Binder Distribution Research Articles

Optimizing Si-Dominant Anodes in High-Energy Li-Ion Batteries with a Binary Binder System: Exploring Impacts on Adhesion, Cohesion, and Electrochemical Performance

Silicon anode stands out as a promising game-changer for Li-ion batteries (LIBs) due to its remarkable gravimetric and volumetric capacities, boasting 4200 mAh/g1 and 2200 mAh/cm3, respectively. In addition, its operating voltage of 0.4 V vs Li/Li+, abundant availability, and environmental friendliness make Si a strong candidate to revolutionize energy densities in the next-generation high-performance LIBs. However, challenges arise during lithiation as silicon undergoes an expansion of ~300% of its initial volume, leading to a cascade of detrimental effects on the electrode.1 The micron-sized silicon particles tend to pulverize, and resulting in fragmented silicon particles that become electrically isolated. Such volume variations compromise the adhesion of the Si electrode to the current collector. Furthermore, the repetitive expansion and shrinkage cycles contribute to cohesive failure within the electrode. Collectively, these factors considerably diminish the electrochemical performance and lifespan of Si anodes. Consequently, these challenges have placed major constraints on the utilization of silicon, making it currently viable only at levels below 10 wt% in LIB anodes, thereby impacting the commercial feasibility of Si-dominant anodes in high-energy LIBs.Such challenges in Si anodes impose strict demands on the binder, requiring it to maintain intimate contact between electrode components and to the current collector and preserve the integrity of ion and electron transport channels during frequent volume changes upon cycling. Obviously, the traditional binders like PVDF or carboxymethylcellulose (CMC)/Styrene-butadiene rubber (SBR) are not suitable options for addressing these specific challenges.Many approaches have been explored to address such requirements including increased crosslinking, different binding functionalities, adhesion promoters, etc.2 In this study, we investigate a binder system comprising two key components: (i) an acrylic acid-based polymer enriched with a high concentration of carboxyl groups. This component not only forms effective bonds with the silicon surface but also fosters interactions with other polar species, facilitating the self-healing properties. (ii) Incorporating a styrene-butadiene-based polymer, renowned for its exceptional flexibility, improves adhesion and enhances the tensile properties of the electrode, particularly in response to volume expansion challenges. We evaluated the characteristics of the binders and electrode properties, including adhesion to the current collector, cohesion within the electrode, and binder distribution. These properties were subsequently correlated with the initial columbic efficiencies (IEC) and electrode cycle life in Si-dominant/NMC811 cells. We show that there is an optimal binder ratio that achieves the desired adhesion and significantly enhances cohesive strength, leading to improved cycling stability compared to a single binder system.

(Invited) Optimizing the Binder Distribution in Battery Electrodes with Manufacturing Process Simulations and Machine Learning

The performance of lithium-ion battery cells strongly depends on the microstructure of the electrodes, which is determined by the spatial distribution of the active material, carbon additive, binder, and pores within the electrode volume. The manufacturing process determines this spatial distribution, which, in turn, determines the interfaces between these materials and the pores, thereby impacting the practical properties of the electrodes, such as their electrical conductivity, energy density, and wettability. The binder plays a crucial role in this process, as its spatial distribution controls the degree of percolation between the particles and the adhesion of the electrode with the current collector.Since 2017, we have been developing the ARTISTIC computational platform,1 which constitutes a digital twin of the battery electrode and cell manufacturing process. Supported by a combination of physics-based models and machine learning, this platform has been demonstrated by us for lithium-ion, sodium-ion, and solid-state batteries with electrodes produced by wet processing.2 The platform simulates each step of the manufacturing process, including mixing, coating/drying, calendering, electrolyte infiltration, and resulting cell performance. It allows for predicting 3D-resolved electrode and cell sandwich microstructures with their associated electrochemical performance as a function of the manufacturing parameters.In this talk, I will discuss how the ARTISTIC computational platform can optimize the spatial distribution of active material, carbon additive, and binder within the electrode volume. Using Bayesian Optimization, the platform predicts the manufacturing parameters required to obtain optimal electrodes in terms of several properties, such as electric conductivity, tortuosity factor, electroactive surface area, and energy density. I will particularly discuss the platform's capabilities to capture the adhesion of the electrode with the current collector through the binder. Additionally, I will present an extension of this digital twin for the 3D-resolved simulation of the dry processing of active material, carbon additive, and binder based on extrusion and compare the results (in the form of 3D-resolved electrode microstructures) with experimental data. Results from the wet and dry processing simulations will be discussed for electrodes made with different active material chemistries, such as NMC and LFP, and the crucial role of the binder in the heterogeneity of lithiation/delithiation of the electrodes upon their electrochemical cycling will be explored.Finally, building on our previously reported virtual reality digital tools for battery manufacturing,3 I will present a novel virtual reality interface that allows for the interactive and immersive use of the ARTISTIC computational platform to track the influence of manufacturing parameters on the active material, carbon additive, and binder's spatial location, as well as the resulting electrode properties. I will conclude by discussing why this virtual interface is also a powerful tool to assist in the electrode manufacturing optimization.

