Charging Process Research Articles

Switching regulator based on an adaptive DC-DC buck converter for a lithium-ion battery charging interface

A switching regulator based on an adaptive DC-DC buck converter for a Li-ion battery charging interface is introduced in this paper with the aim of improving the efficiency of charging the Li-ion battery during the whole charging process. By using the battery voltage as feedback, an adaptive reference is generated. This reference is employed by the converter, which is in continuous conduction mode (CCM), to produce a wide adaptive output voltage that closely tracks the battery voltage, intended to serve as the power source for the multimode charging interface. The converter was implemented in a 180 nm complementary metal oxide semiconductor (CMOS) process and simulated using the Cadence Virtuoso tool. With an input voltage of 5 V and a switching frequency selected at 500 kHz, the simulation results show that the converter produces different charging currents for each battery charging mode, and an adaptive output voltage ranging from 2.8 V to 4.38 V, with the current ripple of 38 mA in CC mode and voltage ripple factor less than 1% in constant voltage (CV) mode. The average converter efficiency is 83.5%.

Data-Driven Cycle Life Prediction of Lithium Metal-Based Rechargeable Battery Based on Discharge/Charge Capacity and Relaxation Features.

Achieving precise estimates of battery cycle life is a formidable challenge due to the nonlinear nature of battery degradation. This study explores an approach using machine learning (ML) methods to predict the cycle life of lithium-metal-based rechargeable batteries with high mass loading LiNi0.8Mn0.1Co0.1O2 electrode, which exhibits more complicated and electrochemical profile during battery operating conditions than typically studied LiFePO₄/graphite based rechargeable batteries. Extracting diverse features from discharge, charge, and relaxation processes, the intricacies of cell behavior without relying on specific degradation mechanisms are navigated. The best-performing ML model, after feature selection, achieves an R2 of 0.89, showcasing the application of ML in accurately forecasting cycle life. Feature importance analysis unveils the logarithm of the minimum value of discharge capacity difference between 100 and 10 cycle (Log(|min(ΔDQ 100-10(V))|)) as the most important feature. Despite the inherent challenges, this model demonstrates a remarkable 6.6% test error on unseen data, underscoring its robustness and potential for transformative advancements in battery management systems. This study contributes to the successful application of ML in the realm of cycle life prediction for lithium-metal-based rechargeable batteries with practically high energy density design.

Revealing capacitive behaviors of graphene in ionic liquids using molecular dynamics simulation

Abstract This work reveals the capacitive behaviors of graphene nanomaterials in typical ionic liquids of [BMI+] [BF4 −] using molecular dynamics simulations. It is found that the charging process induces a structural transition from disordered to partially ordered and then ordered multilayer structures of [BMI+][BF4 −] electrolyte, yielding a multiple layer-by-layer packing structure of BMI+ cation and BF4 − anion. Especially, a counterion-adsorption-dominated Helmholtz layer is revealed at a high charge density of 16 μC/cm2, which is primarily responsible for the superior capacitance results. Besides, the differential capacitance of [BMI+][BF4 −] exhibits a symmetric convexity-shaped curve, showing a maximal capacitance value of 4.83 μF/cm2. The as-obtain simulation results help to understand the microscopic charge storage mechanisms of graphene in ionic liquids.

Electrochemical sodium storage properties in monolayer VOPO4: A density functional theory prediction

The unique structural properties of two-dimensional materials make them promising for energy storage applications. This work theoretically predicts for the first time that Monolayer VOPO4 (MNL VOPO4), exfoliated from the delithiated phase of tetragonal LiVOPO4, is stable at room temperature, exhibiting excellent thermodynamic and kinetic stability, thus making it a promising high-capacity anode material for sodium-ion batteries (SIBs). Compared to bulk VOPO4, the monolayer structure significantly reduces the sodium ion migration energy barrier from 1.006 to 0.0795 eV, thereby markedly enhancing sodium ion migration kinetics. MNL VOPO4 can adsorb up to 32 sodium ions, corresponding to a theoretical capacity of 634.88 mA h g−1 and an energy density of 895.18 Wh kg−1. Furthermore, the excellent structural stability of MNL VOPO4 favors its cycling performance during charge and discharge processes. This work provides theoretical insights for better utilizing and developing multi-atomic phosphate compounds as electrode materials for secondary batteries.

