Jet formation and penetration performance of a double-layer charge liner with chemically-deposited tungsten as the inner liner

This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.

Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

High Density 3D Carbon Tube Nanoarray Electrode Boosting the Capacitance of Filter Capacitor

Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.

Magnetization-induced double-layer capacitance enhancement in active carbon/Fe_3O_4 nanocomposites

The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in im- proving capacitor performance. In this study, active carbon/Fe304-NPs nanocomposites （AC/Fe304-NPs） were synthesized using a facile hy- drothermal method and ultrasonic technique. Transmission electron micrographs （TEM） showed that Fe304 nanoparticles （Fe304-NPs） grew along the edge of AC. AC/Fe304-NPs nanocomposites were further used as an electrochemical electrode, and its electrochemical performance was tested under magnetization and non-magnetization conditions, respectively, in a three-electrode electrochemical device. Micro-magnetic field could improve the electric double-layer capacitance, reduce the charge transfer resistance, and enhance the discharge performance. The capacitance enhancement of magnetized electrode was increased by 33.1% at the current density of 1 A/g, and the energy density was improved to 15.97 Wh/kg, due to the addition of magnetic particles.

Influence of polyethylene glycol on pore structure and electric double-layer capacitance of carbon xerogel

Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable polyethylene glycol with organic monomers, resorcinol and formaldehyde and then subjected to pyrolization at 1 000 ℃. The influences of mass ratio of PEG to the theoretical yield of RF xerogel, m（PEG）/m（RF） and the （relative） molecular mass of PEG on the pore structure and electric double layer capacitance（EDLC） performance of PEG-RF carbon xerogels were investigated. The results show that PEG under different conditions leads to the difference of phase separation structure of the polymer blend and thus the change of pore structure of PEG-RF carbon xerogels. Specific surface area and capacity of PEG-RF carbon xerogels in 30% H2SO4 solution can reach （755 m2/g） and 150 F/g, respectively. Their surface can be fully utilized to form electric double layer. However, the pore structure differences of PEG-RF carbon xerogels result in their different EDLC performances. The distributed capacitance effect increases with decreasing the pore size of PEG-RF carbon xerogels.

Structure-guided Capacitance Relationships in Oxidized Graphene Porous Materials Based Supercapacitors

Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g^(−1).This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable factors.This work demonstrates important structure-controlled charge storage relationships.For this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic components.Experimental results show significantly varied capacitance values between 30 and 250 F g^(−1)at 1.0 A g^(−1)in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250–300%higher compared to typical mesoporous carbon materials.GEGs with identical oxygen functionality show a surface area governed capacitance.This allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.

N-Doped rGO-Like Carbon Prepared from Coconut Shell:Structure and Specific Capacitance

An rGO−like carbon compound has been synthesized from biomass,i.e.,old coconut shell,by a carbonization process followed by heating at 400°C for 5 h.The nitrogen doping was achieved by adding the urea(CH4N2O)and stirring at 70°C for 14 h.The morphology and structure of the rGO-like carbon were investigated by electron microscopies and Raman spectroscopy.The presence of C-N functional groups was analyzed by Fourier transform infrared and synchrotron X-ray photoemission spectroscopy,while the particle and the specific capacitance were measured by particle sizer and cyclic voltammetry.The highest specific capacitance of 72.78 F/g is achieved by the sample with 20%urea,having the smallest particles size and the largest surface area.The corresponding sample has shown to be constituted by the appropriate amount of C–N pyrrolic and pyridinic defects.

