In this work, the three-dimensional phase-field-based lattice Boltzmann method is adopted to investigate the non-Newtonian effects on droplet coalescence in an electric field. The numerical approach is validated by simulating droplet deformation in a uniform electric field and two-phase non-Newtonian flow between two plates. Results show that size asymmetry induces asymmetric deformation: smaller droplets tend to flatten while larger ones elongate along the electric field. Non-Newtonian rheology further modulates this deformation—shear-thinning fluids promote oblate shapes, while shear-thickening fluids enhance axial elongation. Moreover, both droplet size asymmetry and non-Newtonian rheology significantly influence the approach time prior to coalescence. In addition, increasing the electric capillary number further amplifies droplet deformation and accelerates coalescence. Due to their distinct rheological responses, shear-thinning fluids undergo a more rapid reduction in apparent viscosity during approach, promoting faster coalescence, whereas shear-thickening fluids experience greater viscous resistance, limiting acceleration. These results underscore the coupled effects of droplet size asymmetry, electric forcing, and fluid rheology in governing droplet dynamics under electric fields.

Uneven heat flux and non-uniform microchannels result in varying temperature distributions within the microchannel, affecting flow and transmission behaviors. Therefore, investigating flow and transmission behaviors under different temperature distributions is essential. This study establishes a three-dimensional numerical model of the Knudsen pump with non-uniform temperature distribution along the wall. The effects of temperature distributions on flow behavior and transmission performance are analyzed. Results show that temperature variations lead to opposite pressure distributions in the microchannel. For conditions with a large outlet temperature gradient, a negative pressure of −25 Pa is generated, whereas a positive pressure of 30 Pa forms with a larger inlet temperature gradient. Negative pressure promotes hydrogen flow, improving transmission performance by 5.4%. Additionally, when a temperature lower than the low-temperature container exists in the microchannel, a low pressure of −93 Pa is generated, enhancing transmission capacity by 9.6% compared to uniform temperature gradient conditions. This study provides theoretical support for regulating the flow and transmission of hydrogen in Knudsen pumps through temperature control.

In this work, a Lattice Boltzmann (LB) method is developed to simulate electrohydrodynamics (EHD) under the conduction phenomenon in a square cavity with vertically asymmetric electrodes, focusing on the effects of applied voltage and electrode position on the resulting charge distribution and vortex structures. The results reveal that the applied voltage, ranging from 0.5kV to 5.0kV, and the vertical position of the electrode are key control parameters, strongly affecting these flow and charge patterns. Increasing the voltage induces a transition from the Ohmic to the saturation state, transforming the flow from a simple vortex to a complex multi-vortex pattern. Meanwhile, the electrode's vertical placement directly relocates the charge region, fundamentally altering the flow structure and intensity.

The global surging demand for lithium iron phosphate batteries necessitates efficient recycling strategies to ensure environmental sustainability and resource conservation. While direct regeneration is considered sustainable, its widespread adoption is hindered by three critical challenges: 1) heterogeneous and unquantifiable lithium loss across waste streams, 2) abnormal particle growth during high-temperature restoration, and 3) limited economic returns arising from the low-value elements and complex process. Here, we report a universal and scalable "x -> 0 -> 1" normalization strategy. All spent LixFePO4 is first reset to Li-free olivine FePO4 (x -> 0) via mechanochemical delithiation, eliminating batch-specific variability. Benefiting from the olivine FePO4 with pre-existing Li+ diffusion channels and nonequilibrium kinetics, subsequent ultrafast heating resynthesis (UHR) restores stoichiometric lithium iron phosphate (0 -> 1) in just 35 s, effectively suppressing particle coarsening while cutting energy/time consumption by >99% compared to furnace sintering. This approach accommodates diverse degradation levels and their mixture, yielding regenerated lithium iron phosphate with consistent capacity, superior rate capability (84.3 mAh g(-1) at 10 C) and cycling stability (89.1% retention after 1000 cycles at 10 C), outperforming fresh commercial lithium iron phosphate (73.3 mAh g(-1), 66.6%). Beyond regeneration, flash upcycling to lithium manganese iron phosphate further enhances energy density to 549 Wh kg(-1). Techno-economic analysis confirms strong profitability (lithium iron phosphate: 4.86 $ kg(-1) cell, lithium manganese iron phosphate: 10.98 $ kg(-1) cell), low energy demand (6.56 MJ kg(-1) cell), and reduced emissions (2.95 kg CO2-eq kg(-1) cell). Our strategy therefore establishes a general and robust platform for closed-loop cathode recycling and upcycling.

