Search Results (4,984)

Reactions of anhydrous Zn(II) iodides with redox-active 1,4-diaza-1,3-butadiene (DAD) and its bis(imino)acenaphtene (BIAN) derivatives in absolute acetonitrile yielded a series of new complexes: [(Mes-DAD)ZnI₂] (1), [(dpp-DAD)ZnI₂] (2), and [(dpp-BIAN)ZnI₂] (3). Single crystals of all compounds were obtained, and their molecular structures were unambiguously determined by X-ray diffraction analysis. Purity of bulk samples in solid state was confirmed by PXRD. Stability of the complexes in solution was investigated by means of UV-Vis and NMR spectroscopy. Cyclic voltammetry revealed two or three quasi-reversible reduction waves in the cathodic region for complexes 1–3. The ability of 3 to accept up to three electrons highlights the potential of these compounds as electrocatalysts for reductive transformations. Full article

This article investigates the anticorrosive properties of Zr-ZrN coatings, including Zr-(Zr,Hf)N, Zr-(Zr,Ti)N, Zr,Hf-(Zr,Hf,Nb)N, and Zr,Nb-(Zr,Nb)N, deposited on AISI 321 stainless steel substrates. The hardness and elasticity modulus of these coatings, as well as their scratch test strength, were measured. Corrosion current densities were calculated using the polarisation resistance method and by extrapolating the linear sections of the cathodic and anodic curves under electrode polarisation. The structure and composition of the sample surfaces were analysed by transmission electron microscopy. Notably, the nitride coatings reduced the corrosion current density in a 3% aqueous NaCl solution at 25 °C by more than 10 times, from 6.96 for the uncoated substrate to 0.17 μA/cm² for the Zr-(Zr,Ti)N-coated sample. The addition of Ti nitride to Zr-ZrN led to the most significant decrease in the corrosion current density. However, the introduction of Nb caused an increase in the corrosion rate and a decrease in the polarisation resistance, and Hf did not affect the corrosion-protective properties of the studied nitride coatings. Full article

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their intrinsic safety, low cost, and environmental friendliness. However, drastic volume expansion, sluggish reaction kinetics, and the insufficient structural stability of electrode materials still remain key challenges. In this work, a cascade structure-guided electron transport strategy was used to construct a vanadium nitride@carbon nanosheet/carbon nanofiber (VN@CNS/CNF) composite as a high-performance cathode for AZIBs. In this rationally engineered architecture, carbon-coated VN nanoparticles are uniformly anchored on a conductive carbon nanofiber network, forming a multidimensional interconnected structure that enables fast electron/ion transport and robust mechanical stability. The carbon shell effectively alleviates volume expansion and prevents VN nanoparticle agglomeration, while the continuous carbon fiber backbone reduces charge transfer resistance and enhances reaction kinetics. Benefiting from this synergistic structural design, the VN@CNS/CNF electrode delivers a high specific capacity of 564 mAh g⁻¹ at 0.1 A g⁻¹, maintains 99% capacity retention after 50 cycles, and retains 280 mAh g⁻¹ even at 8 A g⁻¹ after prolonged cycling. This study provides a new structural engineering strategy for vanadium nitride-based electrodes and provides strategic guidance for the development of fast-charging, durable aqueous zinc-ion batteries. Full article

In deep coal mines characterized by high temperature, high humidity, high-salinity water, and elevated ground stress, stress corrosion cracking (SCC) of bolts is widespread, causing frequent instability of roadway surrounding rock and hindering long-term stability. This study systematically examines the failure characteristics of anchorage materials in highly corrosive roadways and clarifies the effects of deep-mine temperature and humidity on material corrosion. Long-term corrosion tests on bolts reveal changes in mechanical properties and macroscopic morphology and elucidate the intrinsic mechanisms of SCC. The results show that with the increase in corrosion time, the yield strength, ultimate load and elongation of the anchor rod decrease by up to 11.8%, 13.6%, and 7.08%, respectively. Under high stress, localized corrosion pits form on bolt surfaces, rupturing the oxide film and initiating rapid anodic dissolution and cathodic hydrogen evolution. Interaction between corroded surfaces and microcracks produced by internal impurities leads to progressive damage accumulation and ultimate fracture of the bolts. These findings provide guidance for corrosion protection of coal mine roadway support materials and for improving the long-term performance of roadway supports. Full article

