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There are three main methods for preparing chlorinated polyethylene: the solution method, suspension method, and solid-phase method. This article studies the process of preparing chlorinated polyethylene by the aqueous suspension method, introduces the production process of chlorinated polyethylene, first understands the reaction mechanism of the chlorination reaction, then explores the production process of chlorinated polyethylene by the suspension method, and finds the optimal process conditions through experiments. The results showed that the optimal reaction temperature for the chlorination reaction of chlorinated polyethylene was 135°C, the optimal amount of initiator was 3%, and the optimal amount of chlorine gas added was 1.5%/min. This article explores the influencing factors of the optimal reaction conditions, laying a theoretical foundation for industrial production after the suspension method.
Hu, ShiguoZhao, RuchenYu, BinJiao, MingquanBai, Zhirui
The core challenge of in-service welding repair of oil and gas pipelines is the risk control of burn-through. Current research primarily focuses on macroscopic phenomena, lacking a systematic multi-scale analysis of burn-through mechanisms and their dynamic evolution. Existing criteria are primarily based on qualitative experience, and widely accepted quantitative safety assessment standards have yet to be established. Furthermore, insufficient understanding of multi-scale damage failure mechanisms and weak theoretical foundations have become bottlenecks in this field. This study targets X65 pipeline steel and combines in-service welding experiments with in-situ scanning electron microscope tensile tests to elucidate the formation mechanism of burn-through from a multi- scale perspective. The results show that during in-service welding, the remaining wall thickness of the pipeline continuously decreases with the welding process, ultimately resulting in burn-through holes. On one hand, the welding arc drives the expansion of the hole; on the other hand, the internal pressure of the medium further enlarges the hole, leading to the expulsion of water and rapid pressure loss in the pipeline. Notably, the fusion zone behind the maximum melt depth is subject to high temperatures, which reduces strength and degrades plasticity, exhibiting significant plastic strain, making it a high-risk area for burn-through instability. Before instability occurs, this region shows evident grain coalescence, with plastic deformation primarily occurring through dislocation slip; when the difficulty of activating slip systems increases, twinning deformation may be induced, and large twin grains rarely develop cracks. Strain concentration and crack initiation are more likely to occur between grains with significant orientation differences.
Wang, BangyuQiao, YingJieLi, DongXu, ShiHang
As a critical component in vehicular passive safety systems, the automotive bumper beam significantly influences overall crash safety performance and lightweight potential. This study presents a comprehensive investigation into the lightweight design of a carbon fiber reinforced polymer (CFRP) bumper beam, systematically substituting a conventional aluminum alloy component based on the principle of equivalent bending stiffness. The research methodology integrates finite element modeling, design of experiments, and multi-objective decision-making to optimize crashworthiness. Initial design replaced the 3 mm aluminum beam with a 2.4 mm CFRP configuration using a [0°, 45°, 90°, -45°] ply sequence, demonstrating maintained structural integrity with substantial mass reduction potential. Through Latin Hypercube Sampling, 50 design configurations incorporating variations in panel thicknesses (five distinct sections) and ply orientation sequences were generated and evaluated under an 8 km/h frontal impact simulation. Crashworthiness was assessed through four key indicators: mass, specific energy absorption (SEA), maximum intrusion distance (Dm), and peak impact force (Fm). The entropy weight method objectively determined indicator weights, revealing maximum intrusion (49.27%) as the most critical factor, followed by mass (32.75%), peak force (9.75%), and SEA (8.23%). Subsequently, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to comprehensively evaluate and rank all design alternatives. The optimized CFRP configuration (Scheme #38) achieved remarkable performance: 69.1% mass reduction (from 4.505 kg to 1.392 kg), 379.6% improvement in specific energy absorption, 12.6% reduction in peak impact force, while maintaining intrusion within acceptable design limits. This research establishes a robust framework for CFRP bumper beam optimization, successfully balancing lightweight objectives with enhanced crashworthiness, providing valuable insights for automotive lightweight safety component development.
Wang, YizhiZhong, RongLong, Jiangqi
The grouted composite pavement combines the advantages of flexibility and rigidity through the composite structure of organic-inorganic materials, but the optimisation of its performance is affected by the complexity of the matrix asphalt mixture void ratio and grouting material type. This study has revealed the influence of matrix asphalt mixture porosity and grouting material type on the grouting effect and road performance of grouted composite asphalt pavement. The results showed that the increase of matrix porosity could significantly improve the grouting rate and resistance to high-temperature rutting of the mortar, but the high porosity led to a decrease of low temperature cracking resistance of the materials. CA mortar enhanced the flexible deformation capacity by optimising the interfacial bond, and its low-temperature cracking resistance was better than that of ordinary cement mortar, but the grouting efficiency and high-temperature performance were slightly lower. In addition, ordinary cement mortar demonstrated better performance regarding high-temperature stability and resistance to water damage.
