Thickness Of Solid Layer Research Articles

Improvement of Activation Processes for Lithium-Ion Secondary Battery through Electrochemical Characteristics

A lithium-ion secondary battery that has not undergone the activation process may experience compromised cycleability and safety. Therefore, the activation process following the manufacturing of lithium-ion secondary batteries plays a crucial role in enhancing safety and extending cycleability. Through the pre-charging process of the activation procedure, additives within the electrolyte undergo chemical reactions at the anode interface, forming a thin solid layer on the anode surface. The solid layer formed on the anode surface through this process is referred to as the Solid Electrolyte Interphase (SEI) layer. The SEI (Solid Electrolyte Interphase) layer serves to inhibit direct decomposition reactions between the electrolyte and the anode interface, similar to the role of a separator. It can contribute to long-term lifespan and safety. However, if formed beyond a certain thickness, the SEI (Solid Electrolyte Interphase) layer may go beyond the function of a separator and instead develop into a single, thick solid layer. Furthermore, if formed below a certain thickness, the SEI (Solid Electrolyte Interphase) may easily collapse, failing to fulfill the role of the solid layer and leading to issues of capacity loss and safety concerns. Therefore, the process of creating a robust SEI (Solid Electrolyte Interphase) layer with a consistent thickness, without deviation, is of utmost importance.In this study, to enhance the activation process, a Double Layer Cell (DLC) with a capacity of 80 mAh was manufactured, and the State of Charge (SOC, %) during the pre-charging process was adjusted. To create a robust SEI (Solid Electrolyte Interphase) layer, the State of Charge (SOC, %) was maintained at 20%, 50%, and 80% after pre-charging at temperatures of 25°C, 45°C, and 60°C for a specified duration in each formation process. During these formation processes, impedance analysis (EIS) was employed to evaluate the resistance of the cell itself and the interface resistance in relation to changes in SOC (%) and temperature. Additionally, the crystal structure of the SEI was elucidated through XRD. Furthermore, chemical characteristics and bonding states of the cathode surface were analyzed using XPS. The morphology and composition of the SEI were observed through SEM and EDS, providing an analysis of the components of the SEI. Subsequently, the DLC was subjected to output verification through C-rate at room temperature based on SOC (%). The electrochemical characteristics were evaluated by measuring the cycleability of 1000 cycles at both room temperature and high temperature, assessing the impact of the pre-charging process.

Improving Cell-Level Specific Energy for All-Solid-State Lithium Sulfur Batteries

All-solid-state lithium-sulfur (Li-S) batteries are considered as one of the top choices toward 500 Wh/kg of specific energy, a key metric for an energy storage system that enables large regional electric aircrafts. Many obstacles remain, such as S utilization in the cathode, cyclability with regard to both cathode and anode as well as electrode-electrolyte interfaces, and effective means to increase the S content within the all-solid-state cell architecture. The latter is directly related to cell-level specific energy when considering the weights of all battery cell components. In this presentation, we discuss the efforts in both cathode optimization and cell-level improvement toward increasing the overall specific energy. Various strategies in improving S utilization and reducing the solid electrolyte layer thickness will be presented.

Experimental Study of the Particles Influence on the Pyramid Wake within the Turbulent Boundary Layer

Particle imaging velocimetry (PIV) was used to study the near-field variation of a pyramid rough element in clear water and a liquid–solid boundary layer (thickness: 60 mm). Particles with an average diameter of 355 µm and Stokes number of 4.3 were injected into a 1:1000 mass ratio (solid particles: water) liquid–solid two-phase solution. Experiments were conducted to collect instantaneous velocity field information in the streamwise–normal direction and streamwise–spanwise direction at a Reynolds number of 8350. Then, the average velocity field and turbulence intensity of the rough element wake under single-phase and two-phase conditions were compared, and the morphology and periodicity of the shedding structure were analyzed by using proper orthogonal decomposition (POD) combined with the power spectral density function (PSD). Particles were shown to have no significant impact on the recirculation area in the streamwise–spanwise plane but did result in a reduction of the recirculation zone in the streamwise–normal plane and a 0.2h closer location of the streamline's origin to the obstacle. Along with the weakening of the upwash structure, the particle phase diminishes the velocity gradient along the span direction and turbulence intensity. Structural shedding at the top of the pyramid and near the wall occurred simultaneously, and the same shedding period was maintained. Particularly, in the first two POD modes, the energy of the shedding structure near the wall was higher than that at the obstacle tip, with a maximum energy differential of approximately 6%. The Strouhal number of the shedding structure decreased by particles from 0.217 to 0.209. The concentration distribution and degree of dispersion in the particle-laden flow illustrate different results, with lower statistics in the wake flow field.