NCM811(LiNi0.8Co0.1Mn0.1O2) is regarded as one of the most promising cathode materials for high energy density batteries, but the high nickel content leads to poor stability. Cathode degradation in lithium-ion batteries is a key issue that leads to performance fading. The main reason for this degradation is the strain and stress caused by the structural changes due to the variation of Li+ concentration during charge/discharge cycles. In this work, a machine learning potential for Li-Co-Ni-Mn-O system is developed based on neuroevolution potential model. This potential is used to investigate the influence of defects on crystal structure, Li+ diffusion kinetics, and mechanical properties of NCM811 through molecular dynamics simulation. The results show that large structural changes and poor stability occur at low Li+ concentration while Li+ diffusion is restricted at high concentration. Li/Ni mixing enhances structural stability but constrains the Li+ diffusion, while oxygen vacancies improve diffusivity but cause greater instability. We consider simultaneously introducing Li/Ni mixing and oxygen vacancies into NCM811 and find improved properties. Our findings elucidate the coupling effects of Li+ concentration and crystal defects on NCM811 performance, and provide a fundamental guidance for optimizing defect engineering strategies in Ni-rich cathode materials.

This study investigates electrothermal convection driven by oscillating electric fields, with particular emphasis on how variations in the electro-Rayleigh number (RaE) and oscillation frequency (f ) affect flow structures and heat transfer behavior. As RaE increases, the electrohydrodynamic driving force intensifies, leading the flow to evolve from a stable, symmetric vortex pattern to a complex multi-vortex configuration, accompanied by enhanced temperature fluctuations. The thermal boundary layer becomes thinner, and the Nuav rises significantly, emphasizing the dominant role of electrothermal convection in improving heat transfer efficiency. Moreover, at a fixed RaE, the oscillation frequency f strongly influences the flow dynamics and thermal transport. At low frequencies, the flow exhibits quasi-steady oscillations with weak perturbations, while moderate frequencies promote the formation of stronger vortical structures and enhance fluid mixing. When the frequency becomes excessively high, the rapid oscillations of the electric field lead to phase mismatching between charge transport and flow response, resulting in reduced heat transfer efficiency. These findings provide valuable insights for optimizing electrothermal convection systems and establish a theoretical foundation for advanced thermal management applications.

This study proposed a heat sink consisting of double-layered fully wavy wall microchannels (DL-FWWMCs). The thermal-hydraulic performance of a DL-FWWMC was numerically investigated and the flow mixing mechanism was elucidated via Poincar & eacute; section analysis. Comparison was made with the performances of a single-layered wavy wall microchannel (SL-FWWMC), a double-layered smooth wall microchannel (DL-SWMC) and a double-layered left-right wavy wall microchannel (DL-LRWMC) across Reynolds numbers (Re) of 167 similar to 835. Results indicate that DL-FWWMC achieves significantly higher Nusselt numbers (Nu) than others, accompanied by a higher pressure drop (Delta p). Meanwhile, DL-FWWMCs can achieve a much better comprehensive thermohydraulic performance compared to others. Specifically, the maximum Nu of DL-FWWMC reaches 92.33 at a total mass flowrate of 6 x 10(-)(4) kgs(-)(1), which is respectively 2.11 times and 3.33 times the counterpart of SL-FWWMC and DL-SWMC. Meanwhile, the highest performance evaluation criterion (PEC) of DL-FWWMC is 2.78. The impacts of height ratio alpha between the lower and upper channels were further explored for DL-FWWMCs. Both Nu and PEC exhibit non-monotonic variation with alpha, reaching their optimum at alpha = 5/5. This optimal performance design achieves a balance between the flow and thermal resistances of the two layers. This balance allows both layers to develop equally effective secondary flows, maximizing the overall heat transfer performance without creating localized regions of excessively high flow resistance (Delta p variation within 7.81%). The DL-FWWMC configuration demonstrates excellent potential for thermal management applications in high-heat-flux electronic devices, offering an optimal combination of enhanced heat transfer capability and structural practicality.

