Uniform Diffusion Research Articles

Stable Lithium Metal Batteries Enabled by Lithiophilic Core-Shell Nanowires on Copper Foam.

Lithium (Li) metal batteries have attracted considerable research attention due to their exceptionally high theoretical capacity. However, the commercialization of Li metal batteries faces challenges, primarily attributed to uncontrolled growth of Li dendrites, which raises safety concerns and lowers coulombic efficiency. To mitigate Li dendrites growth and attain dense Li deposition, the hybrid SiO2-Cu2O lithiophilic film applied to a 3D copper foam current collector is developed to regulate the interfacial properties for achieving even and dense Li deposition. The SiO2-Cu2O possesses strong Li+ trapping capability through strong lithiophilicity from Cu2O. Additionally, the SiO2-Cu2O enables uniform ion diffusion through the domain-limiting effect of the holes in the SiO2 layer, inducing an even and dense Li plating/stripping behavior at a large capacity. Furthermore, the SiO2 layer promotes the formation of an initial high inorganic content Solid Electrolyte Interphase (SEI) through selective preferential binding with anion and solvent molecules. When the SiO2-Cu2O@Li anode is coupled with a LiFePO4 (LFP) cathode, the resulting full cell exhibits superior cycling stability and rate performance. These results provide a facile approach to construct a lithiophilic current collector for practical Li metal anodes.

High-Performance Dendrite-Free Lithium Metal Anode Based on Metal-Organic Framework Glass.

The performance of lithium metal batteries is severely hampered by uncontrollable dendrite growth and volume change within the anode. This work addresses these obstacles by introducing a novel strategy: applying an isotropic and internal grain-boundary-free layer, specifically, a metal-organic framework (MOF) glass layer with nano-porosity onto the electrochemically plated lithium metal anode. Both ab initio and classical molecular dynamics simulations indicate that the MOF glass layer makes the lithium transport smooth and uniform via its internal monolithic and interfacial advantages. This MOF glass layer with the fast and more uniform lithium diffusion in the monolithic interior and its interface enables dendrite-free lithium plating and stripping through surface confinement effect and interfacial effect. When employed in symmetric batteries, the achieved Li metal anode can operate over 300h at 1mAcm-2. The full batteries matched with LiFePO4 exhibit high capacity (148mAhg-1), excellent rate performance (61mAhg-1 at 5C), and outstanding cycling stability (with capacity retention of ≈90% after 1000 cycles). The full batteries matched with high-voltage LiCoO2 also show superior performances. Therefore, the strategy of utilizing a MOF glass layer enables the development of high-performance lithium metal anodes.

Cation-Loaded Porous Mg2+-Zeolite Layer Direct Dendrite-Free Deposition toward Long-Life Lithium Metal Anodes.

Lithium metal, with ultrahigh theoretical specific capacity, is considered as an ideal anode material for the lithium-ion batteries. However, its practical application is severely plagued by the uncontrolled formation of dendritic Li. Here, a cation-loaded porous Mg2+-Zeolite layer is proposed to enable the dendrite-free deposition on the surface of Li metal anode. The skeleton channels of zeolite provide the low coordinated Li+-solvation groups, leading to the faster desolvation process at the interface. Meanwhile, anions-involved solvation sheath induces a stable, inorganic-rich SEI, contributing to the uniform Li+ flux through the interface. Furthermore, the co-deposition of sustained release Mg2+ realizes a new faster migration pathway, which proactively facilitates the uniform diffusion of Li on the lithium substrate. The synergistic modulation of these kinetic processes facilitates the homogeneous Li plating/stripping behavior. Based on this synergistic mechanism, the high-efficiency deposition with cyclic longevity exceeding 2100h is observed in the symmetric Li/Li cell with Mg2+-Zeolite modified anode at 1mA cm-2. The pouch cell matched with LiFePO4 cathode fulfills a capacity retention of 88.4% after 100 cycles at a severe current density of 1 C charge/discharge. This synergistic protective mechanism can give new guidance for realizing the safe and high-performance Li metal batteries.

