Expanded in situ aging indicators for lithium-ion batteries with a blended NMC-LMO electrode cycled at sub-ambient temperature

An important step toward safer and more reliable lithium-ion battery systems is the development of better methods for detection and characterization of battery degradation. For a method to be suitable for online application (e.g., onboard an electric vehicle), it must be simple, explanatory, and non-invasive. In this work, we develop and track aging indicators over the life of 18650-format lithium-ion batteries with a blended NMC532-LMO positive electrode and graphite negative electrode. Cells are cycled until reaching 80 % of their original capacity under combinations of four different cycling conditions: ambient and sub-ambient temperatures (29 and 10 °C) and fast and mild rates (2.7 and 1.0C). Loss of lithium inventory dominates aging for all cases, with additional loss of NMC capacity under the combination of sub-ambient temperature and mild rate. A novel, easily acquired polarization factor (supported by electrochemical impedance spectroscopy) complements capacity fade analysis; it correlates well with ultimate cell lifetime and indicates changes in active aging processes. These processes are further revealed by differential voltage analysis (DVA) and incremental capacity analysis (ICA). New indicators and aging scenarios are evaluated for these techniques and supported by post mortem analysis. From in operando cycling data and a single, slow discharge curve, these four methods (capacity fade, polarization factor, DVA, and ICA) comprise a simple, explanatory, and non-invasive toolbox for evaluating aging online in lithium-ion battery systems.

Tunable side-bounce monochromator

Side-bounce beamlines with fixed-exit angles have been intended to operate with only one selected energy. However, a tunable monochromator in a new geometry is presented here that will make side-bounce beamlines energy tunable. It requires the addition of two more rotations. Analytic solutions for the values of these two rotation angles are provided. The validity of the new concept was checked by ray tracing and two-dimensional searches in the additional angles. Operational details on the new scheme, including the exit offset and steering of the beams, were determined. In addition to tunability, the new monochromator will reduce the loss from the polarization factor at low energies.

Dynamic dielectric properties characterization of tapered dielectrophoresis microelectrodes for selective detection and rapid manipulation of cells

Purpose This paper aims to present the dielectrophoresis (DEP) force (FDEP), defined as microelectrofluidics mechanism capabilities in performing selective detection and rapid manipulation of blood components such as red blood cells (RBC) and platelets. The purpose of this investigation is to understand FDEP correlation to the variation of dynamic dielectric properties of cells under an applied voltage bias. Design/methodology/approach In this paper, tapered design DEP microelectrodes are used and explained. To perform the characterization and optimization by analysing the DEP polarization factor, the change in dynamic dielectric properties of blood components are observed according to the crossover frequency (fxo) and adjustment frequency (fadj) variation for selective detection and rapid manipulation. Findings Experimental observation of dynamic dielectric properties change shows clear correlation to DEP polarization factor when performing selective detection and rapid manipulation. These tapered DEP microelectrodes demonstrate an in situ DEP patterning efficiency more than 95%. Research limitations/implications The capabilities of tapered DEP microelectrode devices are introduced in this paper. However, they are not yet mature in medical research studies for various purposes such as identifying cells and bio-molecules for detection, isolation and manipulation application. This is because of biological property variations that require further DEP characterization and optimization. Practical implications The introduction of microelectrofluidics using DEP microelectrodes operate by selective detecting and rapid manipulating via lateral and vertical forces. This can be implemented on precision health-care development for lab-on-a-chip application in microfluidic diagnostic and prognostic devices. Originality/value This study introduces a new concept to understand the dynamic dielectric properties change. This is useful for rapid, label free and precise methods to conduct selective detection and rapid manipulation of mixtures of RBC and platelets. Further, potential applications that can be considered are for protein, toxin, cancer cell and bacteria detections and manipulation. Implementation of tapered DEP microelectrodes can be used based on the understanding of dynamic dielectric properties of polarization factor analysis.

Ionization profile of meteors from simultaneous video and radio forward scatter observations

<p>In this study, optical video observations of meteors with the CAMS (Camera for All-sky Meteor Surveillance)-BeNeLux network and radio forward scatter observations with the BRAMS (Belgian RAdio Meteor Stations) network obtained on 4-5 October 2018  are combined in order to obtain an ionization profile along a meteor path.</p><p>The trajectory, initial speed and deceleration parameters of a given meteor are provided by the CAMS-BeNeLux data. For a given trajectory, the positions of the specular reflection points for radio waves are computed for each combination of a given BRAMS receiving station and the BRAMS transmitter. For each receiving station which recorded a meteor echo (depending on the geometry and the SNR ratio), the power profile is computed and the peak power values of the underdense meteor profiles are used to determine the ionization (electron line density) at the various specular reflection points along the meteor path. This is done using the McKinley (1961) formula which is strictly valid for underdense meteor echoes.  We discuss how we compute the gains of the antennas, the polarization factor, and how the peak power values are transformed from arbitrary units into watts using the signal recorded from a device called the BRAMS calibrator. We also discuss how to extend this study to overdense meteor echoes or those with intermediate electron line densities.</p><p>Finally, these results are combined with a simple ablation meteor model in order to obtain an estimate of the initial mass of the meteoroid.</p><p>Mc Kinley D.W.R., Meteor science and engineering, Mc Graw-Hill eds, 1961</p>