High Energy Characteristics Research Articles

Application and research of three-dimensional composite fiber interlayer in lithium-sulfur battery

Lithium-sulfur (Li-S) batteries are regarded to be the most probable‌ electrochemical energy storage devices for large-scale applications because of their high energy and green characteristics. Nevertheless, the polysulfides generated during the cycle of Li-S batteries can cause the "shuttle effect", reducing the utilization rate of sulfur (S) and electrochemical performance. In this study, a novel three-dimensional composite fiber (TDCF) interlayer was prepared and placed between the S cathode and the PP separator to adsorb polysulfide and restrain the "shuttle effect". The results show that the capacity retention rate of Li-S battery is still higher 3:50 ratio, 200ml of anhydrous ethanol was added to moisten, than 70% after 200 charge-discharge cycles at 1C.

Physico-chemical and microbiological parameters of natural, industrial recycled water and its treatment

Background: Under conditions of anthropogenic impact, the chemical composition of water in surface rivers and groundwater bodies is subjected to pollution, which leads not only to a decrease in water quality, but also to an increase in the number of pathogenic and opportunistic bacteria. Aim: The purpose of this work is to study the physicochemical and microbiological parameters of natural and industrial recycled water before and after treatment with coagulants based on activated aluminum alloys. Materials and methods: As natural waters were analyzed: natural waters from water intake “Almaty SU”, “Medeu” tract, Zhaiyk river, from the well of experimental metallurgical production of IMOB. As recycled water was analyzed water taken from the water treatment unit of deep oil refining production. Turbidity was measured using HACH 2100Q turbidimeter and 2100Qis turbidimeter (USA). Cell morphology of microorganism cultures was studied by light microscopy using a MicroOptix MX-1150 (T) stereoscopic-sotrinocular microscope. Results: An effective and technologically simple method of obtaining aluminum polyoxychloride with the content of the main substance from 33 to 41.0% by Al2O3 and basicity from 55.1 to 66.5% has been developed. The method consists in dissolution of aluminum alloy activated by metal-activators (indium, gallium, tin) in the amount of 0.5–1.0 wt.% of each in 3% HCl. Physico-chemical and microbiological parameters of natural and industrial recycled water have been studied. The efficiency of the obtained aluminum polyoxychloride for treatment and conditioning of drinking water and industrial recycled water was evaluated. Conclusion: Unique alloys with high energy characteristics based on aluminum containing indium, gallium, tin from 0.5–1.0 wt.% have been created. The alloy has high activity in various oxidizing media (water, hydrochloric acid). A technologically simple method of obtaining aluminum polyoxychloride has been developed. Chemical and microbiological composition of natural and industrial recycled water has been studied. Coagulants based on activated aluminum alloys are effective in the processes of conditioning and purification of natural and recycled water from toxic compounds, have bactericidal activity, the level of gram-negative bacteria is reduced to 73%, gram-positive bacteria to 84% and to 96% of other groups of microorganisms. Fungi and yeasts (Mucor, Fusarium) were not detected after water treatment. Efficiency of water turbidity reduction reaches 90–99%, permanganate oxidizability up to 93%.

Ultra-fast, Self-destructing technology based on autocatalytic energetic conductive ink

Transient electronics show promising potential in data security and privacy preservation. Key criteria for transient electronic devices include quick production, short lifespan, and irreversible degradation. This article proposes a novel energetic conductive ink (EILs-Fc-SWNTs/EMOFs) with ultra-fast self-destruct performance for information protection. The ink based on carbon nanotubes modified with energetic ionic liquids and combustion rate catalysts, has advantages of high conductivity, high energy properties, and rapid production. Transient electronic devices containing micro-storage chips are achieved through direct writing technology. The writing circuit exhibits excellent conductivity (65.57 S/cm), high flexibility (2000 bending cycles), and high-energy characteristics (1640.3 J/g). The combustion temperature of the printing circuit is estimated at approximately 2100 °C. More importantly, transient electronics device commercial storage chips can be destroyed within 0.9 s.