Conjugate mass transfer from a spherical moving droplet: Direct numerical simulations of enhancement by a chemical reaction

Chemical reactions can have a significant impact on the overall rate of mass transfer in fluid–fluid applications (such as gas absorption in a liquid or liquid–liquid extraction). However, as for non reacting systems, the rate at which a solute is exchanged between the two fluids is difficult to predict accurately. Yet from a theoretical point of view, most studies address uniform diffusion transport or creeping flow, i.e. conditions enabling the derivation of analytical or simple numerical solutions of the solute transport equation, therefore neglecting the effect of convection in the case of coupled mass transfer problems. On the other hand, experimental investigations available in the literature provided correlations corresponding to flow conditions, shape and contamination of the interface which are extremely difficult to control precisely.Direct numerical simulation (DNS) is therefore a powerful tool to investigate the coupling of hydrodynamics with transfer and reaction. It was recently applied to model the internal and external resistances (or Sherwood numbers, Shi and She) prevailing during the transfer of a non reacting solute, in the general case of conjugate mass transfer from a moving spherical droplet (Godé et al., 2023; 2024). This study is complemented by considering a first order reaction that consumes the transferred solute in the continuous phase. The results indicate that the double film model, based on these last correlations for Shi and She, with She corrected by an enhancement factor allows obtaining accurate predictions of the overall mass transfer coefficient in the case of a reactive conjugate problem, thus extending the work of Juncu (2002) to flows at moderate or even high Re, as long as the droplet remains spherical and the flow axisymmetric.

Self-organization of PIP3 waves is controlled by the topology and curvature of cell membranes

Phosphatidylinositol (3,4,5)-trisphosphate (PIP3) is a signaling lipid on the plasma membrane that plays a fundamental role in cell signaling with a strong impact on cell physiology and diseases. It is responsible for the protruding edge formation, cell polarization, macropinocytosis, and other membrane remodeling dynamics in cells. It has been shown that the membrane confinement and curvature affects the wave formation of PIP3 and F-actin. But, even in the absence of F-actin, a complex self-organization of the spatiotemporal PIP3 waves is observed. In recent findings, we have shown that these waves can be guided and pinned on strongly bended Dictyostelium membranes caused by molecular crowding and curvature-limited diffusion. Based on these experimental findings, we investigate the spatiotemporal PIP3 wave dynamics on realistic three-dimensional cell-like membranes to explore the effect of curvature-limited diffusion, as observed experimentally. We use an established stochastic reaction-diffusion model with enzymatic Michaelis-Menten-type reactions that mimics the dynamics of Dictyostelium cells. As these cells mimic the three-dimensional shape and size observed experimentally, we found that the PIP3 wave directionality can be explained by a Hopf-like and a reverse periodic-doubling bifurcation for uniform diffusion and curvature-limited diffusion properties. Finally, we compare the results with recent experimental findings and discuss the discrepancy between the biological and numerical results.

Extraction of geometric features and analysis of flow mechanism of high loaded compressor airfoils at low Reynolds number

When the aircraft cruising at high altitude, the aerodynamic performance of the compressor sharply decreases due to the enhanced boundary layer separation loss. Therefore, it is of great significance to design the high-performance airfoils suitable for low Reynolds numbers (Re) to improve the aerodynamic performance of compressor. In this paper, numerical simulations were carried out on a high-loaded subsonic compressor cascade V103 at low Re. Meanwhile, a multi-objective optimization of blade profile was performed to get optimal solutions, and data mining techniques were applied to extract valuable design knowledge from the optimal database. The results show that the Pareto-optimal airfoils achieve a maximum reduction of 27.32% in total pressure loss coefficient under design condition and 36.71% under near stall condition. Compared with the original airfoil, the curvature distribution law of the camber line with larger values at both ends and smaller values in the middle is advantageous for the performance of the compressor cascade under design condition. This distribution pattern causes a forward shift for the loading distribution of airfoils, accompanied by an earlier transition onset. Additionally, it reduces adverse pressure gradient at the rear part of suction surface, which suppresses the development and growth of laminar separation bubble and delays the separation of turbulent boundary layer. Under near stall condition, maintaining larger leading edge angle and uniform flow diffusion is beneficial for improving the performance of compressor cascade. This is because the larger leading edge angle reduces incidence angle, while the uniform flow diffusion inhibits a great flow separation.

