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Lithium plating can cause capacity fade and thermal runaway safety issues in lithium-ion batteries. Therefore, accurately detecting the amount of lithium plating on the surface of the battery's negative electrode is crucial for battery safety. This is especially crucial in high-energy-density applications such as battery energy storage systems or in electric vehicles (EVs). Early detection of lithium plating is crucial for evaluation of reliability and longevity. It also serves as a method for early diagnostics in practical industrial applications or infrastructure, such as EV transportation. This can enhance its impact on customers. This study validates the effectiveness of titration gas chromatography (TGC) technology in quantitatively detecting lithium plating on graphite negative electrodes in lithium-ion batteries. The results show that it can detect a minimum of 2.4 μmol of metallic lithium. Compared with the heating direct current resistance and reference electrode methods, which can be used to perform only qualitative dendrite detection, TGC has a wider range of detection. Compared with the nuclear magnetic resonance (NMR) method with higher quantitative detection accuracy, the maximum difference between the detection results of the two methods was only 7.2%, but the TGC method had lower cost and higher implementation convenience. In summary, among various dendrite detection methods, the TGC method can not only realize the effective quantitative detection of lithium plating, but also comprehensively consider its detection range, implementation convenience, cost, and detection accuracy, indicating that it is suitable for engineering applications and has the prospect of realizing large-scale quantitative detection of lithium plating in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A model expressing beams, pillars, and electrical wiring in a building for lightning surge simulation by circuit analysis method is proposed in this paper. The proposed model expresses the self‐surge impedance of the electrical wiring as a function of the distance between conductors and the radius of the electrical wiring. The mutual impedance is expressed by the distance between the surfaces of a structure and a nearby wire instead of the distance between the conductor centers. In the case of two conductors having far different radii in proximity, the distribution of electromagnetic fields around the two conductors is similar in horizontal and vertical arrangements. Thus, the electrical wiring nearby pillars can be treated as a horizontal conductor. The circuit analysis results show that the voltage difference generated between the structure and the electrical wiring is calculated more precisely by the proposed model than by the conventional model. [ABSTRACT FROM AUTHOR]

We have shown that finite-difference time-domain (FDTD) electromagnetic computations for a conductor system having a radius smaller than 0.15[DELTA]r or larger than 0.65[DELTA]r ([DELTA]r is the lateral side length of cells employed), modeled using arbitrary-radius-wire representations proposed so far with a time increment determined from the upper limit of Courant's stability condition, result in numerical instability. A primary factor causing this numerical instability is that the speed of waves propagating in the radial direction from the wire in the immediate vicinity of the wire exceeds the speed of light, and therefore, Courant's condition is not satisfied there. It is further shown that for these cases, the arbitrary-radius-wire representation can be improved by modifying the material parameters for the axial field components closest to the wire as well as those for the radial electric and circulating magnetic field components. The improved wire representation is effective in representing a wire whose radius ranges from 0.0001[DELTA]r to 0.9[DELTA]r. Index Terms--Electromagnetic fields, finite-difference time-do-main (FDTD) methods, transient analysis, wire.

This paper has investigated the nonuniform characteristics of a counterpoise based on the frequency-dependence of R, L, C, and G and propagation parameters identified from measured results of transient voltages and currents on the counterpoise. It becomes clear that the characteristic impedance is significantly length-dependent (i.e non-uniform, at a high frequency). As the frequency tends to infinity, the maximum value of the characteristic impedance is almost the same irrespective of its geometry, physical constants and soil conditions. However, the characteristic impedance at a section near to source end is far smaller than that near to the remote end. The apparent series impedance increases and the admittance decreases for a counterpoise section farther to the source end. The propagation constant shows less noticeable nonuniformity than that for the characteristic impedance. Index Terms--Admittance, distributed-line, grounding electrode, impedance, nonuniform line, numerical identification.