Synthesis and Characterization of 3,4-Bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF): A Novel Low-Melting Insensitive Energetic Material.

The synthesis and characterization of low-melting-point insensitive energetic materials are crucial due to their increasing applications in melt-cast explosives. In this work, a furazan-derived energetic compound, 3,4-bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF), exhibiting insensitive and high-energy characteristics, is rationally designed and synthesized. The structure of DAeTF is characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elemental analysis, mass spectrometry, and single-crystal X-ray diffraction. The thermal properties of DAeTF are investigated using differential scanning calorimetry, in situ FTIR spectroscopy and thermogravimetric-differential scanning calorimetry-Fourier transform infrared-mass spectrometry and thermal decomposition mechanism was elucidated in combination with bond energy calculations. The detonation performance of DAeTF is predicted by the EXPLO5 program. The results indicate that DAeTF has thermal stability (Td = 251.7 °C), high energy level (D = 7270 m/s) and significant insensitivity (IS = 60 J). Additionally, its relatively low melting point (Tm = 60.5 °C) facilitates processing and loading. These characteristics indicate that DAeTF is a promising candidate as an insensitive melt-cast explosive in future applications.

Elucidating the Electrochemical Impact of the Calendering Process on Three-Dimensional Designed Electrodes for Lithium-Ion Batteries

Significant advancements in battery technology are imperative to meet the ambitious demands for electromobility and stand-alone energy storage devices. This stems from the need to achieve operations with high energy and power density, coupled with stringent safety standards and extended lifespans, while reducing production and material costs. The preferred energy storage technology for the coming decade is anticipated to remain lithium-ion battery (LIB) technology. The focus on researching high-energy active materials to optimize this technology is paramount. In addition to optimizing materials, significant performance enhancements can be achieved by using electrodes with high mass loading and a multiscale tailored electrode design that can be scaled up to production level.The technological challenges of achieving a breakthrough in gaining simultaneously high energy and power density characteristics while maintaining high process and operational reliability with significant cost savings are the subject of current research and development in the field of LIB technology. To tackle this, the study explores the laser-assisted generation of three-dimensional (3D) electrode architectures and assesses its impact on battery performance and future integration into battery production. The advanced electrode design involves micro and sub-micron structures that can be tailored in various ways, leading to notable improvements in battery lifespan, battery safety, and fast charging and high-power operation capabilities compared to batteries with conventional two-dimensional (2D) electrodes. High-power ultrafast laser ablation emerges as a precise method for introducing such structures.Coordinating the production of 3D electrodes with laser assistance necessitates synchronization with established manufacturing steps in the battery production process. Notably, the calendering of electrodes holds significance due to its substantial influence on the microstructural properties of the electrode material, encompassing porosity, material density, and layer adhesion. The study investigates the impact of laser-induced structuring, encompassing micro-/nano-porosities and microtopography, on electrodes with varying mass loadings ranging from 2mAh/cm² to 6mAh/cm². Electrochemical characteristics such as high-rate capability, fast charging, and cycle lifetime are evaluated accordingly, employing cells with graphite anodes and lithium-nickel-manganese-cobalt oxide cathodes.

A 5 V Ultrahigh Energy Density Lithium Metal Capacitor Enabled by the Fluorinated Electrolyte

Lithium metal capacitor (LMC), incorporating a redox-type lithium metal anode and a capacitive-type carbon cathode, delivers a combination of high energy and power characteristics, which is regarded as a promising electrochemical energy storage system. However, the unstable interface stability of lithium anode and the unclear capacitive mechanism of carbon cathode seriously restrict the advancement of LMC. Herein, an all-fluorinated electrolyte with high voltage stability has been designed for engineering 5 V LMC. It is noticed that a high-quality LiF-rich solid electrolyte interphase derived from all-fluorinated electrolyte effectively improves the interfacial stability of lithium metal anode, boosting the reversible Li plating/stripping behavior and suppressing dendrite growth. Moreover, analyzed by the thermodynamic perspective, the stable PF6−(FEC)2(FEMC)4 configuration with the lowest solvation energy mainly exists in the all-fluorinated electrolyte, which reveals that the suitable pore size distribution (1.3–4.6 nm) can ensure the strong adsorption/desorption process. Endowed by the all-fluorinated electrolyte, the established 5 V LMC paired with an optimized porous carbon sheet cathode manifests excellent electrochemical performances with an ultrahigh energy density of 537.6 Wh kgcathode−1 and a large power density of 17500 W kgcathode−1. This elaborate work affords in-depth insights based on fluorinated electrolyte strategy into the fabrication guidance of LMC.