Allulose‐crystallized fruits: Effect of non‐thermal air‐drying and UV‐A light dehydration of osmotic solutions

AbstractThe purpose of this research was to confirm the suitability of allulose to produce crystallized fruits under nonthermal conditions and the suitability of UV‐A light dehydration to concentrate the osmotic solutions. Mangoes and apples were subjected to osmotic drying with either sucrose or allulose, which was followed by an air‐drying step at room temperature to further concentrate the crystallized fruits. There was no significant difference in the dehydration kinetics parameters between the two sugars in each crystallized fruit. Color evaluations showed that allulose was able to better preserve the color of the original raw fruits in the final crystallized samples. Electron microscopy images suggested a more uniform diffusion of allulose as compared to sucrose for both fruits. Similarly, liquid chromatography and infrared spectroscopy analyses confirmed the successful absorption of both sugars into both fruits, with allulose having a final higher concentration in both mango and apple (51.7 ± 5.6% and 70.8 ± 7.7% w/w, respectively) as compared to sucrose (48.6 ± 2.9% and 58.3 ± 3.4% w/w, respectively). UV‐A light dehydration showed to be able to increase the recovery of the sugars from osmotic solutions better than in conditions without UV‐A light exposure. When only air flow was used, it was possible to remove 85.3 ± 4.6% and 78.6 ± 0.6% of the original moisture in the sucrose and allulose solutions, respectively. In contrast, under UV‐A light dehydration, the percentage of the original water removed from the sucrose and allulose solutions was 95.2 ± 1.8% and 83.1 ± 1.9%, respectively.Practical applicationsThere is an increasing trend toward producing foods that are healthier for the general population. The use of rare sugars like allulose offers a promising alternative to accomplishing this. In addition, it has become imperative to develop processes that are more sustainable. The use of air‐drying at room temperature can represent an effective approach to develop more sustainable food manufacturing processes. More specifically, the use of UV‐A light dehydration (which is a non‐thermal food dehydration technique) for the recovery of solutes or the concentration of osmotic solutions can also represent an effective aid in this type of processes.

Spherical Graphite Anodes: Influence of Particle Size Distribution and Multilayer Structuring in Lithium-Ion Battery Cells

Current research focuses on lithium-ion battery cells with a high energy density and efficient fast-charging capabilities. However, transport limitations, and, therefore, the uniform diffusion of lithium-ions across the electrode layers, remain a challenge and could lead to reduced cell performance. One approach to overcome these transport challenges is the use of subsequently produced two-layer anodes with the particle size variation of spherical graphite (x50 = 18 µm; x50 = 11 µm). Thereby, a defined pore network is created, which reduces the ionic resistance and ensuring improved fast charging capabilities. The analysis focuses on the evaluation of electrode properties and the electrochemical performance. By examining the pore size distribution of the anodes, it has been found that during the manufacturing of the two-layer anodes, carbon black and binder particles are transported into the existing microstructure of the lower layer, resulting in localized densification between the anode layers. This could also be supported by color measurements. This effect also extends to electrochemical investigations, with electrochemical impedance spectroscopy showing significantly lower ionic resistances in all two-layer anodes. Reduced ionic resistance and tortuosity near the separator due to absorption effects enhance the ion diffusion and have a direct impact on anode performance. Cell ageing analysis showed a significant capacity decrease of almost 15 mAh g −1 in the single-layer references only, in contrast to the stability of the two-layer anodes. This could also be attributed to the reduced ionic resistance and active counteraction of binder migration. In conclusion, this study highlights how subsequently produced two-layer anodes significantly shape the electrode properties and cell performance of lithium-ion batteries.

