Influence of electrode corrugation after calendering on the geometry of single electrode sheets in battery cell production

Calendering is an essential process step in battery cell production. By selective compaction of the material, the performance of the battery cell can be optimized. During processing, corrugations can occur in the machine direction, which are characterized in this article in relation to the material systems LiNi$_{0.8}$Mn$_{0.1}$Co$_{0.1}$O$_2$ (NMC811) and LiNi$_{0.6}$Mn$_{0.2}$Co$_{0.2}$O$_2$ (NMC622) as well as the rate of compaction and the web tension. It is shown that the corrugations are strongly dependent on the rate of compaction. The material system and the web tension show a weaker influence on the corrugation characteristics. Subsequently, single electrode sheets are cut from the coils and their geometry is investigated. It is shown that the corrugation hardly propagates further into the single electrodes, which is explained with the storage time of the electrodes. Rather, the coil bending strongly influences the electrode sheet geometry. It is shown that the position of the conductor tab also has an important influence

Kältemittelbasierte Direkttemperierung von Batteriesystemen - Ein alternatives Kühlkonzept zur Schnellladung von zwei- und vierrädrigen E-Fahrzeugen

Die Schnellladung von Elektrofahrzeugen stellt neue Herausforderungen an das Batterie-Thermomanagement. Die beim Laden erzeugte Verlustwärme übersteigt die Kühlleistung der heute eingesetzten Systeme. Der Vortrag stellt ein alternatives Konzept zur Kühlung und Heizung von Batterien vor. Dieses basiert auf der Entkopplung der Batterie vom Kältekreis der Klimaanlage bzw. auf der Nutzung eines eigenen Kältekreises zur ausschließlichen Temperierung der Batterie. Dies wirkt sich bezüglich der Umschaltung der Klimaanlage als Wärmepumpe günstig auf die Systemkomplexität aus. Gleichzeitig kann durch eine Anpassung der Verdampfungstemperatur auf die Anforderungen der Batterie und der Einsatz von alternativen Kältemitteln eine Erhöhung der Leistungsfähigkeit und der Effizienz des Batteriekältekreises erreicht werden. Speziell bei Fahrzeugen ohne Klimaanlage wie z.B. E-Mopeds und E-Motorräder herrscht dringender Bedarf nach kompakten Kühlkonzepten, da sonst in dieser Fahrzeugklasse keine Schnellladung durchführbar ist. Der Vortrag befasst sich zunächst mit den thermischen Anforderungen der Batterie an das Thermomanagement und gibt nachfolgend einen Überblick über die weiteren Vor- und Nachteile der Direkttemperierung. Desweiteren werden der Stand der Technik (Tesla, Kreisel, etc.) und neue Lösungen bezüglich der thermischen Schnittstelle von zylindrischen Zellen vorgestellt. Abschließend soll kurz auf das Förderprojekt ZEC-Bike (Zero Emission Cargo Bike) eingegangen werden, bei dem das Thermomanagement nicht nur für die Schnellladung benötigt wird, sondern auch zur intensiven Rekuperation über das Vorderrad

Entwicklungsansatz für On Bord - Ladesysteme

Zur Erhöhung der Reichweite von konventionellen Elektrofahrzeugen bietet sich der Einsatz von Range-Extender-Modulen auf Basis von Brennstoffzellen an. Am Institut für Fahrzeugkonzepte des Deutschen Zentrums für Luft- und Raumfahrt wird die Eignung von Hochtemperatur-PEM–Brennstoffzellen erforscht. Diese Brennstoffzellen weisen neben elektrischen Wirkungsgraden von ~ 40 % auch hohe Abwärmetemperaturen auf einem Temperaturniveau von T ~170 °C auf. Zur Konzeptvalidierung wurde ein Brennstoffzellenprüfstand aufgebaut, um die Aufheizzeit und die dafür benötigte Energiemenge zu bestimmen. Durch ein neues Brennstoffzellenkühlsystem werden Einsparpotentiale beim stationären Erhaltungsheizen erwartet. Weiter wird durch das neue Kühlsystem eine Verbesserung der Wärmenutzung angestrebt. Außerdem wird der Klimatisierungsbedarf eines Demonstratorfahrzeugs anhand von verschiedenen klimatischen Bedingungen am Klimarollenprüfstand untersucht. Dadurch wird eine Dimensionierungs- und Validierungsgrundlage sowohl für die im Projekt erstellten Simulationsmodelle als auch für das Thermomanagementkonzept geschaffen. Die gewonnen Daten dienen nach der Integration des Brennstoffzellensystems ins Fahrzeug als Vergleichs-grundlage. Dieser Beitrag fasst die Ergebnisse zusammen

Relationships between emotional intelligence and sales performance in Kuwait

This study investigates the relationship between emotional intelligence (EI) and Total Sales Performance (TSP), and whether EI contributes to predicting the performance of sales professionals in Kuwait. The sample was 218 sales professionals working for 24 different car dealerships. An ability model of EI was measured using the Assessing Emotions Scale (AES) developed by Schutte et al. (1998) and its Arabic version. The trait model of EI was assessed using the Effective Intelligence Scale (EIS). The findings showed a negative but weak correlation between TSP and the AES and all its subscales. No correlation was found between TSP and the EIS. A weak positive correlation existed between Objective Sales Performance and each of total EIS, Accuracy, and Patience subscales

