No abstract

formaldehyde, phenol formaldehyde, silicone, vinyl ester, cyanate ester, unsaturated polyester resin, etc. The properties of thermoset materials can be further improved by reinforcing them with fi llers, most commonly used being clays, carbon nanotubes, and graphene nanoplatelets. GrapheneGraphene is a fundamental building block of all graphitic forms of carbon and consists of a single layer of sp 2 -hybridized carbon atoms arranged in a honeycomb structure. A single defect-free graphene layer has Young's modulus of 1.0 TPa, intrinsic strength 42 N m −1 , thermal conductivity 4840-5300 W (m K) −1 , electron mobility exceeding 25 000 cm 2 V −1 s −1 , excellent gas impermeability and specifi c surface area of 2630 m 2 g −1 . [3][4][5][6][7][8][9][10][11] On incorporation into polymers, the mechanical, thermal, as well as electrical properties of the polymeric materials are significantly improved. [ 3,[12][13][14][15] The geometry differs with size and number of atomic layers, which determines the aspect ratio and the specifi c surface area. Generally speaking, GNSs have higher specifi c surface area than CNTs, thus, having higher potential of property enhancement in Graphene has resulted in signifi cant research effort to generate polymer nanocomposites with improved mechanical, thermal as electrical properties as compared to pure polymers. A large number of studies have been undertaken using different graphene derivatives, fi ller loadings, synthesis methods, and so on to obtain optimum fi ller dispersion as well as fi ller-matrix interactions, which are crucial for achieving signifi cant enhancement in the properties, especially at low fi ller fraction. This review summarizes the mechanical and thermal properties of numerous studies carried out for the property enhancements of commercially relevant thermosetting materials such as epoxy, polyurethane, natural rubber, melamine formaldehyde, phenol formaldehyde, silicones, vinyl ester, cyanate ester, and unsaturated polyester resin.

An economical and binder-free electrode was fabricated by impregnation of sub-5 nm MoS 2 nanodots (MoS 2 NDs) onto a three-dimensional (3D) nickel substrate using the facile dip-coating method. The MoS 2 NDs were successfully synthesized by controlled bath sonication of highly crystalline MoS 2 nanosheets. The as-fabricated high-surface area electrode demonstrated promising electrochemical properties. It was observed that the as-synthesized NDs outperformed the layered MoS 2 peers as the electrode for supercapacitors. MoS 2 NDs exhibited an excellent specific capacitance (C sp ) of 395 F/g at a current load of 1.5 A/g in a three-electrode configuration. In addition, the fabricated symmetric supercapacitor demonstrated a C sp value of 122 F/g at 1 A/g and a cyclic performance of 86% over 1000 cycles with a gravimetric power and energy density of 10,000 W/kg and 22 W h/kg, respectively. Owing to its simple and efficient fabrication and high surface area, such 3D electrodes show high promise for various energy storage devices.

Lithium–sulfur batteries are regarded as the imminent energy storage device for high energy density applications. However, at practical sulfur loadings >5 mg cm−2, the cell suffers from severe capacity fade and durability. In the present work, a hybrid MoS2–WS2 heterodimensional structure is reported. The strain induced growth of transition metal dichalcogenides preferentially exposes edge sites and maximizes the geometric coverage for anchoring‐diffusion‐conversion of polysulfides to restrain the shuttle effect at practical S‐loadings. The systematic analysis (5–50 mg cm−2 of S‐loadings) reveals that the unique cathode architecture exhibits reversible S‐loading tolerance up to 28 mg cm−2. A high initial areal capacity of 32 mAh cm−2 with an area specific energy density of 67 mWh cm−2 is achieved with a low electrolyte volume/S‐loading ratio of 5 mL g−1. The strategy presented here can unlock high S‐loading Li–S cells with extended cyclability and high energy density.

Widespread commercialization of high-energy-density lithium-sulfur (Li-S) batteries is difficult due to the lithium polysulfide, Li 2 S n (n = 4, 6, 8), shuttle effect. Efficient adsorption/conversion of Li 2 S n species on an electrocatalytic surface can suppress the shuttle effect. Modeling of the adsorption of Li 2 S n species using density functional theory (DFT) calculations has contributed significantly toward an understanding of their anchoring mechanism at a surface. Different surfaces show a unique range of binding energies for faster Li 2 S n adsorption/reaction kinetics. To predict the optimum binding energy zone, a systematic DFT study is performed on transition-metal sulfide (TMS) surfaces including TiS 2 , VS 2 , NbS 2 , MoS 2 , WS 2 , and SnS 2 . The investigation revealed that the geometric properties at the anchoring site possibly regulate the adsorption energy of Li 2 S n species. A geometry parameter, G score , is defined as a function of bond length and number of lithium-atom interactions between the Li 2 S n species and the binding surface. The design principle is extended to sulfur-deficient (TMSs-x) and edge-exposed (TMS(100)) surfaces. The G score predicts the most effective binding energy zone distinctive to these materials-TMS (1.7-2.1 eV/G score ≥ 2.0), TMSs-x (2.0-2.8 eV/G score ≥ 2.1), and TMS(100) (2.5-3.2 eV/G score ≥ 1.09).