Lubrication effects on droplet manipulation by electrowetting-on-dielectric (EWOD)

Electrowetting has the potential to realize stand-alone point-of-care devices. Here, we report droplet-migration characteristics on oil-infused electrowetting-on-dielectric substrates. We prepare sparse micropillars to retain the oil layer in order to exploit the layer as a lubricating film. A physical model of the droplet velocity is developed, and the effects of the lubrication, the oil viscosity, the droplet volume, and the thickness of solid and liquid dielectric layers are discussed. It is found that the droplet velocity is scaled as U≈E2, which differs from a relationship of U≈E3, which is predicted from the dominant drag force for droplets sliding down on liquid-infused surfaces by gravity. Furthermore, our device achieves droplet velocity (19 μl) of ∼1 mm s−1 at the applied voltage of 15 V. The velocity is approximately tenfold as high as the same condition (applied voltage and oil viscosity) on porous-structure-based liquid-infused surfaces. The achieved high velocity is explained by a lubrication-flow effect.

Promoted diffusion mechanism of Fe2.7wt.%Si-Fe10wt.%Si couples under magnetic field by atomic-scale observations

Diffusion behavior of newly designed Fe2.7wt.%Si-Fe10wt.%Si couples at 1100 °C for up to 12 h has been investigated under the 0, 0.8 and 3 T magnetic fields. Diffusion thickness of solid solution layer and weight percent of Si on Fe2.7wt.%Si side increase significantly under a magnetic field. Application of a magnetic field promotes the diffusion of solid solution layer through the possible diffusion of vacancies mainly due to the appearance of defects, which has been demonstrated by the increased dislocation density and broadening of the typical XRD peaks. Replacement of Si sits by Fe atoms in the crystal structure leads to the appearance of Fe diffraction peaks, which has been confirmed by the increased interplanar spacings under a magnetic field. The magnetic field benefits the depinning of dislocations and leads to higher dislocation density because of the magnetoplastic effect which has been confirmed by the significantly reduced thickness of Fe2.7wt.%Si. Nano-sized Fe3Si particles precipitate in the matrix with an orientation relationship on Fe10wt.%Si side as {220}Fe3Si || {220}matrix & < 1–10 >Fe3Si || < 1–10 >matrix. Fe3Si particles pin dislocation moving and lead to higher dislocation density.

Integrated Fluid Dynamic Gauge for Measuring the Thickness of Soft Solid Layers Immersed in Opaque, Viscous, and/or Non-Newtonian Liquids in Situ

A new fluid-dynamic gauging (FDG) device for monitoring the thickness of soft solid layers immersed in liquid in real time and in situ is demonstrated. An inductive proximity sensor is incorporated in the FDG nozzle head to allow the distance between the head and the layer, and an underlying metal substrate, to be determined simultaneously. The concept is demonstrated for copper, mild and stainless steel substrates, for coated substrates, and for liquids spanning a range of opacity and viscosity including water; whole UHT milk and commercial washing-up liquid (both opaque); 1 and 3 wt% CMC solutions (exhibiting non-Newtonian behaviour). The resolution of the inductive sensor was ± 10 μm or better, and was unaffected by the liquid. Computational fluid dynamics simulations using OpenFOAM gave good agreement with experimental discharge coefficients for viscous and non-Newtonian fluids. A short study of the growth of ice crystals from skimmed UHT milk is presented.