Electrochemical Impact of Inhomogeneous Binder Distribution in Lithium-Ion Battery Electrodes

In recent years, the application possibilities of the lithium-ion battery (LIB) have increased significantly. Moreover, the demand for LIBs will rise in the next few years, especially in the automotive sector. This leads to an increasing importance of careful management of the limited lithium resources. Battery production offers high savings potential, as the current scrap rate is around 5-30% [1,2]. The scrap arises in the various process steps such as electrode production, battery conditioning or even from impure raw materials. Especially during the electrode production including mixing, coating, drying and calendaring, various defects can be implemented into the electrodes. Defects such as compositional inhomogeneities (e.g., inhomogeneous binder distribution), microstructural inhomogeneities (e.g., thickness variations), line defects, point defects or even foreign particle contamination can lead to increased scrap rates [3].For the detection of defects, there are already a few established methods such as computed thermography, camera-based optical systems, or post-mortem analyses. However, the detection of the defects might not be sufficient to evaluate the electrode usability since the influence might still be tolerable. Therefore, the impact of the defect type, size, and concentration and resulting determination of the tolerance limits is decisive for the reduction of production waste.In this work we focus on the influence of compositional inhomogeneities on the battery performance. Compositional inhomogeneities like inhomogeneous binder distribution can modify the local electrode characteristics e. g. porosity/tortuosity. This can lead to local higher or lower c-rate followed by faster or slower local degradation. In worst case these inhomogeneities can cause lithium plating or short circuits and shorten the lifetime of LIBs significantly.To determine the criticality and establish tolerance limits, we produced and analyzed defective and defect-free electrodes. For the determination of the impact of the inhomogeneities we developed a special experimental setup that allows us the analysis of the internal dynamics of the interaction between defect-containing (selective modification of the binder content) and defect-free (target binder content) electrodes. Therein, compensating currents continuously redistribute the inhomogeneous charges in electrodes with different binder content. This balancing effect was studied in terms of the caused accelerated aging.This experimental approach provides a foundation for further investigation and for deep understanding of the effect of electrode defects. This knowledge represents a basis for further developing of effective quality assurance strategies and reducing scrap rates accompanying by careful management of the limited lithium resources.[1] Gaines, L.; Dai, Q.; Vaughey, J. T.; Gillard, S.: Direct Recycling R&D at the ReCell Center. Recycling. 2021, 6 (2), 31. DOI: 10.3390/recycling6020031. [2] Brückner, L.; Frank, J.; Elwert, T.: Industrial Recycling of Lithium-Ion Batteries—A Critical Review of Metallurgical Process Routes. Metals 2020, 10 (8), 1107. DOI: 10.3390/met10081107. [3] du Baret de Limé, A.; Lein, T., Maletti, S.; Schmal, K.; Reuber, S.; Heubner, C. and Michaelis, A.: Impact of Electrode Defects on Battery Cell Performance: A Mini Review. Batteries & Supercaps 2022, 5, e202200239, doi.org/10.1002/batt.202200239.

