Lithium sulfur (Li-S) batteries hold great promising for high-energy-density batteries, but appear rapid capacity fading due to the lack of overall and elaborated design of both sulfur host and ...interlayer. Herein, we developed a novel two-dimensional (2D) hierarchical yolk-shell heterostructure, constructed by a graphene yolk, 2D void and outer shell of vertically aligned carbon-mediated MoS2 nanosheets (G@void@MoS2/C), as advanced host-interlayer integrated electrode for Li-S batteries. Notably, the 2D void, with a typical thickness of ∼80 nm, provided suitable space for loading and confining nano sulfur, and vertically aligned ultrathin MoS2 nanosheets guaranteed enriched catalytically active sites to effectively promote the transition of soluble polysulfides. The conductive graphene yolk and carbon mediated shell sufficiently accelerated electron transport. Therefore, the integrated electrode of G@void@MoS2/C not only exceptionally confined the sulfur/polysulfides in 2D yolk-shell heterostructures, but also achieved catalytic transition of the residual polysulfides dissolved in electrolyte to solid Li2S2/Li2S, both of which synergistically achieved an extremely low capacity fading rate of 0.05% per cycle over 1000 times at 2 C, outperforming most reported Mo based cathodes and interlayers for Li-S batteries. 2D hierarchical yolk-shell heterostructures developed here may shed new insight on elaborated design of integrated electrodes for Li-S batteries.
2D hierarchical yolk-shell heterostructures were constructed with graphene yolk, 2D void and outer shell of vertically aligned carbon-mediated MoS2 nanosheets as advanced host-interlayer integrated electrode for high-performance Li-S batteries. Display omitted
Self-powered and flexible sensitive systems are highly demanded in various situations such as daily lives, industrial production, personal health and multifunctional entertainments, but they are ...still facing great challenge in realization of excellent flexibility, maintenance-free property, high integration and favorable sensitivity. Herein, we demonstrate scalable construction of in-plane microscale self-powered integrated systems, composed of Si based photovoltaics as energy harvester to generate electricity, graphene-carbon nanotube micro-supercapacitors (MSCs) for energy storage, and dual-channel gas sensors for fast-response and highly selective detection towards NH3 and aniline, by a novel continuous centrifugal coating strategy. Notably, the prepared high-conducting graphene-carbon nanotube films can serve as both patterned microelectrodes of embedded MSCs and metal-free interconnects of the circuit, endowing the self-powered systems high integrity and splendid flexibility. Remarkably, the self-powered gas detection system exhibits excellent response (~20%, 100 ppm), ideal linear sensibility (from 25 ppm to 100 ppm) and outstanding selectivity to NH3 and aniline. Therefore, this work paves a novel avenue for scalable fabrication of highly integrated and self-powered multi-functional sensitive systems towards flexible electronics.
The in-plane microscale self-powered integrated systems is demonstrated through seamless integration of Si based photovoltaics, micro-supercapacitors and dual-channel gas sensors by continuous centrifugal coating strategy. The resulting integrated systems exhibits high integrity, favorable flexibility, maintenance-free property, and excellent gas detection performance including high response, ideal linear sensibility and outstanding selectivity towards NH3 and aniline. Display omitted
•In-plane self-powered dual-channel gas detection systems were constructed by continuous centrifugal coating strategy.•High-conducting graphene-carbon nanotube films endow the systems high integrity and remarkable flexibility.•The system exhibits excellent response, ideal linear sensibility and outstanding selectivity to NH3 and aniline.
An all-in-one self-sustained integrated system composed of a Si film solar cell, spray-printed a micro-supercapacitor and a gas sensor, exhibits excellent flexibility and durability.
Display omitted
...Printable micro-supercapacitors (MSCs) with remarkable versatility, customizability, high power density and long cycling lifespan, are regarded as a promising class of miniaturized power source for wearable and portable microelectronics. Herein, we demonstrate a novel Fe-based zeolitic imidazolate framework (Fe-ZIF)/graphene (FZG) heterostructure with high specific surface area and outstanding electrical conductivity for planar MSCs (FZG-MSCs) worked in a high-voltage ionic liquid gel electrolyte via a spray-printed strategy. The fully printed FZG-MSCs deliver a high areal energy density of 9.5 μWh/cm2, extraordinary cyclability, and tailored voltage/capacitance output. Furthermore, using a fully printed FZG-MSC, we seamlessly integrate a monolithically planar all-flexible self-sustained sensor system with a mounted solar cell and a printable NH3 gas sensor on the same side of single flexible substrate. The self-sustained sensor system exhibits high-sensitivity NH3 detection with a good response of 18.3% at 20 ppm and linear sensibility exposed to 2–20 ppm. Such a fully integrated system can utilize the converted solar energy stored in the MSC, and offer efficient electricity to power microelectronics whenever needed. Therefore, this contribution of printable planar device and integrated system paves a new avenue for constructing flexible microelectronics.
