Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the ...Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.展开更多
Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication,...Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication, and portable/wearable electronic equipment.In this work, a nacre-inspired multifunctional heterocyclic aramid(HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper withlarge-scale, high strength, super toughness, and excellent tolerance tocomplex conditions is fabricated through the strategy of HA/MXenehydrogel template-assisted in-situ assembly of PPy. Benefiting from the"brick-and-mortar" layered structure and the strong hydrogen-bondinginteractions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa),outstanding toughness (57.6 MJ m−3), exceptional foldability, and structural stability against ultrasonication. By using the template effect ofHA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly,the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dBat an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2g−1. In addition, the papers also have excellent applicationsin electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developinghigh-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management.展开更多
This study introduces a cut-to-fit methodology for customizing bulk aramid aerogels into form factors suitable for wearable energy storage.Owing to strong intercomponent bonds within aramid-based building blocks,it is...This study introduces a cut-to-fit methodology for customizing bulk aramid aerogels into form factors suitable for wearable energy storage.Owing to strong intercomponent bonds within aramid-based building blocks,it is possible to delaminate layered bulk aerogel into flexible and thinner sheets,enabling efficient mass production.This process allows for precise customization of aerogel dimensions,shape,and elasticity,ensuring high resilience to deformation along with excellent thermal and impact resistance.Incorporation of conductive carbon nanotubes on the surface significantly enhances electrical conductivity and multi-catalytic activity while retaining the inherent advantages of aramids.These advancements facilitate the use of flexible and conductive electrodes as air cathodes in solid-state zinc–air batteries(ZABs),which demonstrate superior cyclic performance and lifecycles exceeding 160 h.Furthermore,aramid-based packaging provides superior protection for pouch-type ZABs,ensuring a consistent power supply even in severe conditions.These batteries are capable of withstanding structural deformations and absorbing physical and thermal shocks,such as impacts and exposure to fire.Moreover,the innovative reassembly of custom-cut single-pouch cells into battery modules allows for enhanced power output,tailored to wearable applications.This highlights the potential of the technology for a wide array of wearable devices requiring dependable energy sources in demanding environments.展开更多
Nanofiber carbon aerogels with 3D interconnected microfibrillar networks exhibit fascinating physical properties and present great application potential.However,it is still a challenge to fabricate superelastic nanofi...Nanofiber carbon aerogels with 3D interconnected microfibrillar networks exhibit fascinating physical properties and present great application potential.However,it is still a challenge to fabricate superelastic nanofiber carbon aerogels owing to their extremely dilute brittle interconnections and poor fiber toughness after carbonization.Herein,aramid nanofibers(ANF)/nanocellulose(CNF)dual-fibrous carbon aerogels are prepared,which exhibited supercompressibility and superelasticity due to the"skeleton-binder"synergistic effect of ANF and CNF and the design of in-plane micro-wrinkle honeycomb structure.The"skeleton-binder"synergistic effect improves interfacial interactions of nanofibers and optimizes the stress distribution of carbon aerogel.The highly ordered honeycomb structure with in-plane microwrinkles,formed by the bidirectional freezing and the difference in volume shrinkage during the carbonization between CNFs and ANFs,endows the CNF/ANF carbon aerogel with negative Poisson's ratio and high energy absorption capacity.These strategies significantly improve the overall mechanical properties of ANF/CNF carbon aerogel including the elasticity and fatigue resistance.As a result,the ultralight carbon aerogel(3.46 mg/cm^(3))exhibits excellent supercompression(undergoing an extreme strain of 95%)and elasticity(a stress retention up to 81.38% at 90% strain with 500 cycles and 96.15% at 50%strain with 10,000 cycles).The nanofiber carbon aerogel shows excellent multifunctional properties in flexible piezoresistive sensor and anisotropic thermal insulation materials,including a desirable sensitivity(as high as 48.74 kPa^(-1))and an instant response time(~40 ms),an anisotropy factor of 3.69 and an ultralow radial thermal conductivity(0.012 W m^(-1) K^(-1)).These properties make dual-fibrous carbon aerogels highly attractive in pressure sensors and thermal management applications.展开更多
Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechan...Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechanical and inadequate thermal properties present significant challenges for practical applications in diverse complex scenarios.Herein,lightweight,high-strength and flame-retardant aramid nanofibers-based honeycombs(MANHs)for integrated microwave absorption and thermal insulation are successfully fabricated via the hydrogen bonding assembly,mold forming and aerogel filling strategy using aramid waste as raw material.The dense network structure formed by the interwoven aramid nanofibers(ANFs)in the honeycomb body acts as a framework endows the MANH with impressive mechanical performance,and the specific strength and toughness of MANH reach 153.6 MPa g^(−1) cm^(−3) and 13.9 MJ m^(−3),respectively,which are 3.5 and 19 times higher than those of commercial microwave absorption honeycombs(CMAH).The ultralight MXene/ANFs aerogels(a density of 25 mg cm^(−3))with multiscale pore structure filled in the honeycomb apertures give the honeycomb outstanding microwave absorption performance,with a minimum reflection loss of−62.5 dB,and can cover the entire X-band with a thickness of only 3.5 mm.Meanwhile,compared with CMAH,the thermal insulation and flame-retardant performance of MANH are also significantly improved.Notably,MANH also demonstrates favorable sound absorption performance at high-frequency bands.The MANH is considered to be a promising candidate for aerospace and military stealth applications as a result of its lightweight,high strength,exceptional microwave absorption,and remarkable thermal insulation performance.展开更多
Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current r...Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.展开更多
In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its thei...In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its their applications in extreme circumstances.Herein,an ultra-thin and highly flexible aramid nanofiber(ANF)/MXene(Ti_(3)C_(2)T_(x))/Ni nanochain composite paper was prepared through vacuum-assisted filtration and freeze-drying technology.Owing to the synergistic effect between ANF and MXene,the composite paper not only possessed excellent mechanical properties,which were able to withstand over 10,000 times its own weight,but also exhibited outstanding flame-retardant and controllable Joule heating ca-pabilities.Moreover,the mechanical energy capture characteristics of the composite paper-based TENG were evaluated,resulting in the open-circuit voltage(55.6 V),short-circuit current(0.62μA),and trans-ferred charge quantity(25μC).It also could enable self-powering as a wearable electronic device with an instantaneous power of 15.6μW at the optimal external resistance of 10 MΩ.This work is intended to set TENG as safe energy harvesting devices for reducing fire hazards,and will provide a new strategy to broaden the application ranges of TENG.展开更多
This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recen...This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.展开更多
The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will dep...The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will depend upon the consistency of the properties of the constituent materials.In a body armour system for example,fibre diameter,areal density of woven fabric,and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures.What is often overlooked,because it can fall into the User’s domain,are the interfaces that exist between the various products;the carrier,the Soft Armour Insert(SAI),and the one or two hard armour plates(HAP1 and HAP2).This is especially true if the various products are sourced from different suppliers.展开更多
Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles,it is still a challenge to simultaneously enhance both conductivity and mechanical propert...Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles,it is still a challenge to simultaneously enhance both conductivity and mechanical properties of MXene fibers because of the high rigidity of MXene sheets and insufficient inter-sheet interactions.Herein,we demonstrate a core-shell wet-spinning methodology for fabricating highly conductive,super-tough,ultra-strong,and environmentally stable Ti_(3)C_(2)T_(x) MXene-based core-shell fibers with conductive MXene cores and tough aramid nanofiber(ANF)shells.The highly orientated and low-defect structure endows the ANF@MXene core-shell fiber with supertoughness of~48.1 MJ m^(-3),high strength of~502.9 MPa,and high conductivity of~3.0×10^(5)S m^(-1).The super-tough and conductive ANF@MXene fibers can be woven into textiles,exhibiting an excellent electromagnetic interference(EMI)shielding efficiency of 83.4 dB at a small thickness of 213μm.Importantly,the protection of the ANF shells provides the fibers with satisfactory cyclic stability under dynamic stretching and bending,and excellent resistance to acid,alkali,seawater,cryogenic and high temperatures,and fire.The oxidation resistance of the fibers is demonstrated by their wellmaintained EMI shielding performances.The multifunctional core-shell fibers would be highly promising in the fields of EMI shielding textiles,wearable electronics and aerospace.展开更多