Quantifying Volume Change in Battery Electrode Microstructures

A three-dimensional microstructure-based modeling method (3DMS) is developed [1, 2] to predict the mechanical behaviors of porous electrode that includes both active material (AM) and binders inside lithium-ion battery during compression, reversible expansion (intercalation dependent), and irreversible expansion (aging dependent). The geometry of both AM and binder is generated stochastically to create microstructures by using a modified MATBOX opensource program with our in-house code. The advanced technique of volume element generation is also established to overcome the interfacial error due to complexity of binder distribution. The Finite Element Analysis (FEA) based solid-stress model is applied to predict local mechanical activities including stress-strain relationship and microstructure evolution during compression, intercalation, and aging.The predictions of behavior in the porous electrode under compressive loads will be presented and the insights into the microstructure deformation will be discussed. Further, the analysis results will be validated using experimental testing results acquired at various length scales. This work can be used for the model-based FEA platform to predict the impact of volume change under charge/discharge cycles, volume change of a jelly-roll during formation, and the response of the active material in typical pouch cells during battery module assembly.The predictions of reversible expansion in the porous electrode during cycling will be presented and the insights into the microstructure expansion as compared to continuum porous electrode models from previous work [3-8] will be discussed.Finally, insights into the linkage between irreversible volume expansion in the porous electrode during aging cycling will be discussed and compared to testing acquired for automotive-relevant large format [9] pouch cells.References J. S. Lopata, T. R. Garrick, F. Wang, H. Zhang, Y. Zeng and S. Shimpalee, ECSarXiv (2022).J. S. Lopata, T. R. Garrick, F. Wang, H. Zhang, Y. Zeng and S. Shimpalee, J Electrochem Soc, 170, 020530 (2023).D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).T. R. Garrick, K. Kanneganti, X. Y. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).T. R. Garrick and J. W. Weidner, in Electrochemical Society Meeting s 233, p. 1345 (2018).

Migration of binder and conductive agent during drying process of Li-ion battery cathodes

Drying of an electrode film during a wet coating process for Li-ion batteries often leads to a heterogeneous distribution of the binder and conductive agent in the film thickness direction. Because this heterogeneous distribution affects battery performance and durability, understanding and controlling the migration behavior are important. Herein, the distribution of the components (active material/conductive agent/binder) of a cathode is investigated by a novel method and their relationship with the electrode properties is determined. The binder distribution is investigated via two methods: pyrolysis gas chromatography mass spectrometry (Py-GC/MS) analysis of cut electrodes, and low-voltage scanning electron microscopy with energy-dispersive X-ray spectroscopy. In the sample dried at 30 °C, more binder and conductive agent exists in the bottom layer. With increasing drying temperature, the binder and conductive agent migrate from the bottom to the surface because they are transported by capillary-driven convective flow through the pores between the active material particles. Drying at high temperatures causes migration, resulting in reduced adhesion between the electrode film and the current collector, and increases the electrode resistance. The Py-GC/MS method of characterizing the cut electrodes is shown to be a complementary method that can analyze a wider area than cross-sectional observation.

Stress Analysis of Graphite Anode under Various Binder Conditions in a Multiparticle Model through Multiscale Simulation and Experimental Verification

Quantifying and analyzing the stress of the battery system at different levels are important for ensuring battery stability and performance. Herein, a three‐dimensional multiparticle model to evaluate the stress generated within the active material particles of battery due to the particle–particle and particle–binder interactions is developed. Variations in binder conditions, such as binder distribution, thickness, and radius, as well as Young's modulus, are introduced to investigate their effects on the mechanical stress of graphite particles in the battery. Herein, it is demonstrated that larger binder distributions, lower thicknesses, and smaller Young's moduli and radii reduce the maximum particle stress of graphite. Moreover, smaller binder distributions and Young's moduli along with larger thicknesses and radii reduce the maximum and average binder stress values. The interfaces between the particle–particle and particle–current collector are the typical maximum stress locations. The average stress data obtained are applied at the electrode level for comparison with the experimental stress value. The experimental and the model average stresses are comparable, indicating the credibility of our model. These findings have considerable implications for minimizing the mechanical stress and probability of electrode fracture in the battery electrode operation and fabrication processes.