He, MuWang, YanYe, MingYu, ChaoYe, Xiao
Based on the engineering context of a shield tunnel section with ultra-shallow overburden along the coastal express line in a certain region, this study addresses the technical challenge of surface heave deformation during the construction of long-distance, large-section shield tunnels in shallow burial conditions. A numerical model for shield tunneling in complex underground environments with ultra-shallow overburden and large cross-sections was established using the software FLAC3D. Based on three different ground reinforcement conditions (no reinforcement, full-area reinforcement, and grid-type reinforcement), the control effect of grid-type ground reinforcement on surface deformation and heave during the shield tunneling process was systematically analyzed. The results show that: (1) The Z-direction displacement trends of the surface under the three conditions are consistent, with heave concentrated above the tunnel crown. Without cement-soil reinforcement, the surface heave increases significantly, with the maximum heave being approximately 52% higher than that of reinforced conditions, indicating that ground reinforcement measures are highly effective in controlling surface heave deformation; (2) Compared to full-area reinforcement, grid-type reinforcement reduces the reinforcement range by 22%, with only a 2% decrease in displacement. When the spacing between the cement-soil reinforcement layer and the tunnel bottom is 1 m, the heave increases by 6.5% compared to a spacing of 3 m, demonstrating that a larger spacing significantly enhances the reinforcement effect, and depth adjustment has a noticeable impact; (3) The scheme with a grid spacing of 4.65 m and a cement-soil layer bottom 2 m away from the tunnel bottom effectively controls surface heave, reduces cement usage, lowers construction costs and duration, and ensures tunnel safety and stability, providing a valuable reference for shield tunneling in shallow overburden sections. The research results can provide valuable references for controlling surface deformation during shield tunneling through ultra-shallow overburden sections.
Shi, CehuiZhang, Yang
The design of integrated station-bridge structures is challenged by the coexistence of building codes based on Limit State Design (LSD) and railway codes using Allowable Stress Design (ASD). This study employs finite element analysis to compare the performance of Steel Reinforced Concrete (SRC) columns designed under these two philosophies. The results demonstrate the significant conservatism of the ASD method: When achieving the same safety margin, the ASD-designed column required 2.36 times the cross-sectional area, yielding an 89% higher axial capacity but a disproportionately small increase in shear strength, indicating material inefficiency. A subsequent parametric analysis identified steel strength as key to axial capacity and concrete strength as critical for shear capacity, with shear performance reaching its maximum at an axial compression ratio of 0.6. These findings quantify these behavioral differences, offering a basis for refining design methods and codes harmonization for such structural members.
Tang, JiaDuan, LinliChen, NanHuang, YunfeiGuo, WeiJiang, LizhongYu, YujieXu, Yongjia
Carbon materials, as typical dielectric loss media, possess the characteristics of low density, stable chemical properties, wide sources, and diverse existing forms, and have been attracting much attention in the microwave absorption field. Based on carbon materials, the rational design and construction of microscopic morphology and microscopic structure is an effective way to improve their microwave absorption performance. Up to now, unique microstructures such as hollow, core-shell, and porous have been widely used in the design of microwave absorption materials, and their performance improvement has also been reliably confirmed. This paper mainly focuses on the research of the preparation and microwave absorption performance of porous carbon foams (CF-x). Firstly, it achieves the fabrication of porous carbon foams by the one-step pyrolysis using readily available glucose and NH4Cl, avoiding the need for polymer templates or magnetic element incorporation. In addition, this paper focuses on investigating the effect of the dosage of NH4Cl on the pore structure and dielectric properties of CF-x, and it reveals the advantages of the foam structure in terms of enhancing microwave absorption performance.