Effect of wall deformability on the stability of surfactant-laden visco-elastic liquid film falling down an inclined plane

The stability behavior of a visco-elastic (Upper Convected Maxwell) liquid film flowing down an inclined plane is examined using the standard normal mode linear stability analysis in creeping flow limit. The inclined plane is coated with a deformable solid layer, and the gas-liquid interface is covered with a monolayer of an insoluble surfactant. There exist three modes of instabilities for this composite fluid-solid system: (i) the free surface gas-liquid (GL) mode, (ii) the surfactant or Marangoni mode, and (iii) the liquid-solid (LS) mode. Previous studies have shown that the Marangoni mode remains stable for film flowing down a rigid inclined plane. We show that when the rigid wall is replaced by a deformable wall, the Marangoni mode becomes unstable when a non-dimensional deformability parameter, defined as G=μV/EsR, increases above a threshold value (μ, V, Es, and R are fluid viscosity, free-surface velocity, shear modulus of soft solid layer, and fluid thickness, respectively). It is well known that the GL mode remains stable for Newtonian liquid film at zero Reynolds number, but becomes unstable for a visco-elastic film flowing past a rigid inclined plane even in creeping flow limit purely because of fluid elasticity. Previous studies have shown that the presence of soft solid layer can suppress this free surface GL mode instability. The presence of surfactant also has a stabilizing effect on this GL mode instability in rigid limit. Here, we evaluate whether a soft solid coating can be used to obtain a stable flow configuration for a surfactant-covered visco-elastic film as well particularly (i) in view of the above mentioned Marangoni mode destabilization observed solely due to wall deformability, and (ii) when the surfactant stabilizing contribution remains insufficient to suppress the free-surface instability. We demonstrate that there exists a window in terms of parameter G where the free surface GL mode instability is suppressed without exciting any other mode. We also identify the parameter regimes where it is not possible to achieve stable film flow, however, in these cases, we show that the Marangoni mode can be selectively destabilized by appropriately selecting the thickness and shear modulus of solid layer.

Ultrasonic semi-solid soldering 6061 aluminum alloys joint with Sn-9Zn solder reinforced with nano/nano+micron Al2O3 particles

In this study, the joint at low temperature with nano-Al2O3 particles and Al2O3 nano + micro particles were fabricated by semisolid assisted ultrasonic vibration with nano-Al2O3 particle of 50 nm and volume fractions of 1% and micron-Al2O3 particle of 10 μm and volume fractions of 1%. The joints were examined in order to understand the effects of Al2O3 additions as microstructure, interface morphology and shear strength as well as mechanical properties of soldering 6061 aluminum alloys. Due to different size, the scallop-shaped solid solution layer was changed into a groove layer, and its thickness of Al3Zn2 solid solution layer was decreased. The grain refinement mechanism of Sn-9Zn-1 nmAl2O3 is mainly sono-crystallization (enhanced nucleation). However, the grain refinement mechanisms of Sn-9Zn-1 nm1 μm Al2O3 change to be mainly sono-crystallization + sono-fragmentation. With the increase of different size particles, the fracture mode transforms from brittleness to ductile fracture and finally to dimple structure. Micro particles may contribute less to the strength compared to the refining effect, but significantly improve the plasticity.

High-order adaptive arbitrary-Lagrangian–Eulerian (ALE) simulations of solidification

A high-order-accurate method for simulation of solidification is presented. The solidification front is tracked using a triangular, Arbitrary-Lagrangian–Eulerian moving mesh, and a mesh adaption algorithm is used to allow simulations of unsteady problems with large interfacial movement. An improved mesh coarsening algorithm is presented that maintains high quality deforming meshes while reducing the amount of interpolation needed to transfer solutions between meshes. An hp-finite element method is used to resolve the thermal and flow fields. This is combined with an A-stable diagonally-implicit Runge–Kutta temporal scheme. The method was demonstrated to give a temporal order of accuracy near 3 by comparing to a 1D analytic solution of melting. The spatial accuracy was calculated to be nearly 5th order for an approximation degree, p, equal to 4. Even for this simple case, the mesh adaption algorithm improved the accuracy over a simulation where the mesh only deformed. For a practical demonstration, the algorithm was used to simulate horizontal ribbon growth of single-crystal silicon and was able to resolve solutions where the solid layer thickness decreased by a factor of 20 over the course of the simulation.

