Ultralow Thermal Conductivity Research Articles

Hydrophobic Silk Fibroin–Agarose Composite Aerogel Fibers with Elasticity for Thermal Insulation Applications

Aerogel fibers, characterized by their ultra-low density and ultra-low thermal conductivity, are an ideal candidate for personal thermal management as they hold the potential to effectively reduce the energy consumption of room heating and significantly contribute to energy conservation. However, most aerogel fibers have weak mechanical properties or require complex manufacturing processes. In this study, simple continuous silk fibroin–agarose composite aerogel fibers (SCAFs) were prepared by mixing agarose with silk fibroin through wet spinning and rapid gelation, followed by solvent replacement and supercritical carbon dioxide treatment. Among them, the rapid gelation of the SCAFs was achieved using agarose physical methods with heat-reversible gel properties, simplifying the preparation process. Hydrophobic silk fibroin–agarose composite aerogel fibers (HSCAFs) were prepared using a simple chemical vapor deposition (CVD) method. After CVD, the HSCAFs’ gel skeletons were uniformly coated with a silica layer containing methyl groups, endowing them with outstanding radial elasticity. Moreover, the HSCAFs exhibited low density (≤0.153 g/cm3), a large specific surface area (≥254.0 m2/g), high porosity (91.1–94.7%), and excellent hydrophobicity (a water contact angle of 136.8°). More importantly, they showed excellent thermal insulation performance in low-temperature (−60 °C) or high-temperature (140 °C) environments. The designed HSCAFs may provide a new approach for the preparation of high-performance aerogel fibers for personal thermal management.

Silver Copper Chalcogenide Thermoelectrics: Advance, Controversy, and Perspective.

Thermoelectric technology, which enables a direct and pollution-free conversion of heat into electricity, provides a promising path to address the current global energy crisis. Among the broad range of thermoelectric materials, silver copper chalcogenides (AgCuQ, Q = S, Se, Te) have garnered significant attention in thermoelectric community in light of inherently ultra-low lattice thermal conductivity, controllable electronic transport properties, excellent thermoelectric performance across various temperature ranges, and a degree of ductility. This review epitomizes the recent progress in AgCuQ-based thermoelectric materials, from the optimization of thermoelectric performance to the rational design of devices, encompassing the fundamental understanding of crystal structures, electronic band structures, mechanical properties, and quasi-liquid behaviors. The correlation between chemical composition, mechanical properties, and thermoelectric performance in this material system is also highlighted. Finally, several key issues and prospects are proposed targeting further optimizing AgCuQ-based thermoelectric materials. This article is protected by copyright. All rights reserved.

Surface decoration of flexible Si3N4 nanowire membrane by hydroxyapatite micron-flake with excellent thermal insulation at 1300 °C

Flexible and excellent thermal insulation membranes are required as the thermal protection system materials of aerospace vehicles for next-generation space missions. Using ceramic membranes with ultralow thermal conductivity has been proved to be an effective way to protect the electronic components inside the fuselage. Herein, we decorate hydroxyapatite (HA) micron-flake onto Si3N4 nanowire membrane (SR), and investigate the thermal stability, fire-resistance and thermal insulating properties of the obtained SR decorated by HA micron-flake (SRHM). Surface decoration of HA micron-flake onto the SR results in the formation of well-interconnected junctions and the increase of interfacial thermal resistance. Due to the increased interfacial thermal resistance, the as-prepared SRHM exhibits good thermal insulation and outstanding fire-retardant performance. SRHM shows robust mechanical property with tensile strength value of 4.10 MPa, increased by 247.5% compared to the SR without the surface decoration by HA micron-flake. The thermal conductivity of SRHM is as low as 0.037 W m−1 K−1, reduced by 33.9% compared to the SR without the surface decoration by HA micron-flake. After SRHM is heated by a butane blow torch at 1300 °C for 30 min, no obvious change is observed in the macroscopic morphology. And the temperature of the backside for SRHM maintains at a stable temperature of ∼260 °C for 300 s, which is 1040 °C lower than that of the front side. Additionally, SRHM can protect the electronic components form being burnt under the heating of an alcohol lamp for 30 min. The successful preparation of such thermal insulating and fire-retardant SRHM will open up a new world for the widespread applications of ceramic membranes in the fields of aerospace vehicles.