High-performance ballistic fibers,such as aramid fiber and ultra-high-molecular-weight polyethylene(UHMWPE),are commonly used in anti-ballistic structures due to their low density,high tensile strength and high specif...High-performance ballistic fibers,such as aramid fiber and ultra-high-molecular-weight polyethylene(UHMWPE),are commonly used in anti-ballistic structures due to their low density,high tensile strength and high specific modulus.However,their low modulus in the thickness direction and insufficient shear strength limits their application in certain ballistic structure.In contrast,carbon fiber reinforced epoxy resin matrix composites(CFRP)have the characteristics of high modulus in the thickness direction and high shear resistance.However,carbon fibers are rarely used and applied for protection purposes.A hybridization with aramid fiber reinforced epoxy resin matrix composites(AFRP)and CFRP has the potential to improve the stiffness and the ballistic property of the typical ballistic fiber composites.The hybrid effects on the flexural property and ballistic performance of the hybrid CFRP/AFRP laminates were investigated.Through conducting mechanical property tests and ballistic tests,two sets of reliable simulation parameters for AFRP and CFRP were established using LS-DYNA software,respectively.The experimental results suggested that by increasing the content of CFRP that the flexural properties of hybrid CFRP/AFRP laminates were enhanced.The ballistic tests'results and the simulation illustrated that the specific energy absorption by the perforation method of CFRP achieved 77.7%of AFRP.When CFRP was on the striking face,the shear resistance of the laminates and the resistance force to the projectiles was promoted at the initial penetration stage.The proportion of fiber tensile failures in the AFRP layers was also enhanced with the addition of CFRP during the penetration process.These improvements resulted in the ballistic performance of hybrid CFRP/AFRP laminates was better than AFRP when the CFRP content was 20 wt%and 30 wt%.展开更多
An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate compo...An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate composed of aramid and carbon fibers was innovatively used in flexible Electromagnetic Interference(EMI)shielding materials.The natural network structure is advantageous to the uniform deposition of metal particles to the establishment of conductive pathways subsequently in order to improve conductivity.The induction of a synergistic effect from Electromagnetic(EM)wave-reflection and EM wave-absorption through the whole carbonCo-Ni-ternary system notably enhanced the EMI Shielding Effectiveness(SE)value to an average of 42.57 d B in the range of 30-6000 MHz.On the other hand,together with the inherent toughness of the alloy coatings,the tensile strength of the aramid fibers used for bulletproof made a significant contribution to the desired mechanical properties.The light weight of the resultant composite made it applicable to aerospace vehicles simultaneously.X-ray Photoelectron Spectroscopy(XPS)was conducted to investigate the variations of elements and groups on the sample surface in pretreating process.The elemental components and surface morphologies of fabric samples during different stages of the process were investigated by Scanning Electron Microscope(SEM)and Energy Dispersive spectrometer(EDX)measurements.X-Ray Diffraction(XRD)results indicated that the obtained Co-Ni alloy coating had a combined Hexagonal Closed-Packed(HCP)and FacedCentered Cubic(FCC)crystalline phase.The relatively high corrosion resistance demonstrated in different acid and alkaline conditions was instrumental in more complex environments as well.展开更多
The design of flexible polymeric films with internal porous structures has received increasing attention in low dielectric applications.The highly porous metal-organic frameworks(MOFs)of[Cu_(3)(BTC)_(2)]_(n)(BTC=benze...The design of flexible polymeric films with internal porous structures has received increasing attention in low dielectric applications.The highly porous metal-organic frameworks(MOFs)of[Cu_(3)(BTC)_(2)]_(n)(BTC=benzene-1,3,5-tricarboxylate)were introduced into aramid nanofibers(ANF)matrix by using carboxylated cellulose nanofibrils(CNF)as carriers to obtain strong,flexible,and ultra-low dielectric films.The well-dispersed“flowers-branch”like CNF@CuBTC through in-situ growth of CuBTC on CNF surface endowed the ANF/CNF@Cu BTC films with excellent thermal stability,mechanical integrity and low dielectric properties.Besides,the flexible dielectric films exhibited superior ultraviolet(UV)resistance,lower coefficient of thermal expansion(4.28×10^(-5)℃^(-1))and increased water contact angle(83.81°).More interestingly,the removal of vip molecules from the ANF/CNF@CuBTC films according to the vacuum heat treatment(VHT)process significantly improved their dielectric response.The specific surface areas of the composite films after VHT increased obviously,and the dielectric constant and dielectric loss tangent decreased to the expected 1.8-2.2 and 0.001-0.03 at 100 MHz,respectively.Consequently,such designable ultra-low dielectric films with high flexibility play an incredible significance in applications of microelectronics under large deformation conditions,especially in flexible/wearable devices at the arrival of 5 G era.展开更多