Effects of asphalt binder type, aggregate type, and gradation characteristics on fracture properties and performance of asphalt mixtures at intermediate temperatures

This study aimed to design and evaluate asphalt mixtures by considering various factors including different binders, aggregate types, and gradation characteristics of the fine portion of mixtures, referred to as the interstitial component (IC). The mixtures were compacted to 93% of maximum theoretical density to prepare specimens for Superpave IDT tests, which included resilient modulus, creep compliance, and fracture tests. Parameters such as failure limit (fracture energy), damage rate (dissipated creep strain energy per cycle), and the relative cracking performance indicator (number of cycles to failure) were assessed for test specimens subjected to the long-term oven aging and the cyclic pore pressure conditioning. The results showed that mixtures with styrene–butadiene–styrene modified binders exhibited slightly higher failure limits but significantly lower damage rates compared to mixtures with unmodified binders, indicating improved cracking performance. Similarly, the limestone mixtures demonstrated equivalent failure limit but much lower damage rate to the granite mixtures, attributed to the porous surface morphology and inherent weakness of limestone aggregates. Notably, even small changes in the IC characteristics of the mixtures yielded substantial differences in fracture properties and performance, a phenomenon believed to be linked to the distribution of asphalt binder and the structure of air voids within the mixture. In conclusion, a thorough examination confirmed the impact of polymer modification and aggregate type on fracture properties and, notably, highlighted the pivotal role of the fine portion's characteristics in determining mixture cracking performance.

Impact of fabrication methods on binder distribution and charge transport in composite cathodes of all-solid-state batteries

The manufacturing process of all-solid-state batteries necessitates the use of polymer binders. However, these binders, being ionic insulators by nature, can adversely affect charge transport within composite cathodes, thereby impacting the rate performance of the batteries. In this work, we aim to investigate the impact of fabrication methods, specifically the solvent-free dry process versus the slurry-cast wet process, on binder distribution and charge transport in composite cathodes of solid-state batteries. In the dry process, the binder forms a fibrous network, while the wet process results in binder coverage on the surface of cathode active materials. The difference in microstructure leads to a notable 20-fold increase in ionic conductivity in the dry-processed cathode. Consequently, the cells processed via the dry method exhibit higher capacity retention of 89% and 83% at C/3 and C/2 rates, respectively, in comparison to 68% and 58% for the wet-processed cells at the same rate. These findings provide valuable insights into the influence of fabrication methods on binder distribution and charge transport, contributing to a better understanding of the binder’s role in manufacturing of all-solid-state batteries.

Enabling the Production of Homogeneous High-Load Positive Electrodes by Tailoring the Electrode Formulation – a Conductive Additive and Solvent Approach