This study presents a three-dimensional numerical investigation into the deformation and breakup behavior of a single leaky dielectric droplet in an oscillatory confined shear flow under a uniform electric field. A coupled lattice Boltzmann model incorporating the conservative Allen-Cahn phase-field method and the leaky dielectric framework is adopted to simulate the complex electrohydrodynamic (EHD) interactions. Model validation is performed through benchmark comparisons against theoretical predictions and experimental data for droplet deformation in both shear flow and uniform electric fields. The effects of electric field strength, shear frequency, hydrodynamic capillary number (Ca), and electric capillary number ( Ca-E) are systematically explored. Results show that increasing Ca-E significantly enhances interfacial Maxwell stresses, promoting earlier and more intense droplet breakup. Longer shear periods allow greater droplet elongation within each cycle, increasing the likelihood of breakup. A parametric phase diagram is constructed to classify four distinct breakup modes based on droplet count. Notably, in high Ca-E and low Ca regimes, irreversible breakup is observed where daughter droplets remain permanently separated despite oscillatory flow reversals. Force and energy analyses reveal that electric field-induced elongation and anisotropic alignment play a critical role in maintaining this non-coalescent state. These findings offer new insights into the control of droplet morphology and fragmentation in microfluidic EHD systems.

Lithium iron phosphate (LFP) offers excellent structural and performance stability derived from the (PO4)(3-) polyanionic structure, which is beneficial for longterm usage. However, this inherent stability also comes along with intrinsically poor ionic and electronic conductivities, which have been notoriously plaguing its high-rate performance and broader applications. Here, we present a gas-assisted transient synthesis (GATS, similar to 30 s) of LFP with controllable oxygen vacancies (O-v) for enhanced rate performance yet without sacrificing structural integrity or cycling stability. Benefited by the ultrafast heating and a higher synthesis temperature, we revealed that the LFP synthesis in GATS followed an interface reaction mechanism (rapid core shrinking) with a low activation energy (E-a), thus reducing the synthesis time from similar to 16.5 h in tube furnace heating (TFH, often nuclei-growth mechanism) to merely seconds. The optimized LFP sample demonstrates an 8-fold enhancement in ionic conductivity and a 12-fold increase in electronic conductivity compared to LFP obtained by TFH and attains exceptional cycling stability even at high rates of 10 C, as evidenced by a higher capacity retention of 93.8% (vs. 63.6% of commercial LFP) after 1000 cycles. Our strategy offers a kinetic pathway for rapid synthesis and structural engineering of LFP, thus unlocking its potential for broader energy storage applications.

Rayleigh–Bénard (RB) convection is a canonical model for buoyancy-driven thermal flows and is widely encountered in geophysical and industrial systems such as mantle convection, electronic cooling, solar air heating and heat exchangers. Although asymmetric thermal boundary conditions and temperature-dependent fluid viscosity have been extensively studied, previous works have primarily focused on symmetric configurations or uniform heating. The combined effect of localized bottom-wall heating and temperature-sensitive viscosity remains insufficiently explored, particularly regarding its nonlinear influence on flow structure and heat transfer. This study investigates the influence of the localized heating length L (the portion of the bottom wall subjected to heating) and the viscosity–temperature coupling parameter b on the flow and thermal transport characteristics of RB convection using the lattice Boltzmann method. The viscosity variation follows an exponential model [Formula: see text], where [Formula: see text] is the dimensionless temperature and [Formula: see text] is the reference viscosity. Here, b quantifies how strongly the viscosity depends on temperature: [Formula: see text] represents fluids whose viscosity decreases with temperature (e.g. water), while [Formula: see text] represents fluids whose viscosity increases with temperature (e.g. oils). The wall-averaged Nusselt number [Formula: see text] is used to characterize heat transfer performance, and the Prandtl number [Formula: see text] represents the ratio of momentum diffusivity to thermal diffusivity. Simulations are conducted at a fixed Rayleigh number of [Formula: see text] and for Prandtl numbers in the range [Formula: see text], covering both low-[Formula: see text] (liquid-metal-like) and high-[Formula: see text] (oil-like) fluids. This range ensures a laminar yet convectively active regime that balances numerical stability with physically meaningful dynamics. Results show that [Formula: see text] exhibits a nonmonotonic dependence on b. As b increases from [Formula: see text] to [Formula: see text], [Formula: see text] initially decreases and reaches a minimum near [Formula: see text]. Beyond this point, its behavior strongly depends on [Formula: see text]. For low-[Formula: see text] fluids (e.g. [Formula: see text]) at [Formula: see text], [Formula: see text] increases by up to [Formula: see text] due to enhanced cold-plume activity, whereas high-[Formula: see text] fluids show limited or even reduced heat transfer. Furthermore, when [Formula: see text], the heating length L significantly affects the flow mode. A critical length [Formula: see text] exists, beyond which the flow transitions from central upwelling to sidewall-dominated convection, resulting in a sudden [Formula: see text] increase in [Formula: see text]. Despite this transition, the overall trend indicates that [Formula: see text] decreases as L increases. These findings highlight the intricate interplay between viscosity stratification and geometric asymmetry in thermal convection. They provide valuable insights for the design and optimization of thermal systems involving nonuniform heating and variable-viscosity fluids, as well as for understanding natural convection processes in geophysical contexts.

We propose a multiple-relaxation-time lattice Boltzmann method for anisotropic convection-diffusion equation with a divergence-free velocity field. In this approach, the convection term is handled as a source term in the lattice Boltzmann evolution equation; thus, the derivation term that may be induced by the convection term disappears. By using the Chapman-Enskog analysis, the anisotropic convection-diffusion equation is recovered up to second-order accurate in space. In particular, we also present a local scheme for computing the convection term, indicating that the present method retains the main advantages of the lattice Boltzmann method. We then test the proposed model by considering the Gaussian hill problem and an anisotropic convection diffusion equation with constant velocity and diffusion tensor. The results illustrate that our model has acceptable numerical accuracy and can be a good candidate for simulating anisotropic convection-diffusion equation.

Droplet impact behavior has attracted much attention recently due to its academic significance and diverse industrial applications. In this paper, the lattice Boltzmann method is employed to simulate the impact of a droplet on a hydrophobic plate featuring a square orifice. Unlike previous studies, the chemical property of the orifice considered in the current work is not homogeneous but heterogeneous, and its cross-sectional wettability changes from hydrophobicity to hydrophilicity. We first validate the numerical method against the experiment and then investigate the influences of the Weber number (We = 10.0,40.0,65.0), wettability difference (Delta theta = 0 degrees, 70 degrees, 100 degrees), as well as pore size (r/R = 0.2, 0.4, 0.6, 0.8). According to the numerical results, it is observed that the evolutionary stages of the impinging droplet always include the spreading phase and the rebounding phase. However, whether the droplet undergoes a splitting phase depends on the combined effect of the wettability difference and the Weber number. In addition, it is noted that the wettability-patterned pore tends to promote the adhesion of droplets on the plate, resulting in the droplet impact behaviors being largely different from that for the case of homogeneous pores. To further explore the physical mechanisms of the droplet impact behavior, we also perform an energy balance analysis for different dimensionless parameters. It is found that the viscous dissipation energy is increased with the wettability difference, and a relatively larger Weber number usually corresponds to a higher surface energy. Moreover, by analyzing the pressure at the droplet equilibrium state, we construct a phase diagram for different pore sizes and Weber numbers, and it shows that there exists a critical Weber number fora given pore size, above which a portion of the droplet will pass through the orifice.

The ion transport mechanism in polymers plays a vital role in improving the ionic conductivity of solid polymer electrolytes. In this work, we adopt molecular dynamics simulation and density functional theory calculation to study the effect of anion size on the structural and dynamical properties of solid polymer electrolytes based on poly(ethylene oxide) (PEO) at high temperatures over a range of salt concentrations ( x = [Li]/[EO]) from 0.02 to 0.2 and then analyzed the effect on ion transport properties. We selected three perfluorinated sulfonimide anions (FSI ^- , TFSI ^- , PFSI ^- ) of different sizes to form three PEO-based solid polymer electrolytes. Based on calculations of various salt concentrations, we revealed that x = 0.1 is a significant turning point in structural properties. Among the three solid polymer electrolytes we simulated, LiTFSI/PEO exhibits the best ion transport performance and the highest ionic conductivity, while LiFSI/PEO performs the worst. Through density functional theory calculations, we found that the dissociation of lithium salt and the interaction between anions and PEO chains are two key factors determining the ion transport performance at high temperatures. Our work indicates that larger anions are not always better at high temperatures.

