Conductive additives, like carbon black or graphite, are essential components of lithium ion batteries due to the limited electrical conductivity of most electrode materials. However, there is still ...a lack of knowledge about the optimized distribution of these materials within the electrode. A dry mixing process is used in order to prepare a conductive coating by depositing carbon black on the surface of Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathode particles. It is demonstrated that this – from a theoretically point of view – favorable distribution does not allow the preparation of working electrodes without taking into account the role of the binder. After adding an organic binder to the slurry, the polymer deposits on top of the carbon shell during drying and inhibits the conductive contact between the particles. This can be avoided by a fraction of distributed carbon particles which are associated with the binder phase providing conductive paths through the isolating organic material. It is shown that carbon black and graphite are principally fulfilling this task, but both materials are leading to varying processing behavior and electrode properties.
•A model is presented that explains the conductivity drop after dry mixing of active material and carbon black.•It is shown how the conductivity drop can be avoided by an admixture of carbon materials.•Recommendations are given in order to optimize the carbon distribution.
Many processes involve solid bowl centrifuges as a solid–liquid separation step, typically used for clarification, thickening, classification, degritting, mechanical dewatering, and screening. In ...order to operate solid bowl centrifuges safely, with minimum resource consumption and reduced setup times, modeling and optimization are necessary steps. This is a challenge due to the complex process behavior, which can be overcome by developing advanced physical models and process analysis. This review provides an overview of solid bowl centrifuge applications, their modeling, and addresses future optimization potentials through digital tools. The impact of dispersed phase properties such as particle size, shape, surface roughness, structure, composition, and continuous liquid phase is the reason for the lack of generally applicable models. Laboratory-scale batch sedimentation centrifuges are used to predict material behavior and develop material functions describing separation-related properties such as sedimentation, sediment build-up and sediment transport. The combination of material functions and modeling allows accurate simulation of solid bowl centrifuges from laboratory to industrial scale. Since models usually do not cover all influencing variables, there are often deviations between predictions and the real process behavior. Gray-box modeling and on-line or in-situ process analytics are tools to improve centrifuge operation.
Inline analytics in industrial processes reduce operating costs and production rejection. Dedicated sensors enable inline process monitoring and control tailored to the application of interest. ...Nuclear Magnetic Resonance is a well-known analytical technique but needs adapting for low-cost, reliable and robust process monitoring. A V-shaped low-field NMR sensor was developed for inline process monitoring and allows non-destructive and non-invasive measurements of materials, for example in a pipe. In this paper, the industrial application is specifically devoted to the quality control of anode slurries in battery production. The characterization of anode slurries was performed with the sensor to determine chemical composition and detect gas inclusions. Additionally, flow properties play an important role in continuous production processes. Therefore, the in- and outflow effects were investigated with the V-shaped NMR sensor as a basis for the future determination of slurry flow fields.
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•Tubular centrifuges enable bench scale fractionation of colloidal particles in single or multi component systems.•Machine learning algorithm predicts solids volume concentration ...based on spectroscopic sensor data.•New insights into the process monitoring of multidimensional property distributions are gained.
Centrifugation is an established tool in solids process technology to handle classification of particulate products. However, dispersions with strict specifications for product-relevant properties often require a different approach. Fractionation is necessary when both geometric and material properties matter. Due to their high throughput and centrifugal acceleration, semi-continuous tubular centrifuges are suitable for the effective performance of such tasks. In order to monitor this mechanism for several size and density fractions, the separation efficiency is correlated with optical properties. Titanium dioxide and pigment particles serve as experimental products. Coarser size fractions are separated and overflow samples are analysed with analytical centrifugation and UV–vis spectroscopy. Each extinction spectrum is labeled with distinctive target values and a regression model is build. Finally, mixtures are processed and targets determined using the machine learning algorithm. It is discussed to what extent the advanced methodology can be applied to multidimensional unit operations such as density fractionation.
Inline NMR via a Dedicated V-Shaped Sensor Schmid, Eric; Rondeau, Simon; Rudszuck, Thomas ...
Sensors (Basel, Switzerland),
02/2023, Letnik:
23, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Process monitoring and control require dedicated and reliable measures which reflect the status of the process under investigation. Although nuclear magnetic resonance is known to be a versatile ...analytical technique, it is only seldomly found in process monitoring. Single-sided nuclear magnetic resonance is one well known approach for being applied in process monitoring. The dedicated V-sensor is a recent approach that allows the inline investigation of materials in a pipe non-destructively and non-invasively. An open geometry of the radiofrequency unit is realized using a tailored coil, enabling the sensor to be applied for manifold mobile applications in in-line process monitoring. Stationary liquids were measured, and their properties were integrally quantified as the basis for successful process monitoring. The sensor, in its inline version, is presented along with its characteristics. An exemplary field of application is battery production in terms of anode slurries; thus, the first results on graphite slurries will demonstrate the added value of the sensor in process monitoring.
In this work, we take on an in-depth characterization of the complex particle structures made by spray flame synthesis. Because of the resulting hierarchical aggregates, very few measurement ...techniques are available to analyze their primary particle and fractal properties. Therefore, we use small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) to investigate the influence of the precursor concentration on the fractal structures of zirconia nanoparticles. The combination of information gained from these measurement results leads to a detailed description of the particle system, including the polydispersity and size distribution of the primary particles. Based on our findings, unstable process conditions could be identified at low precursor concentrations resulting in the broadest size distribution of primary particles with rough surfaces. Higher precursor concentrations lead to reproducible primary particle sizes almost independent of the initial precursor concentration. Regarding the fractal properties, the typical shape of aggregates for aerosols is present for the investigated range of precursor concentrations. In conclusion, the consistent results for SAXS and TEM show a conclusive characterization of a complex particle system, allowing for the identification of the underlying particle formation mechanism.