Dynamic tensile impact properties of aramid (Technora) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns ...Dynamic tensile impact properties of aramid (Technora) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.展开更多
Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductilit...Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.展开更多
Compressive strengths and elastic moduli of Carbon Fiber Reinforced Polymer(CFRP)composites can be noticeably improved by multiple ultra-thin interlays with non-woven Aramid Pulp(AP)micro/nano-fibers.10-ply CFRP speci...Compressive strengths and elastic moduli of Carbon Fiber Reinforced Polymer(CFRP)composites can be noticeably improved by multiple ultra-thin interlays with non-woven Aramid Pulp(AP)micro/nano-fibers.10-ply CFRP specimens with 0,2,4,6,8 g/m^(2)AP were tested under uniaxial compression.Those flexible AP fibers,filling the resin-rich regions and further constructing the fiber bridging at the ply interfaces,can effectively suppress delamination growth and lead to very good improvements both in the compressive strength and the elastic modulus.The CFRP specimen with an optimum interlay thickness has a distinct shear failure mode instead of the typical delamination cracking along the direction of continuous carbon fibers.Compressive Strengths After Impacts(CAI)of 12.35 J were also measured,up to 90%improvement in CAI has been observed.It is concluded those ultra-thin interlays of non-woven AP micro/nano-fibers are beneficial to design and manufacture“high strength”CFRP composites.展开更多
Separators is indispensable for the normal operation of lithium-ion batteries(LIBs).However,the widely used commercial polyolefin separators have some inherent deficiencies such as poor thermotolerance,high inflammabi...Separators is indispensable for the normal operation of lithium-ion batteries(LIBs).However,the widely used commercial polyolefin separators have some inherent deficiencies such as poor thermotolerance,high inflammability and inferior electrolyte wettability,which restrict their further applications of the advanced and safe batteries.Herein,we design a novel thermotolerant(a shrinkage percentage of 0%at 300℃)and flame retarded aerogel separator consisting of aramid nanofibers(ANFs).Because of its high porosity(86.5%±6.1%)and excellent electrolyte uptake(695%),the ANFs aerogel separator has an ionic conductivity of 1.04 mS/cm and a high lithium-ion transference number(0.67),which can endow LIBs with outstanding rate performance and superior cycling performance.Specifically,the ANFs aerogel separator-based batteries possess a discharge specific capacity of 102 m Ah/g with a capacity retention of 90.7%and a Coulombic efficiency of 99.3%after 600 cycles at 5 C.In addition,under an operated temperature of 90℃,the battery with ANFs aerogel separator can still conduct the very steady chargedischarge,presenting a capacity retention of 90.1%and a Coulombic efficiency of 99.6%after 200 cycles at 3 C.Accordingly,the separator can probably serve as a potential candidate for application to advanced and safe LIBs.展开更多
Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macros...Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the composites.Herein,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-πinteractions.The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer channel.The composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.展开更多
基金supported by the National Natural Science Foundation of China(No.22278260)the Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry(No.KFKT2021-14)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology(No.KFKT2021-14).
文摘Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.
基金supported by the Fundamental Research Funds for the Central Universities and Heilongjiang Provincial Natural Science Foundation of China(Grant No.YQ2020E009).
文摘Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication, and portable/wearable electronic equipment.In this work, a nacre-inspired multifunctional heterocyclic aramid(HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper withlarge-scale, high strength, super toughness, and excellent tolerance tocomplex conditions is fabricated through the strategy of HA/MXenehydrogel template-assisted in-situ assembly of PPy. Benefiting from the"brick-and-mortar" layered structure and the strong hydrogen-bondinginteractions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa),outstanding toughness (57.6 MJ m−3), exceptional foldability, and structural stability against ultrasonication. By using the template effect ofHA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly,the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dBat an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2g−1. In addition, the papers also have excellent applicationsin electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developinghigh-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management.
基金supported by‘Regional Innovation Strategy(RIS)’through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(MOE)(2021RIS-002)supported by NRF grant funded by Ministry of Science,ICT and Future Planning(No.NRF-2018R1C1B6005009,NRF-2021R1C1C1012676,and 2009-0082580).
