Charging Current Research Articles

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials.

An often observed artifact in atomic force microscopy investigations of individual monolayer flakes of 2D materials is the inaccurate height derived from topography images, often attributed to capillary or electrostatic forces. Here, we show the existence of a Joule dissipative mechanism related to charge dynamics and supplementing the dissipation due to capillary forces. This particular mechanism arises from the surface conductivity and assumes significance specially in the context of 2D materials on insulating supports. In such scenarios, the oscillating tip induces in-plane charge currents that in many circumstances constitute the main dissipative contribution to amplitude reduction and, consequently, affect the measured height. To investigate this phenomenon, we conduct measurements on monolayer flakes of co-deposited graphene oxide and reduced graphene oxide. Subsequently, we introduce a general model that elucidates our observations. This approach offers valuable insights into the dynamics of surface charges and their intricate interaction with the tip.

The impact of integrated circuits’ performance in low-temperature environments on charging efficiency of chargers

Abstract This paper explores the current research status of chargers and lithium-ion batteries in low-temperature environments. Based on this, it provides a detailed discussion and analysis of charger charging conditions, lithium-ion battery performance analysis, the correlation between low-temperature environments and charging, and optimization design strategies for charging in low-temperature environments. The study reveals that low-temperature environments distort charger current harmonics, disrupt the power supply capacity of the grid, and reduce fast charging conversion efficiency. The paper elucidates the lithium-ion battery lithiation mechanism, lithiation detection methods, and countermeasures for lithiation issues in low temperatures. Besides highlighting the various adverse effects of lithiation on low-temperature charging, it also points out the shortcomings of detection methods and proposes appropriate strategies to inhibit lithiation. Addressing charging issues in low-temperature environments, the paper introduces charging optimization design strategies involving temperature-modulated current charging and genetic algorithm optimization. This research offers theoretical guidance and technical support for the design and optimization of chargers and lithium-ion batteries in low-temperature environments, further advancing the development and application of low-temperature charging technology.

Can Electrochemical Impedance Spectroscopy be Replaced by Direct Current Techniques in Battery Diagnosis?

Electrochemical impedance spectroscopy (EIS), a conventional and alternating-current-(AC)-based technique for impedance measurement, is commonly used in battery diagnosis. However, it requires expensive equipment and demanding operating conditions and is complex and model-dependent in data analysis. Recently, novel direct current (DC) analytics have emerged as an alternative to EIS. They are simple yet powerful, being capable of revealing impedance information that traditionally could only be obtained through EIS and determining Li-ion diffusion coefficient. Besides, a complete EIS spectrum can be predicted based on constant current charging curves in the support of machine learning methods. This work highlights the similarities and discrepancies between DC techniques and EIS in the electrochemical analysis of Li-ion batteries. Looking ahead, DC techniques may be a promising substitute for EIS in future battery diagnosis, requiring simplified equipment while offering a deep understanding of battery impedance and its underlying electrochemical processes.

Substantially boosted energy density of NiCoMn layered double hydroxides with nanocrystalline-amorphous domains

To promote the energy density (E) of the hybrid asymmetric supercapacitance (ASC) device, both anode and cathode materials are crucial. The multi-component layered double hydroxides (LDH) as anode materials boost a surprisingly supercapacitance, while the functions of dual-phase nanodomains induced by multi-constituents on the electrochemical reactions are still puzzled and need to be explored. In this work, Ni1Co1Mnx (Ni/Co/Mn = 1/1/x) LDH microspheres are developed, characterizing by quantum-sized nanocrystals embedded in amorphous matrix modulated via Mn doping. The specific capacities (C) of Ni1Co1Mn1.5 reach up to 5750 at 1 A g−1 and 5300 F g−1 at 10 A g−1, exceeding four times of 1367 (1 A g−1) and 1133 F g−1 (10 A g−1) of the Ni1Co1Mn0 counterpart. To break through the upper limit of the traditional active cardon cathode, bamboo-derived porous carbon (BPC) powders are produced from green raw resource by two stages calcination to increase the C. The assembled ASC cell with Ni1Co1Mn1.5 as an anode and BPC as a cathode possesses a large E of 97.8 Wh kg−1 at a power density (P) of 749.2 W kg−1. An exceptional sustainability of Ni1Co1Mn1.5//BPC device is attained with 91.4 % retention after 8000 cycles at a large charging current of 10 A g−1. The insights of Mn-regulated transition of nanocrystal-amorphous microstructure and the enhanced energy storage performance are explored.

