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Solid polymer electrolytes (SPEs) hold a great promise in the application of solid‐state lithium batteries, but suffer from poor mechanical properties and uncontrolled electrode/electrolyte interfacial reaction, which restrict their overall electrochemical performance. Herein, the design of 2D fluorinated graphene‐reinforced PVDF‐HFP‐LiTFSI (FPH‐Li) polymer electrolytes to address these challenges is reported. Uniformly dispersed fluorinated graphene induces a unique grain refinement effect, which effectively improves the mechanical properties without excessively increasing the thickness of the polymer electrolyte. Significant reduction in polymer grain size enhances interfacial lithium ion (Li‐ion) transport and homogenizes Li‐ion flux, thereby improving Li‐ion conductivity and promoting uniform Li plating/stripping. Furthermore, extensive characterizations show that fluorinated graphene is involved in the construction of a stable artificial interface, which effectively prevents the side reactions between the lithium metal anode and solvated molecules. As a result, the use of thin FPH‐Li polymer electrolytes (thickness of ≈45 µm) enables long‐term Li plating/stripping with a small overpotential in Li/Li symmetrical cells and stable cycling of Li/LiNi0.6Co0.2Mn0.2O2 full cells with a high average Coulombic efficiency of 99.5% at 1.0 C. This work verifies the effectiveness of 2D materials in improving the comprehensive properties of polymer electrolytes and promotes the applications of SPEs in high‐performance solid‐state lithium batteries. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) atomic layers such as graphene, and metal chalcogenides have recently attracted tremendous attention due to their unique properties and potential applications. Unfortunately, in most cases, the free-standing nanosheets easily re-stack due to their van der Waals forces, and lose the advantages of their separated atomic layer state. Here, a bottom-up approach is developed to build three-dimensional (3D) architectures by 2D nanosheets such as MoS2 and graphene oxide nanosheets as building blocks, the thin nature of which can be well retained. After simply chemical reduction, the resulting 3D MoS2-graphene architectures possess high surface area, porous structure, thin walls and high electrical conductivity. Such unique features are favorable for the rapid diffusions of both lithium ions and electrons during lithium storage. As a consequence, MoS2-graphene electrodes exhibit high reversible capacity of ≈1200 mAh g−1, with very good cycling performance. Moreover, such a simple and low-cost assembly protocol can provide a new pathway for the large-scale production of various functional 3D architectures for energy storage and conversions. [ABSTRACT FROM AUTHOR]

Although lithium ion batteries havegained commercial success owingto their high energy density, they lack suitable electrodes capableof rapid charging and discharging to enable a high power density criticalfor broad applications. Here, we demonstrate a simple bottom-up approachtoward single crystalline vanadium oxide (VO2) ribbonswith graphene layers. The unique structure of VO2-grapheneribbons thus provides the right combination of electrode propertiesand could enable the design of high-power lithium ion batteries. Asa consequence, a high reversible capacity and ultrafast charging anddischarging capability is achieved with these ribbons as cathodesfor lithium storage. A full charge or discharge is capable in 20 s.More remarkably, the resulting electrodes retain more than 90% ofthe initial capacity after cycling more than 1000 times at an ultrahighrate of 190C, providing the best reported rate performance for cathodesin lithium ion batteries to date. [ABSTRACT FROM AUTHOR]

Graphene and hexagonal boron nitride (h-BN) have similar crystal structures with a lattice constant difference of only 2%. However, graphene is a zero-bandgap semiconductor with remarkably high carrier mobility at room temperature, whereas an atomically thin layer of h-BN is a dielectric with a wide bandgap of ?5.9 eV. Accordingly, if precise two-dimensional domains of graphene and h-BN can be seamlessly stitched together, hybrid atomic layers with interesting electronic applications could be created. Here, we show that planar graphene/h-BN heterostructures can be formed by growing graphene in lithographically patterned h-BN atomic layers. Our approach can create periodic arrangements of domains with size ranging from tens of nanometres to millimetres. The resulting graphene/h-BN atomic layers can be peeled off the growth substrate and transferred to various platforms including flexible substrates. We also show that the technique can be used to fabricate two-dimensional devices, such as a split closed-loop resonator that works as a bandpass filter. [ABSTRACT FROM AUTHOR]

Compared with a disordered network, the ordered framework is more beneficial to improving the multifunctional properties (including thermal, electrical, and mechanical properties) of epoxy-based composites. However, current methods for building aligned structures are both energy and time-consuming on account of the tedious and lengthy lyophilization process. Herein, a new strategy is proposed to obtain low-density graphene aerogels (GAs) with long-range oriented structures through a lyophilization-free processes. Due to the minimum thermal boundary resistance, the prepared aligned graphene/epoxy composite exhibits an ultrahigh thermal conductivity of ∼11.6 W/(m·K) at a graphene content of 1.84 vol%, i.e., an enhancement efficiency of 3640% per 1 vol%. In addition, the compressive strength of the composite is increased by 2.6 times compared to epoxy (from 0.29 MPa to 0.76 MPa). Because the composite shows a modulus as low as 0.5–1.0 MPa, it has excellent deformability and compression performance. Moreover, the obtained 3-mm-thick composite achieves an electromagnetic interference shielding effectiveness (EMI SE) of 40 dB due to the interconnected graphene network structure, which meets the requirements of commercial EMI shielding applications. Hence, this strategy can be used to synthesize aligned graphene/epoxy composites with excellent multifunctional performances, which can be simultaneously used as elastic thermal interface materials (TIMs) and EMI shielding materials in the fields of advanced electronic packaging. [Display omitted] • Aligned graphene aerogel (GA) was fabricated by a lyophilization-free approach. • The compressive strength of the composite is increased by 2.6 times compared to epoxy (0.29 MPa to 0.76 MPa) and the composite shows a modulus as low as 0.48–1.0 MPa, exhibiting excellent deformability and compression performance. • The vertical pathways and high-quality give composite an ultrahigh thermal conductivity (∼11.6 W/m·K) with ultralow graphene loading (1.84 vol%), i.e., an enhancement efficiency of 3640% per 1 vol%. • The obtained 3-mm-thick composite achieves an electromagnetic interference shielding effectiveness of 40 dB due to the interconnected network structure. [ABSTRACT FROM AUTHOR]

Conventionalwisdom suggests that decreasing dimensions of dielectricmaterials (e.g., thickness of a film) should yield increasing capacitance.However, the quantum capacitance and the so-called “dead-layer”effect often conspire to decrease the capacitance of extremely smallnanostructures, which is in sharp contrast to what is expected fromclassical electrostatics. Very recently, first-principles studieshave predicted that a nanocapacitor made of graphene and hexagonalboron nitride (h-BN) films can achieve superior capacitor properties.In this work, we fabricate the thinnest possible nanocapacitor system,essentially consisting of only monolayer materials: h-BN with grapheneelectrodes. We experimentally demonstrate an increase of the h-BNfilms’ permittivity in different stack structures combinedwith graphene. We find a significant increase in capacitance belowa thickness of ∼5 nm, more than 100% of what is predicted byclassical electrostatics. Detailed quantum mechanical calculationssuggest that this anomalous increase in capacitance is due to thenegative quantum capacitance that this particular materials systemexhibits. [ABSTRACT FROM AUTHOR]