Machine learning techniques for prediction of capacitance and remaining useful life of supercapacitors: A comprehensive review

Supercapacitors are appealing energy storage devices for their promising features like high power density,outstanding cycling stability,and a quick charge–discharge cycle.The exceptional life cycle and ultimate power capability of supercapacitors are needed in the transportation and renewable energy generation sectors.Hence,predicting the capacitance and lifecycle of supercapacitors is significant for selecting the suitable material and planning replacement intervals for supercapacitors.In addition,system failures can be better addressed by accurately forecasting the lifecycle of SCs.Recently,the use of machine learning for performance prediction of energy storage materials has drawn increasing attention from researchers globally because of its superiority in prediction accuracy,time efficiency,and costeffectiveness.This article presents a detailed review of the progress and advancement of ML techniques for the prediction of capacitance and remaining useful life(RUL)of supercapacitors.The review starts with an introduction to supercapacitor materials and ML applications in energy storage devices,followed by workflow for ML model building for supercapacitor materials.Then,the summary of machine learning applications for the prediction of capacitance and RUL of different supercapacitor materials including EDLCs(carbon based materials),pesudocapacitive(oxides and composites)and hybrid materials is presented.Finally,the general perspective for future directions is also presented.

Time-sequenced damage behavior of reactive projectile impacting double-layer plates

The time-sequenced damage behavior of the reactive projectile impacting double-layer plates is discussed.The analytical model considering the combined effect of kinetic and chemical energy is developed to reveal the damage mechanism.The influences of impact velocity and reactive projectile chemical characteristics on the damage effect are decoupled analyzed based on this model.These analyses indicate that the high energy releasing efficiency and fast reaction propagation velocity of the reactive projectile are conducive to enhancing the damage effect.The experiments with various reactive projectiles impact velocity increasing from 702 to 1385 m/s were conducted to verify this model.The experimental results presented that,the damage hole radius of the rear-plate increases with the increase of impact velocity.At the impact velocity of 1350 m/s,the radius of damage hole formed by PTFE/Al/Bi_(2)O_(3),PTFE/Al/MoO_(3),PTFE/Al/Fe_(2)O_(3)projectile on the rear-plate become smaller in sequence.These results are consistent with the analytical model prediction,demonstrating that this model can predict the damage effect quantitatively.This work is of constructive significance to the application of reactive projectiles.

Gas-and plasma-driven hydrogen permeation behavior of stagnant eutectic-solid GaInSn/Fe double-layer structure

Gas-driven permeation(GDP)and plasma-driven permeation(PDP)of hydrogen gas through Ga In Sn/Fe are systematically investigated in this work.The permeation parameters of hydrogen through Ga In Sn/Fe,including diffusivity,Sieverts'constant,permeability,and surface recombination coefficient are obtained.The permeation flux of hydrogen through Ga In Sn/Fe shows great dependence on external conditions such as temperature,hydrogen pressure,and thickness of liquid Ga In Sn.Furthermore,the hydrogen permeation behavior through Ga In Sn/Fe is well consistent with the multilayer permeation theory.In PDP and GDP experiments,hydrogen through Ga In Sn/Fe satisfies the diffusion-limited regime.In addition,the permeation flux of PDP is greater than that of GDP.The increase of hydrogen plasma density hardly causes the hydrogen PDP flux to change within the test scope of this work,which is due to the dissolution saturation.These findings provide guidance for a comprehensive and systematic understanding of hydrogen isotope recycling,permeation,and retention in plasma-facing components under actual conditions.

Preparation and Microwave Absorbing Properties of Double-layer Fine Iron Tailings Cementitious Materials

To develop the microwave absorbing(MA)properties of cementitious material mixed with mine solid waste,the iron tailings cementitious microwave absorbing materials were prepared.The iron tailings was treated into different particle sizes by planetary ball mill,and the physicochemical properties of iron tailings were tested by laser particle size analyzer and scanning electron microscope(SEM).The electromagnetic parameters of iron tailings cementitious materials were characterized by a vector network analyzer and simulated MA properties,and the MA properties of iron tailings-cement composite system with steel fiber as absorber was studied.Based on the design of the single-layer structure,optimum mix ratio and thickness configuration method of double-layer structure were further studied,meanwhile,the mechanical properties and engineering application were analyzed and discussed.The results show that the particle size of iron tailings can afiect its electromagnetic behavior in cementitious materials,and the smaller particles lead the increase of demagnetisation efiect induced by domain wall motion and achieve better microwave absorbing properties in cementitious materials.When the thickness of matching layer and absorbing layer is 5 mm,the optimized microwave absorbing properties of C1/C3 double-layer cementitious material can obtain optimal RL value of-27.61 dB and efiective absorbing bandwidth of 0.97 GHz,which attributes to the synergistic efiect of impedance matching and attenuation characteristics.The double-layer microwave absorbing materials obtain excellent absorbing properties and show great design flexibility and diversity,which can be used as a suitable candidate for the preparation of favorable microwave absorbing cementitious materials.

Adsorption of K^+ from an aqueous phase onto an activated carbon used as an electric double-layer capacitor electrode

The adsorption capacity and absorption rate for electrolyte onto activated carbon are important parameters used to characterize activated carbon electric double-layer capacitor electrodes. In this paper the pore structure of typical commercial activated carbons, and various Mn-doped activated carbons prepared on a laboratory scale, are described. The pore structure was character-ized by N2 adsorption/desorption isotherms. Isotherms for K+ adsorption onto these activated carbons from the aqueous phase were also obtained. The experimental, equilibrium K+ adsorption data were fitted to the Langmuir, Freundlich or Temkin equations. Adsorption of K+ onto the activated carbons was measured and plotted as a function of time. The adsorption kinetic data were modeled by either pseudo-first or pseudo-second order equations. The Elvoich equation, a liquid film diffusion and an intra-particle diffusion model were used to fit the kinetic data. The results indicate that the adsorption of K+ onto activated carbon is influenced by many factors including pore size distribution, specific surface area and the surface chemistry of the activated carbons. The Temkin equation best describes the equilibrium adsorption data. The pseudo-second order model exactly describes the whole adsorption process, which is controlled by both liquid film and intra-particle diffusion.

Characterization of Microporous Activated Carbon Electrodes for Electric Double-layer Capacitors

Activated carbons(ACs) with a wide range of surface areas were made from petroleum coke by means of KOH activation. The electrochemical characterization was carried out for several activated carbons used as polarizable electrodes of electric double-layer capacitors(EDLCs) in an aqueous electrolytic solution. The porous structures and electrochemical double-layer capacitance of the activated carbons were investigated by virtue of nitrogen gas adsorption and constant current cycling(CCC) methods. The relationship among the surface area, pore volume of the activated carbons and specific double-layer capacitance was discussed. It was found that the specific capacitance of ACs increased linearly with the increase of surface area. The presence of mesopores in the activated carbons with very high surface area(>2000 m\+2/g) was not very effective for them to be used as EDLCs. The influence of chemical characteristics of the activated carbons on the double layer formation could be considered to be negligible.

Double-Layer-Optimizing Method of Hybrid Energy Storage Microgrid Based on Improved Grey Wolf Optimization

To reduce the comprehensive costs of the construction and operation of microgrids and to minimize the power fluctuations caused by randomness and intermittency in distributed generation,a double-layer optimizing configuration method of hybrid energy storage microgrid based on improved grey wolf optimization(IGWO)is proposed.Firstly,building a microgrid system containing a wind-solar power station and electric-hydrogen coupling hybrid energy storage system.Secondly,the minimum comprehensive cost of the construction and operation of the microgrid is taken as the outer objective function,and the minimum peak-to-valley of the microgrid’s daily output is taken as the inner objective function.By iterating through the outer and inner layers,the system improves operational stability while achieving economic configuration.Then,using the energy-self-smoothness of the microgrid as the evaluation index,a double-layer optimizing configuration method of the microgrid is constructed.Finally,to improve the disadvantages of grey wolf optimization(GWO),such as slow convergence in the later period and easy falling into local optima,by introducing the convergence factor nonlinear adjustment strategy and Cauchy mutation operator,an IGWO with excellent global performance is proposed.After testing with the typical test functions,the superiority of IGWO is verified.Next,using IGWO to solve the double-layer model.The case analysis shows that compared to GWO and particle swarm optimization(PSO),the IGWO reduced the comprehensive cost by 15.6%and 18.8%,respectively.Therefore,the proposed double-layer optimizationmethod of capacity configuration ofmicrogrid with wind-solar-hybrid energy storage based on IGWO could effectively improve the independence and stability of the microgrid and significantly reduce the comprehensive cost.

Porous monoliths of 3D graphene for electric double-layer supercapacitors

For delivering the nanoscaled extraordinary characteristics in macroscopical bulk,it is essential to integrate two-dimensional nanosheets into threedimensional(3D)porous monoliths,alternatively called as 3D architectures,3D networks,or aerogels.The intersupported structure of porous monolithic 3D graphene(3DG)can prevent aggregation or restacking of graphene individuals,and the interconnected sp^(2) network of 3DG not only can provide the highway for the transport of electron/phonon but also can present continual cavities/channels for mass transfer.This review summarizes the synthesis methodology of 3DG porous monoliths and highlights the application for electric double-layer capacitors.Present challenges and future prospects about the manufacture and application of 3DG are also discussed.

Compensation of Parasitic Capacitance of Quartz Tuning Fork in AFM

We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this report, we demonstrated a simple but effective method to compensate for this parasitic capacitance by adding a compensator circuit consisting of an inverting amplifier and a capacitor. The capacitor is connected in series with the inverting amplifier and the compensator is connected in parallel with the quartz tuning fork. The resonance curve of the system measured after adding the homemade compensator resembles that of a pure RLC circuit, meaning that the stray capacitance is successfully eliminated. Furthermore, we tried to use our equipment to measure PDMS sample and got clean data. This system can be further combined with confocal microscope and diamond with NV defect to build scanning NV magnetometry.

Integration of pore structure modulation and B,N co-doping for enhanced capacitance deionization of biomass-derived carbon

Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.

Carbon aerogels for electric double-layer capacitors

In this study, carbon aerogels were derived via the pyrolysis of resorcinol-formaldehyde (RF) aerogels, which were cost-effectively manufactured from RF wet gels by an ambient drying technique instead of conventional supercritical drying. By varying the R/C ratio (molar ratio of resorcinol to catalyst), mesoporous carbon aerogels with high specific surface area were prepared successfully and further investigated as electrode materials for electric double-layer capacitors (EDLCs). The textural properties of carbon aerogels obtained were characterized by nitrogen adsorption/desorption analysis and SEM. The electrochemical performances of carbon aerogels were investigated by impedance spectroscopy, galvanostatic charge/discharge and cyclic voltammetry methods. The results show that BET surface area and specific capacitance increase with R/C ratio, the maximum values of 727 m2·g-1 and 132 F·g-1 are achieved at R/C ratio will of 300. Increasing R/C ratio increase the average pore size of carbon aerogel electrode, which has improved the rate capability. Furthermore, EDLC with carbon aerogel electrodes has an excellent stability at large discharge current and long cycle life.

Preparation of spiro-type quaternary ammonium salt via economical and efficient synthetic route as electrolyte for electric double-layer capacitor

A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-dibromobutane and pyrrolidine, and subsequent ion exchange pathway with KOH followed by neutralization reaction via HBF4 in the system of ethanol solution. 1H NMR, 13 C NMR, FI-IR and XPS analyses showed the structure of SBP-BF4. The as-obtained SBP-BF4 was dissolved in AN and used as the electrolyte for supercapacitor. Electrochemical measurements demonstrate that, compared with commercial electrolyte TEMA-BF4/AN, SBP-BF4/AN exhibits high ionic conductivity, lower resistance and improved cycling performance, which is due to its smaller ion size and stable symmetry structure.

Design optimization of a silicon-germanium heterojunction negative capacitance gate-all-around tunneling field effect transistor based on a simulation study

The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in integrated circuits.In this study,an innovative gate-all-around(GAA)TFET,which represents a negative capacitance GAA gate-to-source overlap TFET(NCGAA-SOL-TFET),is proposed to increase the driving current.The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design(TCAD)simulations.The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes.In addition,due to the negative capacitance effect,the surface potential of the channel can be amplified,thus enhancing the driving current.The gateto-source overlap(SOL)technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon-germanium heterojunction.By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness,a sufficiently large on-state current of 17.20μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade.Finally,the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem,achieving a driving current that is comparable to that of the traditional complementary metal-oxide semiconductor devices.