The nanosize effect in nanostructured electrode materials is significant for boosting rate performance; however, it brings about low capacity, low Coulombic efficiency, and poor stability. In this ...work, 2D atomically thin (001)-oriented single-crystalline LCO (SC-LCO) nanosheets with longer Li+ intercalation distance and a surface dominated with (001) planes are constructed to regulate the nanosize effect. The SC-LCO not only owns large plateau region capacity even at high rate (194 mAh g–1 at 1C and 111 mAh g–1 at 50C) but also realizes remarkable improvement in the initial Coulombic efficiency (92% at 1C) and cycling stability (83% capacity retention for 500 cycles). The battery-supercapacitor hybrid devices (BSHDs) assembled with kinetics and capacity doubly matched SC-LCO and mesoporous TiNb2O7 nanosheets offer high energy density (244 Wh kg–1 @ 693 W kg–1) and power density (15 kW kg–1 @ 151 Wh kg–1). Further, pouch-type full cells are assembled, demonstrating the enormous applicability of this strategy.
Accurate determination of impact loads is of great necessity for safe and economical design of flexible barriers. Nevertheless, measurement of the impact force on a flexible barrier is still an open ...problem due to the highly deformable flexible net under impact and stress concentration on force transducers. In this study, large-scale flume tests with new design of instrumentation were adopted to validate and optimise existing methods for measuring the impact forces on a flexible barrier. Specifically, single-boulder impact tests were conducted to verify the accuracy of those methods. A debris flow impact test was performed to quantitatively investigate the dynamic behaviour of a flexible barrier under the impact of a debris flow. Thanks to the well-designed instrumentation, the impact force distribution characteristics of a debris flow on a flexible barrier are discovered. During the interaction process, the debris flow first impacted on the bottom area of the flexible net, then the dynamic impact moved up with gradual deposition of debris material. It is found that the impact pressure on the central area of the net is much larger than that on two sides. Therefore, triangular-shaped load distribution is used to optimise the existing methods for measuring the impact force induced by a debris flow. Attributable to the good accuracy and simple instrumentation requirement, a new simple method can be generalized for real-time monitoring of impacts on flexible barriers installed in natural terrains
•Methods for measuring impact forces on flexible barriers are reviewed and verified.•Large-scale physical modelling is adopted to validate and optimise those methods.•The impact force characteristics of a debris flow on a flexible barrier are revealed.•A new method is optimised to measure impact forces induced by a debris flow.•This new method can be generalized for monitoring of impacts on flexible barriers.
The present work aims to systematically study the aggregation behavior of one halogen-free surface active ionic liquid (SAIL), i.e., 1-butyl-3-methylimidazolum dodecylsulfonate (C4mimC12H25SO3), in ...water and ethylammonium nitrate (EAN), respectively. Multiple-state ordered aggregates, viz. lyotropic liquid crystals (LLCs) (normal hexagonal and laminar lyotropic liquid phases, i.e. H1 and Lα phases) and lamellar gels, were facilely tuned only by the concentration of SAIL or solvent type. Furthermore, it is particularly interesting that LLC phases were constructed in H2O while lamellar gels were obtained in the EAN media environment, which were characterized by polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). According to the investigative SAXS patterns, some structural parameters were calculated, suggesting that a higher concentration of SAIL results in a denser arrangement whereas an opposite trend generates because of a higher temperature. FT-IR spectra and density functional theory (DFT) calculations reveal that both strong H-bonding and electrostatic interactions between EAN and the headgroups of C4mimC12H25SO3 facilitate gelation. For the self-assembled lamellar gels formed by C4mimC12H25SO3 in EAN, a thermally reversible sol–gel transition was observed by differential scanning calorimetry (DSC). The rheological results show that the H1 phase formed by C4mimC12H25SO3 in water exhibits a viscoelastic gel-like behavior among the whole frequency region while Lα phase displays a viscous behavior at lower frequencies and an elastic behavior at higher frequencies. This work is expected to set a basis for application of the eco-friendly halogen-free SAIL in some fields, e.g. electrochemistry, supramolecular chemistry and drug delivery.
Display omitted
•A halogen-free alkyl sulfonate-based surface active ionic liquid was synthesized.•Multiple-state ordered aggregates were systematically studied in water and ethylammonium nitrate.•The concentration of SAIL or solvent type can facilely tune the aggregation behaviors.•LLC phases were constructed in H2O while lamellar gels were obtained in the EAN media environment.
Two-dimensional (2D) mesoporous pseudocapacitive polymer/graphene heterostructures combine the advanced merits of 2D materials and mesoporous materials, possessing unique nanosheet structure, large ...specific surface area (SSA), abundant oxygen/nitrogen-containing groups, desirable electrical conductivity and admirable electrochemical redox activity, and hold great potential for constructing high-performance planar micro-supercapacitors (MSCs). Herein, we demonstrate the interfacial assembly of 2D mesoporous polydopamine/graphene (mPDG) heterostructures with well-defined mesopore structure (12 nm) and adjustable thickness (7.5–14.1 nm) for planar high-energy pseudocapacitive MSCs. Attributed to medium thickness, exposed mesopore of 12 nm and large SSA of 108 m2/g, the mPDG with 10.8 nm thickness reveals prominent mass capacitance of 419 F/g and impressive cycling stability with ∼96% capacitance retention after 5000 cycles. Furthermore, the symmetric mPDG-based MSCs with “water-in-salt” gel electrolyte present wide voltage window of 1.6 V, superior volumetric energy density of 11.5 mWh/cm3, outstanding flexibility and self-integration ability. Therefore, this work offers a new platform of controllably synthesizing 2D mesoporous heterostructures for high-performance MSCs.
The interfacial assembly of 2D polydopamine/graphene heterostructures with well-defined mesopore structure of 12 nm and adjustable thickness of 7.5–14.1 nm is demonstrated for high-energy pseudocapacitive micro-supercapacitors. Display omitted
A series of butynediol-ethoxylate based polysiloxanes (PSi-EOs) with same composition but different lengths of siloxane backbone were designed and synthesized via hydrosilylation reaction. Their ...physicochemical properties and application performances have been discussed. With the increase of the length of siloxane backbone, the critical aggregation concentration (CAC) decreases and the surface tension at CAC (γCAC) increases, but the dynamic adsorption at the air/water interface has no significant change. Above the CAC, all of these three surfactants can self-assemble into spherical aggregates of 100 to 500nm in aqueous solution. Moreover, the contact angle measurement on Paraffin film demonstrates that shorter siloxane backbone length of PSi-EO leads to lower contact angle and shows better spreading and wetting abilities. Using the foaming power test, PSi-EO with a longer siloxane backbone exhibits lower foaming and more effective anti-foaming properties in water.
Three butynediol-ethoxylate based polysiloxanes (PSi-EOs) with different lengths of siloxane backbone were successfully synthesized and characterized. Such surfactants exhibit powerful surface activity, unique aggregation behavior, outstanding propensity for spreading and wetting, and significantly low foaming property in aqueous solution. The siloxane backbone length of PSi-EO plays an important role in their physicochemical properties and application performances, which may be useful to design and synthesize novel polysiloxane amphiphiles and develop their interesting practical applications concerning agricultural adjuvants, home care products and coatings. Display omitted
•Three butynediol-ethoxylate based polysiloxanes (PSi-EOs) were synthesized via hydrosilylation reaction.•The properties of PSi-EOs in aqueous solutions were studied systematically.•The effects of siloxane backbone length of PSi-EOs on their properties were elucidated and discussed.
Debris flow normally occurs after heavy rains in mountainous regions with multiple surges. Flexible barriers are installed in torrents to intercept debris flows in an early stage. For the safer ...design of a flexible barrier installed in the upstream, the forces on the barrier invaded by debris flows should be taken into consideration. An outdoor physical modelling facility was utilized to study the interaction between debris flows and a flexible barrier. Three continuous debris flow impact tests were conducted to investigate the performance of a flexible barrier affected and overflowed by multiple surges of debris flow. A parameter named Initial Block Ratio (IBR) is introduced in this study to describe the initial condition of a flexible barrier filled by the earlier debris flow surges. By analysing the results of these tests, the dynamic response of a flexible barrier under the impact of multiple surges of debris flow is studied, and the influence of IBR on the interaction of debris flow with the flexible barrier is investigated. Based on the findings of the experimental study, a new simple method is proposed to calculate the loads on a filled flexible barrier overflowed by debris flow. By comparing with the measured impact force in the overflow test, this method has a good performance and can be utilized in design analysis with further calibration.
PDF
