Stacking Process Research Articles

Magnetically Guided Diagnosis of Current Flow Patterns inside Fault-Simulated Li-Ion Batteries

As the energy industry shifts towards cleaner and more electrified solutions, there's a growing demand for improved batteries, especially for electric vehicles (EVs) and stationary energy storage systems (ESSs). Lithium-ion batteries (LIBs) have been dominant due to their advantages such as high energy/power density, long lifespan, and fast charging capabilities. Despite advancements in cell design making them more efficient and compact, current LIBs face new challenges, particularly in improving reliability and addressing safety concerns. Recent instances of battery recalls due to explosions and fires have underscored the need to address potential failures stemming from internal faults in large-format cell designs and manufacturing, or from "latent" defects arising from misuse or aging under extreme conditions. Therefore, understanding failure scenarios and developing diagnostic tools are crucial for facilitating smoother troubleshooting for battery manufacturers and ensuring the development of safer battery technologies.Advanced imaging methods, both postmortem and in situ, have been developed to reveal the underlying causes of battery failures at the material level. These techniques help identify physical and chemical defects in active materials, degradation of electrolytes, and structural damage in inactive components like separators and current collectors. However, connecting these material-level defects with overall cell failure is difficult due to their random occurrence within complex cell structures. Additionally, many microscale imaging tools designed for customized cells are impractical for commercial cells, making it nearly impossible to detect small errors in large-scale cells during postmortem analysis. Therefore, global imaging techniques are more effective for identifying abnormalities and examining local faults. One powerful tool for this purpose is cell-penetrating X-ray computed tomography, which provides 3D images of the cell's internal structures, although it is time-consuming. However, this method may struggle to detect invisible errors that can lead to abnormal current flow in areas where latent defects exist. Thermal imaging is another useful tool for detecting abnormal heat generation in batteries caused by current flow, but without information on current direction, determining the type and extent of defects and cell degradation may be limited.This research introduces a real-time, noninvasive method for imaging magnetic fields (MFI) generated by current flow within Li-ion pouch cells. This technique provides fast scanning speeds (~100 mm/min), high spatial resolution (0.161 mm2), and a simple setup without the need for magnetic field shielding. Initially, we verified the correlation between magnetic fields and current by conducting MFI studies on 1D straight wires and 2D sheets carrying current. Subsequently, we identified an appropriate pouch cell geometry for analyzing current flow patterns using MFI, cross-referencing with current distribution maps generated by COMSOL simulations. To illustrate the effectiveness of current pattern analysis in identifying failure modes, we analyzed MFI data from fault-simulated batteries (FSBs) deliberately manufactured with faults like lead-tab contact failure, electrode misalignment, and stacking process folds. By using MFI destructive interference with a countercurrent-carrying cell-shaped 2D sheet below, we could selectively enhance areas of failure where abnormal current flows occur. This MFI-guided visualization of current distribution patterns in FSBs provides a nondestructive, immediate diagnostic approach to identify fault types that may not be discernible through electrochemical analysis alone.

3D Crystal Construction by Single-Crystal 2D Material Supercell Multiplying.

2D stacking presents a promising avenue for creating periodic superstructures that unveil novel physical phenomena. While extensive research has focused on lateral 2D material superstructures formed through composition modulation and twisted moiré structures, the exploration of vertical periodicity in 2D material superstructures remains limited. Although weak van der Waals interfaces enable layer-by-layer vertical stacking, traditional methods struggle to control in-plane crystal orientation over large areas, and the vertical dimension is constrained by unscalable, low-throughput processes, preventing the achievement of global order structures. In this study, a supercell multiplying approach is introduced that enables high-throughput construction of 3D superstructures on a macroscopic scale, utilizing artificially stacked single-crystalline 2D multilayers as foundational repeating units. By employing wafer-scale single-crystalline 2D materials and referencing the crystal orientation of substrates, the method ensures precise alignment of crystal orientation within and across each supercell, thereby achieving controllable periodicity along all three axes. A centimeter-scale 3R-MoS₂ crystal is successfully constructed, comprising over 200 monolayers of single-crystalline MoS₂, through a bottom-up stacking process. Additionally, the approach accommodates the integration of amorphous oxide, enabling the assembly of 3D non-linear optical crystals with quasi-phase matching. This method paves the way for the bottom-up construction of macroscopic artificial 3D crystals with atomic plane precision, enabling tailored optical, electrical, and thermal properties and advancing the development of novel artificial materials and high-performance applications.