文摘This study introduces a cut-to-fit methodology for customizing bulk aramid aerogels into form factors suitable for wearable energy storage.Owing to strong intercomponent bonds within aramid-based building blocks,it is possible to delaminate layered bulk aerogel into flexible and thinner sheets,enabling efficient mass production.This process allows for precise customization of aerogel dimensions,shape,and elasticity,ensuring high resilience to deformation along with excellent thermal and impact resistance.Incorporation of conductive carbon nanotubes on the surface significantly enhances electrical conductivity and multi-catalytic activity while retaining the inherent advantages of aramids.These advancements facilitate the use of flexible and conductive electrodes as air cathodes in solid-state zinc–air batteries(ZABs),which demonstrate superior cyclic performance and lifecycles exceeding 160 h.Furthermore,aramid-based packaging provides superior protection for pouch-type ZABs,ensuring a consistent power supply even in severe conditions.These batteries are capable of withstanding structural deformations and absorbing physical and thermal shocks,such as impacts and exposure to fire.Moreover,the innovative reassembly of custom-cut single-pouch cells into battery modules allows for enhanced power output,tailored to wearable applications.This highlights the potential of the technology for a wide array of wearable devices requiring dependable energy sources in demanding environments.
文摘Nanofiber carbon aerogels with 3D interconnected microfibrillar networks exhibit fascinating physical properties and present great application potential.However,it is still a challenge to fabricate superelastic nanofiber carbon aerogels owing to their extremely dilute brittle interconnections and poor fiber toughness after carbonization.Herein,aramid nanofibers(ANF)/nanocellulose(CNF)dual-fibrous carbon aerogels are prepared,which exhibited supercompressibility and superelasticity due to the"skeleton-binder"synergistic effect of ANF and CNF and the design of in-plane micro-wrinkle honeycomb structure.The"skeleton-binder"synergistic effect improves interfacial interactions of nanofibers and optimizes the stress distribution of carbon aerogel.The highly ordered honeycomb structure with in-plane microwrinkles,formed by the bidirectional freezing and the difference in volume shrinkage during the carbonization between CNFs and ANFs,endows the CNF/ANF carbon aerogel with negative Poisson's ratio and high energy absorption capacity.These strategies significantly improve the overall mechanical properties of ANF/CNF carbon aerogel including the elasticity and fatigue resistance.As a result,the ultralight carbon aerogel(3.46 mg/cm^(3))exhibits excellent supercompression(undergoing an extreme strain of 95%)and elasticity(a stress retention up to 81.38% at 90% strain with 500 cycles and 96.15% at 50%strain with 10,000 cycles).The nanofiber carbon aerogel shows excellent multifunctional properties in flexible piezoresistive sensor and anisotropic thermal insulation materials,including a desirable sensitivity(as high as 48.74 kPa^(-1))and an instant response time(~40 ms),an anisotropy factor of 3.69 and an ultralow radial thermal conductivity(0.012 W m^(-1) K^(-1)).These properties make dual-fibrous carbon aerogels highly attractive in pressure sensors and thermal management applications.
基金supported by the Key Research and Development Project of Shaanxi Province(No.2024GX-YBXM-331)the Scientific Research Plan Projects of Shaanxi Education Department(Program No.24JC009)the National Natural Science Foundation of China(No.22278260).
文摘Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechanical and inadequate thermal properties present significant challenges for practical applications in diverse complex scenarios.Herein,lightweight,high-strength and flame-retardant aramid nanofibers-based honeycombs(MANHs)for integrated microwave absorption and thermal insulation are successfully fabricated via the hydrogen bonding assembly,mold forming and aerogel filling strategy using aramid waste as raw material.The dense network structure formed by the interwoven aramid nanofibers(ANFs)in the honeycomb body acts as a framework endows the MANH with impressive mechanical performance,and the specific strength and toughness of MANH reach 153.6 MPa g^(−1) cm^(−3) and 13.9 MJ m^(−3),respectively,which are 3.5 and 19 times higher than those of commercial microwave absorption honeycombs(CMAH).The ultralight MXene/ANFs aerogels(a density of 25 mg cm^(−3))with multiscale pore structure filled in the honeycomb apertures give the honeycomb outstanding microwave absorption performance,with a minimum reflection loss of−62.5 dB,and can cover the entire X-band with a thickness of only 3.5 mm.Meanwhile,compared with CMAH,the thermal insulation and flame-retardant performance of MANH are also significantly improved.Notably,MANH also demonstrates favorable sound absorption performance at high-frequency bands.The MANH is considered to be a promising candidate for aerospace and military stealth applications as a result of its lightweight,high strength,exceptional microwave absorption,and remarkable thermal insulation performance.
基金National Natural Science Foundation of China(Grant Nos.12172179,11802141 and U2341244)National Natural Science Foundation for Young Scientists of China(Grant No.12202207)+3 种基金China Postdoctoral Science Foundation(Grant No.2022M711623)Natural Science Foundation of Jiangsu Province(Grant No.BK20220968)Open Funds for Key Laboratory of Impact and Safety Engineering(Ningbo University),Ministry of Education(Grant No.CJ202201)Open Funds for Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province(Grant No.22kfgk03)。
文摘Aramid fibers,due to their relatively high inter-yarn friction,high strength,high modulus,and other characteristics,have become a typical representative of flexible anti-ballistic materials in modern warfare.Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles,with fewer studies on the coupled effect of both on ballistic performance.This study analyzes how the coupling relationship(or size effect)between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective.Taking plain weave aramid fabric as the research object,considering different diameter projectiles,through a large number of ballistic impact tests and numerical simulations,parameters such as ballistic limit velocity,average energy absorption of fabric,and specific energy absorption ratio(average energy absorption of fabric divided by projectile cross-sectional area)are obtained for ballistic performance analysis.The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows:The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases,indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm;The average ballistic limit velocity at three impact positions,P1,P2,and P3,provides the corresponding ballistic limit velocity for 1000D aramid fabric,which increases with projectile diameter but the rate of increase slows down at an inflection point,which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm;The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm,reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect.The projectile diameter of 12 mm corresponds to the coupling size of 11.159,which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.
基金financially supported by the Zhejiang Provin-cial Natural Science Foundation of China(No.LQ22E030016)the National Natural Science Foundation of China(Nos.52275137,51705467),the China Postdoctoral Science Foundation(No.2022M722831)+2 种基金the Postdoctoral Research Selected Funding Project of Zhejiang Province(No.ZJ2022063)the Self-Topic Fund of Zhe-jiang Normal University(No.2020ZS04)the National Key Re-search and Development Program of China(No.2018YFE0199100).
文摘In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its their applications in extreme circumstances.Herein,an ultra-thin and highly flexible aramid nanofiber(ANF)/MXene(Ti_(3)C_(2)T_(x))/Ni nanochain composite paper was prepared through vacuum-assisted filtration and freeze-drying technology.Owing to the synergistic effect between ANF and MXene,the composite paper not only possessed excellent mechanical properties,which were able to withstand over 10,000 times its own weight,but also exhibited outstanding flame-retardant and controllable Joule heating ca-pabilities.Moreover,the mechanical energy capture characteristics of the composite paper-based TENG were evaluated,resulting in the open-circuit voltage(55.6 V),short-circuit current(0.62μA),and trans-ferred charge quantity(25μC).It also could enable self-powering as a wearable electronic device with an instantaneous power of 15.6μW at the optimal external resistance of 10 MΩ.This work is intended to set TENG as safe energy harvesting devices for reducing fire hazards,and will provide a new strategy to broaden the application ranges of TENG.
文摘This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.
文摘The ballistic performance,and behaviour,of an armour system is governed by two major sets of variables,geometrical and material.Of these,the consistency of performance,especially against small arms ammunition,will depend upon the consistency of the properties of the constituent materials.In a body armour system for example,fibre diameter,areal density of woven fabric,and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures.What is often overlooked,because it can fall into the User’s domain,are the interfaces that exist between the various products;the carrier,the Soft Armour Insert(SAI),and the one or two hard armour plates(HAP1 and HAP2).This is especially true if the various products are sourced from different suppliers.
基金Financial support from the National Natural Science Foundation of China(51922020,52090034)the Fundamental Research Funds for the Central Universities(BHYC1707B,XK1802-2)。
文摘Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles,it is still a challenge to simultaneously enhance both conductivity and mechanical properties of MXene fibers because of the high rigidity of MXene sheets and insufficient inter-sheet interactions.Herein,we demonstrate a core-shell wet-spinning methodology for fabricating highly conductive,super-tough,ultra-strong,and environmentally stable Ti_(3)C_(2)T_(x) MXene-based core-shell fibers with conductive MXene cores and tough aramid nanofiber(ANF)shells.The highly orientated and low-defect structure endows the ANF@MXene core-shell fiber with supertoughness of~48.1 MJ m^(-3),high strength of~502.9 MPa,and high conductivity of~3.0×10^(5)S m^(-1).The super-tough and conductive ANF@MXene fibers can be woven into textiles,exhibiting an excellent electromagnetic interference(EMI)shielding efficiency of 83.4 dB at a small thickness of 213μm.Importantly,the protection of the ANF shells provides the fibers with satisfactory cyclic stability under dynamic stretching and bending,and excellent resistance to acid,alkali,seawater,cryogenic and high temperatures,and fire.The oxidation resistance of the fibers is demonstrated by their wellmaintained EMI shielding performances.The multifunctional core-shell fibers would be highly promising in the fields of EMI shielding textiles,wearable electronics and aerospace.