Interface characteristics and tensile fracture behavior of CoCrFeNi/6061Al matrix composites fabricated via spark plasma sintering and heat treatment

In this study, 3vol%CoCrFeNi high-entropy alloy (HEA) reinforced 6061Al matrix composites were prepared using spark plasma sintering (SPS), and a new strategy to regulate the interfacial structure of the diffusion layer by solid solution heat treatment was proposed. Based on the thermodynamics and kinetics of solid-state diffusion, the mechanism of the formation and growth of the diffusion layer and its influence on the mechanical properties of the composites were analyzed. At a solid solution temperature of 535 °C, a uniform diffusion layer forms between HEA and Al matrix, and the thickness of the diffusion layer increases with the extension of solid solution time. The diffusion layer is determined as a two-layer structure, with a columnar solid solution grain near HEA and an equiaxed crystal along with Al9Co2 solid solution layer near Al matrix. Optimal tensile strength and elongation of 211.5 MPa and 21.4% respectively are obtained at solid solution time of 60 min, with 12.8 μm in thickness. Superior interface bonding resulting from diffusion layer prevents the crack from expanding into the matrix, contributing to an enhanced ductility with the extension of solid solution time. This study provides valuable insights and theoretical guidance for developing HEA/Al composites with superior strength-ductility synergy.

Achieving a high loading of cathode in PVDF-based solid-state battery

We construct an efficient Li+ transport network in a high loading cathode using carbon coated Li1.4Al0.4Ti1.6(PO4)3 nanowires, which has a strong adsorption for [Li(DMF)x]+ of PVDF-based SPEs to promote its uniform diffusion and stability in cathode.

Detailed approaches to heat and mass transfer by exponentially accelerating a fluid over an inclined plate subjected to temperature variation and uniform mass diffusion

Detailed approaches to heat and mass transfer by exponentially accelerating a fluid over an inclined plate subjected to temperature variation and uniform mass diffusion

Impact of chemical reaction, viscous dissipation and thermal radiation on MHD flow past an oscillating plate

This study analyzes the consequences of first-order chemical reactions, radiation, and viscous dissipation on the unsteady magnetohydrodynamic natural convective flow of a viscous incompressible fluid over a vertically positioned semi-boundless oscillating plate with uniform mass diffusion and temperature. An implicit finite-difference technique is employed to solve a set of dimensionless, coupled, nonlinear partial differential equations. The numerical results for fluid velocity, concentration, and temperature at the plate under different dimensionless parameters are graphically displayed. Due to first-order homogeneous chemical reactions, it has been discovered that the velocity rises at the time of a generative reaction and drops during a destructive reaction. A decline in velocity is observed with an increase in the phase angle, radiation parameter, and chemical reaction parameter. Further, it has been revealed that plate oscillation, radiation, chemical reactions, and the magnetic field significantly influence the flow behavior.

Improving the cycling stability of lithium metal anodes through separator modification with nano-molybdenum powder.

The deposition of lithium ions in an uneven manner can lead to the formation of lithium dendrites, which can puncture the battery separator and cause a short circuit. Additionally, intermediate polysulfides can shuttle between the separator, resulting in damage to the capacity of lithium-sulfur batteries and corrosion of the negative electrode. It is crucial to address these issues promptly. Hence, we developed a modified separator using nano-molybdenum powder, which effectively inhibits the growth of lithium dendrites and suppresses the shuttle effect of polysulfides. The modified separator extends the lifetime of the lithium metal anode, and the uniform pore distribution of the molybdenum powder facilitates the uniform diffusion of Li+ ions, thereby slowing down the detrimental effects. As a result, Li-S cells equipped with the nano-molybdenum powder modified separator achieve a remarkable capacity of 802 mA h g-1 at a current density of 0.5C and maintain a capacity of up to 614 mA h g-1 after 200 cycles.