Due to their low cost, high stability and low toxicity, metal oxide nanomaterials are widely used for applications in various fields such as electronics, cosmetics and photocatalysis. There is an ...increasing demand thereby for nanoparticles with highly defined properties, in particular a narrow particle size distribution and a well-defined morphology. Such products can be obtained under high control via bottom-up synthesis approaches. Although aqueous processes are largely found in literature, they often lead to particles with low crystallinity and broad size distribution. Thus, there has been a growing trend towards the use of non-aqueous and non-hydrolytic synthesis routes. Through variation of the reaction medium and the use of adequate additives, such non-aqueous systems can be tuned to adapt the product properties, and especially to yield anisotropic nanoparticles with peculiar shapes and even complex architectures. Anisotropic particle growth enables the exposure of specific facets of the oxide nanocrystal, leading to extraordinary properties such as enhanced catalytic activity. Thus, there is an increasing demand for anisotropic nanoparticles with tailored morphologies. In this review, the non-aqueous and non-hydrolytic synthesis of anisotropic metal oxide nanoparticles is presented, with a particular focus on the different parameters resulting in anisotropic growth to enable the rational design of specific morphologies. Furthermore, secondary phenomena occurring during anisotropic particle growth, such as oriented attachment mechanisms, will be discussed.
Fluorocarbons are novel systems in the fast-growing fields of diverse biomedical applications and fluorocarbon-water emulsions. However, characterization of these systems with modern measuring ...techniques such as drop profile analysis tensiometry is almost impossible because of practically identical refractive indexes and high-density differences. Due to the material properties of the fluorocarbon-water system, the invasive Du Noüy ring is the most appropriate method to measure interfacial tensions over long times. However, the influence of the ring on a fluorocarbon/water interface packed with phospholipids needs careful analysis. For the proof of methodology, the spinning drop tensiometry was used for comparison as a non-invasive technique to measure interfacial tension between water and perfluoroperhydrophenanthrene (PFPH) covered by 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) proving almost identical results. This demonstrates the validity of the invasive measurement technique for the studied system. The Du Noüy ring method was applied for further measurements of phospholipids with different chain lengths (1,2-dmyristoyl-sn-glycero-3-phostphatidylcholine, DMPC; 1,2-distearoyl-sn-glycero-3-phosphatidylcholine, DSPC) which revealed a difference in interfacial adsorption kinetics and equilibrium tensions. The Du Noüy ring tensiometry is appropriate to examine the slow adsorption kinetics of phospholipids emulsifying fluorocarbons. The results enable functional optimization of fluorocarbon emulsions regarding physical emulsification parameters and the selection of lipids.
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•Transient calculation of the clarification process in decanter centrifuges.•Fast simulation tool for application in flow sheet simulators.•Process simulation tool for continuous ...centrifuges in the lab-scale.•Changes in sediment solids concentration cannot be calculated.
In recent years, the concept of flow sheet simulation of fluid processes has been extended to the dynamic performance of solids handling by considering the particle size distribution as one relevant material property. Continuous centrifugation is widely used throughout the process industry and applied to separate finely dispersed particles from a liquid phase. Current process simulation tools for calculation of separation in decanter centrifuges are limited to steady-state conditions and are currently not applicable for real time simulations. This work illustrates the basic framework of a new dynamic flow sheet approach to predict the clarification process of stabilized particles in decanter centrifuges. The solids residence time distribution describes the transient behavior of a lab decanter centrifuge. This allows the simulation of the complex process behavior with small numerical effort. In the presented approach, the number of related compartments is one key parameter. It could be shown that the concept is suitable for real time simulations of decanter centrifuges. The presented numerical algorithm is capable of real time simulations and model-based process control of a lab decanter centrifuge. This is guaranteed by connecting the solids residence time distribution with the properties of the material for the sedimentation and sediment build-up. The accuracy of the new approach is shown by comparing numerical simulations with experimental results. The presented model is unsuitable to predict the sediment solids concentration of a material which forms a compressible cake. An extension of the basic framework to tubular centrifuges or filter centrifuges is also applicable by considering the solids residence time distribution of these types of machines, the properties of the processed materials and neglecting the sediment transport.
This research highlights the capacity of a newly introduced centrifugation process to form liposomes from water-in-fluorocarbon nano-emulsions stabilized with phospholipids to incorporate ...macromolecular and sensitive active pharmaceutical ingredients (API). The encapsulation efficiency of the produced liposomes, incorporating fluorescein-sodium, bovine serum albumin and fluorecein isothiocyanate dextran as model APIs, is determined by applying Vivaspin® centrifugation filtration and quantified by UV-Vis spectroscopy. It was found that higher densities of the fluorocarbons used as the hydrophobic phase enable a higher encapsulation efficiency and that an efficiency of up to 98% is possible depending on the used phospholipid. Among the engineering aspects of the process, a comparison between different membrane substances was performed. Efficiency increases with a higher phospholipid concentration but decreases with the addition of cholesterol. Due to the higher bending modulus, liposome formation is slowed down by cholesterol during liposome closure leading to a greater leakage of the model API. The encapsulation of bovine serum albumin and dextran, both investigated under different osmotic conditions, shows that an efflux negatively affects the encapsulation efficiency while an influx increases the stability. Overall, the process shows the potential for a very high encapsulation efficiency for macromolecules and future pharmaceutical applications.
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