文摘High-performance ballistic fibers,such as aramid fiber and ultra-high-molecular-weight polyethylene(UHMWPE),are commonly used in anti-ballistic structures due to their low density,high tensile strength and high specific modulus.However,their low modulus in the thickness direction and insufficient shear strength limits their application in certain ballistic structure.In contrast,carbon fiber reinforced epoxy resin matrix composites(CFRP)have the characteristics of high modulus in the thickness direction and high shear resistance.However,carbon fibers are rarely used and applied for protection purposes.A hybridization with aramid fiber reinforced epoxy resin matrix composites(AFRP)and CFRP has the potential to improve the stiffness and the ballistic property of the typical ballistic fiber composites.The hybrid effects on the flexural property and ballistic performance of the hybrid CFRP/AFRP laminates were investigated.Through conducting mechanical property tests and ballistic tests,two sets of reliable simulation parameters for AFRP and CFRP were established using LS-DYNA software,respectively.The experimental results suggested that by increasing the content of CFRP that the flexural properties of hybrid CFRP/AFRP laminates were enhanced.The ballistic tests'results and the simulation illustrated that the specific energy absorption by the perforation method of CFRP achieved 77.7%of AFRP.When CFRP was on the striking face,the shear resistance of the laminates and the resistance force to the projectiles was promoted at the initial penetration stage.The proportion of fiber tensile failures in the AFRP layers was also enhanced with the addition of CFRP during the penetration process.These improvements resulted in the ballistic performance of hybrid CFRP/AFRP laminates was better than AFRP when the CFRP content was 20 wt%and 30 wt%.
基金supported by the National Natural Science Foundation of China(No.U1830108)the Shanghai Natural Science Foundation,China(No.20ZR1405000)+1 种基金the Innovation Foundation of Shanghai Aerospace Science and Technology,China(No.SAST2018-061)the Exploratory Research Project of“Yanchang Petroleum(Group)-Fudan University”,China。
文摘An efficient method was proposed to prepare high-performance conductive AramidCarbon Blend Fabrics(ACBF)with cobalt-nickel(Co-Ni)alloy coatings,which is conducive to industrial production.The grid-like substrate composed of aramid and carbon fibers was innovatively used in flexible Electromagnetic Interference(EMI)shielding materials.The natural network structure is advantageous to the uniform deposition of metal particles to the establishment of conductive pathways subsequently in order to improve conductivity.The induction of a synergistic effect from Electromagnetic(EM)wave-reflection and EM wave-absorption through the whole carbonCo-Ni-ternary system notably enhanced the EMI Shielding Effectiveness(SE)value to an average of 42.57 d B in the range of 30-6000 MHz.On the other hand,together with the inherent toughness of the alloy coatings,the tensile strength of the aramid fibers used for bulletproof made a significant contribution to the desired mechanical properties.The light weight of the resultant composite made it applicable to aerospace vehicles simultaneously.X-ray Photoelectron Spectroscopy(XPS)was conducted to investigate the variations of elements and groups on the sample surface in pretreating process.The elemental components and surface morphologies of fabric samples during different stages of the process were investigated by Scanning Electron Microscope(SEM)and Energy Dispersive spectrometer(EDX)measurements.X-Ray Diffraction(XRD)results indicated that the obtained Co-Ni alloy coating had a combined Hexagonal Closed-Packed(HCP)and FacedCentered Cubic(FCC)crystalline phase.The relatively high corrosion resistance demonstrated in different acid and alkaline conditions was instrumental in more complex environments as well.
