW), and ii) decrease the thermal conductivity in the oxide‐based MQW. Herein, the study demonstrates amorphous based PbTe/amorphous‐STO MQWs with ultrahigh power factor of 40.9 µW cm−1 K−2and record low thermal conductivity of ≈0.49 W m−1 K−1at room temperature. The high performance of PbTe/amorphous‐STO MQWs is attributed to strong quantum confine effect and its intrinsic low thermal conductivity of amorphous superlattice structure. The results open up a new avenue toward modulating thermoelectric properties beyond traditional MQWs of thermoelectric materials.

Tuning band structure and texture for improved thermoelectric performance in BiSe

Layer-structured BiSe has emerged as a promising Te-free thermoelectric (TE) material because of its intrinsic low thermal conductivity. Herein we report the optimization of TE performance for BiSe through In doping to tune the band structure and the proper annealing treatment to adjust the texture. The first-principles calculations and doping experiments reveal that In dopant in BiSe introduces additional energy levels near Fermi level leading to the increase of carrier effective mass. The preferred orientation of (00l) plane in BiSe was well adjusted to optimize the electrical conductivity and Seebeck coefficient. Through tuning band structure and texture simultaneously, the Bi0.995In0.005Se sample exhibited a maximum figure of merit ZT value of 0.33 at 523 K, which is about 43.5 % higher than that of the pristine BiSe sample without the texture adjustment. This work presents a potential route to promote the TE performance of layer-structured materials.

Linking Interfacial Bonding and Thermal Conductivity in Molecularly-Confined Polymer-Glass Nanocomposites with Ultra-High Interfacial Density.

Thermal transport in polymer nanocomposites becomes dependent on the interfacial thermal conductance due to the ultra-high density of the internal interfaces when the polymer and filler domains are intimately mixed at the nanoscale. However, there is a lack of experimental measurements that can link the thermal conductance across the interfaces to the chemistry and bonding between the polymer molecules and the glass surface. Characterizing the thermal properties of amorphous composites are a particular challenge as their low intrinsic thermal conductivity leads to poor measurement sensitivity of the interfacial thermal conductance. To address this issue here, polymers are confined in porous organosilicates with high interfacial densities, stable composite structure, and varying surface chemistries. The thermal conductivities and fracture energies of the composites are measured with frequency dependent time-domain thermoreflectance (TDTR) and thin-film fracture testing, respectively. Effective medium theory (EMT) along with finite element analysis (FEA) is then used to uniquely extract the thermal boundary conductance (TBC) from the measured thermal conductivity of the composites. Changes in TBC are then linked to the hydrogen bonding between the polymer and organosilicate as quantified by Fourier-transform infrared (FTIR)and X-ray photoelectron (XPS)spectroscopy. This platform for analysis is a new paradigm in the experimental investigation of heat flow across constituent domains.

Dual-Porosity (Ta0.2Nb0.2Ti0.2Zr0.2Hf0.2)C High-Entropy Ceramics with High Compressive Strength and Low Thermal Conductivity Prepared by Pressureless Sintering

Porous (Ta0.2Nb0.2Ti0.2Zr0.2Hf0.2)C high-entropy ceramics (HEC) with a dual-porosity structure were fabricated by pressureless sintering using a mixture powder of ceramic precursor and SiO2 microspheres. The carbothermal reduction in the ceramic precursor led to the formation of pores with sizes of 0.4-3 μm, while the addition of SiO2 microspheres caused the appearance of pores with sizes of 20-50 μm. The porous HECs exhibit competitive thermal insulation (4.12-1.11 W·m-1 k-1) and extraordinary compressive strength (133.1-41.9 MPa), which can be tailored by the porosity of the ceramics. The excellent properties are ascribed to the high-entropy effects and dual-porosity structures. The severe lattice distortions in the HECs lead to low intrinsic thermal conductivity and high compressive strength. The dual-porosity structure is efficient at phonon scattering and inhabiting crack propagations, which can further improve the thermal insulation and mechanical properties of the porous HECs.