Commercial polyolefin separators in lithium batteries encounter issues of uncontrolled lithium-dendrite growth and safety incidents due to their low Li+ transference numbers ( t Li + ${t}_{{\mathrm{Li}}<^>{+}}$) and low melting points. To address these challenges, this study proposes an innovative approach by upgrading conventional separators through the incorporation of metal-organic framework (MOF)-confined polyoxometalate (POM). The presence of POM restricts anion diffusion through electrostatic repulsion while facilitating Li+ transport within MOF nanochannels through their affinity for lithium ions. Moreover, MOF confinement effectively mitigates the acidification of electrolytes induced by POM. As a proof-of-concept, the polypropylene separators decorated with phosphotungstic acid@UIO66 (denoted as PW12@UIO66-PP) exhibit remarkable lithium-ion conductivity of 0.78 mS cm-1 with a high t Li + ${t}_{{\mathrm{Li}}<^>{+}}$ of 0.75 at room temperature. The modified separators also display excellent thermal stability, preventing significant shrinkage even at 150 degrees C. Furthermore, Li symmetric cells employing PW12@UIO66-PP separators exhibit stable cycling for 1000 h, benefiting from rapid Li-ion transport and uniform deposition. Additionally, the modified separator shows promising adaptability to industrial manufacturing of lithium-ion batteries, as evidenced by the assembly of a 4 Ah NCM811/graphite pouch cell that retains 97% capacity after 350 cycles at C/3, thus highlighting its potential for practical applications.

The limited Li+ transport capacity of poly(ethylene oxide) (PEO)-based solid polymer electrolytes restricts their practical applications. To enhance the Li+ diffusion coefficient, CuF2 was incorporated. Molecular dynamics simulations were performed on LiTFSI/PEO systems and CuF2/LiTFSI/PEO systems at varying lithium salt concentrations. The findings indicate that the inclusion of CuF2 in LiTFSI/PEO systems with high lithium salt concentration enhances the Li+ diffusion coefficient, whereas it diminishes at low lithium salt concentration. This phenomenon is attributed to the abundant coordination properties of Cu2+.

In this paper, we numerically simulate the thermocapillary motion of a two-phase non-Newtonian power-law fluid by using a phase-field-based lattice Boltzmann (LB) model. In this model, a total of three LB evolution equations are used to solve the macroscopic equations. One of them is used to solve the Allen–Cahn equation for describing the phase interface variation, one is used to solve the incompressible Navier–Stokes equation for describing the non-Newtonian power-law fluid dynamics. In addition, the last LB equation is used to solve the temperature field, where the collision terms are modified and improved to take into account the effect of thermodynamic parameter comparisons. In particular, we consider a parabolic relation rather than a linear one between the interfacial tension and the temperature in this study. Furthermore, two numerical cases were used to validate this LB model: the thermocapillary flow of two superposed planar fluids and the flow of power-law fluid between two parallel plates. It shows that the numerical solutions computed by this model agree well with the theoretical solutions, thus proving the accuracy and feasibility of this LB model. Afterward, we used this method to simulate the thermocapillary motion of bubbles in a microchannel filled with power-law fluids, and the results show that the model is accurate in studying two-phase power-law fluids. In addition, we consider the differences in flow patterns between Newtonian and non-Newtonian fluids and discuss the effects of factors such as viscosity ratios, temperature gradients, inlet velocities, and power-law index on the thermocapillary migration of bubbles. The results show that the above-mentioned factors have a great influence on the position, velocity, and equilibrium flow field of the bubbles.