Wang, FengyuanWei, Qi
This study produced autogenous gas tungsten arc welds in 6 mm thick Inconel 690 plates using Ar-He shielding gas. The influence of helium content on arc characteristics, molten-pool geometry, microstructure, and mechanical properties was investigated systematically. With increasing helium fraction, the arc adopts a flattened, fan-shaped profile, leading to significantly greater penetration and bead width, accompanied by higher arc voltage and heat input. The weld-metal grain size is refined by up to 13.25%, while the solidification grain-boundary morphology shifts from cellular to a mixed equiaxed/cellular structure, and the fraction of high-angle grain boundaries increases. These microstructural changes reduce the ultimate tensile strength by a maximum of 12.21% and the elongation by 3.23%. Balancing weld quality and mechanical performance, gas mixtures of 60% Ar-40% He or 40% Ar-60% He are recommended as optimal shielding compositions for GTAW of Inconel 690.
Wang, ZhanfangLi, ZhenlongLei, JiaxuanChi, HouchaoNiu, BenJiang, GuoyanZhang, XuanbinHe, Bing
The scheme of photocatalysis of water, a way of hydrogen generation as a clean, high-efficiency fuel source for aircraft and long-range transport systems has received considerable interest. The development of the covalent organic framework (COF) - derived materials for hydrogen evolution reaction (HER) has since become a research highlight. Compared to traditional methods, photocatalytic hydrogen evolution systems based on COFs can provide ways of generating hydrogen gas without depending upon noble metal catalysts, thereby enhancing the sustainability and prospects of this technology for future aerospace energy applications.In this work, two covalent organic frameworks (COFs) with distinct linkages—a vinylene-linked COF A (via Knoevenagel condensation) and an imine-linked COF B (via Schiff-base reaction)—were designed and synthesized to compare their performance in the photocatalystic hydrogen evolution reaction (HER). Structural and electrochemical characterizations confirmed that, despite lower crystallinity and specific surface area due to pore blockage, COF A exhibited a suitable band structure for photocatalysis and achieved an HER rate of 56 μmol h^–1 g^–1 under simulated sunlight. In contrast, COF B was ineffective. This study experimentally validates the superior photocatalytic potential of vinylene-linked COFs over imine-linked counterparts for HER, highlighting their potential as non-noble-metal catalysts for aerospace and transport-oriented fuel generation.
Cao, YijieLuo, Xin
Materials, such as vehicle lightweighting, intelligent materials, and aviation damping material, are frequently subjected to prolonged loading conditions. During the service life of materials, micro-damage will inevitably occur. The ultrasonic wave-mixing method is an emerging technique in detecting subtle damage in materials. Investigating the interaction between two waves in nonlinear materials guides the non-destructive detection of defects. In the ultrasonic wave-mixing technique, the resonance condition is commonly employed for the selection of the two primary wave frequencies. However, resonance conditions are often not strictly satisfied in practical applications. The mixing wave still contains important information that requires attention in detection. The theoretical solution of the mixing wave interacted by two-way collinear waves with arbitrary frequencies is derived. The results advance us to understand the intrinsic properties of wave interaction.
Wang, LiLiu, XiqiangHe, ManliZhou, Huaren
Ultrasonic TOFD detection is one of the most important non-destructive testing techniques for welds. However, the complex beam deflection, scattering, and attenuation of ultrasonic waves in the heterogeneous weld structure lead to the weak signal of the defect diffraction wave received by the probe and the low signal-to-noise ratio, which has a negative impact on the engineering application of ultrasonic TOFD detection technology in austenitic stainless steel welds. In this study, a numerical model of the ultrasonic TOFD detection process for austenitic stainless steel welds was established based on the finite element method. Combined with the test method, the interaction mechanism between the ultrasonic wave and weld structure is analyzed, and the probe arrangement method to reduce the interference of weld scattering noise is proposed. The results show that the finite element model can simulate the anisotropic characteristics of ultrasonic waves in austenitic stainless steel welds, including sound field distortion, sound energy scattering, and attenuation. Combined with the detection test, it has been proven that the adverse effect of the weld structure on the TOFD detection signal can be reduced by changing the probe detection surface.
Hu, LichenHuang, HuiQian, ShengjieHu, WeiweiChen, Zhenhua
This study used hexacarbon polyether (EPEG), acrylic acid (AA), polyethylene glycol maleate (MAPG), and vinyl acetate (VA) as the main raw materials to synthesize a highly workable polycarboxylate superplasticizer (CE-02) under the action of an initiator. The structure of the target product was characterized by FTIR and GPC. Tests showed that under conditions of low water dosage (150 kg), low cementitious material content (220 kg of cement), and poor aggregate gradation, the concrete mixed with CE-02 exhibited an initial slump flow increase of 25 mm, a bleeding rate of 0.6%, no stone exposure, and excellent workability.