Analysis of the Influence of the Charging Process of an Electrical Vehicle on Voltage Distortions in the Electrical Installation

Analysis of the Influence of the Charging Process of an Electrical Vehicle on Voltage Distortions in the Electrical Installation

Controllable preparation and performance study of DAP-4/CuO high-energy microspheres

To enhance the dispersion uniformity of DAP-4/CuO composite fuel and improve the stability and consistency of the entire charge, particularly in small doses, DAP-4/CuO composite microspheres were prepared using a self-built coaxial microfluidic platform. This addressed the issue of uneven dispersion of DAP-4 and CuO, resulting in excellent dispersion of DAP-4/CuO composite microspheres. Furthermore, the impact of CuO content on DAP-4 microspheres was investigated. The samples were analyzed using scanning electron microscopy, laser confocal microscopy, differential scanning calorimetry, high-speed photography, and infrared thermal imaging. The findings revealed that when 1 % NC was added to the binder, FN-5 components were evenly dispersed. Microspheres produced through microfluidic technology exhibited a narrow particle size distribution which significantly improved sample dispersion and enhanced charging process safety. The addition of CuO notably accelerated the thermal decomposition process of DAP-4 microspheres and substantially increased sample burning rate. However, when CuO content exceeded 10 %, further increases did not continue to raise burning rate but led to decreased flame temperature. This study provides a reference for relevant workers.

Insight into the Enforced Stability of the Solid Electrolyte Interphase on the Graphite Anode by Prelithiation.

Prelithiation in a graphite anode is widely considered as an effective strategy to compensate for the lithium loss due to the formation of the solid electrolyte interphase (SEI), thus improving the cycle life of lithium-ion batteries (LIBs). However, less attention has been paid to the difference of the SEI established by prelithiation from that resulting from the charging process. To address this issue, a prelithiated graphite anode is prepared by thermal contact and its performances are investigated by electrochemical measurements and spectral characterizations. It is found that the significantly improved initial coulombic efficiency (ICE) and cyclic stability of the graphite anode by prelitiation are attributed to the formation of LiF-rich SEI. Different from the charging process that favors decomposition of solvents and results in a SEI mainly consisting of organic and inorganic carbonates, prelithiation is beneficial for the reduction of LiPF6 and results in a LiF-rich SEI that presents high stability and robustness, enabling the graphite anode with significantly improved cyclic stability.

Sodium storage performance and mechanism of amorphous FePO4/rGO nanocomposite as a novel anode material for sodium ion batteries

Exploring novel and cost-effective anode materials is highly desired for the development of sodium-ion batteries (SIBs). Herein, an amorphous FePO4/reduced graphene oxide (FP-G) composite is prepared by a simple chemical precipitation method with leaching liquor of jarosite residue as Fe source. When used as a novel anode material for SIBs, this FP-G composite exhibits a high sodium storage activity (341.6 mAh g−1 after 100 cycles at 0.2 A g−1), superior long-term cycling stability (215.8 mAh g−1 after 1500 cycles at 0.5 A g−1), and outstanding high-rate capability (190.8 mAh g−1 at 5.0 A g−1). The FP-G composite shows a significant pseudocapacitance behavior and good electrochemical reversibility during discharge and charge processes. This work proposes a simple, feasible, and cost-effective strategy for the high-valued utilization of jarosite residue, and deeply investigates the sodium storage mechanism and potential value of FP-G composite as a novel anode material for SIBs.

High-Performance p-type organic electrode materials with oxygen atoms as active centers enabled by molecular design and in situ electropolymerization

Redox-active organic molecules are considered to be one type of promising electrode materials for next generation lithium-ion batteries (LIBs), among which p-type electrode materials with higher voltage and outstanding reaction kinetics receive much attention. However, it is a great challenge to develop p-type materials with oxygen atom as the active center and the electrochemical performance of the few reported examples needs significant improvement. Herein, 1,3,5-tri(benzofuran-2-yl)benzene (TBFB) was elaborately designed and facilely synthesized through one-step Suzuki coupling reaction from commercially available raw reagents. When used as p-type electrode material for LIBs, it was found that TBFB with poor solubility can be effectively in situ electropolymerized during the charging process, forming more insoluble polymers. Experimental results demonstrate that TBFB electrode achieves a high specific capacity of 179.1 mAh g−1 and an ultralong cycle life of 8000 cycles. This work manifests the electrochemical performance of p-type organic electrode materials with oxygen atom as active center can be effectively enhanced by rational molecular design and in situ electropolymerization method.