Study on ductile iron surface laser cladding austenitic stainless steel coating heat treatment to enhance wear resistance

In this paper, laser cladding technology coated the ductile iron surface with austenitic stainless steel. To improve the wear resistance of the coating, consider a heat treatment way to strengthen it. The effects of temperature and time on microstructure, hardness, and wear resistance of austenitic stainless steel coating were investigated. The results show that the martensitic phase was added to the samples at different times of 950 ℃, and the carbide precipitated phase was the main change in the microstructure. At 1050 ℃, the samples also changed from austenite to martensite at different deal times, and the microstructure mainly changed between dendrites. The hardness and abrasion resistance of the 1050 °C/2 h process improved with a hardness of 40.6 HRC, an increase of 26.1%, and a maximum relative abrasion resistance improvement of 84.63%. Which strengthening mechanism was mainly coating dendrites coarse and uniform diffusion occurs, martensite uniform phase transition presented on the surface, coating austenite grain size 9.08 µm smaller, martensite recrystallization and larger grain size of 28.57 µm, the coating as a whole in the uniform phase transition and dendritic crystal strengthening synergistic effect, hardness increased, resistance to wear became stronger.

A Parabolic Flow with MHD, the Dufour and Rotational Effects of Uniform Temperature and Mass Diffusion through an Accelerating Vertical Plate in the Presence of Chemical Reaction

A study that was carried out to analyses the movement and behavior of a vertically infinite plate with a parabolic beginning velocity profile in an unsteady flow scenario, taking into account numerous elements such as rotation, chemical reaction, and the Dufour effect. The investigation included evaluating heat readings from the plate as well as accumulation levels in its surroundings. The inverse Laplace technique was used to solve the governing equations. The research looked at two fundamental governing flow constraints: rotation and diffusion, velocity, temperature (Dufour), and how they affect the speed, temperature, and accumulation of a vertically oriented plate. These flow parameters' effects on mass and heat transfer proportions were also graphically represented using Matlab R 2020a. The study's findings were supported by referencing and aligning with earlier research.

Na5YSi4O12 fast ion conductor protection layer enabled dendrite-free Zn metal anode

Aqueous zinc-ion batteries (AZIBs) are promising for future large-scale energy storage systems, however, suffer from inferior cycling life due to the dendrites growth and side reaction on Zn metal anode. Herein, a fast ion conductor Na5YSi4O12 (NYSO) was synthesized and fabricated as a protection layer of the Zn metal anode. By adjusting the thickness, an optimized NYSO coating of 20.3 µm was obtained and the corresponding symmetry cell demonstrates an extended life span of 1896 h at the current density of 0.5 mA cm−2. In addition, a favorable rate performance of the NYSO@Zn anode at a high current density of 10 mA cm−2 was achieved. Benefiting from the NYSO coating, uniform diffusion and deposition of Zn2+ on the Zn anode could be realized, leading to the elimination of Zn dendrites and side reactions. Therefore, the aqueous NYSO@Zn|CNT@MnO2 full cell shows superior capacity and cycling stability to that of the bare Zn full cell.

Maximizing the heat-recovery potential of nano-modified phase-change materials through gradual degradation of nanoparticle concentration

Efficient energy storage is a crucial aspect of renewable-energy production, particularly for addressing the time gap between energy generation and use. Nano-modified phase-change materials (nano-PCMs) have emerged as promising solutions for heat storage, enabling improved energy utilization. This study introduces a novel approach to enhancing the heat-recovery capabilities of nano-PCM composites by grading the nanoparticle concentration along the heat flow direction. This method addresses limitations of traditional uniform-concentration nano-PCMs that exhibit decreasing heat communication farther from the heat transfer surface. Computational fluid dynamics simulations examined solidification in a hexahedron enclosure and cylindrical shell-and-tube configuration using water and RT55 as base PCMs. Three nanoparticle concentration arrangements were tested: no-degrading concentration, three-concentration grading, and five-concentration grading, maintaining an overall 0.10 volume fraction. Results demonstrate that degraded concentrations accelerate solidification versus uniform concentration, improving heat recovery rate up to 12 % and 27 % for the hexahedron and cylindrical cases, respectively. Graded concentrations promote uniform temperature distribution and diffusion by improving nanoparticle-PCM communication compared to traditional nano-PCMs. The study provides novel insights into maximizing heat recovery performance of nano-PCM composites, with significant implications for energy storage and thermal management applications.

A permselective protection layer assembled by two-dimensional organic vermiculite produces a highly stable lithium metal anode for lithium-sulfur batteries

Designing a protective coating for the lithium metal anode is the crucial yet challenging solution to its practical applications. How to well isolate the reactants in electrolytes but allow fast and uniform ion diffusion is the greatest challenge for various high energy density batteries, e.g., lithium–sulfur batteries. Herein, we propose a permselective protect coating, which has the ability to accelerate the homogeneous fast Li-ion diffusion but block the polysulfide anion penetration, and obtain a dendrite-free and corrosion-resistive lithium metal anode. The above ion-sieving function is realized by a membrane assembled with cetyltrimethylammonium (CTA+)-modified two-dimensional organic vermiculite nanosheets. The enlarged interlayer spacing of the membrane with CTA+ and the negative charges on the vermiculite nanosheets enhance the fast Li-ion transmission across the membrane for uniform Li deposition. At the same time, the non-polar alkyl of CTA+ and the negatively charged surface effectively block the polysulfide adsorption and penetration. Therefore, the side reactions and dendrite growth are effectively suppressed, and with the high sulfur loading (5 mg/cm2) and limited E/S ratio, the assembled lithium–sulfur cell shows good cycling stability at 0.1C, revealing a high capacity retention of 65.9 % over 300 cycles.

Microstructure evolution and enhanced mechanical properties of as-rolled TiB/(TA15-Si) composite via heat treatment

To improve the mechanical properties of the as-rolled composite under large rolling deformation, the effect of solid solution and aging on the microstructural characteristics and mechanical properties of the as-rolled TiB/(TA15-Si) composite was detailedly investigated. The solid solution temperatures of 1050 °C in the β-phase field and different aging temperatures of 550–750 °C were chosen to regulate the evolution of matrix and silicides. After solid solution treatment, the matrix transformed from elongated and kinkled lamella into acicular martensite microstructure. And the silicides completely redissolved into matrix and a uniform diffusion of Si atom was presented. Meanwhile, the aging temperature can obviously affect the evolution of martensite and silicides. As aging temperature increased, the martensite gradually decomposed into acicular α+β lamella (at 650–700 °C) and abnormal growth of α phase appeared (at 750 °C), which dominated the decreasing trend of microhardness and high-temperature strength. Besides, the silicides gradually precipitated along the prior β phase and TiB whiskers (at 600 °C) as well as α/β phase boundaries (at 650 °C). Eventually, 600 °C and 700 °C strengths of the as-rolled composite can be obviously improved by 39.7 % and 84.6 % after solid solution and aging processes. And the composite aged at 600 °C can obtain the highest 600 °C strength of 992 MPa, which is mainly attributed to martensite, precipitation of silicides and weak α2 phase.

Unsteady Flow Past an Accelerated Vertical Plate through Porous Medium in The Presence of Magneto-Hydro Dynamic (MHD) and Thermal Radiation with Variable Temperature and Uniform Mass Diffusion

Unsteady Flow Past an Accelerated Vertical Plate through Porous Medium in The Presence of Magneto-Hydro Dynamic (MHD) and Thermal Radiation with Variable Temperature and Uniform Mass Diffusion