Control of Spin on Ferromagnetism and Thermoelectric Properties of Sr(V/Cr)2S4; Emergent Spintronic Aspirant

Abstract Strontium-based spinel chalcogenides show great potential in energy harvesting and spintronics applications. This study extensively examines the electronic, ferromagnetic, and thermoelectric characteristics of SrZ2S4 (Z = V, Cr) spinels. Stability of the cubic phase in a ferromagnetic state is confirmed through formation energy and the energy released upon optimization. Spin polarization and Curie temperature were assessed using density of states (DOSs) analysis and the Heisenberg model, respectively. The investigation of ferromagnetism encompassed exchange energies, the double exchange mechanism, exchange constants, and hybridization processes. The observed reduction in magnetic moment for V/Cr and its redistribution to nonmagnetic (Sr, S) sites suggest that ferromagnetism stems from electron exchange, not from clustering of V/Cr atoms. Furthermore, the study delves into thermoelectric properties, including electrical and thermal conductivities, the Seebeck coefficient (S), and power factor, highlighting their significance for energy applications. The findings reveal ultralow thermal conductivity values, which minimize thermal effects on electron spin, thereby enhancing device longevity. Collectively, these insights underscore the critical role of electron exchange in ferromagnetism and its implications for energy device performance.

Achieving High Isotropic Figure of Merit in Cd and in Codoped Polycrystalline SnSe.

Here, we combined Cd and In codoping with a simple hydrothermal synthesis method to prepare SnSe powders composed of nanorod-like flowers. After spark plasma sintering, its internal grains inherited well the morphological features of the precursor, and the multiscale microstructure included nanorod-shaped grains, high-density dislocations, and stacking faults, as well as abundant nanoprecipitates, resulting in an ultralow thermal conductivity of 0.15 W m-1 K-1 for the synthesized material. At the same time, Cd and In synergistically regulated the electrical conductivity and Seebeck coefficient of SnSe, leading to an enhanced power factor. Among them, Sn0.94Cd0.03In0.03Se achieved a peak ZT of 1.50 parallel to the pressing direction, representing an 87.5% improvement compared with pure SnSe. Notably, the material possesses isotropic ZT values parallel and perpendicular to the pressing direction, overcoming the characteristic anisotropy in thermal performance observed in previous polycrystalline SnSe-based materials. Our results provide a new strategy for optimizing the performance of thermoelectric materials through structural engineering.

Pushing thermal conductivity to its lower limit in crystals with simple structures

Materials with low thermal conductivity usually have complex crystal structures. Herein we experimentally find that a simple crystal structure material AgTlI2 (I4/mcm) owns an extremely low thermal conductivity of 0.25 W/mK at room temperature. To understand this anomaly, we perform in-depth theoretical studies based on ab initio molecular dynamics simulations and anharmonic lattice dynamics. We find that the unique atomic arrangement and weak chemical bonding provide a permissive environment for strong oscillations of Ag atoms, leading to a considerable rattling behaviour and giant lattice anharmonicity. This feature is also verified by the experimental probability density function refinement of single-crystal diffraction. The particularly strong anharmonicity breaks down the conventional phonon gas model, giving rise to non-negligible wavelike phonon behaviours in AgTlI2 at 300 K. Intriguingly, unlike many strongly anharmonic materials where a small propagative thermal conductivity is often accompanied by a large diffusive thermal conductivity, we find an unusual coexistence of ultralow propagative and diffusive thermal conductivities in AgTlI2 based on the thermal transport unified theory. This study underscores the potential of simple crystal structures in achieving low thermal conductivity and encourages further experimental research to enrich the family of materials with ultralow thermal conductivity.

Realization of Fine-Tuning the Lattice Thermal Conductivity and Anharmonicity in Layered Semiconductors via Entropy Engineering.

Entropy engineering is widely proven to be effective in achieving ultra-low thermal conductivity for well-performed thermoelectric and heat management applications. However, no strong correlation between entropy and lattice thermal conductivity is found until now, and the fine-tuning of thermal conductivity continuously via entropy-engineering in a wide entropy range is still lacking. Here, a series of high-entropy layered semiconductors, Ni1- x(Fe0.25Co0.25Mn0.25Zn0.25)xPS3, where 0 ≤ x < 1, with low mass/size disorder is designed. High-purity samples with mixing configuration entropy of metal atomic site in a wide range of 0-1.61R are achieved. Umklapp phonon-phonon scattering is found to be the dominating phonon scattering mechanism, as revealed by the linear T-1 dependence of thermal conductivity. Meanwhile, fine tuning of the lattice thermal conductivity via continuous entropy engineering at metal atomic sites is achieved, in an almost linear dependence in middle-/high- entropy range. Moreover, the slope of the κ- T-1 curve reduces with the increase in entropy, and a linear response of the reduced Grüneisen parameter is revealed. This work provides an entropy engineering strategy by choosing multiple metal elements with low mass/size disorder to achieve the fine tuning of the lattice thermal conductivity and the anharmonic effect.

Three-Fold Coordination of Copper in Sulfides: A Blockade for Hole Carrier Delocalization but a Driving Force for Ultralow Thermal Conductivity.

Copper-rich sulfides are very promising for energy conversion applications due to their environmental compatibility, cost effectiveness, and earth abundance. Based on a comparative analysis of the structural and transport properties of Cu3BiS3 with those of tetrahedrite (Cu12Sb4S13) and other Cu-rich sulfides, we highlight the role of the cationic coordination types and networks on the electrical and thermal properties. By precession-assisted 3D electron diffraction analysis, we find very high anisotropic thermal vibration of copper attributed to its 3-fold coordination, with an anisotropic atomic displacement parameter up to 0.09 Å2. Density functional theory calculations reveal that these Cu atoms are weakly bonded and give rise to low-energy Einstein-like vibrational modes that strongly scatter heat-carrying acoustic phonons, leading to ultralow thermal conductivity. Importantly, we demonstrate that the 3-fold coordination of copper in Cu3BiS3 and in other copper-rich sulfides constituted of interconnected CuS3 networks causes a hole blockade. This phenomenon hinders the possibility of optimizing the carrier concentration and electronic properties through mixed valency Cu+/Cu2+, differently from tetrahedrite and most other copper-rich chalcogenides, where the main interconnected Cu-S network is built of CuS4 tetrahedra. The comparison with various copper-rich sulfides demonstrates that seeking for frameworks characterized by the coexistence of tetrahedral and 3-fold coordinated copper is very attractive for the discovery of efficient thermoelectric copper-rich sulfides. Considering that lattice vibrations and carrier concentration are key factors for engineering transport phenomena (electronic, phonon, ionic, etc.) in copper-rich chalcogenides for various types of applications, our findings improve the guidelines for the design of materials enabling sustainable energy solutions with wide-ranging applications.

Synergistically optimized electron and phonon transport in high-performance copper sulfides thermoelectric materials via one-pot modulation

Optimizing thermoelectric conversion efficiency requires the compromise of electrical and thermal properties of materials, which are hard to simultaneously improve due to the strong coupling of carrier and phonon transport. Herein, a one-pot approach realizing simultaneous second phase and Cu vacancies modulation is proposed, which is effective in synergistically optimizing thermoelectric performance in copper sulfides. Multiple lattice defects, including nanoprecipitates, dislocations, and nanopores are produced by adding a refined ratio of Sn and Se. Phonon transport is significantly suppressed by multiple mechanisms. An ultralow lattice thermal conductivity is therefore obtained. Furthermore, extra Se is added in the copper sulfide for optimizing electrical transport properties by inducing generating Cu vacancies. Ultimately, an excellent figure of merit of ~1.6 at 873 K is realized in the Cu1.992SSe0.016(Cu2SnSe4)0.004 bulk sample. The simple strategy of inducing compositional and structural modulation for improving thermoelectric parameters promotes low-cost high-performance copper sulfides as alternatives in thermoelectric applications.

Amorphous-Like Ultralow Thermal Transport in Crystalline Argyrodite Cu7PS6.

Due to their amorphous-like ultralow lattice thermal conductivity both below and above the superionic phase transition, crystalline Cu- and Ag-based superionic argyrodites have garnered widespread attention as promising thermoelectric materials. However, despite their intriguing properties, quantifying their lattice thermal conductivities and a comprehensive understanding of the microscopic dynamics that drive these extraordinary properties are still lacking. Here, an integrated experimental and theoretical approach is adopted to reveal the presence of Cu-dominated low-energy optical phonons in the Cu-based argyrodite Cu7PS6. These phonons yield strong acoustic-optical phonon scattering through avoided crossing, enabling ultralow lattice thermal conductivity. The Unified Theory of thermal transport is employed to analyze heat conduction and successfully reproduce the experimental amorphous-like ultralow lattice thermal conductivities, ranging from 0.43 to 0.58Wm-1 K-1, in the temperature range of 100-400 K. The study reveals that the amorphous-like ultralow thermal conductivity of Cu7PS6 stems from a significantly dominant wave-like conduction mechanism. Moreover, the simulations elucidate the wave-like thermal transport mainly results from the contribution of Cu-associated low-energy overlapping optical phonons. This study highlights the crucial role of low-energy and overlapping optical modes in facilitating amorphous-like ultralow thermal transport, providing a thorough understanding of the underlying complex dynamics of argyrodites.

Giant Deformation Induced Staggered-Layer Structure Promoting the Thermoelectric and Mechanical Performance in n-Type Bi2(Te, Se)3.

Bismuth telluride has long been recognized as the most promising near-room temperature thermoelectric material for commercial application; however, the thermoelectric performance for n-type Bi2(Te, Se)3-based alloys is far lagging behind that of its p-type counterpart. In this work, a giant hot deformation (GD) process is implemented in an optimized Bi2Te2.694Se0.3I0.006+3 wt%K2Bi8Se13 precursor and generates a unique staggered-layer structure. The staggered-layered structure, which is only observed in severely deformed crystals, exhibits a preferential scattering on heat-carrying phonons rather than charge-carrying electrons, thus resulting in an ultralow lattice thermal conductivity while retaining high-weight carrier mobility. Moreover, the staggered-layer structure is located adjacent to the van der Waals gap in Bi2(Te, Se)3 lattice and is able to strengthen the interaction between anion layers across the gap, leading to obviously improved compressive strength and Vickers hardness. Consequently, a high peak figure of merit ZT of ≈ 1.3 at 423 K, and an average ZT of ≈ 1.2 at 300-473 K can be achieved in GD sample. This study demonstrates that the GD process can successfully decouple the electrical and thermal transports with simultaneously enhanced mechanic performance.

Liquid metal-modified boron nitride for polytetrafluoroethylene composites with enhanced thermal conductivity and peel strength

Polytetrafluoroethylene (PTFE)/boron nitride (BN) composites has ultra-low dielectric loss and thermal conductivity, making it a suitable choice for high-frequency communication copper-clad laminate. However, the low peel strengthens of these composites restricted the further application, due to the low polarity and smooth surface of BN. Here, we assemble liquid metal (LM) on BN filler (LM-BN) via a mechanochemistry method. The surface polarity and roughness of BN can be enhanced by the oxidized layer from LM. The thermal interfacial overlap between BN sheets can be enhanced by LM droplets. Consequently, at filler content of 50 vol%, the thermal conductivity increases from 0.3 W/m⋅K of PTFE to 1.90 W/m⋅K for PTFE/BN composites, to 2.05 W/m⋅K for PTFE/LM-BN composites, and the peel strength exhibit a nearly 100% increment from 0.19 of PTFE/BN to 0.39 N/mm of PTFE/LM-BN. Along with low dielectric loss, excellent thermal conductivity, peel strength, and reduced thermal expansion, this method ensures a wider application of PTFE/LM-BN composites in electronic packaging.

Study of electronic, mechanical, thermoelectric, and optical aspects of K2AlAg(Br/I)6 for solar cells, and energy storage applications

Double perovskite materials exhibit considerable potential in addressing global energy challenges and advancing renewable energy technologies. This study focuses on K2AlAg(Br/I)6 and employs a comprehensive DFT approach to explore its structural, mechanical, thermodynamic, optical, and thermoelectric properties. The structural and thermodynamic stabilities of K2AlAg(Br/I)6 are accurately examined through tolerance factor (τF) and formation energy analysis. The mechanical stability and ductile characteristics are affirmed by studying elastic constants, Passion's, and Pugh's ratios. Additionally, insights into hardness, Debye temperature, as well as transverse and longitudinal sound velocities contribute to a deeper understanding of the material's thermodynamic response. The band gap of K2AlAgBr6 is identified as 2.71 eV, which undergoes a reduction to 1.17 eV when Br is substituted with I, attributed to the pd-hybridization of cations and anions. Exploring optical properties reveals valuable information through dielectric constants ε(ω), refractive index (n(ω)), absorption (α(ω)), and reflectivity (R(ω)). Notably, absorption in both visible and ultraviolet ranges underscores the material's significance for solar cell applications. Furthermore, the computed ultralow lattice thermal conductivity and higher figure of merit are noteworthy outcomes, driven by the substantial Seebeck coefficient and electrical conductivity of the material. These results collectively highlight the exclusive and promising characteristics of K2AlAg(Br/I)6 in the area of renewable energy materials.

Realizing Ultrahigh Thermoelectric Performance in n‐Type PbSe Through Lattice Planification and Introducing Liquid‐Like Cu Ions

AbstractThe coupling relationship between electrical and thermal transports makes it rather challenging to enhance thermoelectric performance. Here, electrical and thermal transports are successfully decoupled to realize high performance in n‐type PbSe by utilizing a stepwise strategy. First, the PbSe lattice is plained with extra Pb to compensate for the intrinsic Pb vacancies, which can weaken defect scattering and improve carrier mobility to ≈1230 cm2 V−1 s−1. The room‐temperature power factor triples and reaches ≈32 µW cm−1 K−2, and ZT is significantly enhanced to ≈0.6 in Pb1.006Se. Subsequently, liquid‐like interstitial Cu ions are introduced to inhibit heat conduction without damaging electrical transport. While maintaining a high power factor of ≈25 µW cm−1 K−2, Cu ions strongly suppress phonon transport at high temperature, leading to an ultralow lattice thermal conductivity of ≈0.28 W m−1 K−1 in Pb1.006Cu0.006Se, only 30% of the Cu‐free PbSe. Eventually, a remarkable peak ZT of ≈1.8 at 773 K is achieved along with a high average ZT of ≈1.1 from 300 to 823 K in Pb1.006Cu0.006Se. An outstanding experimental conversion efficiency of ≈7.1% is obtained in the single‐leg device, demonstrating great potential for PbSe as low‐ to mid‐temperature thermoelectrics.

S-filled and Te-doped CoSb3 materials prepared by HPHT method with ultra-low thermal conductivity

In this paper, a series of S[Formula: see text]Co4Sb[Formula: see text]Te[Formula: see text] samples were prepared by high pressure and high temperature (HPHT) method under different pressures. The synthesis time was shortened from several days to 0.5 h. Te doping and S filling simultaneously optimized the thermal and electrical transport properties of the CoSb3 materials. We found a porous architecture containing rich grain boundaries, different grain sizes, nano- to micrometer-sized pores, and a large number of dislocations, which can scatter a wide spectrum of phonons. Seebeck coefficient [Formula: see text], electrical resistivity [Formula: see text], and thermal conductivity [Formula: see text] were measured between 295 K and 773 K. The minimum thermal conductivity of S[Formula: see text]Co4Sb[Formula: see text]Te[Formula: see text] synthesized at 3.0 GPa was 1.23 Wm[Formula: see text] K[Formula: see text], and its maximum zT value reached 1.07 at 773 K, especially the lattice thermal conductivity was as low as 0.49 Wm[Formula: see text] K[Formula: see text].

Phonon relaxation effect by regeneration of nano-inclusions in SiGe for ultralow thermal conductivity and enhanced thermoelectric performance

SiGe alloys exhibit high thermoelectric performance at mid to high temperatures, but their wide applications are hindered by intrinsically high thermal conductivity. Here, we report a new strategy for regenerating ultrafine nano phases of CrSi2 and SiO2 with an average grain size of approximate 130 nm by chemical reaction of Si and strong oxidizing CrO3 in a p-type SiGe matrix. Based on the Debye-Callaway calculation, the nano-sized second phase leads to a reduction in phonon relaxation time, thereby lowering the thermal conductivity to an ultralow value of 2.15 W m−1 K−1 at 873 K. The boundaries between the second phases (CrSi2) and the matrix (SiGe) establish potential barriers, allowing carrier filtering and phonon scattering, thus increasing the power factor. Eventually, the sample (CrO3)0.3-Si80Ge20B0.5 reaches a peak ZT of approximately 1.12 at 873 K, with an average ZT of approximately 0.62 from 323 K to 873 K, representing a 55.56% improvement compared with Si80Ge20B0.5. Our method provides a promising approach for enhancing the thermoelectric performance of SiGe.

Ultra-High Temperature Operated Ni-Rich Cathode Stabilized by Thermal Barrier for High-Energy Lithium-Ion Batteries.