Transient responses of a horizontal grounding electrode in three different arrangements of a current lead wire and a voltage reference wire are calculated using the finite-difference time-domain (FDTD) method for solving Maxwell's equations. The test arrangement does not significantly influence the transient response of the horizontal grounding electrode. The transient response calculated using the electromagnetic transients program (EMTP) for Sunde's equivalent circuit agrees reasonably well with the corresponding response calculated using the FDTD method, except for the initial rising portion of the voltage at the close end (to the excitation point) of the horizontal grounding electrode. The EMTP-calculated response for an equivalent circuit, modified to improve this discrepancy, agrees better with the corresponding FDTD-calculated response. Index Terms--Electromagnetic transient analysis, equivalent circuits, finite difference methods, grounding electrodes.

An equivalent radius of a thin wire in a lossy medium, represented by the finite-difference time-domain method, is derived using the concept that was proposed to derive an equivalent radius of a thin wire in air. Then, a simple technique to specify an arbitrary radius of a thin wire in a lossy medium is proposed. The proposed technique does not employ locally fine or nonuniform subgrids, but is based on an orthogonal and uniform-spacing Cartesian grid. The validity of the proposed technique is investigated in a transient state, as well as in a quasisteady state, and shown to be satisfactory. Index Terms--Finite-difference time-domain (FDTD), grounding electrode, grounding resistance, thin wire.

This paper has derived an impedance formula for conductor's semiconducting layer based on a conventional circuit theory. The formula is confirmed to be identical to an accurate one derived by solving Maxwell's equation. A wave-propagation characteristic and a transient voltage on a cable having the semiconducting layer on the conductor's surface are evaluated by applying the derived formula, and are compared with those on a cable with no semiconducting layer. The semiconducting layer increases the conductor impedance, and thus, the attenuation constant is increased, and the propagation velocity and the characteristic impedance are decreased for a coaxial mode by the semiconducting layer, but the inter-phase mode of propagation is not affected. A transient voltage is attenuated more and its oscillating period becomes greater than those on a cable with no semiconducting layer. The effect of the semiconducting layer impedance on the wave-propagation characteristic and the transient voltage is rather minor when the layer thickness is small and the resistivity is high, and the semiconducting layer effect is dominated by its admittance. Index Terms--Cable, impedance, semiconducting layer, transient, wave propagation.

This paper has proposed an impedance formula of pipe enclosed and tunnel-installed cables of which the thickness of the pipe and tunnel wall is finite. Thus, it is composed of a two-layered conductor (i.e., the first medium is the finite thickness pipe or the finite thickness tunnel wall, and the second medium is the outer conductor to infinite). The impedance by the formula developed in the paper shows a quite different characteristic from that calculated by an existing impedance formula which was derived from the assumption of an infinitely thick pipe. Wave propagation and transient voltage characteristics are investigated using the proposed formula, and a difference from those by the existing formula is made clear. The proposed impedance formula has made it possible a detailed and more accurate analysis of wave propagation and transient overvoltage characteristics on pipe-enclosed and tunnel-installed cables. Index Terms--Impedance, pipe-enclosed cable, transient, tunnel installed cable, wave propagation.

Archorn voltages of a simulated 500-kV twin-circuit line, in the case of one-phase back-flashover due to lightning to a tower top, are analyzed by the thin-wire time-domain analysis (TWTDA) code. Prior to this analysis, a recently proposed flashover model is incorporated into TWTDA. It becomes clear that the archorn voltages of the other two phases show a quite similar time-varying characteristic after one-phase back-flashover. An EMTP simulation is also carried out. The archorn voltages computed by the electromagnetic transients program (EMTP) agree well with those computed by TWTDA before the back-flashover on one phase. On the other hand, during about 1 [micro]s after the one-phase back-flashover, the archorn voltages of the other two phases computed by EMTP deviate much from those computed by TWTDA. Particularly in the case of the middle- or the lower-phase back-flashover, the deviation is noticeable. The reason for this discrepancy is discussed. Index Terms--Back-flashover, electromagnetic transients program (EMTP), lightning surge, numerical electromagnetic field analysis.