Rechargeable sodium-ion batteries (SIBs) have attracted considerable attention owing to the natural abundance and accessibility of sodium. Maricite NaMnPO₄, a phosphate-based cathode material with high theoretical capacity, suffers from blocked sodium-ion diffusion channels. In this study, atomistic simulations using pair potentials and density functional theory (DFT) are employed to investigate intrinsic defect mechanisms, sodium-ion migration pathways, and the role of dopant incorporation at Na, Mn, and P sites in generating Na vacancies and interstitials. Among the intrinsic defects, the Na–Mn anti-site cluster emerges as the most favorable, exhibiting a very low formation energy of 0.12 eV, while the Na Frenkel pair (1.93 eV) is the next most stable defect, indicating that sodium diffusion is primarily facilitated by vacancy formation. Nevertheless, sodium-ion mobility in NaMnPO₄ remains limited, as reflected by the relatively high migration activation energy of 1.28 eV. Among the isovalent substitutions, K is predicted to be the most favorable dopant at the Na site, whereas Ca and Cu are the most favorable at the Mn site. Thallium is identified as a promising dopant at the Mn site for generating Na vacancies that facilitate Na-ion migration, while Ge substitution at the P site is predicted to enhance the sodium content in the material. Full article

Element doping technology is widely recognized as an effective strategy for high-performance MnO₂-based cathode materials. While this approach improves the electronic and ionic conductivity of MnO₂, it is often accompanied by the introduction of oxygen vacancies. This synergistic effect poses challenges for precisely investigating the effect of doping elements on the d-electron configuration of the Mn site and establishing atomic-level structure-activity relationships for high-energy aqueous zinc-MnO₂ batteries. In this paper, the rational design of d-electron configurations in the Mn site has been achieved through simple Co doping in α-MnO₂ (CMO). Experimental results confirm that the introduction of Co can delocalize the d-electrons of the Mn site and increase the ratio of e_g (d_z² and d_x²_−y²) occupancy. Consequently, the charge transfer resistance, electrode polarization, and Zn²⁺ diffusion coefficient of the CMO-2 cathode have been greatly optimized. Thus, the as-prepared electrode delivers a high specific capacity of 287.4 mAh g⁻¹ at 1 A g⁻¹, with a capacity retention rate of 92.8% and a corresponding remaining capacity of 199.7 mAh g⁻¹ after 700 cycles. This study paves the road for the designation and construction of high-energy MnO₂ cathodes with optimized electronic structures for advanced aqueous zinc ion batteries. Full article

This study investigates the influence of current density distribution on the hardening behavior of 20GL cast steel during electrolytic plasma processing (EPP). Experimental and numerical methods were combined to establish the relationship between discharge dynamics, heat flux, microstructural transformation. Electrolytic plasma hardening was carried out at cathodic voltages of 150 V and 250 V in a 20% Na₂CO₃ solution. The transient evolution of current density was analyzed using a 3D COMSOL Multiphysics model incorporating a vapor–gas shell (VGS) represented as a distributed impedance layer with realistic conductivity and permittivity. High-speed video confirmed that microdischarges preferentially initiate at sample corners, where modeling also predicts local current concentration and heat flux up to 12 MW/m². Experimental current density values (3–4 × 10⁴ A/m²) showed good agreement with the simulations. Microhardness tests revealed that increasing voltage from 150 V to 250 V increases the thickness of the hardened layer (from ~250 µm to ~600 µm) and raises surface hardness (up to 750 HV), while polarization tests showed a 40% reduction in corrosion rate. The results highlight that current density distribution governs the non-uniformity of thermal effects and surface strengthening during EPP, emphasizing the importance of electrode alignment and VGS stability for uniform hardening. Full article