Optimization research on control strategies for photovoltaic energy storage systems considering multi-mode operation

In this paper, a selective input/output strategy is proposed for improving the life of photovoltaic energy storage (PV-storage) virtual synchronous generator (VSG) caused by random load interference, which can sharply reduce costs of storage device. The strategy consists of two operating modes and a power coordination control method for the VSGs. Firstly, a selective VSG input strategy is proposed based on the magnitude of disturbances, a method of offline solving model equation is used for determine the VSG input time. An online method is used for matching the disturbance frequency variations, which enables a selective VSG startup method, allowing the grid to prioritize the utilization of the generator's physical inertia. Secondly, a dynamic VSG exit strategy is developed based on dynamic frequency characteristics to prevent secondary oscillations in the frequency recovery phase of the PV-storage VSG following grid disturbances. This strategy is crucial as grid variations may affect energy storage lifespan and reduce frequency recovery speed. Finally, the proposed approach is validated for correctness and effectiveness through computer simulations and semi-physical experiments using the NI-PXI + LabVIEW platform. Through the above optimization and research, the selective start of VSG is realized, the energy storage life is improved, the capacity of charge and discharge cycles is reduced by 37.82 % compared with the strategy without investment and withdrawal, and the life loss in the secondary charge and discharge process of PV-storage VSG is avoided, which is conducive to frequency recovery.

Modification of high-density polyethylene-based separator to improve lithium-ion battery performance using nano-silica and maleic anhydride

Due to its good mechanical properties and chemical stability, high-density polyethylene (HDPE) has become a fantastic polyolefin for its application in lithium-ion batteries (LIBs) as the separator of electrodes. In this work, nano-silica as a mineral material and maleic anhydride as the compatibilizer of HDPE-silica were used at different combinations to promote the HDPE-based separator efficiency. According to the results, maleic anhydride caused a perfect distribution of nano-silica particles in the polymer media leading to increasing its porosity and reducing the separator heat-shrinkability by 98 %. Also, they improved the compound electrolyte absorption from 49.4 to 94.2 % which led to a decrease in the contact angle value from 65 to 40.2 degrees. The thermal analysis showed a ~10 % reduction in the compound crystallinity without any significant change in the melting point. The obtained data indicated that the HDPE separators made of 5 wt% silica and maleic anhydride are the best candidates for LIBs. The mentioned formulation decreased the separator resistance from 860 and 410 Ω, electrolyte resistance from 13 to 8 Ω, and the increment of the ion conductivity from 0.78 to 1.24 × 10−3 S.cm−1, the LIB capacities from 99.8 to 129.8 mAh/g and 97.8 to 127.59 mAh/g at the charge and discharge processes.

Frequency optimization of the AUV wireless charging system for minimum energy dissipation

With the growing demand for ocean exploration, research on docking technology is gaining popularity, resulting in the development of various types of docking systems. In contrast to traditional cable-based systems, this paper introduces a self-powered docking system designed for AUV recovery and recharging. To minimize energy loss in the self-powered system, an analysis of eddy current loss produced by the coils in the seawater is conducted, and a calculation method for determining the equivalent eddy current impedance is proposed. This allows for the transformation of energy loss analysis from the magnetic field to circuit analysis. Then the efficiency of the inductively coupled power transmission system in seawater is analyzed, and a frequency optimization method is proposed to minimize dissipated energy during the AUV battery charging process. Finally, the effectiveness of the frequency optimization method is validated through laboratory experiments. Moreover, the results of the sea trial confirm the feasibility of the optimal wireless charging system operating in a seawater environment.

Speed Strategy on High-Pressure Compressor for the Charging Process of Advanced Adiabatic Compressed Air Energy Storage During Dynamic Shutdown

Abstract Advanced adiabatic compressed air energy storage (AA-CAES) starts and shuts down frequently. A detailed charging process comprising three series of centrifugal compressors with intercoolers was constructed within the framework of UniSim® Design. The safety measures were meticulously considered by integrating anti-surge circuits, vent valves, and check valves. PI controllers were allocated to the primary component to govern the shutdown procedure. The speed strategy of the HP inverter motor during the load shedding stage is the focus of research. Six speed strategies, including decreasing speed, constant speed, and increasing speed, were discussed, respectively. The discussion focused on changes made to air injection, inlet mass flow of the HP, inlet and outlet pressure of both the middle-pressure compressor (MP) and HP, and energy efficiency. The study found that implementing the minimum allowable speed for the inverter motor speed (IMS) and increasing speed during the load shedding stage can cause fluctuations in the air injection. As IMS increases at the end of the load shedding stage, the pressure anomalies at the MP outlet and the HP inlet weaken, and the shutdown process's energy efficiency improves. The HP inlet flow fluctuations caused by various strategies were within an acceptable range. This study reveals that there is a mutual influence between components in the charging process of AA-CAES. An appropriate speed strategy for the HP inverter motor can mitigate the operational hazards. The results of this study can provide guidance for similar AA-CAES shutdowns.