The automotive industry experiences a substantial change due to electrification of major parts of the transportation system by using lithium ion batteries (LIBs). To facilitate this transition, low cost and high energy density LIBs produced under the most sustainable conditions possible are required. These objectives are amongst others strongly related with the positive electrode. Thus, in order to achieve enhanced energy densities on cell level, the application of high-load positive electrodes for various cell systems ranging from lithium ion to lithium metal batteries is inevitable. However, to ensure high lithium ion mobility within thick composite electrodes and to obtain maximized capacity utilization, it is crucial to tailor the electrode microstructure. With regard to the production, detrimental effects like binder-migration can occur upon drying of thick electrodes inducing inhomogeneous distribution of binder and conductive additive within the electrode coating. Beyond that, the effect of lateral coating shrinkage resulting in electrode cracking during drying plays an increasingly significant role with increasing electrode thickness.The application of high solid contents (SC) during electrode paste processing can widely suppress the effects of binder migration and crack formation.[1,2] However, elevated SCs result in increasing paste viscosities leading to practical limitations for homogeneous electrode coating. By using nano-scale and micro-scale spherical, linear and three-dimensional conductive additives like carbon microfibers (CMF) or conductive graphite (CG) in addition to carbon black (CB), the adjustment of an appropriate paste viscosity can be facilitated. The addition of more carbonaceous additives acting as conductive additive as well as processing additive resolves the rheological requirements for an electrode paste with 80% SC and significantly influences the pore structure of the electrode. Thus, tailoring active and inactive components is crucial to enable processing of high SC electrode pastes with an appropriate viscosity in conjunction with the production of thick electrodes exhibiting an optimized pore structure benefiting the electrochemical performance. The additional introduction of carbon nanotubes (CNTs) leads to the formation of segregated networks providing more stability within the electrode and a favorable electrode microstructure. Moreover, the use of CNTs benefits the electrochemical performance by immensely boosting electronic conductivity resulting in higher rate capability and increased capacity retention. The various electrode formulations containing up to three different conductive additives were compared to the benchmark formulation without further additives in terms of electronic conductivity, adhesion, pore structure and electrochemical performance. Different electrode formulations were investigated and compared regarding the composite electrode adhesion strength, electronic conductivity, microstructure and electrochemical performance over 400 cycles in a coin cell setup with a graphitic negative electrode. However, the optimized formulation containing CNTs enables the production of thick positive electrodes exhibiting significantly higher areal capacities up to 8 mAh cm-2 with superior electrochemical properties and higher content of active material in the formulation resulting in higher energy densities on cell level. In a next step, the state-of-art processing solvent N-Methyl-2-pyrrolidon (NMP) was targeted with the goal of replacing NMP with a non-toxic solvent. The influence of a co-solvent on the electrode paste viscosity was investigated to further increase the SC, lower production costs and enable improved environmental benignity.A comprehensive study on tailoring the rheological, structural and electrochemical properties by processing additives is presented. The increase of the SC to 80% is a first step towards the reduction of the ecologic and economic footprint for LIB production while simultaneously enabling electrodes with high areal capacities exhibiting increased rate capability and capacity retention enabled by the addition of CNTs.[1] J. Seeba, S. Reuber, C. Heubner, A. Müller-Köhn, M. Wolter, A. Michaelis, Chemical Engineering Journal Volume 402, 2020, 125551. [2] L. Ibing, T. Gallasch, P. Schneider, P. Niehoff, A. Hintennach, M. Winter, F. M. Schappacher, Journal of Power Sources 423, 2019, 183–191.

Microstructure Model to Predict Mechanical Behavior of Lithium-Ion Battery Active Material Under Compressive Load

A three-dimensional microstructure-based modeling method (3DMS) is developed to predict the mechanical behaviors of porous electrode that includes both active material (AM) and binders inside lithium-ion battery during compression. The geometry of both AM and binder shown in Fig. 1a is generated stochastically to create microstructures by using a modified MATBOX opensource program with our in-house code. The advanced technique of volume element generation is also established to overcome the interfacial error due to complexity of binder distribution as illustrated in Fig. 1b. The Finite Element Analysis (FEA) based solid-stress model is applied to predict local mechanical activities including stress-strain relationship and microstructure evolution.The predictions of anisotropic behavior in the porous electrode under compressive loads will be presented and the insights into the microstructure deformation will be discussed. Further, the analysis results will be validated using experimental testing results acquired at various length scales. This work can be used for the model-based FEA platform to predict the impact of volume change under charge/discharge cycles, volume change of a jelly-roll during formation, and the response of the active material in typical pouch cells during battery module assembly. Figure 1