Digital Twin‐Assisted Degradation Diagnosis and Quantification of NMC Battery Aging Effects During Fast Charging

AbstractA comprehensive understanding of aging mechanisms and degradation diagnosis under fast charging in battery electric vehicles is needed. However, there is a lack of tools to capture both macroscopic and microscopic parameters, still focusing on experiment results analysis. To get a comprehensive degradation insight for improved service life, this study explores aging mechanisms in LiNi0.5Co0.2Mn0.3O2 graphite batteries under different fast charging conditions (0.6C to 2C) for up to 1000 equivalent full cycles (EFCs). An improved digital twin is used to quantify aging effects and identify aging modes, combining electrochemical techniques with post‐mortem analysis for assessing chemical and structural degradation. After 1000 EFCs, the dominant aging modes are loss of active material (LAM) in the negative electrode and loss of lithium inventory (LLI), surpassing LAM in the positive electrode. Compared to constant current charging, multistep fast charging effectively mitigates Li plating effects and graphite cracking, resulting in a 13% reduction in LAM. Additionally, optimizing the depth of discharge leads to at least 4% reductions in LLI and 16% in LAMpos. This study proves the electrochemical digital twin's potential for quantifying aging effects and serves as a basis for future physics‐informed machine learning to predict aging behavior and modes.

Top-quark FCNC decays, LFVs, lepton g − 2, and W mass anomaly with inert charged Higgses

The observed flavor-changing neutral-current (FCNC) processes in the standard model (SM) arise from the loop diagrams involving the weak charged currents mediated by the W-gauge boson. Nevertheless, the top-quark FCNCs and lepton flavor-violating processes resulting from the same mechanism are highly suppressed. We investigate possible new physics effects that can enhance the suppressed FCNC processes, such as a top quark decaying into a light quark with a Higgs or gauge boson in the final state, i.e. t → q(h, V) with V = γ, Z, g, h→ℓℓ′ , and ℓ→ℓ′γ . To achieve the assumption that the induced FCNCs are all from quantum loops, we consider the scotogenic mechanism, where a Z 2 symmetry is introduced and only new particles carry an odd Z 2 parity. With the extension of the SM to include an inert Higgs doublet, an inert charged Higgs singlet, a vector-like singlet quark, and two neutral leptons, it is found that, with relevant constraints taken into account, the t → c(h, Z), h → μ τ, and τ → ℓ γ decays can be enhanced up to the expected sensitivities in experiments. The branching ratios of h → μ + μ −/τ + τ − from only new physics effects can reach up to O(10−3) . Intriguingly, the resulting muon g − 2 can fit the combined data within 2 standard deviations, whereas the electron g − 2 can have either sign with a magnitude of O(10−13−10−12) . In addition, we examine the oblique parameters in the model and find that the resulting W-mass anomaly observed by CDF II can be accommodated.

Lithium-Ion Battery SOH Estimation Method Based on Multi-Feature and CNN-BiLSTM-MHA

Electric vehicles can reduce the dependence on limited resources such as oil, which is conducive to the development of clean energy. An accurate battery state of health (SOH) is beneficial for the safety of electric vehicles. A multi-feature and Convolutional Neural Network–Bidirectional Long Short-Term Memory–Multi-head Attention (CNN-BiLSTM-MHA)-based lithium-ion battery SOH estimation method is proposed in this paper. First, the voltage, energy, and temperature data of the battery in the constant current charging phase are measured. Then, based on the voltage and energy data, the incremental energy analysis (IEA) is performed to calculate the incremental energy (IE) curve. The IE curve features including IE, peak value, average value, and standard deviation are extracted and combined with the thermal features of the battery to form a complete multi-feature sequence. A CNN-BiLSTM-MHA model is set up to map the features to the battery SOH. Experiments were conducted using batteries with different charging currents, and the results showed that even if the nonlinearity of battery SOH degradation is significant, this method can still achieve a fast and accurate estimation of the battery SOH. The Mean Absolute Error (MAE) is 0.1982%, 0.1873%, 0.1652%, and 0.1968%, and the Root-Mean-Square Error (RMSE) is 0.2921%, 0.2997%, 0.2130%, and 0.2625%, respectively. The average Coefficient of Determination (R2) is above 96%. Compared to the BiLSTM model, the training time is reduced by an average of about 36%.

Research on topology technology of integrated battery energy storage system with reconfigurable battery and converter

In traditional battery energy storage systems (BESS), batteries are usually connected in a simple series or parallel form, and separate converters and balancing modules are typically used for energy exchange between the battery and external sources, as well as for balancing energy between batteries. This paper proposes an integrated battery energy storage system (IBESS) with reconfigurable batteries and DC/DC converters, resulting in a more compact structure. The IBESS can reconfigure the connection of energy storage batteries based on the battery's status and external demand. The DC/DC converters can operate in different modes such as boost, buck, or buck-boost converters. The IBESS has five working modes: discharging mode, balancing mode, battery discharging and balancing mode, constant current and constant voltage (CCCV) charging mode and backup mode. To verify the feasibility of the proposed energy storage system, a model with four battery modules was built using MATLAB/SIMULINK, and the operation of all working modes was demonstrated. The simulation results verified the system's performance and reliability, demonstrating its flexibility and efficiency in different operating modes.

A novel correlation-based approach for combined estimation of state of charge and state of health of lithium-ion batteries

State of charge(SOC) and state of health(SOH) estimation are two critical aspects for the secure operation and echelon utilisation of lithium-ion batteries. Considering the two states are interrelated, combined estimation methods are desired in practice. However, previous machine learning-based or traditional filter-based techniques have high computational requirements or suffer from convergence issues. To this end, the combined SOC and SOH estimation method of lithium-ion batteries using the novel correlation between SOC and SOH is proposed in this study. Specifically, a correlation between the capacity ratio for constant-current charging process and constant-voltage charging process and capacity loss is established. Extended Kalman filter is adopted to track SOC values at the end of constant current charging process instead of relying on the entire charging process during online application and SOH estimation can be accomplished in only one step based on the established correlation. The results show that the proposed combined SOC and SOH estimation method enables precise SOC estimation during both charging and discharging processes and achieves reliable estimation results during battery degradation. Additionally, the proposed method offers a swift means of estimating SOH with guaranteed estimation accuracy.

The sensitive detection of the early-stage internal short circuit triggered by lithium plating through the simplified electrochemical model at various working conditions

The internal short circuit (ISC) is one of the main causes of thermal runaway in batteries. Facing the current fast charging scenario of batteries, this paper aims to explore the sensitivity of solid-phase diffusion coefficient to ISC during high current charging. The voltage and current data of the real ISC is input into the simplified pseudo-two-dimensions model to identify the intrinsic parameters. The results indicate that the positive solid-phase diffusion coefficient (Ds,p) has higher sensitivity and stability than the negative solid-phase diffusion coefficient (Ds,n). For real ISC, the sensitivity of the solid-state diffusion coefficient increases as the charging current increases. This is consistent with the trends in ISC that we have derived from our low-temperature ISC extension experiment. For #1 ISC battery at 25 °C (SOC = 0.3–0.85), Ds,p changes by 56 % (3C) and 96 % (5C), and Ds,n changes by 6.87 × 10−14m2/s (166 %) (3C), 8.38 × 10−14m2/s (670 %) (5C). Moreover, the sensitivity of the solid-state diffusion coefficient to ISC decreases after battery aging, but it still has sufficient ability to diagnose ISC. High temperature will reduce the sensitivity of the solid phase diffusion coefficient.

Impact of Quantum Coherence on Inelastic Thermoelectric Devices: From Diode to Transistor

Abstract We present a study on inelastic thermoelectric devices, wherein charge currents and electronic and phononic heat currents are intricately interconnected. The employment of double quantum dots in conjunction with a phonon reservoir positions them as promising candidates for quantum thermoelectric diodes and transistors. Within this study, we illustrate that quantum coherence yields significant charge and Seebeck rectification effects. It’s worth noting that while the thermal transistor effect is observable in the linear response regime, especially when phonon-assisted inelastic processes dominate the transport, quantum coherence does not enhance thermal amplification. Our work may provide valuable insights for the optimization of inelastic thermoelectric devices.

Primary-Side Indirect Control of the Battery Charging Current in a Wireless Power Transfer Charger Using Adaptive Hill-Climbing Control Technique

This paper addresses the control task of a wireless power transfer (WPT) charger designed for electric vehicles (EVs). The challenge is to maintain a constant battery charging current when the WPT is controlled on the ground side. Indeed, the intermittent latency involved in the wireless data communication between the ground and vehicle sides leads to system instability. To overcome this issue, a new control approach has been proposed in this paper. The proposed technique ensures indirect control of the battery charging current through control of the current on the ground side. The control technique relies on an adaptive hill-climbing algorithm in conjunction with a PI-based controller. The adaptive parameter is adjusted online, during the operation of the charger, only when a new measure of the battery charging current is received on the primary side. This makes it possible to avoid the need for real-time wireless data communication. It should be noted that this aspect is crucial in ensuring the controller’s robustness and stability of the system regardless of potential delays in wireless communication and large misalignments between the coils. The validity of the proposed control technique has been confirmed through simulation. In addition, experimental validation, using a laboratory test bed, demonstrated satisfactory results.

Quantifying the State of the Art of Electric Powertrains in Battery Electric Vehicles: Comprehensive Analysis of the Tesla Model 3 on the Vehicle Level

Data on state-of-the-art battery electric vehicles are crucial to academia; however, these data are not published due to non-disclosure policies in the industry. As a result, simulation models and their analyses are based on assumptions or insider information. To fill this information gap, we present a comprehensive analysis of the electric powertrain of a Tesla Model 3 Standard Range Plus (SR+) from 2020 with lithium iron phosphate (LFP) cells, focusing on the overall range. On the vehicle level, we observe the resulting range in multiple test scenarios, tracing the energy path from source to sink by conducting different test series on the vehicle dynamometer and through alternating current (AC) and direct current (DC) charging measurements. In addition to absolute electric range tests in different operating scenarios and electric and thermal operation strategies on the vehicle level, we analyze the energy density and the power unit’s efficiency on the component level. These tests are performed through procedures on the chassis dynamometer as well as efficiency analysis and electric characterization tests in charge/discharge scenarios. This study includes over 1 GB of attached measurement data on the battery pack and vehicle level from the lab to the real-world environment available as open-source data.

Inverse spin galvanic effect in proximitized superconductor/paramagnet systems

We show that the interplay between spin–orbit coupling (SOC) and the paramagnetic response of itinerant electrons in proximitized superconductor/paramagnet systems gives rise to the inverse spin galvanic effect, i.e., generation of magnetic moment under the influence of the charge current. Depending on the sign of the SOC constant and the system temperature, the corresponding contribution to the magnetic response of the superconductor can be either diamagnetic or paramagnetic. We discuss the relevance between the discovered phenomena and the recent experiments on Pt/Nb heterostructures as well as the puzzling sign change of the magnetic response observed in clean Ag coated Nb cylinders.

Study of direct current charge transport mechanism in a series of iridium metal complexes based on varying ancillary and cyclometalated ligands

The mechanism of charge transport in a series of iridium metal complexes prepared with varying ancillary and cyclometalated ligands is reported here. The structural conformation of the synthesized complexes is acquired via NMR spectroscopy and elemental analysis. The photophysical properties of the samples are investigated through UV–visible and photoluminescence spectroscopy. The investigation of the temperature-dependent dc electrical conductivity of the samples is conducted within the temperature range of 280–473 K. The room temperature conductivity of all samples is determined to be of the order ∼10−8 S/cm. All the complexes exhibit semiconducting behavior in a certain temperature range above room temperature. A continued elevation in temperature leads to reduction in the conductivity of all the samples resulting in metal-like conduction behavior above a certain temperature. The transition temperature of the iridium metal complexes is attributed to the removal of the coordinated water molecule from the samples as suggested by thermal analysis of the complexes. The removal of water molecule from the sample is expected to localize the electron densities which consequently results in a fall of the conductivity in the samples. The conduction mechanism in the samples is analyzed in the light of band conduction mechanism and Mott’s variable range hopping model. All the samples are found to obey 1-D VRH mechanism. The activation energy and the corresponding Mott’s parameters are derived from the ln σ vs 1/T curves.

Enormous and Tunable Bulk Charge/Spin Photovoltaic Effect in Piezoelectric Binary Materials T-IV-VI and T-V-V.

Understanding the nonlinear response of light and materials is crucial for fundamental physics and next-generation electronic devices. In this work, we have investigated the second-order nonlinear bulk photovoltaic (BPV) and bulk spin photovoltaic (BSPV) effects in the piezoelectric binary materials T-IV-VI and T-V-V (IV = Ge, Sn; VI = S, Se; and V = P, As, Sb, Bi). The independent nonzero conductivity tensors of charge current are derived for these binaries through the symmetry analysis, along with the mechanism for generating pure spin current. These binaries, with their unique folded structure, exhibit significant charge and spin currents under illumination. Furthermore, we find that strain engineering can effectively modulate charge/spin currents by influencing charge density distribution and built-in electric field due to the piezoelectric effect. Our research suggests that the piezoelectric binary materials possess enormous and tunable charge/spin currents, underscoring their potential for applications in nonlinear flexible optoelectronics and spintronics.