Solid-state electrolytes paired with lithium-metal anodes is considered a next-generation energy storage technology. However, the slow ionic transportation of the solid-state electrolyte and the instability against the lithium-metal anode impede their practical application. Here a cellulose separator modified with highly uniform boric oxide solid acid, contributing to a high transference number (0.75) and good ionic conductivity of 0.52 mS cm-1 due to the strengthened binding of the salt anions with this solid acid, is reported. Moreover, the boron ions with occupied interstitial sites can release free electrons to regulate the electrochemical dynamics of the electrolyte, in situ inducing the formation of Li2CO3/LiF-rich heterostructured solid electrolyte interphase layer. The cellulose/B2O3-based composite electrolyte paired with LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode and Li-metal anode displays a specific capacity of 155 mAh g-1 with a capacity retention of 92% in 200 cycles. Additionally, this electrolyte paired with high-mass-loading NCM622 cathode (10 mg cm-2) in a pouch cell can be stably operated for 50 cycles with a capacity retention of over 90%. Boron ions with occupied interstitial sites can release free electrons, which enhance the electrochemical dynamics of electrolyte to get an in situ formation of Li2CO3/LiF-rich heterostructured solid electrolyte interphase layer. Boric oxide with high acidity is supposed to bind with anions in the electrolyte, tuning the dissociation of lithium salt to improve the lithium-ion transport.image

The unstable interface between lithium metal anodes and carbonate-based electrolytes is a key challenge limiting the cycling lifespan of high-energy lithium metal batteries. Here, a resilient artificial solid electrolyte interphase (RASEI) was designed by regulating poly(hexafluorobutyl acrylate) (PHFBA) matrix with the benzene-containing bisphenol A ethoxylate dimethacrylate (BAED) crosslinker to address this issue. The rigid BAED molecule can finely tune the flexible PHFBA matrix, enabling superior resilience from 600

Droplet impact behavior has attracted much attention recently due to its academic significance and diverse industrial applications. This study employs the lattice Boltzmann method to simulate the impact of a droplet on a hydrophobic plate featuring a square orifice. Unlike previous studies, the chemical property of the orifice considered in this work is not homogeneous but heterogeneous, and its cross-sectional wettability changes from hydrophobicity to hydrophilicity. The study first validates the numerical method against experimental data, and then investigates in detail the influences of the Weber number, wettability difference, and pore size. According to the numerical results, we observed that the evolutionary stages of the impinging droplet always include the spreading phase and the rebounding phase, while whether there exists the splitting phase, it depends on the combined effect of the wettability difference and the Weber number. The impact behavior of droplets is analyzed by evaluating the underlying mechanisms such as kinetic energy, surface energy, viscous dissipation energy, and pressure. It is interesting to note that the existence of wettability-patterned pore tends to promote adhesion of droplets on the plate, resulting in the droplet impact behaviors are largely different from that for the case of homogeneous pore. Additionally, a phase diagram is constructed for various Weber numbers and pore sizes, revealing that the dynamic behavior of droplets is determined by the competition among dynamic pressure, capillary pressure, and viscous pressure losses. These insights from numerical studies guide the development of innovative solid substrates capable of manipulating droplet motion.

The lithium metal batteries coupled with nickel-rich LiNixCoyMn1-x-yO2 (x > 0.7) cathodes hold promise for surpassing the current energy density limit of lithium-ion batteries. However, conventional electrolytes containing free active solvents are highly susceptible to decomposition, particularly at the interfaces of lithium anode and high-voltage cathode. Herein, we have developed a composite quasi-solid electrolyte (CQSE) utilizing sulfated Al2O3 (S-Al2O3)-bridged cellulose triacetate (CTA) to stabilize the interfaces between the electrolyte and electrodes. S-Al2O3 competitively dissociates Li+ through coordination interactions with anions, facilitating the formation of a distinctive solvation structure characterized by prevalent ion pairs and aggregates. In addition, coordination of S-Al2O3 with CTA forms S-Al2O3-bridged CTA molecular chain networks, enhancing the mechanical strength of the CQSE and immobilizing free liquid molecules. Consequently, the CQSE demonstrates an enhanced tensile strength of up to 7.4 MPa and a high ionic conductivity of 1.8 × 10-3 S cm-1 at room temperature. Furthermore, the CQSE not only suppresses electrode-electrolyte side reactions but also enables the formation of an inorganic-rich solid/cathode electrolyte interphase. As a result, the Li|CQSE|LiNi0.83Co0.11Mn0.06O2 (NCM83) batteries retain 84% capacity after 1000 cycles at 1 C, with the pouch cells demonstrating 80% capacity retention after 250 cycles at 0.5 C.