Superior and safer lithium sulfur batteries realized by robust polysulfides-retarding dam with high flame retardance

The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.

Deflagration characteristics of freely propagating flames in magnesium hydride dust clouds

The flame propagation processes of MgH_(2)dust clouds with four different particle sizes were recorded by a high-speed camera.The dynamic flame temperature distributions of MgH_(2)dust clouds were reconstructed by the two-color pyrometer technique,and the chemical composition of solid combustion residues were analyzed.The experimental results showed that the average flame propagation velocities of 23μm,40μm,60μm and 103μm MgH_(2)dust clouds in the stable propagation stage were 3.7 m/s,2.8 m/s,2.1 m/s and 0.9 m/s,respectively.The dust clouds with smaller particle sizes had faster flame propagation velocity and stronger oscillation intensity,and their flame temperature distributions were more even and the temperature gradients were smaller.The flame structures of MgH_(2)dust clouds were significantly affected by the particle sinking velocity,and the combustion processes were accompanied by micro-explosion of particles.The falling velocities of 23μm and 40μm MgH_(2)particles were 2.24 cm/s and 6.71 cm/s,respectively.While the falling velocities of 60μm and 103μm MgH_(2)particles were as high as 15.07 cm/s and 44.42 cm/s,respectively,leading to a more rapid downward development and irregular shape of the flame.Furthermore,the dehydrogenation reaction had a significant effect on the combustion performance of MgH_(2)dust.The combustion of H_(2)enhanced the ignition and combustion characteristics of MgH_(2)dust,resulting in a much higher explosion power than the pure Mg dust.The micro-structure characteristics and combustion residues composition analysis of MgH_(2)dust indicated that the combustion control mechanism of MgH_(2)dust flame was mainly the heterogeneous reaction,which was affected by the dehydrogenation reaction.

Preparation of Polyurea Elastomer with Flame Retardant, Insulation and Thermal Conductivity Properties

By using 6,6-((sulfonylbis(4,1-phenylene)bis(azanediyl))bis(thiophen-2-ylm-ethylene))bis6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide(DOPO-N)as phosphorus-nitrogen flame retardant,the polyurea(PUA)with flame retardant properties(PUA/DOPO-N)was prepared.In addition,organically modified montmorillonite(OMMT)and magnesium hydroxide(MH)were used as co-effectors respectively,and the flame retardant PUA(PUA/DOPO-N/OMMT and PUA/DOPO-N/MH)were also prepared.Thermal properties,flame retardant properties,flame retardant mechanism and mechanical properties of PUA/DOPO-N,PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric(TG)analysis,limiting oxygen index(LOI),UL 94,cone calorimeter test,scanning electron microscopy(SEM),and tensile test.The results show that the LOI value of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%,27.7%,and 28.3%,respectively,and UL 94 V-0 rating is attained.Compared with PUA,the peak heat release rate(pk-HRR),total heat release(THR)and average effective heat combustion(av-EHC)of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease significantly.SEM results indicate that the residual chars of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are completer and more compact.The complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame retardancy.The mechanical properties of PUA can be improved by the addition of DOPO-N,DOPO-N/OMMT and DOPO-N/MH,respectively.The insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×10^(16)Ω.cm.Furthermore,by using modified boron nitride(MBN)as heat dissipating material,the complex of PUA/MBN was prepared,and the thermal conductivity of PUA/MBN was investigated.The thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K),which is a 163%improvement over pure PUA.

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Numerical Simulation of Turbulent Diffusion Flames of a Biogas Enriched with Hydrogen

Any biogas produced by the anaerobic fermentation of organic materials has the advantage of being an environmentally friendly biofuel.Nevertheless,the relatively low calorific value of such gases makes their effective utilization in practical applications relatively difficult.The present study considers the addition of hydrogen as a potential solution to mitigate this issue.In particular,the properties of turbulent diffusion jet flames and the related pollutant emissions are investigated numerically for different operating pressures.The related numerical simulations are conducted by solving the RANS equations in the frame of the Reynolds Stress Model in combination with the flamelet approach.Radiation effects are also taken into account and the combustion kinetics are described via the GRI-Mech 3.0 reaction model.The considered hydrogen fuel enrichment spans the range from 0%to 50%in terms of volume.Pressure varies between 1 and 10 atm.The results show that both hydrogen addition and pressure increase lead to an improvement in terms of mixing quality and have a significant effect on flame temperature and height.They also reduce CO_(2) emissions but increase NOx production.Prompt NO is shown to be the predominant NO formation mechanism.