Study on the pressure drop characteristics for the particles across fibres

A comparison of the results obtained from typical pressure drop models of fibrous media to experimental values has been done in the paper. Then, the pressure drop characteristics for different structural and operating parameters would be evaluated. The results show that Davies model instead of Kuwabara, Henry and Happel models fits well with the tested data and gives errors of less than 7.0%. Pressure drop across the media increases with increasing solid fraction, superficial velocity and fibre layer thickness, and decreases with increasing fibre diameter. Fibre diameter in the range of smaller values and solid fraction have more significant effects on the air flow resistance than the other factors.

Study on the fabrication of a SU-8 cantilever vertically-allocated in a closed fluidic microchannel

This paper describes the fabrication of a vertically-allocated SU-8 cantilever in a closed fluidic channel. The difficulties to fabricate the vertically-allocated SU-8 cantilever inside the closed channel mainly lie in which kinds of sacrificial layers under the cantilever and sealing methods for enclosing the channel are utilized for the movability of the cantilever. To obtain a suitable sacrificial layer and high sealing quality, the selectivity of sacrificial layers and the sealing conditions based on the SU-8 adhesive are discussed in this paper. The experiments to test different photoresist lead to the conclusion that AZ 5214E is adequate for the sacrificial layer. Also, the bonding results indicate that the thickness of the uncrosslinked SU-8 solid layer is the most important factor which affects the formation of a proper gap between the top coverglass and the SU-8 cantilever. The photos of the movement of the cantilever also show that the free-standing SU-8 cantilever is successfully fabricated by releasing the suitable sacrificial layer and is allocated inside the closed channel by the method of SU-8 adhesive. The fabrication method in this paper is also useful for other microfluidic applications.

Modeling the slag flow and heat transfer with the effect of fluid-solid slag layer interface viscosity in an entrained flow gasifier

The characteristics of slag flow and heat transfer in a gasifier are significant for controlling the operation conditions. Determination of the fluid-solid slag layer interface is a crucial procedure in the studying of slag flow and heat transfer characteristics. The varied absolute viscosities were used as the fluid-solid slag layer interface viscosity to model the slag layer properties in an entrained flow gasifier. The results showed that with the increase of fluid-solid slag layer interface viscosity, the liquid slag layer thickness increased, while the solid slag layer thickness and the liquid slag velocity decreased. Moreover, the slag layer overall thickness had a slight decrease, while the slag heat flux had a slight increase. In addition, the effects of the fluid-solid slag layer interface viscosity on slag layer characteristics with glassy slag and plastic slag were relatively higher than crystalline slag. The smoother the viscosity-temperature profile, the higher the influences of the fluid-solid slag layers interface viscosity. The critical viscosity could be approximate regarded as the fluid-solid slag layer interface viscosity when the slag type was crystalline slag during the model derivation, and the fluid-solid interface viscosity can be defined as about 100Pas for plastic slag and glassy slag.

Stability of gravity-driven free surface flow of surfactant-laden liquid film flowing down a flexible inclined plane

We examined the linear stability of gravity-driven creeping flow of a liquid film flowing down an inclined plane when the inclined plane is coated with a deformable solid layer and the gas-liquid interface is contaminated with a monolayer of insoluble surfactant. The contaminated liquid film flowing down a rigid incline admits gas-liquid (GL) interfacial mode and surfactant-induced Marangoni mode, both of which remain stable in the creeping flow limit. The primary aim of this study is to explore the effect of the presence of a deformable wall, in place of a rigid inclined wall, on the stability behavior of Marangoni mode which originates because of the transport of surfactant at the GL interface. In presence of a deformable solid layer, two additional parameters namely, shear modulus and thickness of deformable solid layer also affects the stability behavior of falling film configuration. Our long-wave asymptotic analysis and results at finite and arbitrary wavenumbers demonstrated the destabilization of Marangoni mode solely due to the presence of deformable solid layer. Specifically, we have shown that for a given solid thickness, the Marangoni mode becomes unstable when the shear modulus of solid layer decreases below a critical value (i.e. the solid layer becomes sufficiently soft). The effect of increasing solid thickness is found to be destabilizing. The LS interfacial mode also becomes unstable at high wavenumbers below a threshold value of shear modulus, however, this value is much smaller than that required to trigger Marangoni mode instability. This implies that as the solid coating becomes more and more deformable, the Marangoni mode becomes unstable first followed by the LS interfacial mode. The GL mode was always found to be stable in creeping flow limit. Further, our long-wave analysis shows that the solid deformability has an additional stabilizing effect on GL mode. The neutral stability curves in nondimensional solid deformability parameter (or equivalently shear modulus) vs. wavenumber plane clearly depicts that the Marangoni mode is the dominant unstable mode in the creeping flow limit. Thus, the present study shows the destabilization of Marangoni mode solely due to presence of deformable solid layer and this we believe is the first example of the case where the instability of the Marangoni mode is observed when the fluid-fluid interface (here, GL interface) remains stress-free in the basic state.

Effect of static magnetic field on microstructure and interdiffusion behavior of Fe/Fe–Si alloy diffusion couple

Effect of static magnetic field on microstructure and interdiffusion behavior in Fe–Fe50wt.%Si diffusion couples has been investigated. The Fe2Si and Fe3Si layers could be hardly observed after annealing at 1050–1150°C for more than 3h without the 0.8T magnetic field, however, the Fe2Si rather than Fe3Si layer could be still observed after prolonged annealing time up to 6h with the magnetic field. The interface with higher Si content moved faster than that with lower Si content, which led to the reduced thickness of Fe2Si and Fe3Si layers, and finally both of them were replaced by the stable FeSi phase. The magnetic field exhibits a suppressing effect on the interdiffusion behavior of Fe/Fe–Si alloy because of the decreased thickness of FeSi and solid solution layers, and no significant difference between the diffusivities parallel and perpendicular to the magnetic field direction has been detected. The growth of FeSi and solid solution layers obeys the parabolic law and is suppressed under magnetic field due to the reduced frequency factor D0 but not the activation energy Q.

Finite Element Legendre Wavelet Galerkin Approch to Inward Solidification in Simple Body Under Most Generalized Boundary Condition

Abstract This paper deals with a mathematical model describing the inward solidification of a melt of phase change material within a container of different geometrical configuration like slab, circular cylinder or sphere under the most generalized boundary conditions. The thermal and physical properties of melt and solid are assumed to be identical. To solve this mathematical model, the finite difference scheme is used to convert the problem into an initial value problem of vector matrix form and further, solving it using the Legendre wavelet Galerkin method. The results thus obtained are analyzed by considering particular cases when one might impose either a constant=time varying temperature or a constant=time varying heat flux or a constant heat transfer coefficient on the surface. The whole analysis is presented in dimensionless form. The effect of variability of shape factor, condition posed at the boundary, Stefan number, Predvoditelev number, Kirpichev number, and Biot number on dimensionless temperature and solid-layer thickness are shown graphically. Furthermore, a comparative study of time for complete solidification is presented.

High-efficiency solid-state polymer electrolyte dye-sensitized solar cells with a bi-functional porous layer

A simple and effective method to increase the energy conversion efficiency is proposed and demonstrated by increasing the ion flux with a reduction in the thickness of solid polymer electrolyte layers and the mass transport distance of I−/I3− redox couples.

Zero discharge fluid dynamic gauging for studying the thickness of soft solid layers

Fluid dynamic gauging (FDG) is an experimental technique for measuring the thickness and strength of solid layers on solid or porous substrates by relating the flow rate of liquid through a nozzle positioned near to, but not touching, the layer. This paper shows that such measurements can be made with the liquid both being ejected from and sucked into the nozzle, so that there is no net flow of liquid into or out of the system. This zero discharge (ZFDG) mode has considerable potential for sterile and aseptic operation. Discharge coefficient profiles are reported for a range of flow rates and show very good agreement with computational fluid dynamics simulations, indicating that the shear stress imposed on the surface can be estimated with confidence. The use of ZFDG to study the thickness and removal of soft layers was demonstrated with layers of a commercial petroleum jelly (Vaseline®) layer. The Vaseline® layers exhibited cohesive breakdown on 316 stainless steel, indium tin oxide coated polyethylene terephthalate (PET), and glass under suction mode testing. The cohesive strength agreed with the yield stress measured in separate rheological tests. When exposed to ejecting liquid on glass, however, the layers switched from cohesive breakdown to an adhesive rupture mechanism which is attributed to an instability in the layer and the observed tendency to slip on smooth substrates.

A fluid dynamic gauging device for measuring fouling deposit thickness in opaque liquids at elevated temperature and pressure

We report proof-of-concept results for a fluid dynamic gauging (FDG) device for measuring the thickness and strength of soft solid fouling layers immersed in an opaque liquid in situ and in real time at elevated pressures and temperatures. The device reported here is configured to make measurements on the inner rod of an annular flow test section but the concept is generic. Data are presented from tests using mineral oil at temperatures and pressures up to 140°C and 10bara, respectively. Problems with the prototype hardware prevented testing up to the design limits of 270°C and 30bara. The practical working range of the gauge, i.e. 0.05<h/dt<0.25, proved to be unaffected by the pressure and temperature. h is the nozzle-surface clearance and dt the nozzle throat diameter. At smaller h/dt values the pressure drop across the nozzle is very high and this can serve as an alarm for close approach. When the Reynolds number at the throat, Ret, is less than 20 the range of discharge coefficient values (0-Cd∞) is small, with a maximum value dependent on Ret. A useful range of Cd∞ values is obtained when Ret>40. Computational fluid dynamics (CFD) simulations of the gauging flow in these quasi-static experiments (no bulk liquid flow) gave good agreement with experimental data for the cases tested. The CFD results showed that the low Ret regime is related to creeping flow in the nozzle. CFD calculations of the shear stress being imposed on the surface being gauged gave good agreement with an analytical model for flow between parallel discs, indicating that the latter can be used to estimate the maximum shear stress imposed by the gauging flow.

Experimental and numerical study on slag deposition and growth at the slag tap hole region of Shell gasifier

Cold model experimental and dynamic modeling studies on the slag flow and heat transfer at the slag tap hole region of Shell gasifier have been carried out. The cold model experiment was set up to observe the simulated slag deposition. The dynamic model was proposed to clarify the slag accumulation on the wall of slag screen. The results show that the simulated slag can be broken up to slender liquid filaments by the high-speed swirling gas flow, and a part of the filaments can deposit on the slag screen wall. When the surface temperature is below the critical temperature, the slag is totally solidified to solid slag layer. At equilibrium, a liquid slag layer covers the solid slag layer and its surface temperature is higher than the critical temperature. The solid slag layer thickness increases along the slag flow. In addition, the solid slag thickness can be decreased by increasing the operating load and operating temperature.

CFD investigation of slagging on a super-heater tube in a kraft recovery boiler

Deposits formed on super-heater tubes decrease the heat transfer. Deposits may also cause corrosion of tube material. In kraft recovery boiler furnaces, the alkali-rich deposits are molten, and flow down along the super-heater tubes. In this work, a sub model which calculates the structure of a slag flow is implemented into a CFD model for super-heater tube sections. Specifically, it is applied to two tube bends on one of the first group of tube banks exposed to the flue gas. By taking into account deposition by inertial impaction, assuming all depositing particles fully molten and the steam temperature in super-heater constant, the slag model can provide thickness and surface temperature distributions of the flowing deposit layer. Furthermore, the thickness of solid deposit layer in contact with the tube and the temperature at the tube surface can be calculated. The local temperature at tube surface can be useful for choosing tube material.