Background/Objectives: Transcutaneous spinal stimulation (TSS) is a noninvasive stimulation approach for spasticity reduction in people with spinal cord injury (SCI). We enrolled 17 individuals with SCI who experience lower extremity hyperreflexia for this randomized crossover study to compare single-session effects of 3 TSS conditions: single-site continuous (SS-CONT), single-site burst (SS-BURST), and dual-site continuous (DS-CONT). Methods: Each TSS condition was delivered for 30 min with participants in supine via a cathode over the thoracic spine (T11–T12) and an anode over the abdomen. A second cathode was placed over the lumbar spine (L1/2 or L2/3) for DS-CONT. SS-CONT and DS-CONT stimulation was delivered as continuous 50 Hz stimulation with a 1 ms pulse width. SS-BURST stimulation was delivered as 4 bursts/second of 50 Hz stimulation with a 1 ms pulse width. Pendulum test first swing excursion (FSE) and ankle clonus drop test first drop excursion (FDE) were measured at baseline and immediately post-intervention to assess quadriceps and soleus spasticity, respectively. FSE and FDE of the first trial (FSE_T1 and FDE_T1) and the average of 3 trials (FSE_avg and FDE_avg) were included in analyses. Subgroup analyses were performed based on baseline level of spasticity (high vs. low). Results: Between-condition analyses showed no significant differences; however, SS-CONT (FSE_T1 d = 0.30, FSE_avg d = 0.27) and DS-CONT (FSE_T1 d = 0.33, FSE_avg d = 0.12) stimulation demonstrated the largest effect sizes for FSE measures, and SS-CONT (FDE_T1 d = 0.32, FDE_avg d = 0.31) stimulation demonstrated the largest effect size for FDE measures. Significant fair correlations between baseline FSE measures and change in FSE were identified when all conditions were combined. A significant fair correlation between baseline FDE_T1 and change in FDE_T1 was identified when data were collapsed across conditions. In subgroup analyses, only participants with high baseline quadriceps spasticity showed a significant decrease in quadriceps spasticity with DS-CONT (∆FSE_T1 = 14.8 ± 13.0°), SS-BURST (∆FSE_T1 = 4.1 ± 4.5°), and with all conditions combined (∆FSE_T1 = 11.3 ± 16.5°, ∆FSE_avg = 7.2 ± 13.1°). For participants with low baseline soleus spasticity, DS-CONT stimulation significantly increased soleus spasticity (∆FDE_T1 = −12.2 ± 9.3°, ∆FDE_avg = −8.5 ± 8.4°). Conclusions: When data were collapsed across conditions, TSS did not result in a significant reduction in quadriceps or soleus spasticity. Continuous stimulation at both single- and dual-sites was associated with the largest effect on quadriceps spasticity when all participants were combined. Lastly, TSS reduced spasticity in a severity-dependent manner. Full article

The recovery of rare earth elements (REEs) from the spent NdFeB magnets has great strategic significance for ensuring the security of critical mineral resources. This process requires scientifically designed separation technologies to ensure high output and purity of the obtained rare earths. Hydrometallurgy has been widely applied to extract REEs from spent permanent magnets. This paper summarizes and reviews hydrometallurgical technologies, mechanisms, and applications for the separation and recovery of REEs and iron (Fe) from the spent permanent magnets. Key methods include: The hydrochloric acid total solution method, where the spent NdFeB is completely dissolved in hydrochloric acid, iron is precipitated and removed, and then REEs are extracted. The hydrochloric acid preferential dissolution method, where spent NdFeB magnets are first fully oxidized by oxidative roasting, converting Fe²⁺ to Fe³⁺, which hydrolyzes to Fe(OH)₃, and is precipitated and removed, allowing for the subsequent extraction of REEs to obtain rare earth oxides. Acid baking and water leaching, where spent NdFeB is calcined with acidification reagents, and the calcined products are dissolved in water to leach out REEs. At the same time, Fe is retained in the leaching residue. Electrolysis in aqueous solution, where Fe is electrolyzed at the anode or deposited at the cathode to separate it from REES. Organic acids leaching, where organic acids dissolve metals through acidolysis and complexation. Bioleaching, which utilizes microorganisms to recover metal through biological oxidation and complexation. Ionic liquid systems, where Fe or REEs are extracted using ionic liquid or leached by deep eutectic solvents. This paper provides an in-depth discussion on the challenges, advantages, and disadvantages of these strategies for recycling spent NdFeB magnets, as well as the leaching and extraction behavior of REEs. It focuses on environmental impact assessment, improving recovery efficiency, and decreasing reagent consumption. The future development direction for recycling spent NdFeB magnets is proposed, and a research idea of proposing a combined process to avoid the drawbacks of a single recycling method is introduced. Full article

