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All‐solid‐state battery (ASSB) is a potential future energy storage technology to power the future world. However, the solid–solid contacts among the various components in ASSB often require a high stack pressure which is unrealistic in practical applications. Here it is shown that by carbon‐coating Sb2Se3 (Sb2Se3@C) nanorods, a record low stack pressure is attained, and the Sb2Se3@C electrode exhibits outstanding performance of 862 mAh g−1 over 50 cycles at 0.1 A g−1 when it is operated at 5 MPa stack pressure in an ASSB using LiIn anode and Li10Si0.3PS6.7Cl1.8 solid‐state electrolytes. Furthermore, a record high active material loading (the mass fraction of Sb2Se3@C being 0.7 in composite cathode) is achieved, and the Sb2Se3@C based ASSB delivers a reversible capacity of 2.6 mAh cm−2 at 0.1 A g−1 after 100 cycles. This work provides a strategy to significantly increase the cathode active material loading and dramatically reduce the stack pressure of ASSBs, which brings it one step closer toward the practical implementation of ASSBs for energy storage applications. [ABSTRACT FROM AUTHOR]

The electron–phonon coupling (EPC) in semiconductors is typically much weaker than phonon–phonon scattering and its effect on lattice thermal conductivity κl has long been considered negligible. Herein, using first‐principle calculations, it is discovered that the EPC can be significant or even dominant over the intrinsic phonon–phonon scattering via doping in 2D semiconductor hexagonal boron phosphorus (h‐BP). Filling electron pocket till van Hove singularity gradually strengthens the EPC and consequently diminishes the room‐temperature κl by 25% and 80% for monolayer and bilayer h‐BP, respectively. Strikingly, at high doping levels, the EPC drives phonon transport in bilayer h‐BP to an anomalous regime where κl becomes nearly temperature (T) independent deviated from the intrinsic 1/T trend. This distinctive behavior is governed by the joint effects of horizontal mirror symmetry breaking, and weak phonon–phonon scattering stemming from the predominance of normal processes. Further considering electronic contributions, the abnormal T‐independent thermal conductivity is still reserved, thereby facilitating the experimental exploration of EPC effect on κl. This study unveils the exotic thermal transport phenomenon in one‐atom‐thick 2D semiconductors and offers a unique avenue to manipulate heat flow by externally controlling the EPC, which calls for future experimental verification. [ABSTRACT FROM AUTHOR]

Liquid metal (LM) droplet‐embedded polymer composites with exceptional thermal, electrical, and mechanical characteristics are attractive for applications in soft electronics and thermal management. Generally, a high volume fraction of LMs is required for desirable thermal and electrical properties, and thus recycling of LMs is favorable and cost effective. However, recycling LMs from composites remains a formidable challenge because the LM droplets are typically dispersed into a permanent covalently crosslinked polymer matrix. Here, a facile synthesis of LM‐polymer composites with high electrical conductivity (1800 S cm−1), high stretchability (1400% tensile strain), as well as degradability and recyclability is reported. The composite comprises a poly(2‐hydroxyethyl acrylate) hydrogel that is physically crosslinked by LM nanodroplets as a polymer matrix and either LM microdroplets or silver microflakes as a conductive filler. A postdrying process improves the mechanical performance of the composite while creating percolating pathways via the rearrangement of the conductive fillers, imparting high electrical conductivity to the composite. Moreover, the composites are readily degraded and dissolved in aqueous alkali solutions at room temperature thanks to the reactive nature of LM crosslinks, enabling high recycling efficiency of ≈80% and 95% for composites with LM microdroplets and silver microflakes as conductive fillers, respectively. [ABSTRACT FROM AUTHOR]