Large strain consolidation analysis of dredged sludge treated with multilayer PHDs combined with vacuum pressure

Multilayer PHDs combined with vacuum pressure for the treatment of dredged sludge yards are effective in avoiding the bending effect of drainage bodies during consolidation. However, the existing theory of self-weight consolidation cannot reflect the actual consolidation properties of dredged sludge treated with multilayer PHDs combined with vacuum pressure. In this study, the nonlinear large-strain consolidation model of dredged sludge treated with multilayer PHDs combined with vacuum pressure was established, considering the nonlinear compressibility and permeability of dredged sludge, self-weight stress of dredged sludge and the variation of dredged sludge height with time. The reliability of the model is verified by comparison with existing consolidation theory, indoor test, and field test data. By researching the effect of the PHDs laying ratios, the height of each dredged sludge layer, and the stacking process time on the consolidation rate of dredge sludge, it is found that if the total height of the treated dredged sludge is 9.0 m and the 5.0 m high yard is designed with double-layer PHDs, the optimal PHDs laying ratios is 20%, the optimal location of the 2nd layer PHDs is at half of the total height of dredged sludge and the optimal stacking time is 140 days.

Model‐Based Exploration of Web Guiding Behavior for a Novel Battery Cell Stacking Process

Innovative production processes are required to meet the rapidly growing demand for batteries and the associated material trends. In particular, the process step of stack assembly using new machine concepts promises a high potential for optimization. However, these concepts are untested in practice. The use of digital models makes it possible to develop corresponding optimization approaches. This article presents the development of a model for the web guiding systems of electrodes and its integration into an overall machine model for a novel machine concept. Finally, optimization approaches are identified by determining appropriate controller parameters for the web guiding systems.

In Situ Formation of SnSe2/SnSe Vertical Heterostructures toward Polarization Selectable Band Alignments.

2D van der Waals (vdW) layered semiconductor vertical heterostructures with controllable band alignment are highly desired for nanodevice applications including photodetection and photovoltaics. However, current 2D vdW heterostructures are mainly obtained via mechanical exfoliation and stacking process, intrinsically limiting the yield and reproducibility, hardly achieving large-area with specific orientation. Here, large-area vdW-epitaxial SnSe2/SnSe heterostructures are obtained by annealing layered SnSe. These in situ Raman analyses reveal the optimized annealing conditions for the phase transition of SnSe to SnSe2. The spherical aberration-corrected transmission electron microscopy investigations demonstrate that layered SnSe2 epitaxially forms on SnSe surface with atomically sharp interface and specific orientation. Optical characterizations and theoretical calculations reveal valley polarization of the heterostructures that originate from SnSe, suggesting a naturally adjustable band alignment between type-II and type-III, only relying on the polarization angle of incident lights. This work not only offers a unique and accessible approach to obtaining large-area SnSe2/SnSe heterostructures with new insight into the formation mechanism of vdW heterostructures, but also opens the intriguing optical applications based on valleytronic nanoheterostructures.

Automated Robotic Cell Fabrication Technology for Stacked‐Type Lithium‐Oxygen Batteries

AbstractRechargeable lithium‐oxygen batteries (LOBs) are gaining interest as next‐generation energy storage devices due to their superior theoretical energy density. While recent years have seen successful operation of LOBs with high cell‐level energy density, the technology for cell fabrication is still in its infancy. This is because the cell fabrication procedure for LOBs is quite different from that of conventional lithium‐ion batteries. The study presents a fully automated sequential robotic experimental setup for the fabrication of stacked‐type LOB cells. This approach allows for high accuracy and high throughput fabrication of the cells. The developed system enables the fabrication of over 80 cells per day, which is 10 times higher than conventional human‐based experiments. In addition, the high alignment accuracy during the electrode stacking and electrolyte injection process results in improved battery performance and reproducibility. The effectiveness of the developed system was also confirmed by investigating a multi‐component electrolyte to maximize battery performance. We believe the methodology demonstrated in the present study is beneficial for accelerating the research and development of LOBs.

Monte‐Carlo Study on Temperature Effect on Scanning Electron Microscopy Contrast for One Spherical Nanoparticle in Multiframe Stacking Mode

Modern scanning electron imaging (SEM) has become an essential tool in various fields. In order to obtain high‐quality images with minimal vibration and drift, the multi‐frame stacking technique is commonly used. However, one aspect that has been overlooked in this process is the electron beam‐induced temperature effect. This study aims to explore the impact of the temperature effect on SEM contrast for a single spherical nanoparticle, specifically a gold nanosphere on a carbon substrate. Through Monte‐Carlo simulation, we investigated how the number of frames in multi‐frame stacking mode affects two types of electron signals: secondary electrons (SE) and backscattering electrons (BSE). Our findings revealed that the SEM contrast is indeed sensitive to the number of frames used in the stacking process. It is observed that the SE contrast decreases while the BSE contrast increases compared to cases without considering temperature effects. It is also found that when using the large primary electron beam energy, the impact of temperature effect was less significant. The electron‐solid interaction theory was utilized to systematically explain the underlying mechanism. This study not only sheds light on how temperature effects can influence SEM imaging but also provides valuable insights for optimizing image acquisition techniques.

Stacking in electrophoresis by electroosmotic flow-assisted admicelle to solvent microextraction.

An in-line sample concentration method for capillary electrophoresis called admicelle to solvent microextraction was proposed. In this technique, analytes were trapped in the cetyltrimethylammonium bromide admicelles formed in situ on the negatively charged capillary surface. A solvent plug was then partially injected hydrodynamically to collapse the admicelles, which liberated and focused the analytes at the solvent front. Voltage was applied across the capillary, completing the stacking process. Various solvents, namely, methanol, ethanol, and acetonitrile, were investigated. The optimal solvent for solvent to admicelle microextraction was 30% acetonitrile in 24mM sodium tetraborate (pH 9.2). Sample injection time and solvent to sample injection ratio were also optimised. For this demonstration, the optimum sample injection time and solvent to sample injection ratio were 320s and 1:2, respectively. Using the optimum conditions, UV detection sensitivity was enhanced 132-176-fold for the model anions. The LOQ, %intra-/inter-day (n = 6/n = 12, 2days) repeatability, and linearity (R2) of admicelle to solvent microextraction were 0.08-2µg/mL, 1.9-3.9%, 2.8-4.9%, and 0.992, respectively. Admicelle to solvent microextraction was applied to the analysis of various fortified water samples, with good repeatability (%RSD = 0.5-3.6%), and no matrix interferences.

Stochastic stability of random stacking of blocks

The paper explores the stability of a tower obtained by stacking identical rectangular blocks on top of each other with an inherent randomness due to slight positional offsets between successive blocks. With probabilistic modeling techniques, the diffusive behavior of the stacking process is studied and the collapse is seen as a first passage time problem. In the considered model, alignment errors are idealized as independent Gaussian random variables with zero mean and given standard deviation. We derive expressions for the joint probability density functions of block positions, and analyze their correlation. The study extends to the stochastic stability of a stack of given height, by exploring the statistical characteristics of the center of gravity of the part of tower above each block. Eventually, the probabilistic analysis of collapse is developed to quantify the statistics of the number of blocks that can be heaped up before the tower topples. Although this problem may initially appear playful, it offers an illustrated introduction to first passage problems on a non homogenous process. From a practical standpoint, this analysis offers a simple understanding of the influence of alignment errors on the overall stability of a stack, which may find several fields of application.

Improved piezoelectric properties of zno films obtained by magnetron sputtering power stacking process

Improved piezoelectric properties of zno films obtained by magnetron sputtering power stacking process

Global dynamic features and information of adjacent hidden layer enhancement based on autoencoder for industrial process soft sensor application

AbstractThere is a lack of consideration of temporal and spatial correlation in the process variables and adjacent hidden layers correlation in the soft sensor model of stacked autoencoders. To address the issue, a novel global dynamic adjacent layer information enhancement auto encoder (GD‐ALIEAE) method is proposed to improve the poor prediction performance. The gated recurrent unit (GRU) and uniform manifold approximation and projection (UMAP) are applied to the GD‐ALIEAE model for obtaining global dynamic features of the temporal and spatial information of process variables by parallel computation. An adjacent layer information correlation algorithm is proposed to avoid the loss of hidden layers information during the stacking process. The algorithm enhances the features of the low layer through nonlinear mapping, combining the low layer and its adjacent layer as input. The input then is fed to the multi‐head attention mechanism to obtain features that contain adjacent layer correlation. Finally, a prediction model is established through a fully connected layer. Through simulation experiments on two industrial cases of sulphur recovery unit and thermal power plant, and compared with models of stacked autoencoder (SAE), stacked isomorphic autoencoder (SIAE), and target‐related stacked autoencoder (TSAE), the effectiveness of the proposed method was verified.

Optimization of surface filtration to enhance wafer uniformity by removing large particle in ceria slurry

Owing to the limitations of scaling down, the development of complex structures for chip design is progressing in the semiconductor industry. As a result, the chemical mechanical polishing (CMP) process has become essential for the precise control of micro-level steps and for maintaining surface uniformity between layers during the stacking process. Structural management and improved performance of the consumables used in CMP processes are required. In particular, controlling the abrasive particles in the slurry that directly contact the wafer surface is crucial. Large particles within the slurry can occur scratches and cause non-uniformity in the polishing process, thus the particle size distribution of the slurry must be regulated. In this study, two types of filtration systems were constructed to determine the optimal conditions for CMP of ceria slurry. Depth filtration effectively removes particles through a cake layer formation mechanism but has limitations in achieving a consistent pore size within the fiber layer. Consequently, separation efficiency for particle sizes is relatively low. In contrast, surface filtration consisting of a single membrane demonstrates a consistent correlation between pore size and the size of the filtered particles, resulting in high particle removal efficiency. The pore size capable of removing large particles without active particle loss was 200 nm. After evaluating slurry productivity and filter-induced agglomeration, 0.8 L per minute (LPM) was identified as the optimal flow rate. Additionally, after filtration at 0.8 LPM, the maximum reduction in removal rates was relatively small at 272.54 Å/min due to decreased edge removal rates. However, by removing large particles to implement a monodisperse state, an improvement in uniformity of 17.11 % was achieved. Therefore, the CMP performance can be enhanced using surface filtration to control the particle size distribution (PSD).

Efficient turbo product code decoder with Build‐In SRAM‐based transpose memory

AbstractTurbo product codes (TPCs) have been widely used for bit error correction in high‐speed applications such as data storage. This letter introduces an efficient hard‐input hard‐output iterating TPC decoder module. A transpose memory utilizing static random access memory (SRAM) is integrated into the decoder to achieve a low hardware overhead. The transpose memory, based on an 8T SRAM bit‐cell, supports both horizontal (row‐wise), and vertical (column‐wise) read/write operations. It is prototyped under a 28nm high‐k/metal gate stack process with bit‐cell size of 0.582 µm2. This specialized SRAM significantly reduces the hardware overhead when compared with a register‐array‐based transpose memory without significant throughput loss. A field programmable gate array (FPGA) evaluation platform is utilized to emulate the TPC decoder module, and the maximum decoder throughput is up to 6.49 Gbps at 250 MHz.

A Self-Adaption Growth Model for the Burden Packing Process in a Bell-Less Blast Furnace

The burden structure directly decides the distribution of gas flow inside a blast furnace (BF). Falling, stacking, and descending bulk materials are the three main processes for burden formation, among which the stacking process plays a decisive role. The Discrete Element Method (DEM) and theoretical modelling were combined to predict stacking behavior in this study. Falling and stacking behaviors were first simulated based on DEM. The repose angle during the stacking process and mass fraction distribution in the radial direction were analyzed. Then, the upper, centroid, and lower trajectory falling lines were determined, and a polynomial relation was found between the angle and the packing height. The influences of three parameters on the repose angle were investigated. Compared with the natural repose angle and chute inclination angle, the effects of the trajectory line depth appeared trivial. The polynomial relation between the repose angle and the packing height was specified to be a function of the natural angle of repose and the chute inclination angle. A three-trajectory falling model and quadratic expression were embedded in the theoretical model, yielding a self-adaption packing model. The model was proved reliable with a low relative error, below 15%.

Determination of Electrode Balancing in Multilayer Pouch Cells Through Tracking and Tracing in Lithium‐Ion Battery Production

AbstractManufacturing lithium‐ion batteries is a complex procedure with interconnected process steps. Unknown interdependencies lead to production deviations, which, in combination with expensive materials, result in costly rejects. To gain better insight into the processes, tracking and tracing systems are increasingly being established in battery cell production. This improves the database and enhances transparency, as quality‐critical production data is already recorded during electrode production and specifically assigned to individual intermediate products. The data assignment aids in characterizing intermediate products properties to identify correlations and defects. An important parameter is the balancing from cathode to anode, which has a crucial influence on cell performance. Therefore, this paper demonstrates the determination of the balancing between all electrode layers in a lithium‐ion pouch cell using a traceability system. The traceable areal mass loading was determined for each electrode sheet. After the stacking process, the opposing electrode areal mass loadings of the cathodes and anodes were used to calculate the electrode balancing. Subsequently, their influence on the cycling performance of the cells was investigated. Battery cells with areal mass loadings within the permissible tolerances showed no abnormalities, whereas cells with production fluctuations exhibited rapid ageing.

High aspect ratio SiO2/SiN (ON) stacked layer etching using C3HF5, C4H2F6, and C4H4F6

High aspect ratio SiO2/SiN (ON) stacked layer etching using hydrofluorocarbon gases was conducted with various ratios of H, F, and C to achieve higher etching rates and precise profile control. The experimental gases were C3HF5, C4HF5, C4H2F4, C4H2F6, C4H4F6 and C5H2F10. The oxygen gas flow rate and mixing ratio were optimized to maximize mask selectivity while avoiding clogging at the top of the mask. For comparison, C4F6/CH2F2/Ar/O2, and C4F6/C4F8/CH2F2/Ar/O2 were used as reference gas mixtures. The initial screening narrowed the candidate pool to 3 gases: C3HF5, C4H2F6, and C4H4F6. At equivalent power, the C3HF5 condition achieved a 15% faster ON etch rate, and C4H2F6 achieved a 9% faster ON etch rate compared to the reference condition. Only C4H4F6 showed a worse ON etch rate than the reference (∼33%) due to severe mask clogging. Furthermore, C3HF5 achieved a 29% faster ON etch rate under high power conditions. It also achieved a 57% faster ON etch rate without excessively compromising selectivity or bow CD expansion after optimization. We report detailed comparisons of etch rate and clogging while controlling the CD profile in the ON stack process.

Synthesis of Porous Connected Cryoaerogel Networks from Cadmium Chalcogenide Nanoplatelet Stacks

Cadmium chalcogenide nanoplatelets (NPLs) are not only known due to their unique optical properties but also because of their ability to self‐assemble into stacks with new collective properties. Only recently, a stacking process in an aqueous medium has been demonstrated, which opens up possible applications and methods such as gelation. Nanoparticle‐based aerogels gain a lot of attention due to their high relative surface areas and porosity and thus, high potential for catalytic applications. Herein, the positive properties of aerogels to the NPL‐stack system by cryoaerogelation of destabilized NPL dispersions are introduced. After the addition of an antisolvent to initiate the stacking, the dispersion is flash‐frozen with liquid nitrogen and freeze‐dried. By this method, porous cryoaerogel networks result in high surface areas and retained stacking of the NPLs. The formed stack‐gels are investigated by electron microscopy and physisorption measurements. Optical and photoelectrochemical measurements verify the charge carrier transport within the stack‐gel network.

Rheological Properties and 3D Printing Behavior of PCL and DMSO2 Composites for Bio-Scaffold.

The significance of rheology in the context of bio three-dimensional (3D) printing lies in its impact on the printing behavior, which shapes material flow and the layer-by-layer stacking process. The objective of this study is to evaluate the rheological and printing behaviors of polycaprolactone (PCL) and dimethyl sulfone (DMSO2) composites. The rheological properties were examined using a rotational rheometer, employing a frequency sweep test. Simultaneously, the printing behavior was investigated using a material extrusion 3D printer, encompassing varying printing temperatures and pressures. Across the temperature range of 120-140 °C, both PCL and PCL/DMSO2 composites demonstrated liquid-like behavior, with a higher loss modulus than storage modulus. This behavior exhibited shear-thinning characteristics. The addition of DMSO2 10, 20, and 30 wt% into the PCL matrix reduced a zero-shear viscosity of 33, 46, and 74% compared to PCL, respectively. The materials exhibited extrusion velocities spanning from 0.0850 to 6.58 mm/s, with velocity being governed by the reciprocal of viscosity. A significant alteration in viscosity by temperature change directly led to a pronounced fluctuation in extrusion velocity. Extrusion velocities below 0.21 mm/s led to the production of unstable printed lines. The presence of distinct viscosities altered extrusion velocity, flow rate, and strut diameter. This phenomenon allowed the categorization of pore shape into three zones: irregular, normal, and no-pore zones. It underscored the importance of comprehending the rheological aspects of biomaterials in enhancing the overall quality of bio-scaffolds during the 3D printing process.

Oxygen influences spatial heterogeneity and microbial succession dynamics during Baijiu stacking process

The spontaneous solid-state stacking process (SSSP) of Baijiu is an environmentally friendly and cost-effective process for enriching and assembling environmental microorganisms to guarantee the subsequent fermentation efficiency. In this study, how SSSP create spatial heterogeneity of stacking piles were found through spatiotemporal sampling. The degree of difficulty in oxygen exchange categorizes the stacking pile into depleted (≤4%), transitional (4 %–17 %), and enriched (≥17 %) oxygen-defined layers. This results in variation in succession rates (Vdepleted > Vtransitional > Venriched), which accelerates spatial heterogeneity during SSSP. As a dominant species (65 %–99 %) in depleted and transitional layers, Acetilactobacillus jinshanensis can rapidly reduce oxygen disturbance by upregulating poxL and catE, that sustains spatial heterogeneity. The findings demonstrated the value of oxygen control in shaping spatial heterogeneity during SSSP processes, which can create specific functional microbiome. Adding spatial heterogeneity management will help achieve more precise control of such solid-state fermentation systems.

An experimental study on 3D printed concrete reinforced with fibers recycled from wind turbine blades

The large-scale retirement and high recycling difficulty of wind turbine blades (WTB) pose great challenges to environment and society. To explore the practical applicability of recycled WTB in 3D printed concrete (3DCP), a systematic experimental study was conducted on the printability and physical-mechanical properties of 3DCP incorporating RWTB fiber. The distribution of RWTB fiber and porosity were analyzed using X-ray CT scan and Scanning Electron Microscopy, with the aim of unveiling the reinforcing and anisotropic mechanisms of 3DCP with RWTB fiber. The concrete with 3%–7% of RWTB fiber presented good extrudability and buildability, although slightly decreased the fluidity. Due to the directional effect and the layer-by-layer stacking process inherent in 3D printing, the RWTB fiber exhibited enhanced alignment along the printing direction, leading to modifications in the porosity. Incorporating 5% RWTB fiber in 3DCP significantly improved mechanical properties, with notable increases of 13.2%–29.9% in unconfined compressive strength and up to 147.4%–465.4% in bending toughness in the Y and Z loading directions, as compared to samples without fiber. Moreover, the mechanical anisotropy of 3DCP with RWTB fiber was less significant than that with the fiber having higher tensile strength, leading to a promising way to repurpose WTB and promote sustainability of 3DCP.