Ten-Minute Synthesis of a New Redox-Active Aqueous Binder for Flame-Retardant Li-S Batteries

As a critical role in battery systems,polymer binders have been shown to efficiently suppress the lithium polysulfide shuttling and accommodate volume changes in recent years.However,preparation processes and safety,as the key criterions for Li-S batteries'practical applications,still attract less attention.Herein,an aqueous multifunction binder(named PEI-TIC)is prepared via an easy and fast epoxy-amine ring-opening reaction(10 min),which can not only give the sulfur cathode a stable mechanical property,a strong chemical adsorption and catalytic conversion ability,but also a fire safety improvement.The Li-S batteries based on the PEI-TIC binder display a high discharge capacity(1297.8 mAh g^(-1)),superior rate performance(823.0 mAh g^(-1)at 2 C),and an ultralow capacity decay rate of 0.035%over more than 800 cycles.Even under 7.1 mg cm^(-2)S-loaded,the PEI-TIC electrode can also achieve a high areal capacity of 7.2 mA h g^(-1)and excellent cycling stability,confirming its application potential.Moreover,it is also noted that TG-FTIR test is performed for the first time to explore the flame-retardant mechanism of polymer binders.This work provides an economically and environmentally friendly binder for the practical application and inspires the exploration of the flame-retardant mechanism of all electrode components.

Experimental investigation for temperature and emissivity by flame emission spectrum in a cavity of rocket based combined cycle combustor chamber

Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combustor.To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor,a new radiation thermometry combined with Levenberg-Marquardt(LM)algorithm and the least squares method was proposed to measure the temperature,emissivity and spectral radiative properties based on the flame emission spectrum.In-situ measurements of the flame temperature,emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement(LIPCE)and without LIPCE.The flame average temperatures at fuel global equivalence ratio(a)of 1.0b and 0.6 with LIPCE were 4.51%and 2.08%higher than those without LIPCE.The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma.The differences of flame temperature at a=1.0b and 0.6 were 503 K and 523 K with LIPCE,which were 20.07%and42.64%lower than those without LIPCE.The flame emissivity with methane assisted ignition was 80.46%lower than that without methane assisted ignition,due to the carbon-hydrogen ratio of kerosene was higher than that of methane.The spectral emissivities at 600 nm with LIPCE were 1.25%,22.2%,and 4.22%lower than those without LIPCE at a=1.0a(with methane assisted ignition),1.0b(without methane assisted ignition)and 0.6.The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber.The maximum differences of flame normalized emissivity were 50.91%without LIPCE and 27.53%with LIPCE.The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at a=0.6.

Comparison of the effect of different external electrodes on discharge plasma-assisted diffusion flame stabilization

To optimize the design of plasma injectors,the influence of different external electrodes on plasma-assisted flame stabilization was assessed by using a nonequilibrium plasma injector flame control setup.The electrical characteristics of the injector,flame structure parameters,flame intensity,discharge power,and cost-to-effectiveness ratio under different external electrodes(four mesh electrodes and one copper foil electrode)were analyzed using electrical and optical methods.The results show that reducing the mesh size of the external electrode leads to a decrease in breakdown voltage.Compared with a ceramic dielectric barrier-based injector,an injector with a quartz dielectric barrier produces a higher breakdown voltage under the same conditions.For the same actuation voltage,the discharge current increases as the mesh size of the external electrode decreases,and combustion is enhanced by the discharge plasma;therefore,it is better to adopt a smaller mesh hole size to realize good flame stabilization under a lower actuation voltage.However,under the studied working conditions,reducing the mesh hole size of the external electrode increases the cost-to-effectiveness ratio of plasma injector-based flame stabilization.Thus,considering the cost-to-effectiveness ratio and the weight of the injector,an external electrode with a larger mesh hole size should be chosen,which contradicts the above rule.

Superior Mechanical Behavior and Flame Retardancy FRP via a Distribution Controllable 1D/2D Hybrid Nanoclay Synergistic Toughening Strategy