Mechanical Properties of PEMFC Electrodes According to Fabrication Methods

Electrodes in a polymer electrolyte membrane fuel cell (PEMFC) are the crucial element performing electrochemical reactions and are the most vulnerable mechanically. Various operating conditions (freeze-thaw, start-up, shut down) generate buckling, cracks, and delamination in electrodes. These mechanical failures not only directly affect the performance of the PEMFC cell but also act as a fatal factor in shortening the lifespan. Therefore, understanding and improving the mechanical properties of electrodes is essential for designing high-durability PEMFCs. Furthermore, the fabrication method of electrodes is a factor that causes not only performance but also distinct mechanical property differences since it determines their internal structure and surface characteristics. However, evaluating the mechanical properties of electrodes has been challenging because they are fragile and hard to separate from substrates. Therefore, this study evaluated the intrinsic mechanical behaviors of the electrodes according to fabrication methods via a free-standing tensile test. The effect of fabrication methods was analyzed for blade coating and spray coating methods used universally from industry to laboratory. The difference in mechanical properties between the two methods was identified by analyzing the internal structure and distribution of ionomer agglomerate. For blade-coated electrodes, modulus (372.5 MPa) and elongation (2.44%) were 2-2.7 times higher than spray-coated electrodes (172.9 MPa,0.9%). The difference in mechanical properties originated from the electrodes’ surface and internal structures. Blade-coated electrodes were composed of smaller pores and volume than the spray coating using FIB-SEM. The modulus ratio according to the internal structure through finite element analysis (using ABAQUS software) was consistent with the actual experimental value. In addition, blade-coated electrodes have high elongation and strength because they enable uniform stress transmission with a smooth surface and uniform ionomer binder distribution (analyzed by HAADF-STEM and EDS). This study contributes to a better understanding of the mechanical properties of electrodes according to the fabrication methods and provides guidelines for mechanical improvement. Figure 1

Meso-scale adhesive/cohesive failure behaviors of porous asphalt mixtures considering random inhomogeneous distribution of binder

Durability failure is the main concern of porous asphalt mixtures (PAC) and is caused by adhesive failure on aggregate-binder interface or cohesive failure within the binder. Adhesive/cohesive failure behaviors of PAC are dependent on the adhesive/cohesive properties of binder, which are influenced by the thickness and composition of binder. The aim of this study is to develop a meso-scale finite element modeling (M−FEM) considering the random inhomogeneous distribution of binder to investigate the meso-scale adhesive/cohesive failure behaviors of PAC. In the M−FEM, two types binder (mastic and mortar) with different thickness were reconstructed. The adhesive/cohesive properties of mastic and mortar with different thickness were evaluated by a modified pull-off test and used to determine the model parameters. A zero-thickness cohesive element was embedded into the interface between aggregate-binder and within binder, and the cohesive element parameters were determined and assigned based on the binder thickness. M−FEM with and without considering the random inhomogeneous distribution of binder (Model B and Model A) were constructed. The adhesive/cohesive strength of mastic increased with the thickness and reached a peak value at the thickness of 0.8 mm. The adhesive/cohesive strength of mortar increased with the thickness. The initial cracking point of Model A and Model B are different. In the cracking extension stage, adhesive failure was found in Model A, while both adhesive and cohesive failure behaviors were found in Model B. The random inhomogeneous distribution of binder has a significant impact on the damage initiation, stress distribution, stress transfer, and evolution of adhesive/cohesive failure behaviors of PAC. M−FEM considering the random inhomogeneous distribution of binder is more reasonable in the simulation of adhesive/cohesive failure behaviors. Increasing the binder thickness may have a contribution to the improvement of durability of PAC.

Performance Evaluation of Extraction Coatings with Different Sorbent Particles and Binder Composition.

Binders are critical components used in the preparation of a range of extraction devices, including solid-phase microextraction (SPME) devices. While the main role of a binder is to affix the sorbent particles to the selected support, it is critical to select the optimal binder to ensure that it does not negatively impact the coating's particle sorption capability. This work presents the first comprehensive investigation of the interactions between binders and solid sorbent particles as these interactions can significantly impact the performance of the coating. Specifically, the findings presented herein provide a better understanding of the extraction mechanisms of composite coatings and new rules for predicting the particle adhesion forces and binder distribution in the coating. The influence of binder chemistry on coating performance is investigated by examining a selection of the most used binders, namely, polydimethylsiloxane (PDMS), polyacrylonitrile (PAN), poly(vinylidene difluoride) (PVDF), polytetrafluoroethylene amorphous fluoroplastics (PTFE AF 2400), and polybenzimidazole (PBI). The solid particles (e.g., hydrophilic-lipophilic balanced (HLB) and C18) used in this work were selected for their ability to provide optimal extraction coverage for a broad range of analytes. The results show that PDMS does not change the properties of the solid particles and that the binder occupies a negligible volume due to shrinking after polymerization, resulting in the solid particles making up most of the coating volume. Hence, the coating sorption characteristics correspond closely to the properties of the selected solid particles. On the other hand, the results also showed that PTFE AF 2400 can interact with the active surface of the sorbent, leading to the deactivation of the sorbent particles. Therefore, the extraction performance and permeability coefficients decrease as the size of the penetrant increases, indicating a rigid porous structure. The results of this study can aid in the optimization of SPME devices as they provide reference values that can be used to determine the optimal binder and the sorbent affinity for the targeted compounds. Finally, the present work also provides the broader scientific community with a strategy for investigating the properties of sorbent particle/binder structures and defines the characteristics of a good coating/membrane by analyzing all parameters such as kinetics, thermodynamic equilibria, and morphology.

