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• Layer-by-layer scraping can produce a powerful shearing effect for UHPE/GNPs gel. • Strong shearing induced dense stacking and ordered alignment of GNPs and PE chains. • The dense and ordered structure drastically enhanced in-plane TC up to 28.88 W/mK. • The solar-thermal conversion ability was also improved by the ordered structure. The simultaneous achievement of ordered alignment for fillers and polymer matrix is highly desired in polymer-based thermally conductive composites, but it is still extremely challenging. Herein, we put forward a layer-by-layer scraping (LbLS) method to simultaneously arrange ultra-high molecular weight polyethylene (UHPE) chains and graphene nanoplates (GNP) into a highly oriented structure. When UHPE/GNP gel suffering the strong shearing effect during LbLS process, the inner UHPE chains and GNP were dragged and orderly arranged along shearing direction, and these oriented structures were retained after rapidly drying by distillation. After layer-by-layer stacking, nacre-like UHPE/GNP films with tightly layered structure were obtained. By adjusting the scraping gap from 200 to 50 μm, the oriented structure can be effectively reinforced with the Herman orientation factors f increasing from 0.83 to 0.88 for GNP and 0.75 to 0.82 for UHPE chains. The highly ordered structure can form a tight and oriented thermal conduction network with low interfacial thermal resistance in plane. The LbLS composite film thus significantly enhanced the in-plane thermal conductivity up to 28.88 W/mK, compared with traditional solution casting film (9.63 W/mK). Moreover, the highly oriented structure can significantly increase the solar-thermal conversion performance (58.1 °C@100 mW/cm2) by improving its light absorption ability comparing to that of solution casting film. Besides, the mechanical strength and toughness that depend on the filler and chain alignment were effectively increased by the oriented structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • ANF-carbonized welding is used to reduce the ITR of 3D graphene architecture. • PCM containing graphene architecture shows a TC of 4.85 W/mK at 4.26 vol% content. • Thermal conductive architecture achieves the rapid heat transfer/storage in PCM. • Graphene architecture enables PCM solar/electric-to-thermal conversion capacity. Graphene-based porous architectures are promising in addressing the poor thermal conductivity, leakage, shape stability problems of organic phase change materials (PCMs), meanwhile endowing them with excellent solar/electric-to-heat conversion ability, but they are still limited by the high interfacial thermal/electrical resistance in architectures caused by organic "binders". In this work, in view of the excellent gel ability of aramid nanofibers (ANF) and its highly ordered conjugate molecular structure, a promising graphene porous architecture assisted by ANF was constructed by unidirectional freeze casting coupled with carbonization welding technique. Due to the similar graphite lattice structure of ANF-derived carbonization and graphene, the interfacial thermal/electrical resistance in highly vertically oriented graphene architecture was greatly reduced. As a result, the PCMs composite encapsulated by the graphene architecture carbonizing at 1500 °C exhibited an outstanding thermal conductivity of as high as 4.85 W/mK at only 4.26 vol%, which enables a rapid heat transfer and storage in PCM composite. The honeycomb porous graphene architecture with high porosity can accommodate sufficient PCMs for energy storage, showing a high latent heat enthalpy of 149.7 J/g with excellent shape stability during phase change process. More importantly, the graphene architecture endows PCM composites with excellent solar/electric-to-thermal conversion capacities, which not only expands the types of energy stored by PCMs, but is also promising in the thermal management application requiring a continuous and stable temperature environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon welding is used to reduce filler-to-filler ITR in 3D graphene skeleton. • Introducing the graphene skeleton into PCM improves its thermal conductivity. • The graphene skeleton can avoid the leakage of PCM during solid–liquid phase change. • The graphene skeleton endows PCM with solar-to-heat conversion capacity. Advanced phase change materials (PCMs) with three-dimensional (3D) thermal conductive skeletons reveal the promising prospect in the thermal management of lithium battery. However, the high filler-to-filler interfacial thermal resistance (ITR) arising from the weak interfacial contact connection in 3D skeleton is still challenging. Herein, we demonstrate a "carbon welding" strategy for reducing the filler-to-filler ITR in 3D graphene skeleton by achieving the lattice connection between contact graphene. Typically, the ordered 3D graphene skeleton was constructed by unidirectionally ice template assembling graphene nanoplates (GNP) with the assistance of poly (amic acid) (PAA). Imidization and carbonization treatments were employed to weld the adjacent GNP in 3D skeleton. The similar lattice structure of carbonized polyimide (PI) and graphene can result in the significant reduction of phonon scattering and ITR at these contact areas. After impregnation with polyvinyl alcohol (PEG), the high-performance PCMs with high-efficient phonon transmission expressway were obtained. As expected, the prepared composites reveal the high thermal conductivities with a maximum value of 7.032 W m−1 K−1 at ~11.6 vol% GNP, which is more than two-fold than that of the composite with uncarbonized skeleton. Finite element simulation and nonlinear model analyses confirm that the reduced filler-to-filler ITR in skeleton is the main reason for the improving thermal conductivity. In addition, the presence of 3D graphene skeleton can effectively avoid the leakage during solid–liquid phase change, and significantly improve the shape stability of the PCMs. At the same time, the graphene skeleton can endow the PCM with an excellent solar-to-heat conversion performance, which ensure a wide range of application in actual environment. [ABSTRACT FROM AUTHOR]

• Flexible HAMS films with alternant graphene and Ni chains were designed firstly. • High-effective electrons and phonons conductive paths were formed in HAMS films. • HAMS films reveal remarkable EMI shielding and thermal conductivity simultaneously. • Stacking hot-pressing for preparing HAMS films is easy to large-scale application. Flexible polyvinylidene fluoride (PVDF) films with various heterogeneous alternating multilayer structure (HAMS) containing high-aligned graphene nanosheets and Ni nanochains were designed for electromagnetic interference (EMI) shielding and heat dissipation applications. Because of the unique structure and highly aligned nanofillers, effective electron and phonon conductive paths were formed in HAMS films with optimal electrical and thermal conductivity of 76.8 S/m and 8.96 W/mK, respectively. Combining the high electrical conductivity and the synergetic electromagnetic loss, as well as multi-level electromagnetic multireflection, the optimal HAMS film with thickness of 0.5 mm exhibits a high EMI shielding effectiveness (SE) of 43.3 dB, showing 98.6% increment compared to homogeneous film (21.8 dB), which can further improve to 51.4 dB when increasing the thickness to 0.7 mm. Simultaneously, the highly concentrated and aligned graphene in alternating layers can contribute to the significant improvement in in-plane thermal conductivity of HAMS films with 14.3% and ~1200% increment comparing to the homogeneous film (7.84 W/mK) and pure PVDF (0.69 W/mK), respectively. Considering the outstanding performance and high-efficiency stacking hot-pressing preparation technique, HAMS films with alternating aligned graphene/Ni nanochain layers present a huge potential in practical large-scale application as advanced EMI protection and thermal management materials. [ABSTRACT FROM AUTHOR]