Chen, WenhongDeng, LeiJiang, YuZhang, Bo
The research focuses on textile material utilization for safety protection product design to meet rising public safety needs and expanding dangerous operational environments. The research begins by identifying essential performance criteria for safety textiles because these materials serve as core carriers due to their excellent plasticity and functional capabilities and comfort properties. The research examines leading protective materials through a comparative analysis which shows their individual benefits and weaknesses. The study implements an experimental method to evaluate a new aramid fabric composite against flame-resistant cotton fabric through standardized tests which assess protective capabilities and comfort levels and product longevity. The experimental results show that the composite aramid fabric surpasses flame-retardant cotton in all tested parameters including flame resistance and tear strength and durability while providing better thermal comfort. The study establishes a solid quantitative basis for selecting and enhancing textile materials in safety protection product development which enables the industry to create sustainable high-performance protective solutions with multiple functions.
Huang, JiaqiLi, HePeng, Tianxiao
Large-section tunnel construction using the mining method can significantly affect the operational safety of existing metro lines and ground stability, while their non-uniform settlement remains challenging to monitor comprehensively. In this study, the post-station section of a metro project in Chengdu was investigated to elucidate the vertical displacement and ground settlement behavior induced by a large-section tunnel undercrossing an existing metro line. A displacement reconstruction method integrating sparse-point monitoring with a radial basis function neural network (RBFNN) was developed to fit the full-field settlement distribution of both the existing line and the ground surface. A finite element model incorporating the existing shield tunnels, station structures, and the newly constructed mined tunnel was established, and the construction process was simulated. The numerical results indicated maximum settlements of 4.42 mm for the existing line and 4.37 mm for the ground surface, with fitting errors below 5.8% and 6.1%, respectively. Physical model tests further validated the approach, yielding maximum settlements of 0.86 mm and 1.01 mm for the existing line and ground surface, respectively, and an average fitting error below 3.5%. Both numerical and experimental findings confirmed that the induced displacements were within a controllable range and that the surrounding strata remained stable. The proposed method enables accurate and intuitive reconstruction of displacement distribution during under-crossing tunnel construction, reducing the number of required monitoring points while maintaining high fitting accuracy.
Wang, RuiChen, JianCheng, TaoDu, LinLi, Ruixiao
Driven by the stringent service conditions of aviation, aerospace, and military equipment, parallel seam welding, as an advanced resistance-welding packaging process, has been widely applied in ceramic-metal packages that require high hermeticity, owing to its excellent sealing performance and reliability. In this study, targeting the hermeticity failures that appear in parallel seam-welded ceramic packages after temperature cycling, molecular dynamics simulation is used to systematically investigate helium diffusion in nanoscale interfacial microchannels and its effect on hermeticity. On the LAMMPS platform, a three-region model is constructed that includes a helium-charging region, a wall-channel region composed of Fe, Ni, and Au, and a vacuum leak region. The Lennard-Jones potential is used to describe interatomic interactions, and a thermal-cycling environment conforming to MIL-STD-883, with a temperature range from -50°C to +125°C, is simulated to represent actual service conditions. The simulation results show that when the channel diameter is less than or equal to 1.2 nanometers, the number of leaked helium atoms remains constant at approximately 22 and is not affected by temperature; when the diameter is greater than or equal to 1.6 nanometers, the leakage exhibits significant temperature dependence. For example, in a 2.6-nanometer channel, 212 atoms leak at 423 K and 176 atoms at 223 K. Both leakage flux and leak rate increase markedly with channel size. OVITO analysis confirms that helium diffusion exhibits molecular-flow characteristics; at very small apertures, atomic escape efficiency is limited by the frequency of collisions with the wall. These findings provide insight for improving hermetic packaging and reliability of critical electronics used in aviation, aerospace, and military equipment.