基金financially sponsored by the Science and Technology Commission of Shanghai Municipality(nos.20230742300 and 18595800700)。
文摘The design of flexible polymeric films with internal porous structures has received increasing attention in low dielectric applications.The highly porous metal-organic frameworks(MOFs)of[Cu_(3)(BTC)_(2)]_(n)(BTC=benzene-1,3,5-tricarboxylate)were introduced into aramid nanofibers(ANF)matrix by using carboxylated cellulose nanofibrils(CNF)as carriers to obtain strong,flexible,and ultra-low dielectric films.The well-dispersed“flowers-branch”like CNF@CuBTC through in-situ growth of CuBTC on CNF surface endowed the ANF/CNF@Cu BTC films with excellent thermal stability,mechanical integrity and low dielectric properties.Besides,the flexible dielectric films exhibited superior ultraviolet(UV)resistance,lower coefficient of thermal expansion(4.28×10^(-5)℃^(-1))and increased water contact angle(83.81°).More interestingly,the removal of vip molecules from the ANF/CNF@CuBTC films according to the vacuum heat treatment(VHT)process significantly improved their dielectric response.The specific surface areas of the composite films after VHT increased obviously,and the dielectric constant and dielectric loss tangent decreased to the expected 1.8-2.2 and 0.001-0.03 at 100 MHz,respectively.Consequently,such designable ultra-low dielectric films with high flexibility play an incredible significance in applications of microelectronics under large deformation conditions,especially in flexible/wearable devices at the arrival of 5 G era.
文摘Dynamic tensile impact properties of aramid (Technora) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.
基金support from the National Natural Science Foundation of China(51973054)Young Talents Program in Hunan Province(2020RC3024)+2 种基金Natural Science Funds of Hunan Province for Distinguished Young Scholar(2021JJ10018)Science Research Project of Hunan Provincial Education Department(21B0027)High-level Innovative Talent Project in Hunan Province(2018RS3055).
文摘Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.
基金the National Natural Science Foundation of China(No.52102115)the Fundamental Research Funds of Southwestern University of Science and Technology,China(No.20zx7141).
文摘Compressive strengths and elastic moduli of Carbon Fiber Reinforced Polymer(CFRP)composites can be noticeably improved by multiple ultra-thin interlays with non-woven Aramid Pulp(AP)micro/nano-fibers.10-ply CFRP specimens with 0,2,4,6,8 g/m^(2)AP were tested under uniaxial compression.Those flexible AP fibers,filling the resin-rich regions and further constructing the fiber bridging at the ply interfaces,can effectively suppress delamination growth and lead to very good improvements both in the compressive strength and the elastic modulus.The CFRP specimen with an optimum interlay thickness has a distinct shear failure mode instead of the typical delamination cracking along the direction of continuous carbon fibers.Compressive Strengths After Impacts(CAI)of 12.35 J were also measured,up to 90%improvement in CAI has been observed.It is concluded those ultra-thin interlays of non-woven AP micro/nano-fibers are beneficial to design and manufacture“high strength”CFRP composites.
基金supported by National Natural Science Foundation of China(Nos.U19A2095,51773134)the Sichuan Province Science and Technology Project(No.2019YFH0112)+1 种基金the Fundamental Research Funds for the Central Universities,Institutional Research Fund from Sichuan University(No.2021SCUNL201)the 111 Project(No.B20001)。
文摘Separators is indispensable for the normal operation of lithium-ion batteries(LIBs).However,the widely used commercial polyolefin separators have some inherent deficiencies such as poor thermotolerance,high inflammability and inferior electrolyte wettability,which restrict their further applications of the advanced and safe batteries.Herein,we design a novel thermotolerant(a shrinkage percentage of 0%at 300℃)and flame retarded aerogel separator consisting of aramid nanofibers(ANFs).Because of its high porosity(86.5%±6.1%)and excellent electrolyte uptake(695%),the ANFs aerogel separator has an ionic conductivity of 1.04 mS/cm and a high lithium-ion transference number(0.67),which can endow LIBs with outstanding rate performance and superior cycling performance.Specifically,the ANFs aerogel separator-based batteries possess a discharge specific capacity of 102 m Ah/g with a capacity retention of 90.7%and a Coulombic efficiency of 99.3%after 600 cycles at 5 C.In addition,under an operated temperature of 90℃,the battery with ANFs aerogel separator can still conduct the very steady chargedischarge,presenting a capacity retention of 90.1%and a Coulombic efficiency of 99.6%after 200 cycles at 3 C.Accordingly,the separator can probably serve as a potential candidate for application to advanced and safe LIBs.
基金the National Natural Science Foundation of China(No.51972162).
文摘Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the composites.Herein,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-πinteractions.The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer channel.The composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.
