Charging Current Research Articles

Electrodeposition of Silicon Fibers from KI–KF–KCl–K2SiF6 Melt and Their Electrochemical Performance during Lithiation/Delithiation

The possibility of using Si-based anodes in lithium-ion batteries is actively investigated due to the increased lithium capacity of silicon. The paper reports the preparation of submicron silicon fibers on glassy carbon in the KI–KF–KCl–K2SiF6 melt at 720 °C. For this purpose, the parameters of silicon electrodeposition in the form of fibers were determined using cyclic voltammetry, and experimental samples of ordered silicon fibers with an average diameter from 0.1 to 0.3 μm were obtained under galvanostatic electrolysis conditions. Using the obtained silicon fibers, anode half-cells of a lithium-ion battery were fabricated, and its electrochemical performance under multiple lithiations and delithiations was studied. By means of voltametric studies, it is observed that charging and discharging the anode based on the obtained silicon fibers occurs at potentials from 0.2 to 0.05 V and from 0.2 to 0.5 V, respectively. A change in discharge capacity from 520 to 200 mAh g−1 during the first 50 charge/discharge cycles at a charge current of 0.1 C and a Coulombic efficiency of 98–100% was shown. The possibility of charging silicon-based anode samples at charging currents up to 2 C was also noted; the discharge capacity ranged from 25 to 250 mAh g−1.

Out-of-equilibrium voltage and thermal bias response of a quantum dot hybrid system coupled to topological superconductor

We investigate theoretically the out-of-equilibrium transport properties of a single-level quantum dot coupled to a normal metal electrode and attached to a topological superconductor. Both voltage and thermal bias responses of the system in the nonequilibrium regime are studied. To obtain transport characteristics we used the nonequilibrium Green’s function approach. Particularly, we calculated the current and the corresponding differential conductance in two distinct cases. In the former situation, the charge current is induced by applying a bias voltage, whereas in the latter case it is generated by setting a temperature difference between the leads with no bias voltage. Moreover, strong diode effect in thermally generated current is found and non-equilibrium thermopower is analyzed.

Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments

Orbitronics is based on the use of orbital currents as information carriers. Orbital currents can be generated from the conversion of charge or spin currents, and inversely, they could be converted back to charge or spin currents. Here we demonstrate that orbital currents can also be generated by femtosecond light pulses on Ni. In multilayers associating Ni with oxides and nonmagnetic metals such as Cu, we detect the orbital currents by their conversion into charge currents and the resulting terahertz emission. We show that the orbital currents extraordinarily predominate the light-induced spin currents in Ni-based systems, whereas only spin currents can be detected with CoFeB-based systems. In addition, the analysis of the time delays of the terahertz pulses leads to relevant information on the velocity and propagation length of orbital carriers. Our finding of light-induced orbital currents and our observation of their conversion into charge currents opens new avenues in orbitronics, including the development of orbitronic terahertz devices.

Anomalies in global SMEFT analyses. A case study of first-row CKM unitarity

Recent developments in the Standard Model analysis of semileptonic charged-current processes involving light quarks have revealed ~ 3σ tensions in Cabibbo universality tests involving meson, neutron, and nuclear beta decays. In this paper, we explore beyond the Standard Model explanations of this so-called Cabibbo Angle Anomaly in the framework of the Standard Model Effective Field Theory (SMEFT), including not only low-energy charged current processes (‘L’), but also electroweak precision observables (‘EW’) and Drell-Yan collider processes (‘C’) that probe the same underlying physics across a broad range of energy scales. The resulting ‘CLEW’ framework not only allows one to test explanations of the Cabibbo Angle Anomaly, but is set up to provide near model-independent analyses with minimal assumptions on the flavor structure of the SMEFT operators. Besides the global analysis, we consider a large number of simpler scenarios, each with a subset of SMEFT operators, and investigate how much they improve upon the Standard Model fit. We find that the most favored scenarios, as judged by the Akaike Information Criterion, are those that involve right-handed charged currents. Additional interactions, namely oblique operators, terms modifying the Fermi constant, and operators involving right-handed neutral currents, play a role if the CDF determination of the W mass is included in the analysis.

S-NiSe/HG Nanocomposites with Balanced Dielectric Loss Encapsulated in Room-Temperature Self-Healing Polyurethane for Microwave Absorption and Corrosion Protection.