The presented research delivers a comprehensive evaluation of anticorrosive cathodic electrodeposition (CED) coatings through an integrated performance and process capability analysis—an approach that remains extremely limited in the literature, particularly in the context of statistically designed experiments (DoEs) applied to CED systems. This study therefore addresses a notable gap by focusing on the role of polymerization variables in determining coating quality through DoE to quantify the influence on coating thickness uniformity, adhesion integrity and impact resistance, while all other deposition parameters were rigorously controlled. Prior to coating application, all specimens were prepared and conditioned in accordance with ISO 1513:2010. Coating thickness was determined in compliance with ISO 2808:2019, adhesion was characterized by cross-cut methodology according to ISO 2409:2020 and dynamic mechanical resistance was evaluated using a falling-weight apparatus in accordance with ISO 6272-1:2011. The obtained datasets were subjected to statistical capability analysis within the PalstatCAQ environment, providing Cp, Cpk, Pp and Ppk indices in line with ISO 22514-7:2021 and IATF 16949:2016 requirements. Results evidenced non-linear dependencies of thickness formation on curing parameters, with potential capability indices (Cp > 1.8; Pp ≈ 1.4) indicating favorable process dispersion, while performance indices (Cpk < 0.5; Ppk < 0.4) revealed systematic mean shifts and deviations from normality confirmed by Shapiro–Wilk and Anderson–Darling tests. Adhesion testing demonstrated a direct correlation between curing conditions and interfacial bonding, reaching ISO Grade 0 classification. Complementary impact resistance assessments corroborated these findings, showing that insufficient curing induced extensive cracking and delamination. Furthermore, SEM–EDX analysis performed on Sample n.3 of X₂ variable confirmed the chemical integrity and multilayered structure of the CED coating. Full article

In high-sulfur environments, the failure risk of completion tubing increases due to the coupling effect of mechanical and electrochemical corrosion during the acidification production process. The corrosion behavior of P110SS tubing steel was investigated by an HTHP corrosion weight loss experiment and an electrochemical corrosion experiment. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to analyze the surface morphology of the corrosion products. In addition, a prediction model for the remaining service life of completion tubing under the synergistic effect of corrosion and stress was established during the acidification production process. The results show that acidification operations have a significant impact on the subsequent service life of tubing; the corrosion rate of P110SS tubing in the full acidification production process is much higher than that after the produced gas field solution corrosion treatment alone. Obvious pitting marks, micropores, and microchannels are observed in the corrosion product film of P110SS steel after acidification treatment, and the corrosion product film structure of P110SS steel is loose and honeycomb-like after acidification production treatment. The corrosion products are mainly FexSy and FeCO₃ after acidification production corrosion treatment. The corrosion during the acidification production stage is controlled by cathodic polarization. The remaining service life of tubing after production corrosion treatment can reach up to 29 years, while the remaining service life of tubing after acidification production corrosion treatment is significantly reduced, with a maximum of only 8 years. The research results have guiding significance for the selection, optimization, and design of high-sulfur-gas well tubing. Full article

Lithium-ion batteries (LIBs) are vital for modern energy storage applications. Lithium iron phosphate (LFP) is a promising cathode material due to its safety, low cost, and environmental friendliness compared to the widely used nickel manganese cobalt oxide (NMC), which contains hazardous nickel and cobalt compounds. However, challenges remain in enhancing the performance of LFP cathodes due to their low electronic and ionic conductivity. To improve both the safety and sustainability of the battery, this work presents a water-based LFP cathode utilizing the bio-based binder carboxymethyl cellulose (CMC), eliminating the need for polyvinylidene fluoride (PVDF) and the toxic solvent N-methyl-2-pyrrolidone (NMP). This study investigates the impact of different dispersing methods—dissolver mixing and wet jet milling—on slurry properties, electrode morphology, and battery performance. Slurries were characterized by rheology, particle size distribution, and sedimentation behavior, while coated and calendered electrodes were examined via thickness measurements and scanning electron microscopy (SEM). Electrochemical performance of the electrodes was evaluated by means of C-Rate testing. The results reveal that dispersing methods significantly influence slurry characteristics but marginally affect electrochemical performance. Compared to dissolver mixing, wet jet milling reduced the median particle size by 39% (ΔD50 = 3.1 µm) and lowered viscosity by 96% at 1 s⁻¹, 80% at 105 s⁻¹, and 64% at 1000 s⁻¹. In contrast, the electrochemical performance of the resulting electrodes differed only slightly, with discharge capacity varying by approximately 12.8% at 1.0 C (Δcapacity = 10.7 mAh g⁻¹). This research highlights the importance of optimizing not only material selection but also processing techniques to advance safer and more sustainable energy storage solutions. Full article

Aluminum-ion batteries (AIBs) are emerging as promising alternatives to lithium-ion batteries due to their cost-effectiveness and resource abundance. However, their practical application is hindered by low capacity, poor cycle life, and limited rate capability. In this study, δ-MnO₂ and δ-MnO₂/Graphene composite cathodes are developed and tested in aqueous aluminum-ion batteries (AAIBs) using a mixture of 0.5 M Al₂(SO₄)₃ and 0.4 M MnSO₄ as the electrolyte. The electrochemical properties are evaluated alongside treated aluminum (TAl) and Zn–Al alloy anodes. Among the configurations tested, the δ-MnO₂/Graphene|0.5 M Al₂(SO₄)₃, 0.4 M MnSO₄|Zn–Al system showed the best performance, achieving a high discharge voltage of 1.63 V, a specific capacity of 746 mAh g⁻¹, and excellent cycling stability over 352 cycles. The stabilizing effect of graphene, due to increased oxygen vacancies and the formation of Mn–O–C bonds, enhances electron and ion transport, thereby improving cathode integrity and the overall performance of the AAIB. Additionally, the Zn–Al alloy anode extends the battery’s cycle life compared to the TAl anode. This work demonstrates the potential for low-cost, high-performance AAIBs, paving the way for more sustainable and scalable energy storage solutions. Full article

Fiber-based and fabric batteries signify a groundbreaking development in energy storage, allowing for the straightforward incorporation of power sources into wearable fabrics, intelligent apparel, and adaptable electronics. In this study, we introduce a novel strategy for one-step fabrication of a flexible lithium titanate oxide (Li₄Ti₅O₁₂, LTO) anode directly on a copper current collector via electrospinning, eliminating the need for high-temperature post-processing. Based on our previous work with electrospun nanofiber cathodes and carbon-based current collector, we prepared the LTO electrode using polyethylene oxide (PEO) as a binder and carbon additives to enhance mechanical integrity and conductivity. LTO fiber mats detached from the current collector were found to endure multiple instances of bending, twisting, and folding without any structural damage. LTO/Li cells incorporating electrospun fiber LTO electrodes with 72 wt% active material loading deliver a high capacity of 170 mAh g⁻¹ at 0.05 C. In addition, they demonstrate excellent cycling stability with a capacity loss of only 0.01% per cycle over 200 cycles and maintain a capacity of 160 mAh g⁻¹ at 0.1 C. The scalability of the heat-treatment-free method for fabricating flexible LTO anodes, together with the improved mechanical durability and electrochemical performance, offers a promising route toward the development of next-generation flexible and wearable energy storage devices. Full article

Dredged sludge is characterized by a high water content, low permeability, and poor load-bearing capacity, which hinder its sustainable utilization as an engineering filler. During the stabilization process using vacuum preloading (VP), fine-grained sludge readily clogs drainage channels, thereby prolonging consolidation duration and compromising drainage efficiency. To address these persistent challenges, this study proposes an improved method that combines electroosmosis, VP, and polyacrylamide (PAM) to enhance the consolidation performance of dredged sludge. Column settling experiments demonstrated that the optimal application dosages of anionic polyacrylamide (APAM) and calcium chloride (CaCl₂) were 0.25% and 4.0% of dry sludge mass, respectively. Excessive dosage of either APAM or CaCl₂ disturbed the agglomeration and sedimentation of fine-grained particles due to surface charge inversion. Electroosmotic VP (EVP) facilitated the directional movement of pore water, which increased the cumulative water discharge mass by 37.3%. The combination of APAM and CaCl₂ enhanced particle flocculation via adsorption and bridging effects, significantly improving soil permeability and dewatering performance. Driven by an electric field, Ca²⁺ ions transported water molecules toward the cathode. Subsequently, these Ca²⁺ ions participated in reactions to generate cementitious agents. Compared with VP, this integrated method increased the sludge shear strength by 108.1% and produced a much denser microstructure. Full article