Stand-Alone Battery Thermal Management for Fast Charging of Electric Two Wheelers - Integrated Busbar Cooling

This paper presents a thermal interface for cylindrical cells using busbar-integrated cooling channels. This interface is available due to the use of a stand-alone refrigerant circuit for the thermal management of the battery. A stand-alone refrigerant circuit offers performance and efficiency increases compared to state-of-the-art battery thermal management systems. This can be achieved by increasing the evaporation temperature to the requirements of the Li-ion cells and the use of alternative refrigerants. The solution proposed in this paper is defined for electric two-wheelers, as the thermal management of these vehicles is currently insufficient for fast charging where high heat losses occur. Three channel patterns for the integrated busbar cooling were examined regarding their thermal performance to cool the li-ion cells of a 16p14s battery pack during fast charging. A method of coupling correlation-based heat transfer and pressure drop with thermal finite element method (FEM) simulations was developed. The symmetric channel pattern offers a good compromise between battery temperatures and homogeneity, as well as the best volumetric and gravimetric energy densities on system level. Average cell temperatures of 22 °C with a maximum temperature spread of 8 K were achieved

A powerful bursting radio source towards the Galactic Centre

Transient astronomical sources are typically powered by compact objects and usually signify highly explosive or dynamic events. While radio astronomy has an impressive record of obtaining high time resolution observations, usually it is achieved in quite narrow fields-of-view. Consequently, the dynamic radio sky is poorly sampled, in contrast to the situation in the X- and gamma-ray bands in which wide-field instruments routinely detect transient sources. Here we report a new transient source, GCRT J1745-3009, detected in 2002 during a moderately wide-field radio transient monitoring program of the Galactic center (GC) region at 0.33 GHz. The characteristics of its bursts are unlike those known for any other class of radio transient. If located in or near the GC, its brightness temperature (~10^16 K) and the implied energy density within GCRT J1745-3009 vastly exceeds that observed in most other classes of radio astronomical sources, and is consistent with coherent emission processes rarely observed. We conclude that GCRT J1745-3009 is the first member of a new class of radio transient sources, the first of possibly many new classes to be identified through current and upcoming radio surveys.Comment: 16 pages including 3 figures. Appears in Nature, 3 March 200

Characterization of White Matter Hyperintensities in Large-Scale MRI-Studies

Background: White matter hyperintensities of presumed vascular origin (WMH) are a common finding in elderly people and a growing social malady in the aging western societies. As a manifestation of cerebral small vessel disease, WMH are considered to be a vascular contributor to various sequelae such as cognitive decline, dementia, depression, stroke as well as gait and balance problems. While pathophysiology and therapeutical options remain unclear, large-scale studies have improved the understanding of WMH, particularly by quantitative assessment of WMH. In this review, we aimed to provide an overview of the characteristics, research subjects and segmentation techniques of these studies.Methods: We performed a systematic review according to the PRISMA statement. One thousand one hundred and ninety-six potentially relevant articles were identified via PubMed search. Six further articles classified as relevant were added manually. After applying a catalog of exclusion criteria, remaining articles were read full-text and the following information was extracted into a standardized form: year of publication, sample size, mean age of subjects in the study, the cohort included, and segmentation details like the definition of WMH, the segmentation method, reference to methods papers as well as validation measurements.Results: Our search resulted in the inclusion and full-text review of 137 articles. One hundred and thirty-four of them belonged to 37 prospective cohort studies. Median sample size was 1,030 with no increase over the covered years. Eighty studies investigated in the association of WMH and risk factors. Most of them focussed on arterial hypertension, diabetes mellitus type II and Apo E genotype and inflammatory markers. Sixty-three studies analyzed the association of WMH and secondary conditions like cognitive decline, mood disorder and brain atrophy. Studies applied various methods based on manual (3), semi-automated (57), and automated segmentation techniques (75). Only 18% of the articles referred to an explicit definition of WMH.Discussion: The review yielded a large number of studies engaged in WMH research. A remarkable variety of segmentation techniques was applied, and only a minority referred to a clear definition of WMH. Most addressed topics were risk factors and secondary clinical conditions. In conclusion, WMH research is a vivid field with a need for further standardization regarding definitions and used methods

Advancing efficiency and reliability in thermal analysis of laser powder-bed fusion

In laser based powder-bed fusion of metals (PBF-LB/M), parts are fabricated by melting layers of powder using a high-intensity laser beam. During this process, the material is exposed to rapid cooling rates and intense thermal gradients, which are the underlying causes of residual stress formation and development of a unique microstructure in these components. Therefore, understanding the heat transfer phenomenon and reliably representing exposed temperature profiles in simulation frameworks are prerequisites for studying the microstructure and residual stress development during the PBF-LB/M process. This work employs a combination of experimental measurements and model development to study this phenomenon. Thermal properties of Hastelloy X were measured in the as-deposited state and used to setup finite element (FE) thermal simulations of the PBF-LB/M process. In addition, in-situ temperature evolutions near the laser tracks were measured by instrumenting thin-wall structures with K-type thermocouples in a two-stage fabrication process. The gathered data was used to calibrate uncertain modelling parameters, and ultimately, the simulation framework could closely represent the measured temperature histories. To address the high computational cost of FE thermal simulations, an adaptive-local/global multiscale modelling approach was proposed, which substantially reduced computation times without compromising the accuracy of the results. The modelling files and scripts are available in github