The investigation of the oxidation behavior of van der Waals chalcogenides holds significant importance in terms of preventing and controlling oxidation, utilizing surface oxidation structures to regulate properties, and advancing applications. Here, taking GaSe as a candidate, its thermal oxidation and surface structure evolution are intensively studied. Through systematic microscopic analyses, oxidized structures at multi‐scale (from atomic scale to millimeters) are resolved, and various assembly heterogeneous surfaces including Ga2Se3/Ga2O3 and Ga2O3 multilayers are uncovered at different oxidation temperatures. The temperature‐dependent oxidation behavior and surface structure evolution of the GaSe are revealed, and the oxidation mechanisms in the entire temperature range are also disclosed. Finally, the photoluminescence regulation of the GaSe is initially explored via thermal oxidation, demonstrating great potential for surface oxidation engineering. This study is not only of great importance for the deep understanding and utilization of GaSe oxidation, but also beneficial for materials/device design and development of relative systems. [ABSTRACT FROM AUTHOR]

Layered van der Waals (vdW) magnets are prominent playgrounds for developing magnetoelectric, magneto‐optic, and spintronic devices. In spintronics, particularly in spincaloritronic applications, low thermal conductivity (κ) is highly desired. Herein, by combining thermal transport measurements with density functional theory calculations, this study demonstrates low κ down to 1 W m−1 K−1 in a typical vdW ferromagnet Cr2Si2Te6. In the paramagnetic state, development of magnetic fluctuations way above Tc = 33 K strongly reduces κ via spin‐phonon scattering, leading to low κ ≈ 1 W m−1 K−1 over a wide temperature range, in comparable to that of amorphous silica. In the magnetically ordered state, emergence of resonant magnon‐phonon scattering limits κ below ≈2 W m−1 K−1, which will be three times larger if magnetic scatterings are absent. Application of magnetic fields strongly suppresses the spin‐phonon scattering, giving rise to large enhancements of κ. This study's calculations well capture these complex behaviors of κ by taking the temperature‐ and magnetic‐field‐dependent spin‐phonon scattering into account. Realization of low κ, which is easily tunable by magnetic fields in Cr2Si2Te6, may further promote spincaloritronic applications of vdW magnets. This study's theoretical approach may also provide a generic understanding of spin‐phonon scattering, which appears to play important roles in various systems. [ABSTRACT FROM AUTHOR]

Keywords: pentatellurides; phonons; thermal conductivities; time-domain thermoreflectance In article number 1907286, Xiaojia Wang, Sokrates T. Pantelides, and co-workers discover that single-crystalline hafnium pentatelluride (HfTe SB 5 sb ) possesses strong thermal anisotropy owing to its quasi-1D asymmetrical structure. The original factors contributing to its substantially higher thermal conductivity along the b-axis ( 0.42 W m SP -1 sp K SP -1 sp ) than the previously reported record-low thermal conductivity ( 0.33 W m SP -1 sp K SP -1 sp ) of zirconium pentatelluride are revealed. [Extracted from the article]

Hafnium pentatelluride (HfTe5) has attracted extensive interest due to its exotic electronic, optical, and thermal properties. As a highly anisotropic crystal (layered structure with in‐plane chains), it has highly anisotropic electrical‐transport properties, but the anisotropy of its thermal‐transport properties has not been established. Here, accurate experimental measurements and theoretical calculations are combined to resolve this issue. Time‐domain thermoreflectance measurements find a highly anisotropic thermal conductivity, 28:1:8, with values of 11.3 ± 2.2, 0.41 ± 0.04, and 3.2 ± 2.0 W m-1 K-1 along the in‐plane a‐axis, through‐plane b‐axis, and in‐plane c‐axis, respectively. This anisotropy is even larger than what was recently established for ZrTe5 (12:1:6), but the individual values are somewhat higher, even though Zr has a smaller atomic mass than Hf. Density‐functional‐theory calculations predict thermal conductivities in good agreement with the experimental data, provide comprehensive insights into the results, and reveal the origin of the apparent anomaly of the relative thermal conductivities of the two pentatellurides. These results establish that HfTe5 and ZrTe5, and by implication their alloys, have highly anisotropic and ultralow through‐plane thermal conductivities, which can provide guidance for the design of materials for new directional‐heat‐management applications and potentially other thermal functionalities. [ABSTRACT FROM AUTHOR]