Obtaining high-strength carbon fiber based on polyphenylene sulfide by ATL method with laser heating

The method of manufacturing high-strength structural carbon fiber from toupreg based on PPS-214 grade polyphenylene sulfide (Fortron, Germany) and AS4 high-strength carbon fiber (Hexcel, USA) using a promising ATL-technology (Automated Tape Laying) with laser heating is considered. The technology was adapted for the material under study, laboratory models in the form of plates were made, physical and mechanical tests of laboratory samples were carried out. The quality of the binder distribution and the presence of defects were assessed by raster electron microscopy. The influence of the reinforcement, pressing and vacuum heat treatment schemes on improving the mechanical properties of the studied carbon fiber was investigated. It has been found that the samples subjected to vacuum heat treatment have higher mechanical properties due to an increase in the adhesion of the toupreg tapes to each other and the removal of discontinuities formed during the calculation. The value of the ultimate strength at interlayer shear of samples made using a parallel-diagonal scheme increases by 108%, at bending by 370% and by 65% at compression.By processing the toupregs by the ATL with laser heating and subsequent thermal treatment of the products, it is possible to obtain high-strength structural materials with improved physical and mechanical properties, as well as high repeatability and equality of properties throughout the area of the products, even using complex reinforcement schemes.

Mitigation of Binder Migration Behavior during the Drying Process by Applying an Electric Field for Fast‐Charging in Lithium‐Ion Batteries

AbstractThe binder migration due to the capillary force‐driven solvent evaporation during the drying process in the electrode manufacturing process induces inhomogeneous binder distribution in the electrode, which deteriorates Li‐ion kinetics and corresponding poor fast‐charging properties in lithium‐ion batteries (LIBs). Here, we report an effective strategy to mitigate the binder migration behavior by applying an electric field during the drying process. As the employed carboxymethyl cellulose (CMC) and styrene‐butadiene rubber (SBR) binders have a negative charge in an aqueous anode slurry system (pH 7), the binder migration behavior could be mitigated by generating an electrical attraction force into the bottom direction by positive electrification of the current collector. The anode prepared with electric field exhibits homogeneous binder distribution in the longitudinal direction, which enhances Li‐ion kinetics, corresponding constant current charging capacity, and cycling stability compared to those of the anode prepared without electric field.

Effect of milling time and sintering temperature on the microstructure and binder distribution of spark plasma sintered NbC-Ni cermets

Niobium carbide (NbC) based cermets are emerging as strong contenders to replace conventional tungsten carbide (WC) based cermets for applications involving abrasion and wear resistance due to their superior mechanical, physical, and chemical properties. NbC cermets with various binders have been explored in literature and nickel has emerged as a promising candidate binder material. Mechanical mixing (MM) followed by spark plasma sintering (SPS) has been shown to be one of the effective methods to synthesize NbC-Ni cermets. However, the effect of certain crucial process parameters during the MM + SPS process on the end product have not been established. To address this, the present study reports the effect of ball milling time and the effect of sintering temperature on the microstructure, binder distribution, hardness, and indentation fracture toughness of NbC – 16 vol% Ni cermets synthesized using MM + SPS. Insufficient milling time resulted in inhomogeneous binder distribution in the consolidated cermets and sintering above a certain temperature resulted in complete loss of binder. Therefore, the combination of sufficient milling time and an appropriate sintering temperature was essential to obtain a consolidated cermet with homogeneous microstructure and uniform mechanical properties.