The incorporation of commercial flame retardants into fiber-reinforced polymer(FRP)composites has been proposed as a potential solution to improve the latter’s poor flame resistance.However,this approach often poses a challenge,as it can adversely affect the mechanical properties of the FRP.Thus,balancing the need for improved flame resistance with the preservation of mechanical integrity remains a complex issue in FRP research.Addressing this critical concern,this study introduces a novel additive system featuring a combination of one-dimensional(1D)hollow tubular structured halloysite nanotubes(HNTs)and two-dimensional(2D)polygonal flake-shaped nano kaolinite(NKN).By employing a 1D/2D hybrid kaolinite nanoclay system,this research aims to simultaneously improve the flame retardancy and mechanical properties.This innovative approach offers several advantages.During combustion and pyrolysis processes,the 1D/2D hybrid kaolinite nanoclay system proves effective in reducing heat release and volatile leaching.Furthermore,the system facilitates the formation of reinforcing skeletons through a crosslinking mechanism during pyrolysis,resulting in the development of a compact char layer.This char layer acts as a protective barrier,enhancing the material’s resistance to heat and flames.In terms of mechanical properties,the multilayered polygonal flake-shaped 2D NKN plays a crucial role by impeding the formation of cracks that typically arise from vulnerable areas,such as adhesive phase particles.Simultaneously,the 1D HNT bridges these cracks within the matrix,ensuring the structural integrity of the composite material.In an optimal scenario,the homogeneously distributed 1D/2D hybrid kaolinite nanoclays exhibit remarkable results,with a 51.0%improvement in mode II fracture toughness(GIIC),indicating increased resistance to crack propagation.In addition,there is a 34.5%reduction in total heat release,signifying improved flame retardancy.This study represents a significant step forward in the field of composite materials.The innovative use of hybrid low-dimensional nanomaterials offers a promising avenue for the development of multifunctional composites.By carefully designing and incorporating these nanoclays,researchers can potentially create a new generation of FRP composites that excel in both flame resistance and mechanical strength.

Mutual effects between a gliding arc discharge and a premixed flame

Mutual effects between a gliding arc(GA)discharge at atmospheric pressure and a premixed CH_(4)/air flame were experimentally investigated.Effects of the flame on the GA were studied using simultaneous measurements of the current,the voltage,and the instantaneous images of the plasma columns.The GA in the flame has a thicker and more diffusive plasma column,and it is more frequently ignited at a smaller breakdown voltage than that in the air.The GA extension velocity and the gliding velocity in the flame are larger than those in the air.The electrode voltage drop of the GA discharge in the flame is about 160 V,whereas that in the air is about 220 V.Compared with the GA in the air,the different features of the GA in the flame can be explained by high-temperature,weakly ionized,and species-abundant environment that are generated by the premixed CH_(4)/air flame.Effects of the gliding arc discharge on the premixed flames were demonstrated using planar laser-induced fluorescence of hydroxyl radicals(OH)and formaldehyde(CH_(2)O).OH and CH_(2)O can be formed in the CH_(4)/air mixture in the presence of the GA due to kinetic effects,and the increase of OH and CH_(2)O shows the great potential of the GA for combustion enhancement.

Biobased Furfurylated Poplar Wood for Flame-Retardant Modification with Boric Acid and Ammonium Dihydrogen Phosphate

Furfurylated wood exhibits excellent dimensional stability and corrosion resistance,making it a promising material for constructing buildings,but it is highly flammable.Herein,flame-retardant furfurylated poplar wood was produced via a two-step process utilizing boric acid(BA)and ammonium dihydrogen phosphate(ADP)as flame-retardant components,and biomass-derived furfuryl alcohol(FA)as a modifier.The acidity of BA and ADP allowed them to catalyze the polymerization of FA,which formed a cross-linked network that immobilized BA and ADP inside the wood.The addition of BA/ADP substantially delayed the time to ignition from 10 to 385 s and reduced the total heat release and total smoke release by 58.75%and 77.31%,respectively.Analysis of the pyrolysis process showed that the decomposition products of BA and ADP protected the underlying furfurylated wood and diluted combustible gases.This method significantly improved the fire retardancy and smokeless properties of furfurylated wood,providing promising prospects for its application as an engineering material.

Research Progress in Flame Retardant in Flame Retardant Coatings

Flame retardant coatings are functional materials that can serve as decorative and protec-tive substrates in the event of a fire.Flame retardant coatings generally consist of two parts:a base material and a flame retardant agent.A detailed introduction was given to the development of flame retardant coatings in recent years and the flame retardants used in flame retardant coatings.Flame retardants mainly include halogen flame retar-dants,phosphorus nitrogen flame retardants,expansion flame retardants,biomass flame retardants,and graphene flame retardants.The application of flame retardant coatings in the fields of epoxy resin,polyurethane,etc.was elaborated.In addition,the application of new biomass flame retardants and graphene flame retardants was introduced,and the future development of flame retardant coatings and flame retardants was described.