Exploring anticorrosion electromagnetic wave (EMW) absorbing materials in harsh conditions remains a challenge. Herein, S-NiSe/HG nanocomposites encapsulated in room-temperature self-healing polyurethane (S-NiSe/HG/SPU) were exploited as superior anticorrosion EMW absorbing materials. A dual-defect engineering collaborative Schottky interface construction endows S-NiSe/HG with a high vacancy concentration, abundant defects, and moderate conductivity. These structural merits synergistically balance dielectric loss by enhancing dipole-interface polarization loss and optimizing conduction loss. As a result, S-NiSe/HG demonstrates the optimal EMW absorption performance with a minimum reflection loss (RLmin) of -54.8 dB and an adequate absorption bandwidth (EAB) of 7.1 GHz. Besides, S-NiSe/HG/SPU combines the maze effect of S-NiSe/HG with the active repair capability of SPU, thereby providing long-term corrosion resistance for the Mg alloy. Even under corrosion for 10 days, S-NiSe/HG/SPU affords a low corrosion current density (1.3 × 10-5 A) and high charge transfer resistance (3796 Ω cm2). Overall, this work provides valuable insights for in-depth exploration of dielectric loss and development of multifunctional EMW-absorbing materials.

A standalone photovoltaic energy storage application with positive pulse current battery charging

In this paper, an innovative standalone photovoltaic (PV) energy storage application is introduced that can charge battery-powered road vehicles and helps to reduce the electrical grid burden in the future. The application couples a PV module and a lithium-ion (Li-ion) battery via an electrical power converter, i.e., a Ĉuk converter. First, the performance of the proposed application is completely analyzed with the mathematical modeling of the PV module, Ĉuk converter, and Li-ion battery. Furthermore, an advanced positive-pulse-current (PPC) battery charge control algorithm is combined with the popular hill-climbing PV MPPT in order to extend the battery life while fetching maximum PV energy. In order to extend the battery life, the PPC charge cycle allows no energy delivery during the half-cycle time, named the rest period. From an energy conversion efficiency point of view, the comparative results illustrate that a single converter and a single battery operation with PPC gains 95.73%, and a double converter and double batteries with “in-phase” PPC operation gains 94.4%. In both of these operations, the PV module delivers half the energy of nearly 19 J due to a rest period in the PPC charge cycle. However, a double converter and double batteries with “out-of-phase” PPC operation gain the highest efficiency 96.5% with full PV energy of 39.56 J. Therefore, the “out-of-phase” PPC operation is mostly recommended for standalone PV energy storage applications. Finally, an experimental hardware setup is developed to test the PPC charge algorithm with a resistive load and to validate the proposed application for different PPC operations with Li-ion batteries.

Laser-driven quasi-static B-fields for magnetized high-energy-density experiments

We present measurements of magnetic fields generated in laser-driven coil targets irradiated by laser pulses of nanosecond duration, 1.053 μm wavelength, 500 J energy, and ∼1015 W/cm2 intensity, at the LULI2000 facility. Using two perpendicular probing axes, proton deflectometry is used to characterize the coil current and static charge at different times. Results reveal various deflection features that can be unambiguously linked to a looping quasi-steady current of well-understood polarity or to a static charging of the coil surface. Measured currents are broadly consistent with predictions from a laser-driven diode-current source and lumped circuit model, supporting the quasi-steady assessment of the discharges. Peak magnetic fields of ∼50 T at the center of 500-μm-diameter coils, obtained at the moderate laser intensity, open up the use of such laser-driven coil targets at facilities worldwide to study numerous phenomena in magnetized high-energy-density plasmas, and its potential applications.

Spin-fluctuation-induced sign reversal of the spin Hall angle in Pt100−x Co x alloys near the Curie temperature

The spin Hall effect (SHE), typically emerging in non-magnetic metals with strong spin-orbit couplings, has attracted significant attention for its ability to convert a charge current into a spin current, a key feature in power-efficient spintronic devices. Recently, an enhanced SHE has been detected in the magnetic alloys, where the spin Hall conductivity is strongly modified by the dynamical and thermal spin fluctuations. We find that the spin Hall angle ( θSH ) in Pt100−x Co x alloys dramatically changes at the Curie temperature, which is positive in the paramagnetic phase akin to Pt, while negative in the ferromagnetic phase. Such intriguing behavior of θSH stemming from individual and collective fluctuations in the magnetic moments is further substantiated with the full-fledged Monte Carlo simulations. Our work broadens insights into the SHE and highlights the importance of spin fluctuations for the spin-current generation near the ferromagnetic instability point of magnetic alloys.