The pursuit of high energy density batteries has expedited the fast development of Ni-rich cathodes. However, the chemo-mechanical degradation induced by local thermal accumulation and anisotropic lattice strain is posing great obstacles for its wide applications. Herein, a highly-antioxidative BaZrO3 thermal barrier engineered LiNi0.8 Co0.1 Mn0.1 O2 cathode through an in situ construction strategy is first reported to circumvent the above issues. It is found that the Zr ions are incorporated to Ni-rich material lattice and influence on the topotactic lithiation as well as enhance the oxygen electronegativity through the rigid Zr─O bonds, which effectively alleviates the lattice strain propagation and decreases the excessive oxidization of lattice oxygen for charge compensation. More importantly, the BaZrO3 thermal barrier with an ultra-low thermal conductivity validly impedes the fast heat exchange between electrode and electrolyte to mitigate the severe surface side reactions. This helps an ultra-high mass loading Li-ion pouch cell deliver a specific energy density of 690Wh kg-1 at active material level and an excellent capacity retention of 92.5% after 1400 cycles under 1 C at 25°C. Tested at a high temperature of 55°C, the pouch type full-cell also exhibits 88.7% in capacity retention after 1200 cycles.

Super thermal insulation SiC aerogel with high elasticity and good adsorption performance prepared by constructing coaxial precursor

Silicon Carbide (SiC) aerogel is a material with 3D network structure, low density, and high-temperature resistance, showing a broad application potential in various areas. It is currently challenging for SiC aerogels to balance the mechanical and high-temperature insulation properties. Here, a novel strategy was implemented for the first time, by constructing coaxial precursors. This structure can achieve in-situ Si-C binding and maximization the reaction sites to achieve fibers growth uniformly. The sintering time is reduced by over 90%. The fatigue resistance and elastic properties of the SiC aerogel were significantly improved. In addition, the uniform nanowire fiber and pore structure enable an ultra-low thermal conductivity of 0.018 W/(m K) at room temperature, 0.082 W/(m K) even at 900 °C, and superior structural stability at 1400 °C. Our strategy provides a feasible approach for the structural design of thermally insulated SiC aerogels with high elastic resilience and good adsorbability.

Al-doped Bi2Se3 nanoparticulate semiconductors with controlled resonance states for enhanced thermoelectric efficiency

The generally lower thermoelectric figure of merit (zT < 0.1) of eco-friendly Bi2Se3 semiconductors constrains the waste energy conversion efficiency in the resulting devices compared to a relatively toxic Bi2Te3. We strategically introduce an aluminium (Al) dopant to create resonance states near the Fermi level and obtain Al–Bi2Se3 nanoparticulate semiconductors with enhanced zT. As an electron feeder, these resonance states significantly improve transport properties within the Al–Bi2Se3 semiconductors. The theoretical calculation shows the creation of the resonance states by hybridizing the dopant's s-orbitals with the host's p-orbitals near the Fermi level. The Al–Bi2Se3 semiconductors effectively moderate electron concentration and the Seebeck-dependent effective mass, resulting in an ultrahigh zT of 0.57 over a broad temperature range of 300–473 K. The nanoparticle size (20 nm) efficiently impedes the propagation of lattice vibration, leading to an ultralow total thermal conductivity of 0.399 Wm−1/K. In contrast to conventional doping approaches, our strategic resonance doping is pivotal to enhancing the thermoelectric performance of the Bi2Se3 semiconductors and providing a pathway for synthesizing other semiconductor materials.

Femtosecond Electron Diffraction Reveals Local Disorder and Local Anharmonicity in Thermoelectric SnSe.

In addition to long-range periodicity, local disorder, with local structures deviating from the average lattice structure, dominates the physical properties of phonons, electrons, and spin subsystems in crystalline functional materials. Experimentally characterizing the 3D atomic configuration of such a local disorder and correlating it with advanced functions remains challenging. Using a combination of femtosecond electron diffraction, structure factor calculations, and time-dependent density functional theory molecular dynamics simulations, the static local disorder and its local anharmonicity in thermoelectric SnSe are identified exclusively. The ultrafast structural dynamics reveal that the crystalline SnSe is composed of multiple locally correlated configurations dominated by the static off-symmetry displacements of Sn (≈0.4 Å) and such a set of locally correlated structures is termed local disorder. Moreover, the anharmonicity of this local disorder induces an ultrafast atomic displacement within 100 fs, indicating the signature of probable THz Einstein oscillators. The identified local disorder and local anharmonicity suggest a glass-like thermal transport channel, which updates the fundamental insight into the long-debated ultralow thermal conductivity of SnSe. The method of revealing the 3D local disorder and the locally correlated interactions by ultrafast structural dynamics will inspire broad interest in the construction of structure-property relationships in material science.