Electrochemical-mechanical coupled lithium growth in fiber-structured electrodes

Lithium plating (stripping) on the electrode surface and embedding inside the electrode occur simultaneously in lithium-ion batteries during fast (dis)charging, which involves both deposition and diffusion mechanisms. The paper presents a developed finite-element procedure that accommodates these two mechanisms, facilitating the modeling of the (dis)charging process in electrodes. The framework, which integrates interface electrochemical reaction kinetics, electrochemical-mechanical coupling, comprehensive constitutive models for silicon/graphite/lithium, and a surface growth re-meshing algorithm, is capable of real-time simulation of the surface deposition and coupled diffusion-deformation processes on the electrode substrate. We examined the effects of charging rate, diffusion rate and volumetric expansion on the stress of the plated lithium layer in a fiber-structured electrode. By accounting for creep in lithium metal and subsequent stress relaxation, we obtained time-dependent stress profiles in the plated lithium layer. As an application, we quantified electroplating stresses in both fiber-structured graphite and silicon electrodes. Taking the silicon electrode as a model case, we demonstrate that hollow fiber structural electrodes can also alleviate the stress in the surface lithium-plating layer. The numerical framework may be further applied to explorations for the optimization of electrode structures in advanced high performance lithium-ion batteries.

A heuristic-fuzzy improved virtual synchronous generator control strategy for charging station frequency regulation

To make use of charging station (CS) frequency regulation (FR) capability to get a better FR effect, a CS virtual synchronous generator (VSG) frequency control strategy based on the heuristic-fuzzy logic controller (FLC) is proposed in this paper. First, a CS VSG control architecture with heuristic-FLC is designed. Second, considering electric vehicle (EV) users' charging demands, a CS FR capability evaluation model based on the constant current-constant voltage (CC-CV) charging process and a V2G power response model based on frequency up/down-regulation participation factor are designed. Furthermore, a heuristic-FLC optimized by genetic algorithm (GA) is designed to improve the FR effect of the VSG control strategy. Simulation results show that the proposed strategy can make full use of the CS FR capability and get a better FR effect. In addition, the V2G power response model proposed in this paper can achieve the orderly responses of EVs in a CS under different scenarios.

Lattice Boltzmann simulation of ion transport during the charging process of porous electrodes in randomly reconstructed seawater desalination batteries

The economics and desalination results of desalination cells are superior to those of other desalination technologies due to their unique electrochemical mechanisms. Nevertheless, there has been a paucity of research into the potential mechanisms of pore-scale ion removal during the operation of this specific type of battery. In this paper, the relationship between electrode microstructure and cell performance is investigated by establishing a lattice Boltzmann model and a high-fidelity two-dimensional electrode structure. The results demonstrate that the random morphology and irregular agglomeration of particles result in significant differences in electrode performance. During electrode deionization, the ion embedding process is faster in particles close to the main flow. In addition, sodium ions are inserted faster in small particles than in large particles. If the particles comprising the electrode exhibit a localized uneven distribution, it is advantageous to have a greater density of particles in the vicinity of the flow channel. The larger the reaction interface per unit area, the faster the interpolation rate of the particle, while the larger the total area, the larger the interpolation capacity of the particle.

Integration and capacity optimization of molten-salt heat storage in coal-fired power plant with carbon capture system

Developing a new generation of economical, low-carbon, and flexible coal-fired power plants (CFPP) is crucial for achieving the low-carbon transformation of the energy industry. Deploying molten salt heat storage (MSHS) in the CFPP can effectively enhance its peak shaving capability and reduce the limitations of carbon capture on wide range operation of the plant. To this end, this paper proposes four integration schemes for MSHS into the power plant-carbon capture system. The thermal efficiencies, exergy efficiencies, and peak shaving capabilities of the entire plant under different integration schemes are evaluated and compared. The results indicate that the optimal integration scheme involves utilizing hot reheat steam to heat the cold molten salt and further provide heat for the carbon capture system during the heat charging process and utilizing hot molten salt to heat the outlet water of the feed water pump during the heat discharging process, which achieves the highest thermal efficiency of 38.00 % and exergy efficiency of 37.09 % across the entire cycle. A novel integrated design, scheduling, and control optimization (IDSCO) method is proposed to find the optimal capacity configuration of MSHS, in which the investment, maintenance, fuel, carbon emission, and long-timescale and short-timescale load tracking deviation penalty costs are fully considered. A design parameter-aware control system is developed based on a multi-parametric programming model predictive control approach to ensure a fair evaluation of closed-loop dynamic performance under different configuration capacities. The simulation results demonstrate that the deployment of MSHS can significantly enhance the flexibility of the power plant-carbon capture system and the proposed IDSCO approach can reduce 17.05 % of load tracking deviation penalty cost and 1.38 % of totalized cost compared to the conventional configuration approach. This paper effectively leverages the potential of MSHS in enhancing the operational flexibility of CFPP-PCC system, thereby providing useful guidance for future deployment of MSHS within CFPP-PCC system.