Fractional order modeling based optimal multistage constant current charging strategy for lithium iron phosphate batteries

AbstractThe primary power source for electric vehicles (EVs) is batteries. Due to the superior characteristics like higher energy density, power density, and life cycle of the lithium iron phosphate (LFP) battery is most frequently chosen among the various types of lithium‐ion batteries (LIBs). The main issues that users encounter are the time required to charge an EV battery and the safety of the EV battery during the charging period. The fast‐charging means, charging a battery with high currents which may lead to a rise in the temperature of a battery. The abrupt rise in battery temperature may cause changes in the internal chemical structures of the battery, reducing battery life even further. In this regard, an optimal charging profile design is of utmost importance in order to satisfy dual objectives simultaneously such as less charging time and improvement in life of the battery. To overcome the conflict between charging speed and rise in temperature an optimal multistage constant current (MSCC) based charging strategy has been investigated under different operating conditions. In addition, the proposed charging profiles have been studied using experimentation.

A Robust RF-Based Wireless Charging System for Dockless Bike-Sharing

In the past few years, dockless bike-sharing has become a popular means of public transportation and brought significant convenience to millions of citizens. As one of the key components of a shared bike, the smart locking/unlocking module has proposed a new challenge of how to provide robust power supplement for them. Current charging solutions for shared bikes are mainly based on mechanical power and solar power, and rarely take user experience and charging delay into consideration. In this paper, we design a robust RF-based wireless charging system for dockless bike-sharing. Our system utilizes radio frequency (RF) power to provide stable charging service while preserving the quality of service. In our system, an RF wireless charging sensing node is integrated on the bike's basket, so that the mutual interference during charging process and space occupation can be reduced. In order to reduce charging delay, we first design an efficient charging direction scheduling algorithm for a single charger. Then, we extend the solution to multiple-charger scenarios via dynamic programming. Our system has been successfully implemented on a dockless bike-sharing system. The experimental results verify that our design can satisfy the charging demands of shared-bikes and achieve <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$85\%$</tex-math></inline-formula> of the optimal solution.

Estimation of the residue capacity of lithium iron phosphate battery based on the internal resistance obtained from charging voltage drop

This study takes the 80 Ah lithium iron phosphate (LFP) prismatic battery that is from the vehicle and is in the middle or end of life as the research target, and the voltage-drop resistance (VDR), which is calculated through the voltage drop at the charging end, is used to for residue capacity estimation. The relationship between the VDR and the residue capacity of the battery is systematically studied, including factors such as charging cut-off voltage, charging current, charging end time, and charging current change mechanism. The results show that the residue capacity is a quadratic function relationship with the charging cut-off voltage and VDR. The VDR is affected by the charging cut-off voltage, charging cut-off current, and charging end time. There is no significant difference in the influence of VDR obtained by the charging modes of step charging and constant current charging. By testing the VDR under different charging conditions and different resting times, and standardizing the VDR, the residue capacity estimation error of 97% of the vehicle’s batteries is within ±5%, which meets the application requirements for residue capacity estimation.

Designing small batteries and adaptive charging strategies for operation on rough terrain

The global trajectory is swiftly progressing towards the adoption of electric vehicles (EVs). Given that batteries constitute a pivotal component within the domain of EV technology, their performance and life have become of utmost importance. Battery life is affected by multiple internal and external factors. This paper addresses real-time challenges associated with using battery packs in dynamic on-road conditions characterized by variable discharge rates, temperatures, depth of discharge, storage conditions, and rough terrains. The study involves designing 2.8kWh battery packs and using them to power e-rickshaws in on-road conditions in places like India. The study shows how minor issues, which are often overlooked during the initial pack design phase, can impact the long-term operational performance of the batteries.In real-world scenarios, users lack control over the discharge of a battery. However, the charging process can be effectively controlled. In this paper, we propose an adaptive slow-charging strategy to prolong the life of the battery pack. The suggested charging algorithm regulates the charging current based on parameters such as battery temperature, state of health, and terminal voltage. To assess the impact of this algorithm, we conducted tests on 2.8kWh battery packs used in e-rickshaws for over two years under real-world driving conditions. The effectiveness of the proposed algorithm is demonstrated by comparing the battery degradation with the standard constant current constant voltage charging. The study also introduces a novel balancing technique involving temporary suspension of balancing and charging currents during voltage measurements, mitigating errors linked to ohmic drops. Additionally, the research examines the degradation caused by parking vehicles for extended periods.