Electrochemical oxidation of ATMP (Amino Trimethylene Phosphonic Acid) in low-concentrated acidic electrolyte on graphite and glassy carbon electrodes using cyclic voltammetry

This study investigates the irreversible electrochemical oxidation of Amino Trimethylene Phosphonic Acid (ATMP) in ClO4−–electrolyte on original unmodified graphite electrodes (GRE) and glassy carbon electrodes (GCE) using cyclic voltammetry (CV) as the main analytical technique. The oxidation reaction starts at ≈ +0.7 V on GRE and ≈ +0.92 V on GCE vs. Ag/AgCl (3M KCl) respectively. Four distinct electrode/electrolyte systems were selected for a comprehensive analysis of charge transfer and mass transport processes at non-Faradaic and Faradaic current regions at various scan rates υ (SR). These systems comprised of GRE/ClO4−–electrolyte, GRE/ATMP–ClO4−–electrolyte, GCE/ClO4−–electrolyte, and GCE/ATMP–ClO4−–electrolyte. Charging currents in the so-called double-layer region of the CV are found to scale linearly with SR on GCE (Adsorption mechanism); instead, the charging currents obey a nearly square root law on GRE (Diffusion mechanism). The electrochemical oxidation kinetics of ATMP in ClO4−–electrolyte using GRE and GCE obey nearly the fourth root law of the maximum oxidation current density (at the upper reverse potential) vs. SR. Finally, we identified the major transformation products generated from the ATMP electrochemical oxidation: ortho-phosphate (o− PO4), iminodimethylphosphonic acid (IDMP), and aminomethylphosphonic acid (AMPA).

Air-Processed All-Inorganic Halide Perovskites Integrated Photorechargeable Supercapacitors.

Due to their easy integration for self-powered operation, integrated energy harvesting and storage could be the game changer in smart, flexible, and portable electronic devices. Three-electrode integration is the most promising approach among all possible configurations because it is less complex and compatible with most techniques. Although the photoconversion efficiency has increased above 20% due to the integration of high-performance perovskite solar cells, the electrochemical storage efficiency (efficacy of the integration) is much below 80% due to a significant potential drop and impedance mismatch. In this context, we introduced perovskite-based solid-state thin film supercapacitors integrated with stable, air-processed perovskite solar cells for an uninterrupted power supply. Our measurement shows that the best performance can be achieved by optimizing several parameters, including series-connected solar cells, light intensity, and photovoltaic active area. The critical challenge with these integrated systems is to maintain a uniform charging current of the supercapacitors throughout the charging cycle while minimizing self-discharging. We achieved an electrochemical storage efficiency of ∼87% at an overpotential of 0.8 V. The overpotential can be as low as 2 mV. We fabricated fully solution-processed series-connected solar cells to integrate with stacked supercapacitors to improve the operating voltage beyond 2.1 V. The photocharging and dark discharging of these integrated devices have been tested over 200 cycles, and a negligible drop in efficiency has been observed. Our detailed energy conversion and storage analysis in these systems unveils the mechanism and losses due to three-terminal integration.

Charging delay elimination of solder impregnated HTS coils with specific excitation current

No-insulation (NI) coil has been recognized as the most practical solution at present to achieve ultra-high magnetic field with the REBCO high temperature superconductor thanks to its passive quench protection mechanism which is originated from the inter-turn current bypass. However, for the NI technique, one of the most important obstacles to a more general application is the field delay which is also a consequence of the lack of inter-turn insulation. The proportional and integral (PI) active feedback control of power supply has been developed to achieve a designed field ramping rate. The efficiency of this method could however be affected by the measurement accuracy of measuring equipment, sampling frequency, control accuracy of power supply and other factors. In this manuscript, we tried to use a more fundamental method to mitigate the field delay. The point is, though unlike in insulated coils the field generated is not proportional to coil current in NI coils, they do have a certain linear relation for a certain coil. Based on the lumped circuit model, the current charging curve corresponding to a desired field excitation could be calculated for a NI coil. We verified this method on several solder impregnated no-insulation coils (SINoInCs) to excite their field with different rates, for which the field delay with normal charging method could be very large because of the very low inter-turn resistance. The test results show that this kind of fast excitation method could successfully achieve the desired field with high accuracy and mitigate the field delay from 130 s to almost 0 s. Besides, the large overshoot current introduced by the fast charging does not quench the coils even with an overshoot current which is almost double of the coils’ operating current.

Leptonic neutral-current probes in a short-distance DUNE-like setup

Precision measurements of neutrino-electron scattering may provide a viable way to test the nonminimal form of the charged and neutral current weak interactions within a hypothetical near-detector setup for the Deep Underground Neutrino Experiment (DUNE). Although low-statistics, these processes are clean and provide information complementing the results derived from oscillation studies. They could shed light on the scale of neutrino mass generation in low-scale seesaw schemes. Published by the American Physical Society 2024