Research on the Evolution Process of New Distribution Network Forms Considering Low Carbon and Sustainable Development

To obtain the planning and development status of new distribution networks under the low-carbon and sustainable development goals, research the evolution process of new distribution network forms under the “carbon peak” and “carbon neutrality” goals (dual carbon goals). Firstly, combining the characteristics of high proportion renewable energy, construct a new distribution network morphology evolution system under the “dual carbon target”. Explore the energy pattern and structural form of the current and medium/long-term new distribution network, and obtain the corresponding evolution process. Then, considering the transmission characteristics of the new distribution network under the “dual carbon target”, an evaluation index system is established in three aspects: power supply, distribution, and transmission. And construct an evaluation model for the development form of distribution networks based on SWOT analysis, to evaluate the new development form of distribution networks. Finally, numerical examples were verified and analyzed using MATLAB simulation software. The method proposed in this article not only intuitively describes the evolution process of the new distribution network morphology, but also obtains the evolution of the new distribution network at different time stages under the “dual carbon target”, as well as the evolution results of the distribution network morphology in terms of carbon emissions and cost investment. The final research results of this article can provide theoretical basis for distribution network planning under the “dual carbon goal”.

Simulation and Suppression Measure Analysis of Electromagnetic Radiation Interference Due to Frequency Converters in Coal Mines

Nowadays, due to their characteristics of high efficiency and energy saving, frequency converters are used in coal mine excavation machines and ventilation machines. They can cause serious electromagnetic radiation interference with the surrounding monitoring, sensing and other equipment. Therefore, it is necessary to explore the electromagnetic interference characteristics of mining converters. By choosing a ZJT-75/660SF mine frequency converter as the research object, an antenna model was established, and the method of moments was used to solve the problem. The electromagnetic radiation characteristics of the frequency converter were analyzed, and a field experiment was conducted to verify the effectiveness of the model by comparing the simulation and experimental data. According to the analysis of the electromagnetic intensity distribution characteristics of the near field and far field, the near-field intensity is concentrated in the inner part of the converter, but the far-field intensity has obvious directional characteristics, which are found to provide a reference value for the location of the underground mining converter. Finally, a method is proposed to improve electromagnetic radiation disturbance by changing the structure of the converter’s heat dissipation hole, and the feasibility of this method is verified.

Coupling effect of defects and enriched adsorption sites in bimetal-MOF derived porous carbonaceous anode for high-performance lithium-ion capacitor

Lithium-ion capacitors (LICs) have attracted considerable attention for their ability to combine the high energy characteristics of lithium-ion batteries and the high power densities of supercapacitors. However, the development of LICs still faces critical challenges. Herein, a robust bimetal-MOF derived fluorine and nitrogen co-doped hierarchical porous carbon embedding with Co nanoparticles anode materials (Co@NFC-800) for LICs are developed, which combined with the advantages of amplified interlayer, enriched active sites and improved electrical conductivity. Both theoretically and experimentally results demonstrate that such advantaged structure via fluorine doping to introduce defects and regulate doped nitrogen atom configuration to enrich Li+ adsorption sites and enhance diffusion kinetics synergistically is attempted. Co@NFC-800 deliveres a high reversible capacity and excellent long cycling stability as anode in LIBs, By coupling the Co@NFC-800 anode with commercial activated carbon (AC) cathode, the assembled LICs deliver a high specific energy of 164 Wh kg−1 at 162.9 W kg−1 and maintained to 68.3 Wh kg−1 even at high specific power of 9.1 kW kg−1 as well as long cycling stability (80.2 % over 2000 cycles).The fluorine doping induced both enriched defects and regulable nitrogen atom configuration strategy opens up a new way of carboneous materials for lithium storage.