Electric Field Switching of Magnon Spin Current in a Compensated Ferrimagnet.

Manipulation of directional magnon propagation, known as magnon spin current, is essential for developing magnonic devices featuring nonvolatile functionalities and ultralow power consumption. Magnon spin current can usually be modulated by magnetic field or current-induced spin torques. However, these approaches may lead to energy dissipation due to Joule heating. Electric-field switching of magnon spin current without charge current is highly preferred but challenging to realize. By integrating magnonic and piezoelectric materials, the manipulation of the magnon spin current generated by the spin Seebeck effect in the ferrimagnetic insulator Gd3Fe5O12 (GdIG) film on a piezoelectric substrate is demonstrated. Reversible electric-field switching of magnon polarization without applied charge current is observed. Through strain-mediated magnetoelectric coupling, the electric field induces the magnetic compensation transition between two magnetic states of the GdIG, resulting in its magnetization reversal and the simultaneous switching of magnon spin current. This work establishes a prototype material platform that paves the way for developing magnon logic devices characterized by all electric field reading and writing and reveals the underlying physics principles of their functions.

Research on control strategy of rapid preheating for power battery in electric vehicle at low temperatures

Due to cold weather conditions, it is not advisable to use the remaining capacity of the power battery to heat it. Instead, the battery can only be preheated during charging when the battery power is almost consumed up. The traditional positive temperature coefficient (PTC) heating system combines the cockpit air conditioning and heating system with the low-temperature preheating system for the power battery cells. The PTC controller is integrated into the air conditioning control system. However, this integration requires the air conditioning to be activated in order to preheat the power battery. As a result, there is energy waste during the charging process. To address the aforementioned issues, this article proposes a rapid preheating system that utilizes an independent liquid circuit equipped with a high-voltage heater. The system achieves a preheating time of 2000 s for a ternary lithium battery with a capacity of 73kWh and a rated voltage of 770 V. Another important finding is that fluctuations in the current of the battery management system (BMS) occur during the rapid preheating process, leading to uncontrolled battery charging and discharging. The battery rapid preheating control strategy has been redesigned to rapidly heat the battery system by disconnecting the rapid charging relay of the high-voltage circuit, thereby prevents over-discharge and overcharge of the power battery. Experiments have shown that the BMS current increases or decreases in a stepwise manner, as expected by the design. The average temperature of the battery pack during onboard charge module slow charging and direct current fast charging is below 35 °C, and the maximum temperature difference is less than 6 °C. The proposed rapid preheating system and improved battery charging architecture can shorten the charging time and reduce energy consumption. This advancement will open up new possibilities for power battery protection and contribute to the development of lithium-ion batteries for electric vehicles at low temperatures.

Self-consistent quantum-kinetic theory for interacting drifting electrons and force-driven phonons in a 1D system

A self-consistent quantum-kinetic model is developed for studying strong-field nonlinear electron transport interacting with force-driven phonons within a nanowire system. For this model, phonons can be dragged into motion through strong electron–phonon scattering by fast-moving electrons along the opposite direction of the DC electric field. Meanwhile, the DC-field induced charge current of electrons can be either enhanced or reduced by the same electron–phonon scattering, depending on the relative direction of a DC field with respect to that of an applied temperature gradient for driving phonons. By making use of this quantum-kinetic model beyond the relaxation-time approximation, neither electron nor phonon temperature is required for describing ultrafast electron–phonon scattering and their correlated transports in this 1D electronic-lattice system.

Constraints on subleading interactions in beta decay Lagrangian

We discuss the effective field theory (EFT) for nuclear beta decay. The general quark-level EFT describing charged-current interactions between quarks and leptons is matched to the nucleon-level non-relativistic EFT at the OMeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left(\ extrm{MeV}\\right) $$\\end{document} momentum scale characteristic for beta transitions. The matching takes into account, for the first time, the effect of all possible beyond-the-Standard-Model interactions at the subleading order in the recoil momentum. We calculate the impact of all the Wilson coefficients of the leading and subleading EFT Lagrangian on the differential decay width in allowed beta transitions. As an example application, we show how the existing experimental data constrain the subleading Wilson coefficients corresponding to pseudoscalar, weak magnetism, and induced tensor interactions. The data display a 3.5 sigma evidence for nucleon weak magnetism, in agreement with the theory prediction based on isospin symmetry.