Systematic Cloud-Based Optimization: Twin-Fold Moth Flame Algorithm for VM Deployment and Load-Balancing

Cloud computing has gained significant recognition due to its ability to provide a broad range of online services and applications.Nevertheless,existing commercial cloud computing models demonstrate an appropriate design by concentrating computational assets,such as preservation and server infrastructure,in a limited number of large-scale worldwide data facilities.Optimizing the deployment of virtual machines(VMs)is crucial in this scenario to ensure system dependability,performance,and minimal latency.A significant barrier in the present scenario is the load distribution,particularly when striving for improved energy consumption in a hypothetical grid computing framework.This design employs load-balancing techniques to allocate different user workloads across several virtual machines.To address this challenge,we propose using the twin-fold moth flame technique,which serves as a very effective optimization technique.Developers intentionally designed the twin-fold moth flame method to consider various restrictions,including energy efficiency,lifespan analysis,and resource expenditures.It provides a thorough approach to evaluating total costs in the cloud computing environment.When assessing the efficacy of our suggested strategy,the study will analyze significant metrics such as energy efficiency,lifespan analysis,and resource expenditures.This investigation aims to enhance cloud computing techniques by developing a new optimization algorithm that considers multiple factors for effective virtual machine placement and load balancing.The proposed work demonstrates notable improvements of 12.15%,10.68%,8.70%,13.29%,18.46%,and 33.39%for 40 count data of nodes using the artificial bee colony-bat algorithm,ant colony optimization,crow search algorithm,krill herd,whale optimization genetic algorithm,and improved Lévy-based whale optimization algorithm,respectively.

Determination of Chromium and Zinc in Soil by Microwave Digestion and Flame Atomic Absorption Spectrometry

[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by combined flame atomic absorption spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-0.8 mg/L for Cr and 0-0.8 mg/L for Zn, the detection limits of Cr and Zn was 0.0025 mg/L and 0.002 3 mg/L, respectively. Recoveries of 102.4%-103.2% for Cr and 97.7%-98.3% for Zn were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of Cr and Zn in soil samples.

DETONATION INITIATION INDUCED BY FLAME IMPLOSION AND SHOCK WAVE FOCUSING

Computational simulations on structurally different detonation generator are carried out to study the phenomena,the mechanism and the gas dynamics characteristics of flame implosion and shock wave focusing.Two-dimensional axisymmetric and unsteady Navier-Stokes equations are numerically solved and detailed chemical reaction kinetics of hydrogen/air mixture is used.The simulation results show that the laminar flame generated by low energy spark in the jet flame burner is accelerated under the narrow channel,the jet flame impinging on the axis strengthens shock wave and the shock wave enhances flame acceleration.Under the function of multiple shock waves and flame,a number of hot spots appear between the wave and the surface.The spots enlarge rapidly,thus forming an over-drive detonation with high pressure,and then declining to stable detonation.Through calculation and analysis,the length of detonation initiation and stable detonation are obtained,thus providing the useful information for further experimental investigations.

Skeleton extraction of boiler flame images based on mathematical morphology

In this paper, a method and algorithm of skeleton extraction based on binary mathematical morphology is presented. Sequential structuring elements (SEs) is also studied, which is the key problem of skeleton extraction. The examples of boiler flame image processing show that the detected skeletons can present the geometric shape of flame images well.

Flame病毒深度分析及防范技术

Flame病毒是一款从事网络间谍活动的病毒,其盗取的信息包罗万象,复杂程度大大超过目前已知的所有病毒。从其传播和部署的原理来看,Flame病毒可以被划分为一种网络武器。文章通过介绍Flame病毒的由来及特点,深度分析了该病毒的工作机理和工作过程,最后提出一些防范措施和检测方法。

Effect of flame rectification on corrosion property of Al-Zn-Mg alloy

The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al？Zn？Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order： base metal〉two times〉three times〉one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.

基于FLAMES和HLA的导弹分队作战仿真系统

研究了基于FLAMES和HLA导弹分队作战仿真。首先介绍了系统架构及工作流程,然后剖析了基于FLAMES和HLA进行导弹分队作战中的仿真实体之间的信息交互机制,最后探讨了基于FLAMES和HLA的开发过程,验证了基于FLAMES和HLA开发的导弹分队作战仿真的实用性,为以后分队作战智能化仿真研究提供借鉴。

一种基于FLAMES框架的工程保障模型体系设计

对联合作战中的工程保障进行需求分析,以FLAMES仿真框架为基础,建立了以工程兵部队保障中的典型兵力——道桥分队、筑城分队、地爆分队、舟桥分队为主的工程保障模型体系,能够在多兵种联合作战仿真研究中体现工程兵部队的作用,能够在工程兵资源配置、调度策略评估等试验中进行应用,同时也为工程兵指挥自动化系统的系列化、组合化、参数化提供参考。