Li, XiangyangGong, YubingZheng, Xianling
Focusing on the protection needs of child occupants in the scenario of aircraft vertical crashes, a finite element calculation model based on the cabin structure of a certain type of small electric aircraft was established. The child seat restraint system was coupled with the THUMS 3YO human body model, and the vertical 15 g condition meeting the requirements of Article 23.562 of CCAR-23-R3 was simulated. The influence law of the safety belt restraint angles (formed by different safety belt routing positions) on the dynamic response and injury indicators of child occupants was explored. To verify the rationality of the simulation results, a physical impact experiment was conducted using a Hybrid III 3YO child dummy and the same type of child seat, with key indicators (e.g., head acceleration, lumbar load) measured and compared with simulation data. The analysis results show that the effect of the safety belt restraint angle on the overall protective performance is less pronounced under vertical conditions, but a clear trend is observed: when the angle is in the range of 76°~84°, the head acceleration is relatively low and the brain tissue injury indicators are in the optimal state, which can effectively reduce the risk of head and neck injuries; when the restraint angle increases to 92°, the lumbar axial load and lung strain increase significantly, indicating a detrimental effect. The results of this study clarify the differences in the protective performance of child seats under different restraint angles, and provide a theoretical basis and technical guidance for the layout of safety belt anchors of aircraft seats and the optimal design of child seats.
Wang, YafengGuo, PanLi, WeiliangShi, Xiaopeng
This study introduces an arc-shaped hourglass re-entrant auxetic honeycomb (AHRH) and examines its impact-induced dynamic response and energy-absorption behavior via finite-element simulations. The conventional re-entrant honeycomb (RH) is adopted as the baseline, and side-by-side simulations are performed at impact speeds of 10, 20, and 30 m/s. The mechanical response of both lattices is assessed through force-displacement characteristics, absorbed-energy histories, and representative deformation modes. Results indicate that the AHRH significantly reduces the initial peak force, prolongs the plateau stage, and exhibits a distinct dual-plateau feature, thereby achieving the desirable crashworthiness mode of “low initial peak-extended plateau-high densification”. Compared with the RH, the AHRH achieves increases of approximately 42.9%-59.7% in total energy absorption and 42.8%-56.1% in specific energy absorption while maintaining nearly identical mass. The enhanced performance arises from the arc-edge geometry, which alleviates local stress concentrations, promotes progressive buckling, and generates multiple plastic hinges. These mechanisms lead to smoother load transfer, avoidance of excessively high initial impact loads, and more efficient crash energy management. Overall, the proposed AHRH structure demonstrates superior energy absorption capacity and deformation stability compared with the conventional RH, providing new insights and practical references for the lightweight design and optimization of advanced protective and crashworthy structures.
Jiang, ZhideChen, LongYu, Ping
The free vibration characteristics of long-span transmission conductors form the fundamental basis for vibration control design, as their natural frequencies and mode shapes directly affect line safety and the selection of vibration suppression devices. In this study, the three-dimensional linear free vibration governing equations were derived through functional integration of the kinetic and potential energies by using Hamilton’s variational principle. Compared with the conventional integral transform method, an improved meshfree discretization strategy is proposed: the shape functions are constructed using the moving least squares (MLS) method, while the boundary conditions are treated with a fully transformed approach, thereby converting the partial differential equations into ordinary differential equations. Subsequently, a corresponding eigenvalue problem is solved to calculate the first few frequencies of the system, and the effect of conductor natural parameters on these frequencies for the transmission conductor is investigated. The results indicate that the natural frequency decreases when the conductor length becomes larger, and the rate of decrease becomes more gradual as the length increases; it decreases with increasing cross-sectional diameter; it decreases linearly with increasing material density; and it increases linearly with increasing elastic modulus. These findings demonstrate that conductor length, cross-sectional diameter, material density, and elastic modulus all have significant effects on the natural frequency. Among them, length and diameter affect the frequency by altering the conductor’s inertia and structural characteristics, whereas density and elastic modulus govern the frequency from the perspectives of inertia and stiffness, respectively.
Li, ChenCheng, YongfengLi, DanyuQiu, Gang
Copper red glazes have received considerable attention due to their perfect decorative effects and vivid coloration. This paper selected four different formula copper red glazes with different colors of bright red, violet blue, dark red, and gray blue as the samples. Based on the analysis of the colorimeter, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscope (SEM), a possible coloration mechanism was proposed to explain the variation of glaze colors. The results indicated that the glaze layers were mainly composed of amorphous phases with few quartz diffraction peaks and mainly presented a granulous structure and phase separation. Increasing the content of CaO could cause color changes of the glaze due to the high ionic potential of calcium ions, which could form a unique feature in the glaze melt. In addition, a small amount of calcium phosphate could greatly change the color of the glaze. The phase separation structure of the blue samples was more obvious than that of the red samples, with a phase separation size of less than 100 nm. The formation of droplet phase separation structure in the glaze could lead to Rayleigh scattering and Mie scattering, which made the color of copper red glazes blue and opacified. Increasing the content of Cu0 and decreasing Cu+ could weaken the structural color, which contributes to a* value of the glaze changing from 26.93 to 22.93. At the same content of Cu0, the higher the ratio of Cu+ /Cu2+ is, the less a* value of the glaze is. Finally, the existence of CuSiO3 in the glaze could also make the blue color.