КОМУТУЮЧА НАПРУГА ТРИФАЗНОГО ДВОМОСТОВОГО КОМПЕНСАЦІЙНОГО ПЕРЕТВОРЮВАЧА

The results of a study of electromagnetic processes in a three-phase two-bridge compensation converter, which is one of the options for the circuit implementation of new generation compensation converters, are presented. The commutating link of the converter contains a three-phase capacitor battery and a three-phase group of fully controlled devices. This technical solution makes it possible to make the process of recharging capacitors controllable. Moreover, it becomes possible to change not only the magnitude of the capacitor voltage, but also its shape. It was noted that in the previous generation of compensation converters there was no ability to change the shape of the commutating voltage. The latter is a significant advantage of new generation devices, since it allows for high energy characteristics of the converter. This is confirmed by the results of a study of the energy capabilities of the converter under study in nine operating modes presented in the publication and the conclusion on the most effective modes. References 9, figures 10.

Insulation of feed water tank in arrangement of transportable boiler plant with direct-flow steam boiler

A transportable boiler plant is used to provide consumers with steam of high energy characteristics, while saving costs for the construction of stationary boiler houses. A transportable boiler plant can be placed in the conditions of the Far North on an oilfield site. It is therefore necessary to organize reliable and safe operation of the boiler house, consisting of a steam direct-flow boiler of the coil type, a feed pump, a feed water tank and other auxiliary elements of the thermal circuit. One of the important elements in the thermal circuit is the feed water tank, in which water accumulates after chemical purification. It is where the water is also heated, increasing the efficiency of the boiler. Methods for calculating the diameters of main steam pipelines and feed water pipelines are described. The theoretical foundations of the operation of the feed water tank, its use in thermal power plants, combined heat and power plants, district industrial and heating boilers using various thermal arrangements of the above-mentioned enterprises are considered. The operation of the feed water tank in the thermal circuit of a steam unit is discussed. A thermal circuit of an industrial boiler house has been designed to generate saturated steam for consumers using direct-flow steam boilers of the coil type. The diameters of the inlet and outlet pipelines of the storage tank are calculated. The effective thickness of thermal insulation required to minimize heat losses during operation of a transportable boiler plant has been determined. Modeling of the design of the feed water tank and heat losses through its surface is carried out. A 3D model of the designed tank is presented, as well as heat losses through the surface of the tank walls when using a thermal insulation material. The importance of using thermal insulation of various tanks for storing feed water, petroleum products, hydrocarbons and other various media is noted.

Durable and high energy yielding PANI/Ni(OH)2 nanocomposites and its supporting electrolyte improved supercapacitance

The driving force behind supercapacitor research is to enhance the energy density (E) to the level of Li-ion batteries, and achieving high power density (P). This task is accomplished by using nanocomposites of polyaniline (PANI) and Ni(OH)2 (PN) as the electrode material for supercapacitors. These nanocomposites were synthesized using acetic acid (PN - AA) (PANI 75% and Ni(OH)2 25%) and methane sulphonic acid (PN - MSA) (PANI 83.33% and Ni(OH)2 16.67%) as dopants for PANI through an in-situ single-step method. The PN – MSA exhibited higher energy storage characters than PN – AA with 1 M H2SO4 (SA) as electrolyte. PN - MSA exhibited high-energy characteristics, including a specific capacitance (Cs) of 735.29 F g‒1, an energy density (E) of 147.05 W h kg‒1 (comparable to Li-ion batteries), and a power density (P) of 2.3466 kW kg‒1 at 1 A g‒1. In addition, it also exhibited an exceptional cyclic stability up to 58,800 cycles at 0.4 V s‒1. The energy characters of PN-AA are also substantially high and are a Cs of 641.02 F g‒1, an E of 128.20 W h kg‒1 (in the same order of Li-ion batteries), a P of 2.0385 kW kg‒1 at 1 A g‒1 and a cyclic stability up to 18,400 cycles was also obtained at 0.4 V s‒1. Both PN - AA and PN - MSA demonstrated an impressive feature of an increase in energy storage with an increase in the number of charge/discharge cycles. PN - MSA exhibited an improvement in energy storage characteristics of up to 44% when a mixture of sulphuric acid and methane sulphonic acid with concentrations of 1 M and 0.33 M, respectively, was used as an electrolyte.

Lithium Battery Technologies for Improvement of Energy Efficiency

With the process of economic globalization and the continuous improvement of energy demand, the search for new energy with higher efficiency has become a hot spot of social concern. Lithium-ion battery (LIB), as the current battery system with the best comprehensive performance, has the characteristics of high specific energy, high cycle life, small size and lightweight, and has rapidly developed into a new generation of energy storage power supply for information technology, new energy vehicles, aerospace and other fields of power support. Therefore, improving the energy efficiency of LIB is the most suitable choice in the current energy shortage. The core and key of LIB is the development and application of new lithium storage materials and electrolyte materials. This paper summarizes the research and application status of the main key materials of LIB. By analyzing the development status and existing problems of mainstream energy efficiency improvement technologies, it can be seen that the energy efficiency of LIB still has great room for improvement in the aspects of key materials and manufacturing technologies. At present, the research status of new anode materials and solid electrolytes is very active, and these technologies are expected to improve the energy efficiency, safety and reliability of lithium batteries. In the future, with more research and innovation, we can expect to see these technologies make even greater breakthroughs in the battery field, driving the development of electric mobility and renewable energy storage.

Strategy for improving the energy output efficiency of TKX-50: introduction of nitroamine explosives

ABSTRACT TKX-50 has attracted the attention of many researchers because of its low sensitivity and high energy characteristics. However, the experimental results show that there is a big gap between the energy level of TKX-50 and the theoretical value. Introducing nitroamine explosives RDX or HMX to stimulate the energy release of TKX-50 is of great significance for improving the energy release efficiency of TKX-50 and expanding its application in the field of energetic materials. In this paper, the properties of different TKX-50/RDX and TKX-50/HMX samples were investigated by thermal analysis and ignition combustion experiments. The results show that RDX has a more obvious catalytic effect on TKX-50. Adding 50% RDX reduces the peak thermal decomposition temperature of TKX-50 from 241.7°C to 218.7°C. At the same time, the flame propagation, maximum combustion pressure, and the pressurization rate of different samples during combustion were analyzed, and the reaction mechanism between RDX (or HMX) with TKX-50 was obtained. Because of the different catalytic effects of RDX and HMX on TKX-50, a strategy was proposed to construct the core-shell structure of TKX-50 to improve the reaction characteristics and energy release efficiency of TKX-50.

Synergistic effect of graphene oxide and partially hydrolyzed polyacrylamide for enhanced oil recovery: Merging coreflood experimental and CFD modeling approaches

The present study provides a comprehensive examination of GO-HPAM polymeric nanocomposite, contributing significantly to enhanced oil recovery (EOR). At the core of this investigation are a series of experimental tests and validations of simulations. The study examines the bonding effects, structural integrity, morphological interconnections, and stability of the GO-HPAM. The significance of reservoir and in-situ fluid conditions in the effort to improve EOR The GO-HPAM stabilization composite was developed, assessed, and examined for its extended core-flooding capabilities owing to its high energy characteristics. The simulation model was built on a Cartesian grid with fixed values for the bulk volume, injection rate, well completion, and rock-fluid properties using ANSYS Fluent. During the flooding experiment, the injections of 2 PV of brine, 0.50 PV of GO-HPAM, and 2 PV of chase water were precursors. The findings showed that 19.67% of the original oil could be recovered after injecting the nanocomposite fluid consisting of GO-HPAM. The GO-HPAM flooding gathered over 60% more oil than the traditional EOR polymer. Moreover, numerical modeling demonstrated a performance of the GO-HPAM combination comparable to the experimental results. The proposed synergetic fluid will assist researchers and industrialists in the design of an EOR process.

Effect of SiO2-H2O nanofluids on wettability of pulverized coal and the modification mechanism

To address the challenge induced by the hydrophobicity of coal dust, it is crucial to explore the impact of innovative wetting agents on the wettability of coal dust. In this regard, the present study focuses on SiO2-H2O nanofluids at four concentrations and pulverized coal with different particle sizes collected from different coal mines. The investigation focuses on the influence of SiO2-H2O nanofluids on the wettability of pulverized coal through an array of tests, encompassing surface tension assessments, viscosity measurements, contact angle analyses, reverse imbibition examinations, shooting of nanoparticle deposition patterns, and scanning electron microscopy. Furthermore, the underlying mechanism by which SiO2-H2O nanofluids enhance the wettability of pulverized coal was analyzed. The findings of the research reveal a substantial enhancement in the wettability of pulverized coal when modified with SiO2-H2O nanofluids. Specifically, when treated with nanofluids at a concentration of 1.5 wt%, the wettability improved by up to 44.61%, while the water absorption rate (WAR) increased by up to 4.82%. Notably, high-concentration nanofluids demonstrated effective suppression of coal dust with larger particle sizes, whereas low-concentration nanofluids addressed smaller particle sizes. SiO2 nanoparticles with high surface energy and robust adsorption characteristics, adhered to and agglomerated on the surface of pulverized coal, forming either globular or chained aggregates. This phenomenon emerged as the main cause for enhancing the wettability of pulverized coal. Finally, the study introduced a concept for an integrated technology aimed at controlling dust in mines, encompassing the preparation, transportation, and spraying of nanofluids. This research holds substantial theoretical and practical importance for the effective management of dust in coal mines.

Improving the electrocatalytic hydrogen evolution reaction through a magnetic field and hydrogen peroxide production co-assisted Ni/Fe3O4@poly(3,4-ethylene-dioxythiophene)/Ni electrode

The production of high-purity hydrogen using surplus electrical energy and abundant water resources has immense potential in mitigating the fossil energy crisis, as hydrogen fuel holds clean, pollution-free, and high-energy characteristics. However, the practical application of large-scale hydrogen production from water faces challenges such as high overpotentials, sluggish dynamics, and limited electrocatalytic lifetime associated with the hydrogen evolution reaction (HER). Here, we fabricated the sandwich structure of a Ni/Fe3O4@poly(3,4-ethylene-dioxythiophene)/Ni (Ni/Fe3O4@PEDOT/Ni) electrode and employed a strong magnet to obtain a magnetic electrode capable of achieving high-activity and durability for HER. Electrochemical analysis reveals that the activated magnetic electrode displays a significantly reduced overpotential and an extended electrocatalytic lifetime of 10 days. Notably, its stability is higher than that of non-magnetic Ni/Fe3O4/Ni and Ni/Fe3O4@PEDOT/Ni electrodes, primarily due to the support from magnetic force and the protective PEDOT layer. Moreover, the minute atomized droplets can form the H2O2 species in a moist environment, facilitating the formation of the NiO layer on the Ni surface, which plays a vital role in boosting catalytic activity. In conclusion, our magnetic electrode strategy, combined with the emergence of the NiO layer, offers valuable insights for the development of advanced HER electrodes.

Experimental study on gasoline-ammonia combustion characteristics with pre-chamber jet ignition

In terms of the characteristics of slow combustion rate and high ignition energy of ammonia, an experimental study of gasoline-ammonia combustion characteristics was conducted and the difference in the combustion process between active and passive pre-chambers was revealed, utilizing gasoline as the ignition fuel in conjunction with jet ignition technology. The results show that employing active pre-chamber jet ignition can achieve a maximum ammonia ratio of 85 %. When the ammonia ratio is lower than 70 %, the coefficient of variation can be controlled with 1.5 %. There exists a sensitive zone around 50 % ammonia ratio, where combustion characteristics display heightened sensitivity to changes in ammonia ratio. As the ammonia ratio increases, the combustion process transitions from gasoline-dominated to ammonia-dominated. Consequently, when the ammonia ratio increases from 43 % to 50 %, the combustion duration increases by 62.8 % and the peak of heat release rate decreases by 43.8 %. With the increase of ammonia ratio, CO2 emissions decrease significantly, and the lowest is within 80 g/kW∙h. NOx emissions increase significantly with ammonia ratio increasing, but the rate of increase slows down when ammonia ratio beyond 50 %, which is attributed to the reduction in combustion temperature. Compared with the passive pre-chamber, the active pre-chamber is less influenced by the proportion of ammonia within main chamber, exhibiting a faster combustion rate, especially for conditions with ammonia ratio exceeding 40 %. At lower ammonia proportions, the combustion process exhibited similarities between active and passive pre-chambers. Furthermore, active pre-chambers exhibit a superior capacity to achieve higher ammonia ratios, underscoring their advantages in enhancing both combustion rate and ammonia concentration.

Unsteady cavitation dynamics and pressure statistical analysis of a hydrofoil using the compressible cavitation model

A compressible cavitation model is developed in this paper, in which the bubble wall velocity is obtained by solving the compressible Rayleigh–Plesset (R–P) equation. Additionally, vapor compressibility is also included during evaporation/condensation to correct the phase change rate. The predicted results around a National Advisory Committee for Aeronautics (NACA) 66 (mod) hydrofoil are compared with the available experimental data, and a satisfied agreement is obtained. By (mod), we mean the NACA 66 hydrofoil modified by Brockett [“Minimum pressure envelopes for modified NACA-66 sections with NACA a = 0.8 camber and BuShips type I and type II sections,” Technical Report No. 1780 (David Taylor Model Basin Washington DC Hydromechanics Lab, 1966)] and Valentine [“The effect of nose radius on the cavitation-inception characteristics of two-dimensional hydrofoils,” Technical Report No. 3813 (Naval Ship Research and Development Center, 1974)]. Several crucial flow properties, e.g., fluid compressibility, cavitation evolution features, and pressure statistical characteristics, are studied in detail. The results suggest that the developed compressible cavitation model is better suited for predicting the collapse behavior of cavitation. Moreover, our work captures the liquid re-entrant jet and bubbly shock waves well and reveals that these two mechanisms jointly dominate the cavity shedding dynamics. Shock-induced pressure pulses play a more important role in flow features, with a maximum amplitude exceeding 200 kPa, significantly larger than the pressure pulse caused by liquid re-entrant jets. Finally, the statistical analysis indicates that the pulsating pressure presents non-Gaussian nature with positive skewness, and shock waves exhibit high-frequency and high-energy characteristics.

High-performance lithium-ion supercapacitors based on electrodes with nanostructures derived from zeolite imidazole frameworks in electrospun nanofibers

Lithium-ion supercapacitors (LICs) have received widespread interests because of their high power density, high energy and long life characteristics. The electrodes for LICs play a significant role in enhancing their performance. Therefore, it is of great significance to design and develop high-performance electrode materials for LIC through integrating various materials to make up for each other’s disadvantages. Herein, a bimetallic composite nanomaterial with hierarchical structures (CoSnX/CNFM) and a porous carbon nanomaterial with high specific surface area (PCNFM) were obtained through combining electrospinning, anion exchange or alkali etching and subsequent high-temperature carbonization, respectively. The LIC assembled with the pre-lithiated CoSnX/CNFM as anode and the PCNFM as cathode exhibited a high energy density of 41.48 Wh/kg at a power density of 1500 W/kg, and still had an energy density of 28.13 Wh/kg at a high power density of 7500 W/kg, illustrating its high power density and high energy density. Thus, this paper proposes an effective method for designing and manufacturing high-performance LICs.