Continuous charging assignment algorithm for heterogeneous robot clusters based on E-CARGO

Forming robot clusters is a common means to improve work efficiency and ensure personnel safety in intelligent logistics warehousing. However, designing a reasonable charging sequence and time for each robot in the cluster poses a major challenge for management personnel. In actual scenarios, the working and charging processes of the robots must be considered simultaneously. This study also considers multiple constraints on robot battery levels and available workstations under different parameters to ensure each team operates normally at any given time. Additionally, to enhance cooperation efficiency and alleviate the workload of management personnel, the problem is transformed from conventional one-time assignments to adaptive continuous assignments within fixed time periods. Accordingly, the ACP-GRAC problem is proposed. Firstly, a group role assignment model with conflicts is introduced to resolve assignment conflicts caused by mismatches between job skills and position requirements. Then, energy information is shared among robots during the charging process, adding adaptive cooperation concepts to address continuous charging issues. Finally, the E-CARGO model is utilized to formalize the ACP-GRAC problem, and the HCCA algorithm is designed for its solution. Furthermore, a classification backtracking strategy is proposed to simultaneously address the constraint of continuous operation at any given time and the problem of constraint violations caused by the HCCA algorithm’s pursuit of maximum team performance. Moreover, since the classification backtracking strategy can compute the theoretical minimum remaining energy of the robot before departing for charging, it further optimizes the overall work efficiency. Additionally, this study addresses the issue of low cluster work efficiency due to the unreasonable initial planning sequence of the algorithm. In the experimental section, comparisons are made with recent excellent heuristic algorithms and deep reinforcement learning algorithms. Experimental results demonstrate that B-HCCA exhibits significant advantages in both solution efficiency and solution quality when addressing adaptive cooperation problems with group role assignment conflicts.

Fluorinated Amide-Based Electrolytes Induce a Sustained Low-Charging Voltage Plateau under Conditions Verifying the Feasibility of Achieving 500 Wh kg-1 Class Li-O2 Batteries.

Although lithium-oxygen batteries (LOBs) hold the promise of high gravimetric energy density, this potential is hindered by high charging voltages. To ensure that the charging voltage remains low, it is crucial to generate discharge products that can be easily decomposed during the successive charging process. In this study, we discovered that the use of amide-based electrolyte solvents containing a fluorinated moiety can notably establish a sustained voltage plateau at low-charging voltages at around 3.5 V. This occurs under conditions that can verify the feasibility of achieving a benchmark energy density value of 500 Wh kg-1. Notably, the achievement of the low-voltage plateau was accomplished solely by relying on the intrinsic properties of the electrolyte solvent. Indeed, synchrotron X-ray diffraction measurements have shown that the use of fluorine-containing amide-based electrolyte solvents results in the formation of highly decomposable discharge products, such as amorphous and Li-deficient lithium peroxides.

Thin-walled aluminium waste remelting in circulation circuit with magnetodynamic pump

Modern technologies for remelting thin-walled aluminium waste are considered, and a new method to implement such process is proposed. This made it possible to increase the yield of a suitable remelted product to 83% from the mass of the initial remelting portion. The main idea is to use indirect heating of the charge. This will allow to significantly reduce the irreversible loss of metal due to burning which can reach 60%. In the proposed process, solid waste is melted by overheated melt stream. The movement of such stream is provided by the action of electromagnetic field. For the practical implementation of the offered idea, there was used a magnetodynamic pump (MDP) designed in the Physico-Technological Institute of Metals and Alloys of National Academy of Sciences of Ukraine. The MDP has a significantly higher heat and power factor than electromagnetic pumps of travelling magnetic field which are often used in similar technologies. Mathematical model of the remelting process of aluminium thin-walled and fine charge due to convective heat transfer was developed. On the basis of this model, an engineering calculation of the specific process of remelting used aluminium cans in the liquid aluminium stream was also carried out. The obtained results were used at further conducting a full-scale experiment. There is designed and successfully practically tested the experimental two-chamber circulation circuit with MDP for remelting thin-walled aluminium waste. Recommendations for further development of the proposed process were formulated.Graphical abstract