Graphite from Dead Li‐Ion Batteries: A “Powerful” Additive for Fabrication of High‐Performance Li‐Ion Capacitors

AbstractLithium‐ion capacitors (LICs) are considered a promising next‐generation energy storage system with high energy density and power capability. The conductive additive is a passive and indispensable material in deciding the electrochemical performance of an energy storage device during high current charging and discharging processes. The incorporation of a suitable conductive additive into the layers of an electrode improves electronic conductivity. It reduces the internal resistance and polarization of the electrode resulting in the enhanced performance of the charge‐storage system. Herein, recovered graphite (RG) is reported from dead Li‐ion batteries as an excellent conductive additive that can improve the electronic conductivity of the electrode material. Compared with commercial conductive additive acetylene black (AB), the TiO2 anode material with 5% RG delivered a high discharge capacity of 163 mAh g−1 at a current rate of 0.15 A g−1 with a coulombic efficiency of ≈99% after 500 cycles in half‐cell assembly. The fabricated AC/TiO2@5%RG LIC displays an excellent electrochemical performance with a maximum energy density of ≈50 Wh kg−1 at a current density of 0.15 A g−1. Notably, the LIC rendered promising performance at different temperature conditions (0, 10, 25, and 50 °C).

Research Progress and Prospects of Public Transportation Charging Station Layout Methods

Electric buses have been vigorously promoted and implemented in major countries worldwide and have generated a huge demand for charging stations. Optimizing the daily charging experience of electric buses, adapting the daily operation scheduling, improving the utilization rate of charging stations, reducing the load on the power grid, and improving the operation efficiency of electric bus line networks require the reasonable layout of the charging stations. In this study, public transportation charging station layout and siting is the research object. We summarize the progress of analysis methods from the charging station and vehicle sides; introduce related research on the planning and layout of charging stations based on optimization models, including cost analysis and siting and layout for electric bus systems; summarize the data-driven station planning and siting research; and provide an overview of the current charging demand estimation, accuracy, and charging efficiency. Finally, we address the problems of the charging demand estimation accuracy, the mismatch between the charging station layouts for electric buses, and the charging demand on a long time scale. We suggest that research be conducted on data fusion for the temporal and spatial refinement of charging demand prediction in the context of the electrification of public transportation systems and the big data of telematics.

A multi-mobility model for polymer insulation: Role of high-mobility space charge on breakdown with high dv/dt voltages

The failure of polymeric solid insulation under transient voltages is closely associated with space charge. In this study, DC and AC field dependent conduction characteristics of epoxy resin were investigated using the space charge limited current and high voltage broadband dielectric spectrum methods. The breakdown voltages (BDVs) were examined over a wide range of DC voltage ramp rates. The results reveal a threshold effect of AC conduction loss below 600 Hz with respect to the electric field. By analyzing charge migration laws, a mobility distribution was deduced, with an upper limit of 10−9m2V−1s−1, which is much higher than the measured DC mobility of 10−14m2V−1s−1. A multi-mobility bipolar charge transport model was proposed by introducing the obtained mobility distribution. Compared to the single-mobility model, high-mobility carriers induce larger unblocked space charge currents for high dv/dt voltages, leading to lower values of BDV, which is consistent with experiment results. As the voltage ramp rate decreases, both simulation and experiment demonstrate higher BDVs due to the field shielding effect of homocharges.

Multi-objective optimization estimation of state of health for lithium-ion battery based on constant current charging profile

The capacity decline, i.e., the state of health trajectory of lithium-ion battery is strongly nonlinear and volatile. Currently, most studies on the state of health assessment focus more on improving the estimation accuracy, rarely taking result stability into consideration. In this paper, a method adopting the multi-objective optimization extreme learning machine for estimating the state of health of lithium-ion battery based on the constant-current charging curve of the battery is proposed to improve both the estimation accuracy and stability. Firstly, apart from isovoltage rise charging time, a logit polynomial fitting model is taken to fit the constant-current charging curve to extract the features which highly associated with battery capacity level and proven by the Spearman coefficient. Then, the MOWOA-ELM prediction model is built for state of health estimation where the multi-objective whale search algorithm improved by non-dominated sorting and congestion calculation is used to optimize the hyperparameters of the extreme learning machine. Finally, the experimental and comparative results show that the root mean square error and the standard deviation of the state of health assessment results are only 0.43 % and 0.28 % respectively, demonstrating the feasibility and validity of the framework built in this paper.