Ding, ErbaoYang, MengliLiu, NannanLi, YaboZheng, RuimiaoXu, Yan
The stress servo mechanism (SSM) is frequently employed in DEM simulations, but the importance of the parameters in the SSM has been seriously underestimated, and it remains unknown whether this affects the reproducibility of numerical simulations. Therefore, in this note, we focus on explaining the stress servo mechanism in numerical simulations by referring to the existing literature. A series of drained biaxial compression simulations was conducted to investigate how the maximum stress servo velocity (umax), a key parameter within the SSM, influences both the macroscopic mechanical response of the specimen and the evolution of the measured confining pressure. It is found that when the umax is large (≥ 0.05 m/s), the simulation results are consistent with the existing studies and are able to reproduce the stress-strain behaviour of the material. Conversely, if umax is set below a critical threshold (e.g., < 0.05 m/s), the servo mechanism fails to function properly. This inadequacy introduces significant numerical artifacts, distorting the simulated response and ultimately misrepresenting the true mechanical behavior of the material. We therefore advocate for the explicit recognition and detailed reporting of umax as a key parameter in all DEM studies utilizing stress servo control. This study helps to improve the reliability of DEM results and provides a reference for the improvement of numerical simulation methods.
Huang, GuangjingJin, JiachengHuang, Liang
This study investigates the cracking problems observed on the surface of T-joint welds and shell welds of storage tanks used for storing crude oil containing trace amounts of hydrogen sulfide (H2S) in a certain oilfield. Tests were conducted on Q235 and Q345R welded joints using electrodes with different hydrogen contents to evaluate their susceptibility to cold cracking, hydrogen-induced cracking (HIC), and sulfide stress corrosion cracking (SSC), as well as the effects of post-weld hydrogen removal treatment. The results show that no delayed cold cracks occurred in any welded joints of either Q235 or Q345R. Both materials exhibited hydrogen-induced cracking (HIC) on the cross-section, and the hydrogen removal treatment had little effect on improving HIC resistance. The overall HIC sensitivities of Q235 and Q345R were similar, both showing susceptibility to hydrogen absorption and internal cracking in the wet H2S environment. In contrast, SSC tests revealed that low-hydrogen welds exhibited no fractures or cracks, whereas high-hydrogen welds developed surface cracks. After hydrogen removal treatment, no SSC cracks were found in any specimens, regardless of electrode type. Therefore, for storage tanks operating in H2S-containing environments, the combination of low-hydrogen electrodes and post-weld hydrogen removal treatment is recommended to improve weld reliability and ensure operational safety.
Kang, ChunDeng, YufaZhang, PenggangHan, XiaochunHuang, MingjiDeng, BanghuiLi, QiangZhang, Shuxin
P2-type layered oxides are good cathode materials in high-performance sodium-ion batteries since they have desirable two-dimensional ion migration pathways. However, their instability at interfaces and their attenuation as cycles persist also remain a significant challenge. To increase their electrochemical stability, surface coating is also a good plan, but the balance between the coating and ionic conductivity is one of the key challenges. This study constructed an immensely thin layer of alumina (Al2O3) coating, and the influence of the amount of the coating (0.3-1.2 wt percent) on the working of the material was methodically examined. Electrochemical analysis showed that the lowest levels of Al2O3 (0.3 wt) provide the greatest improvement in performance. The optimized sample showed a retention capacity of 96.35 after 100 cycles of operation at 1C, significantly higher compared with samples that had increased coating contents. An analysis of cyclic voltammetry and impedance spectroscopy was subsequently done to corroborate the presence of a 0.3 wt% coating, which infected the electrode-electrolyte interface by inhibiting side reactions but minimally obstructing sodium-ion transport and thus promoting reaction reversibility and improved interfacial kinetics. These results highlight the importance of a less-is-more rule when it comes to surface coating and provide a novel understanding of how long-life sodium-ion battery cathodes can be designed by carefully engineered interfaces.
Hu, ChaoPeng, RuiZhou, YuZhou, DengmeiTian, Liangliang
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies