Three-dimensional Composites Research Articles

Free-Standing Carbon Nanofiber Composite Networks Derived from Bacterial Cellulose and Polypyrrole for Ultrastable Potassium-Ion Batteries.

Carbon materials derived from bacterial cellulose have been studied in lithium-ion batteries due to their low cost and flexible characteristics. However, they still face many intractable problems such as low specific capacity and poor electrical conductivity. Herein, bacterial cellulose is used as the carrier and skeleton to creatively realize the composite of polypyrrole on its nanofiber surface. After carbonization treatment, three-dimensional carbon network composites with a porous structure and short-range ordered carbon are obtained for potassium-ion batteries. The introduction of nitrogen doping from polypyrrole can increase the electrical conductivity of carbon composites and provide abundant active sites, improving the comprehensive performance of anode materials. The carbonized bacterial cellulose@polypyrrole (C-BC@PPy) anode exhibits a high capacity of 248 mA h g-1 after 100 cycles at 50 mA g-1 and a capacity retention of 176 mA h g-1 even over 2000 cycles at 500 mA g-1. Combined with density functional theory calculations, these results indicate that the capacity of C-BC@PPy is contributed by N-doped and defect carbon composite materials as well as pseudocapacitance. This study provides a guideline for the development of novel bacterial cellulose composites in the energy storage field.

Mechanical properties and macro–meso coupled damage behavior of three-dimensional four-directional braided composites under bending loading

A hierarchical coupled multiscale method is developed to capture the onset and propagation of damage within the three-dimensional four-directional (3D4D) braided composites subjected to bending loading. Using a directly two-scale coupled scheme, the macroscopic nonlinear behavior at the structural dangerous region could be iteratively solved, combined with the progressive damage response of the realistic mesoscale architecture. The continuum damage model is merely defined at the mesoscale and considers failure in each of constituents with the well-established Hashin failure criteria and the Bažant crack band damage model. To accelerate finite element computation in two scales, a parallel numerical implementation is presented alongside the commercial software ABAQUS/Standard. Besides the good agreement between the experimental and the predicted values, the results also show a significant effect of the braiding angle on the bending performance of 3D4D braided composites. With the increase of braiding angle, the bending stiffness and strength of 3D4D braided composites decreases, but the fracture toughness increases. This phenomenon was numerically investigated by identifying the different fundamental failure mechanism and damage development process at both the scales.

Freestanding TiO2 Nanoparticle-Embedded High Directional Carbon Composite Host for High-Loading Low-Temperature Lithium–Sulfur Batteries

Improving the low-temperature performance of lithium–sulfur batteries is significant for future applications. Meanwhile, a low temperature often leads to sluggish charge transfer kinetics and low energy output. Herein, we designed a thick freestanding TiO2 nanoparticle-embedded three-dimensional carbon composite (TiO2@C@CSC) host with high directional channels, aiming at achieving a high-performance low-temperature lithium–sulfur battery. The carbon-coated TiO2 nanoparticles (TiO2@C) are derived from polyimide-coated TiO2 nanoparticles and embedded in the channels. The chitosan-foam-derived carbon framework (CSC) has vertically aligned channels, which kinetically accelerates ion/electron transport and precisely confines sulfur/polysulfides within its channels. TiO2@C nanoparticles could facilitate the adsorption and conversion of polysulfides. The combination of vertically aligned channels and TiO2@C nanoparticles further provides a chemical gradient that prevents the diffusion of polysulfides and enhances the reaction kinetics at low temperatures. The designed host also has enough accommodation space, which is beneficial to improving the mass loading and utilization efficiency of active sulfur. Finally, the energy storage performance of TiO2@C@CSC as a sulfur host was investigated under 30, −20, and −40 °C. Under 30 °C, the initial discharge capacity of TiO2@C@CSC is 679 mAh g–1 at 1C with 4.0 mg cm–2 sulfur, and an initial capacity of 969 mAh g–1 could be obtained at 0.1C with the sulfur loading mass of 10.0 mg cm–2. Under −20 °C, the performance of TiO2@C@CSC with loading masses of 2.5, 5.0, 10.0, and 20.0 mg cm–2 was investigated, and the corresponding initial capacities at 0.05C were 1573, 924, 242, and 13 mAh g–1, respectively. As the temperature drops to −40 °C, the efficiency becomes lower but the charge–discharge process can still be complete. This work presents a promising direction for developing high-energy low-temperature lithium–sulfur batteries.

A Graphene-Based Aerogel Was Prepared as Solid Adsorbent for the Enrichment of Platinum (IV) at Trace Concentration

A three-dimensional graphene-based composite was prepared by a simple one-step in-site reduced-oxide method under atmospheric pressure. The obtained hydrogel was modified with 4-amino-benzenesulfonic acid and connected with ethylenediamine, and freeze-dried into an aerogel, which was characterized. Then the surface interaction with platinum (Pt, IV) was explored. The obtained aerogel showed good adsorption for Pt (IV) at acid conditions, giving a rising to the adsorption rate > 98% while pH ≥ 6. Using hexadecyl trimethyl ammonium bromide of 2% (m/V) as an eluent to desorb the Pt (IV) from the surface of the aerogel, a desorption rate of 81.1% was obtained in this process. Urea, buffer aquation and other surfactants were used in the desorption experiment to understand the adsorption mechanism between the aerogel and Pt (IV). In this work, hydrogen bond, van der Waals force and electronic interaction force mainly drove the adsorption process. For obtaining more purified Pt (IV), we used 0.5% CTAB to desorb Pd (II). A new three-dimensional graphene-based composite was prepared and the surface interaction between Pt (IV) and composite was experimented for understanding the adsorption mechanism and exploring its potential application in sample preparation in low concentration.

Molding and verification of dielectric constant of three-dimensional woven spacer composites

In this paper, a theoretical model was proposed for predicting the dielectric constant of 3DWSCs as a function of the fiber volume fraction and the composites’ structure. In addition, the formula for the dielectric constant of the spacer layer in this model can be extended to other sandwich composites. 3DWSCs with heights of 6mm, 8mm and 10mm were prepared, and their dielectric constant was obtained by experimental measurement, model prediction and finite element simulation. The results showed that the predicted value of the model was in good agreement with the measurement results and the finite element results, and the maximum errors were 2.5% and 4.9%, respectively. The model will increase the feasibility of designing the dielectric properties of 3DWSCs, which was of great help and convenience to its applications such as radome or microstrip antenna.

Architecture of dual emissive three-dimensional nanostructure composites containing graphitic 2D sheets and iron oxide nanoparticles: detection of short single-stranded DNA sequences.

Here, we report an effect driven by repetitive heating and cooling; as a result, 2D and 1D nanomaterials are parallelly produced locally in a single reactor from the same precursors. Afterward, more repetitive heating and cooling induced the self-folding approach of a 2D nanomaterial with a 1D nanomaterial, giving them a self-assembled biconcave disk-shaped 3D nanostructure. The microscopy and spectroscopy studies reveal that the nanostructure has a diameter of nearly 200 nm and is composed of Fe, C, O and incorporated N and P. This 3D nanostructure composite shows red-shifted dual emission (430 nm and 500 nm) at two different excitations (350 nm and 450 nm), accompanied by a rare large Stokes shift (LSS), and it was employed in the detection of targeted short single-stranded DNA sequences (ssDNA). Upon the addition of target DNA, the specific binding of 3D nanostructure probes with the target triggers variations (off/on) of two signals, and by considering the decreased emission (fluorescence quenching) at 500 nm, we can detect the target ssDNA at the single-molecule level. The change of fluorescence intensity and the concentration of complementary target ssDNA sequences show a better linear relationship than a single emission-based probe, and the limit of detection (LOD) was as low as 0.47 nM.

Fiber inclination model for the anti-penetration performance of a new type three-dimensional angle-interlock woven composite

This study establishes a fiber inclination model suitable for a new three-dimensional angle interlocking woven UHMWPEF/epoxy composite, and evaluates its anti-penetration performance. Specifically, the microstructural characteristics of the composite material were analyzed by CT scan images, the mesostructure model of the material was established with the help of the software TexGen, and the calculation method of the fiber volume fraction of the material was designed. The meta-software ANSYS/LS-DYNA simulated and analyzed the failure mode and stress after ballistic penetration, before verifying it with the ballistic penetration test of the composite material as the target. The results show that the fiber volume fraction of the material is calculated to be 49.5% according to the derivation formula, which is consistent with that measured in the laboratory (50%±1%). By simplifying the numerical simulation model of composite ballistic penetration with the “fiber inclination model,” the residual velocity of the projectile calculated is in good agreement with the experimental value with an error of <7%. In the target penetration test, the damage patterns of the target surface and the ejection surface are similar to the numerical simulation results. In the fiber inclination model, the failure shape of the projectile penetrating the horizontal one-way plate is almost circular, while the failure shape in the inclined one-way plate is irregular with a more severe damage along the inclined direction. In both unidirectional plates the damage area of the incoming surface is smaller than that of the ejected surface. Therefore, it is valid to use the fiber inclination model established to study the penetration performance of composite materials.

Three-dimensional representative volumetric elements for the construction of composite materials with improved mechanical properties

A methodological and software tool was developed for the effective assessment of the properties of three-dimensional composites of the matrix type and periodically structured composite materials using modern methods of boundary and finite elements. Continuum mechanics models have been modified to adequately describe the behavior of composites, numerical simulation models and software have been adapted to these models for solving static problems and problems in the frequency domain. The novelty, advantages and efficiency of the developed computer technology are provided by theoretically grounded models for the analysis of composites of three-dimensional configuration with non-canonical particle shapes, improvement of modern boundary and finite element methods and coupled algorithmic schemes to achieve high accuracy of calculation analysis; suitability for the analysis of both static and dynamic elastic fields in the considered structures. Calculation models and software tools have been developed that allow to take into account special forms of individual and interacting inhomogeneities in a three-dimensional matrix, in particular, with an emphasis on short fibers and tubes. These models and methods are applied to the study of static and dynamic characteristics of launch vehicle tanks made of various composite materials. For the studying free and forced oscillations of shell structures with compartments containing liquid, the method of natural modes has been developed. Composites with an aluminum matrix with steel spherical inclusions and with steel and carbon fiber inclusions were considered as tank materials. The proposed models and computer simulation algorithms allow to carry out the numerical analysis of three-dimensional static problems under classical conditions of contact with the matrix; three-dimensional problems regarding the static interaction of a finite number of inclusions in the matrix; research of ordered and stochastically distributed inclusions; study of inclusions in the form of spheres, cylinders, carbon tubes and inclusions in the form of hollow spheres and to determine the effective elastic parameters of three-dimensional matrix composites with spherical inclusions, fibers and tubes. The results of the calculations showed strengthening of the obtained composite materials with a simultaneous decrease in density

In situ anchoring of MnO nanoparticles into three-dimensional nitrogen-doped porous carbon framework as a stable anode for high-performance lithium storage

Although transition metal oxides have the advantages of large theoretical capacity, low cost and eco-friendliness, their application as anodes for lithium-ion batteries (LIBs) is still limited due to their undesirable electrical conductivity and large volume expansion. Herein, a novel two-step rapid freeze-drying-calcination strategy was applied to prepare highly dispersed nano-MnO-anchored three-dimensional nitrogen-doped porous carbon framework composites (MnO@3D N-PCF). Compared with MnO and undoped MnO@3D PCF, the MnO@3D N-PCF anode exhibits superb cycle stability, remarkable specific capacity and impressive high-rate performance (1037.0 mAh g−1 over 100 cycles at 0.1 A g−1 and 760.9 mAh g−1 over 500 cycles at 5 A g−1), mainly due to its well-designed 3D nanoarchitecture. It is found that 3D nitrogen-doped carbon networks can act as stable conductive bridges to facilitate electron transport and sufficient diffusion channels for Li ions. The MnO nanoparticles obtained by rapid lyophilization and calcination technology are highly dispersed in the porous 3D carbon skeleton, which can buffer volume expansion and preserve the stability of the electrode. It is expected that this simple and green synthesis strategy will open the door for the development of transition metal oxide/carbon three-dimensional nanocomposites with high stability and excellent electrochemical properties.

Inhomogeneous copper matrix composites reinforced by RGO/Cu composite foams with high electrical conductivity, tensile strength and fracture elongation

A three-dimensional (3-D) skeleton-reinforced copper composite was designed to overcome the paradox between strength and ductility or conductivity. Open cell copper matrix foams with uniformly embedded reduced graphene oxide (RGO) were prepared via electrodeposition. The foam pores were filled with pure copper phase via spark plasma sintering (SPS). Cu2O nanoparticles were formed at the RGO-Cu interface, resulting in improved interfacial bonding. Three-dimensional skeleton-reinforced composites showing a combination of high electrical conductivity (93.24% IACS), tensile strength (343 MPa), and fracture elongation (39.4%) were fabricated with low levels of RGO (0.024 wt%). The possible strengthening mechanism of the skeleton-reinforced composites is discussed basing on the test results.

Effects of impactors’ shape on three-dimensional woven fabric composites at low-velocity impacts

This study investigated the fabric resistance of three-dimensional (3D) woven fibreglass composites generated by impactors of three shapes, i.e., hemispherical, conical, and ogival, on four types of composite structures. Composites were fabricated using the hand lay-up technique. Crimp and mechanical impact resistance tests were carried out in accordance with ASTM D2444 standards and ASTM D3883-04, respectively. The four-floating interlocked (4FLL) yielded the strongest fabric damage tolerance for all the three types of impactors’ shapes with 6.3 kN for the hemispherical shape, 4 kN for the conically shaped, and 3.8 kN for the ogival shape. Additionally, the 4FLL generated a fabric crimp of 3.5% and 2.8% on both fabric directions. The post-impact damage showed that the ogival shape impactor penetrated samples of woven composites better than the conical and hemispherical shapes.

Process-structure-performance modelling and progressive damage analysis of 3D rotary-four-directional rectangular braided composites under tensile load

The mechanical properties of braided composites are sensitive to the braiding process. However, the relations between process parameters, yarn structures and mechanical properties of three-dimensional (3D) rotary braided composites have not been investigated. In this study, we aim to establish a model capable of characterizing the yarn structures and mechanical properties of 3D rotary braided composites by treating braiding angles as primary variables. Carrier motions on the bedplate were traced by mathematical functions, where corresponding yarn spatial paths within a representative volume element (RVE) were explored. A parametric finite element model (FEM) of 3D rotary-four-directional (3DR4d) braided composites was established considering realistic yarn cross-sections. A progressive damage model was used to predict the mechanical performance of the composites. Experiments were conducted to verify the proposed model. The results show that the ideal yarn topology of the rotary braided composites is similar to the lattice structure. In addition, the longitudinal tensile modulus and strength of 3DR4d braided composites increase with the decreased braiding angles, while increasing with the increased fiber volume fractions. According to damage analysis, longitudinal tension and transverse shear are the dominant failure modes of 3DR4d composites with small and large braiding angles, respectively.

A novel bottom-up methodology for design and fabrication of three-dimensional braided hybrid composites based on the law of yarn routing and grouping

A hybrid is an effective means to improve the comprehensive properties of composites. In the current article, by investigating the yarn routing and grouping law in three-dimensional braiding, a novel bottom-up methodology for the design and fabrication of three-dimensional braided hybrid composites is proposed based on the [ m, m] hybrid unit. Three-dimensional braided hybrid composites with different sizes of hybrid unit were prepared and drop-hammer based impact tests were conducted to study the composites' dynamic mechanical performances. It was found that the three-dimensional braided hybrid composites based on the bottom-up methodology present much better structural integrity and toughness than conventional ply-stacked hybrid counterparts and significant dependence of mechanical performances on the size of hybrid unit. We found that the smaller the size of hybrid unit, the better the mechanical performance. The results demonstrated the feasibility and effectiveness of the proposed bottom-up methodology and could enable the design and fabrication of three-dimensional braided preforms and composites with certain well designed structures and functions.

Visualization and quantification of low-velocity impact damage of three-dimensional braided CFRP composites by micro-computed tomography

In this paper, the low-velocity impact response and damage of three-dimensional five-directional (3D5d) braided carbon/epoxy composites under different energies (30 J, 65 J, 100 J) are studied. Importantly, the damage is segmented from the axial and radial directions of the yarn to visualize and quantify the damage distributions in different regions based on micro-CT. The results show that as compared with the samples under 30 J and 100 J, the samples under 65 J energy perform higher impact properties. Moreover, as the impact energy increases from 30 J to 100 J, the corresponding damage volume increases from 6.886 mm3 to 477.133 mm3. Furthermore, the damage distributions are almost symmetrical in space.

Compressive behaviors of thermo-oxidative aged three-dimensional angle-interlock woven composites under different strain rates

The mechanical behaviors of three-dimensional angle-interlock woven composites (3DAWCs) after thermo-oxidative aging under different strain rates are imperative to retain safety in high-temperature conditions. This work presents the thermo-oxidative aging effects on strain rate sensitivity and compression failure mechanism of 3DAWCs based on the digital image correlation technique and finite element analysis. The results revealed that the compressive modulus and maximum stress of the 3DAWCs are strain rate sensitive, while the thermo-oxidative aging would reduce the strain rate sensitivity. The strain rate coefficient of the resin and composite decreased by approximately 9% and 25% after thermo-oxidative aging, respectively. The compressive damage failure modes of the 3DAWCs mainly include resin cracks, interfacial debonding, and yarn fracture. The strain rate has effects on damage initiation and brittle-ductile fracture behavior. The aging effect changes the crack propagation path, but does not affect the inclined 45° shear mode. In addition, the strain rate effects on strain localization were found and will be enhanced after thermo-oxidative aging.

Fatigue behavior and failure of three-dimensional six-directional braided composites under tension

Carbon/epoxy-three-dimensional (3D) six-directional braided composites are fabricated and tensile fatigue behavior are reported. The results show that the composites have good fatigue properties and limit with small braiding angle. Fatigue life decreases with increasing the stress level. Dynamic modulus decreases and rate of stiffness degradation is also restricted by cycle number. Moreover, there are two regions on the hysteretic curve where the failure strain suddenly increases. Fracture morphology indicates that fatigue cracks spread from the outside to inside of the material and enter fiber/matrix interface, then to the fibers. The damage degree becomes more serious with increasing the stress level. At low stress levels, composite shows small damage and flush fracture. At high stress levels, it exhibits shear fracture along the braiding angle.

Unit-cell geometry and mechanical properties of three-dimensional seven-directional braided composites

Three theoretical microstructural models were constructed based on manufacturing three-dimensional seven-directional (3D7d) braided preforms, and their relationships with braiding angles, fiber volume fractions, and yarn filling factor were investigated. The influences of braiding parameters, loading directions, and braiding structure on the performances of 3D7d braided composites were predicted in combination with a bridging model. The results concluded that the longitudinal modulus and tensile strength decreased with increasing braiding angles, while the transverse modulus and strength were opposite, and the performances of composites were better at higher fiber volume fractions. Compared with 3D4d braided composites, the transverse strength of 3D7d braided composites improved significantly. Furthermore, the three microstructural models were damaged in the order of interior, surface, and corner unit cell models during tensile loading. Especially, the fifth and seventh yarns within unit cell models were damaged firstly under longitudinal and transverse loads, respectively. This method adopted in this work provides a basis for predicting the mechanical properties of 3D7d braided composites.

Three-dimensional Ti3C2Tx and MnS composites as anode materials for high performance alkalis (Li, Na, K) ion batteries

Exploring capable and universal electrode materials could promote the development of alkalis (Li, Na, K) ion batteries. 2D MXene material is an ideal host for the alkalis (Li, Na, K) ion storage, but its electrochemical performance is limited by serious re-stacking and aggregation problems. Herein, we cleverly combined electrostatic self-assembly with gas-phase vulcanization method to successfully combine Ti3C2Tx-MXene with ultra-long recyclability and high conductivity with MnS, which presents high specific capacity but poor conductivity. The as-prepared 3D hierarchical Ti3C2Tx/MnS composites have an unique sandwich-like constituent units. The tiny MnS nanoparticles are restricted between the Ti3C2Tx layers and play a key role in expanding the Ti3C2Tx interlayer spacing. As a result, the 3D Ti3C2Tx/MnS composites as the anode of LIBs exhibits a superior capacities of 826 and 634 mAh/g after 1000 and 3000 cycles at 0.5 and 1.0 A/g, respectively. More importantly, we reveal the reaction mechanism that the specific capacity first increases and then gradually stabilizes with the increase of charge and discharge cycle times when the as-prepared 3D Ti3C2Tx/MnS was used as the anode of LIBs. In addition, we have also used this material in SIBs and PIBs and achieved remarkable electrochemical capability, with a specific capacity of 107 mAh/g after 2500 cycles at 0.5 A/g or 127 mAh/g after the 2000th cycle at 0.2 A/g, respectively.

In-situ formation of cobalt phosphide nanoparticles confined in three-dimensional porous carbon for high-performing zinc-air battery and water splitting

AbstractThe rational design of efficient and stable carbon-based electrocatalysts for oxygen reduction and oxygen evolution reactions is crucial for improving energy density and long-term stability of rechargeable zinc-air batteries (ZABs). Herein, a general and controllable synthesis method was developed to prepare three-dimensional (3D) porous carbon composites embedded with diverse metal phosphide nanocrystallites by interfacial coordination of transition metal ions with phytic acid-doped polyaniline networks and subsequent pyrolysis. Phytic acid as the dopant of polyaniline provides favorable anchoring sites for metal ions owing to the coordination interaction. Specifically, adjusting the concentration of adsorbed cobalt ions can achieve the phase regulation of transition metal phosphides. Thus, with abundant cobalt phosphide nanoparticles and nitrogen- and phosphorus-doping sites, the obtained carbon-based electrocatalysts exhibited efficient electrocatalytic activities toward oxygen reduction and evolution reactions. Consequently, the fabricated ZABs exhibited a high energy density, high power density of 368 mW cm−2, and good cycling/mechanical stability, which could power water splitting for integrated device fabrication with high gas yields.

Magnetically-oriented porous hydrogel advances wearable electrochemical solidoid sensing heavy metallic ions

Developing wearable sensors to determine chemical contamination in solidoid is currently a great challenge. Hydrogels with polymeric networks have been employed as electrochemical cells and media to realize wearable solidoid sensing. However, it is still a hard task to enable hydrogel to simultaneously possess effective mass transfer, mechanical robustness as well as easy and tight adhesion to sensing electrodes. Routinely, a hydrogel with improved adhesion to the electrode surface by introducing additives may deteriorate the mass transfer capability. Increasing the porosity of hydrogel could enhance mass diffusion but sacrifices mechanical robustness. Herein, a composite hydrogel is achieved by embedding magnetic oriented MWCNT-Fe3O4 strips in porous agarose (MMFPA), which exhibits enhanced permeability and speeding diffusion of electrolyte ions. Moreover, the orientation in order and strip-like MWCNT-Fe3O4 three-dimensional composites improve the compressive strength of hydrogel, which could recover back within 2 min in water after removal of pressure. Such magnetic hydrogel is beneficial to be assembled to the wearable glove sensor by using magnets to achieve a stable and compact sensing platform. As the application example, the resultant wearable sensing protocol is successfully utilized to monitor Cd2+ trace residues in rice, tea, and soil with an affordable response as low as 0.112 mg/kg and rapid signal acquisition (<5 min). It paves an attractive, accessible, and effective way to on-site evaluate solidoid Cd2+ level for forewarning food safety and environmental risk.