Powder Injection Moulded Ti6Al4V-HA Composite for Implants

Powder injection moulding (PIM) is widely used to produce complex shapes of Titanium and its alloys. Ti6Al4V-HA feedstocks at 63, 64 and 66 vol.% were produced by combining a Ti6Al4V-HA powder mixture (90:10 wt.%) with a binder system containing palm stearin (PS) and low-density polyethylene (LDPE). Binder system consisted with 60 wt.% of PS and 40 wt.% of LDPE. All powder loading materials were successfully injection moulded into the shape of a tension bar. Following that, all powder loadings were successfully debound in solvent and thermal methods. Based on SEM observation that 66 vol.% powder loading demonstrated homogenized distribution of powder and binder. Hence, 66 vol.% powder loading was selected for further process sintering at 1300 ºC, and its bending strength was evaluated. Sintered Ti6Al4V-HA with porous structure has Young’s modulus of 11 GPa, within the Young modulus of bone (10 to 30 GPa). The results of this study indicate that sintered Ti6Al4V-HA has potential as an implant material.

Characterization of physical and chemical antioxidative performance of asphalt using Bio-additive from paper pulp black liquor

The main objective of this research is to investigate the effectiveness of lignin bio-additives derived from black liquor paper pulp as asphalt antioxidants. Two lignin bio-additives, H-L and S-L, were developed by acidifying black liquor with hydrochloric and sulfuric acid. The laboratory aging procedures used in this study included the Rolling Thin Film Oven and the Ultraviolet Chamber methods. The crossover modulus (|G*c|) and linear amplitude sweep (LAS) were measured using a Dynamic Shear Rheometer (DSR). Gel Permeation Chromatography (GPC) was also used to characterize the molecular size distribution of the asphalt binder. The combination of carbonyl and sulfoxide aging indices was measured using Fourier Transform Infrared (FTIR) spectroscopy. The S-L modified binder (S-LMB) demonstrated superior aging resistance compared to both the control binder (CB) and the H-L modified binder (H-LMB) by exhibiting the lowest reduction in |G*c|. Furthermore, the LAS test results showed that S-LMB provided the best resistance to aging due to the lowest decrease in fatigue life with age conditioning, followed by CB and H-LMB, with rates of 11%, 13%, and 16%, respectively. The GPC results also confirmed the efficacy of the S-L bio-additive as an antioxidant, exhibiting the lowest increment in asphaltene proportion attributed to age conditioning. The FTIR measurements successfully captured the antioxidant capability of both H-L and S-L bio-additives, with S-L performing better than H-L. Overall, the results suggest that S-L demonstrates superior antioxidant performance compared to H-L.

Regeneration mechanisms of aged SBS modified asphalt from RAP materials: Molecule structure, morphology, phase transition, and interface adhesion characteristics

In this study, the environmentally friendly rejuvenators with waste thermal conductive oil, polymer, and the interfacial reinforcing agent were prepared. And the influence of the different rejuvenators on the rejuvenation mechanisms of aged SBS modified asphalt was characterized by different scales including the molecule structure, morphology, phase transition and interface adhesion characteristic, and macro performance. The results show that the thermal-oxidative aging process increases the molecular weight of asphalt, promotes the SBS phase to agglomerate, and decreases the high and low temperature performance, thermal stability, and adhesion. When the rejuvenator was added, the molecular weight distribution of asphalt binders can be improved, while adding the regenerant-II can supplement the SBS modifier and reform the cross-linking structure. Furthermore, the regenerant-II has a better recovery effect on the morphology structure and resumes the thermal behavior. And then softening point and ductility can be recovered by 89.7% and 94.8% of the original SBS modified asphalt. Under the action of the interfacial reinforcing agent, the regenerant-III could increase the adhesion work to 95.49% of the original SBS modified asphalt.

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries