Current State Research Articles

Determination of a small elliptical anomaly in electrical impedance tomography using minimal measurements

Abstract We consider the problem of determining a small elliptical conductivity anomaly in a unit disc from boundary measurements. The conductivity of the anomaly is assumed to be a small perturbation from the constant background. A measurement of voltage across two point-electrodes on the boundary through which a constant current is passed. We further assume the limiting case when the distance between two electrodes go to zero, creating a dipole field. We show that three such measurements suffice to locate the anomaly size and location inside the disc. Two further measurements are needed to obtain the aspect ratio and the orientation of the ellipse. The investigation includes the studies of the stability of the inverse problem and optimal experiment design.

DAB-Based Bidirectional Wireless Power Transfer System with LCC-S Compensation Network under Grid-Connected Application

To realize two-way power transfer without physical connections under a grid-connected application, bidirectional wireless power transfer (BDWPT) is introduced. This paper proposes an LCC-S compensated BDWPT system based on dual-active-bridge (DAB) topology with the minimum component counts. LCC-S is designed to be a constant voltage (CV) network. To obtain the power transmission characteristics of the system, a mathematical model based on the fundamental harmonic approximation (FHA) method is established, and the result shows that the direction and amount of transfer power can be controlled by changing the magnitude of output voltages of either/both side of H-bridges. The reactive power of the system can be controlled to be zero when the output voltages of two H-bridges are in the same phase. Compared with DAB-based BDWPT systems with constant current (CC) compensation networks, the proposed structure has better transfer power regulation capability and easier control of the direction of power flow. A 1.1 kW experimental prototype is built in the laboratory to verify the characteristics of the proposed system. The results indicate that the power transfer characteristics of the proposed BDWPT system match its mathematical derivation results based on the FHA model.

Electrochemically assisted sol-gel deposition of bioactive gels for biomedical applications

AbstractSo far, the sol-gel process has been available to prepare precursor gels of bioactive glasses with various compositions. In this report, we described a novel coating method of bioactive gels on a titanium substrate where the sol-gel transition is controlled by applying external electric fields. The application of a constant current of 10 mA/cm2 in an acidic sol containing pre-hydrolyzed tetraethoxysilane, calcium nitrate, and ammonium dihydrogen phosphate led to the deposition of gels on the titanium cathodes due to the generation of OH– by water electrolysis as a catalyst of the sol-gel transition. The obtained gels, which were characterized to be amorphous and consisted of Si, Ca, and P, covered the titanium substrates as a coating. The bioactivity of the gels deposited was confirmed by soaking in a simulated body fluid (SBF) up to 7 days, suggesting that the electrochemically assisted sol-gel process is promising for providing bioactive coatings on metallic implants. Graphical Abstract

Status of off-bottom mariculture in wave-exposed environments. Part 2. Comparative loading and motion of longline designs currently used in exposed commercial farms

A global inventory of extractive species mariculture in wave-exposed temperate waters shows that the longline is the technology used in more than 99% of the sites (Part 1 of this review). In this second part, I compare the static (longline at rest), quasi-static (tidal sea surface elevation, steady currents and mainline lifting operation) and dynamic (wind seas and swells) loading and motion of surface, semi-submerged and fully submerged longlines used to grow bivalves and kelp. This review is based on a hundred papers published on the subject mostly after 2010 and on simple analytical models used to illustrate the many compromises that must be made to ensure the survivability of the structure and the survival (retention), growth and quality of the cultured biomass. Surface longlines are unsuitable for fully exposed environments. To mitigate storm energy it is necessary to minimize the volume of surface buoys and submerge the mainline to the maximum depth possible. There is however a limit to minimizing the volume of surface buoys due to the uplifting of the mainline by currents. In the case of kelp, its optimal growing depth is within a few meters from the sea surface. This limitation can be partly circumvented by having the kelp float above the mainline. In the case of bivalves, mainline depth can be tens of meters below the sea surface. This comes with some disadvantages including difficulties in maintaining the delicate buoyancy balance, particularly for fully submerged longlines without legs, and reduced access to the mainline, particularly for fully submerged longlines with legs. Devices that allow autonomous or remote-controlled changes of mainline depth on a daily, occasional (husbandry and harvest operations) or seasonal basis have been tested but are not yet used commercially on longlines.

Steady and transient modeling of dye-sensitive solar cells: The impact of electrode thickness and dye specifications

Investigating the impact of dye compounds on cell performance is crucial for advancing dye-sensitized solar cells (DSSCs). This research focuses on the sensitivity analysis of the effect of critical parameters to enhance DSSC efficiency using a thermo-electric numerical model. These parameters include dye types, trapping parameters, diffusion coefficients, and photoanode thickness. When the type of dye changes, in fact, both physical and chemical properties (molar absorption coefficient, etc.) Change, but to avoid the complexity of solving the equations and only to evaluate the effect of the absorption wavelength range on the cell performance only changes in physical properties are considered. The model calculates steady and transient currents under actual weather conditions and sunlight. It incorporates time/space-dependent relationships for increased accuracy and examines electron, iodide, and triiodide ion interactions under varying environmental conditions. Key concepts include the quasi-Fermi level and the multiple trap model, assuming that trapping processes are faster than electron transport and recombination. The results showed that increasing the trapping parameter can affect the transient current behavior, also increasing the thickness of the photoanode and the wavelength range of the dye increases the efficiency of the cell, so that the N749-BD provides the best performance. The findings provide insights into current–voltage characteristics, electron production, and the effects of photoanode thickness and dye types on cell performance, offering pathways for optimizing DSSC technology.

Therapeutical Approach to Arterial Hypertension - Current State of the Art.

Arterial hypertension (AH) is recognized as the most common illness within the group of cardiovascular diseases and the most massive chronic non-infectious disease in the world. The number of hypertensive patients worldwide has reached 1.28 billion, contributing to an increase in cardiovascular diseases and premature death globally. The high prevalence of hypertension emphasizes the importance of effectively treating this condition. Elevated blood pressure often leads to lethal complications (heart failure, stroke, renal disorders, etc.) if left untreated. Considering an increase in AH prevalence in the future, a successful therapeutical approach to this disease and its complications is essential. The goal of AH treatment is to maintain normotensive blood pressure through various approaches, including lifestyle changes, a well-balanced diet, increased physical activity, psychoeducation, and, when necessary, pharmacotherapy. The evolving pharmacotherapeutic landscape reflects the progress made in our understanding of hypertension and emphasizes the need for continuous innovation to meet the challenges posed by this prevalent global health concern. The journey toward more effective and tailored treatments for hypertension is ongoing, and the introduction of new medications plays a pivotal role in shaping the future of antihypertensive pharmacotherapy.

Assessing the influence of dose modulation on water equivalent diameter estimation in pediatric head CT imaging

Pediatric head computed tomography (CT) scans necessitate precise determination of radiation dose to optimize image quality while minimizing patient exposure. This study explores the influence of head size variation on radiation dose and image quality using phantom and patients set, aiming to investigate the efficacy of Automatic Exposure Control (AEC) in dose modulation. Image noise and radiation dose were assessed using with and without AEC, maintaining a constant tube current of 180 mA. The correlation between CT dose index volume (CTDIvol) and water-equivalent diameter (Dw) was examined across 134 image sets, revealing an exponential relationship indicative of AEC's contribution to elevated radiation exposure in larger heads. Furthermore, a slice-based analysis demonstrated a consistent variation in tube current along the slice location, effectively modulated by Dw. However, discrepancies in tube current were observed in the caudal region, suggesting the influence of factors beyond section size. Refinement of analysis improved curve fitting, highlighting the importance of section size in dose modulation. AEC proved essential in maintaining image quality consistency across slices, with inactive AEC resulting in lower image noise in cranial slices. These findings highlight the significance of AEC-based dose modulation in pediatric head CT to ensure optimal image quality while minimizing radiation exposure, emphasizing the need for comprehensive understanding and implementation of AEC systems from different manufacturers.

A Dual Constant Current Output Ports WPT System Based on Integrated Coil Decoupling: Analysis, Design, and Verification

With the high integration of power electronic devices, wireless power transfer (WPT) systems are required to have output characteristics of different specifications that are independent of the load. However, existing methods for realizing dual-output WPT systems have problems such as complex circuits, cumbersome control schemes, low system stability, insufficient system space utilization, and unnecessary cross-coupling. Therefore, in order to solve the above problems, this paper proposes a dual-receiver WPT system with dual constant current (CC) output based on an integrated decoupling coil. In this system, the DD coil is wound vertically in series with the solenoid coil and serves as the first receiving coil to achieve energy transmission in the system. While the solenoid coil is used in the transmitting coil and the second receiving coil, and the coils are perpendicular to each other to achieve natural decoupling. Furthermore, the receiving coils are integrated together on the receiving side ferrite plate. Therefore, there is no cross-coupling interference in the system, which simplifies the system design. Firstly, the natural decoupling characteristics of the magnetic coupler and the coil optimization method are analyzed in detail theoretically. Secondly, a detailed mathematical analysis is performed on the dual CC output characteristics with different specifications that are load-independent and have zero phase angle operation. Again, the zero voltage switching of the inverter can be achieved by changing the compensation component parameters through simulation verification. Finally, a prototype with a rated power of 283 W is constructed for validation purposes. The first receiver delivers a CC output of 3 A, while the second receiver provides a CC output of 4 A, with the DC–DC conversion efficiency reaching a peak of 90.2%. The experimental results confirm the accuracy of the theoretical analysis.

Full-speed domain position sensorless control strategy for PMSM based on a novel phase-locked loop

This paper proposes a full-speed-domain position-sensor-less control strategy for precise control under forward and reverse rotation conditions to address the weak convex polarity of surface-mounted permanent magnet synchronous motor (SPMSM). The strategy comprises several key stages: pre-positioning of the rotor, constant current variable frequency (I/F) start-up, construct the Luenberger State Observer, and utilization of an improved phase-locked loop (PLL) for position estimation. In the pre-positioning stage, a constant amplitude current is applied to drag the rotor to a predetermined position. Subsequently, the I/F start-up stage accelerates the motor to a predetermined speed before transitioning to the Luenberger observer for closed-loop speed control, which is based on an extended back electromotive force (back-EMF) a two-phase rotating coordinate system. The improved PLL for position and speed estimation features three components: a phase discriminator (PD), a voltage-controlled oscillator (VCO), and loop filter (LF). Experimental results demonstrate the efficacy of the proposed strategy, showing quick start-up response, speed estimation error below 2 RPM, rotor position estimation error under 0.6 degrees post-loop closure, stable tracking during rapid speed changes, and consistent accuracy and stability even under reverse rotation conditions, thereby meeting the control strategy’s objectives.

Efficient power factor correction in single phase AC–DC boost converter for retrofitted electric bicycle battery charging: A finite element analysis approach

This research paper describes modifying a conventional bicycle into an electric bike by retrofitting it with a single-phase boost power factor correction (PFC) rectifier for low power battery chargers. The proposed work was designed and developed in a single stage, as opposed to the traditional two-stage chargers used to charge E-bicycle, to provide the desired outcomes of enhanced efficiency, good power quality, and dependability due to the charger's lower cost. Additionally, the proposed converter uses a single switch, which reduces not necessary body diode conduction and circulating current and enhances the PFC device's thermal management. Additionally, this research makes use of the diode bridge rectifier (DBR) arrangement, which offers low current stress and is suitable for electric bicycles. The converter operates at a low cost with reduced magnetics (DCM) by operating the charger in discontinuous conduction mode at such low voltage levels. It also accomplishes intrinsic power factor at the ac mains by employing a simple control method to maintain the battery in high power density constant current (CC) and constant voltage (CV) states. A thorough state space investigation is carried out in combination with modeling and testing to ensure that the electric bicycle charger operates effectively. Consequently, low power chargers are a good fit for the proposed single stage front-end converter, and a 250 W hardware prototype is used to verify the findings.

ANFIS-based control of resonant converters for optimized charging system of electric vehicle (EV) batteries

This paper presents a resonant converter-based Electric Vehicle (EV) battery charging module utilizing Proportional-Integral (PI) and Adaptive Neuro-Fuzzy Inference System (ANFIS) control for an optimized charging system. The EV charging module is integrated with a resonant converter comprising a full bridge, HFTF, and DBR. The module utilizes a Resonant Converter which reduces the switching loss incurred during converter operation at high frequency by offering ZCS or ZVS at the switching time. A standard PI Controller manages the duty ratios of the primary full bridge switches with tuned gains. The CC and CV controllers each have their own PI Controller for current and voltage, respectively. To enhance the performance of the EV System, the standard PI Controllers in both the CC and CV control systems are replaced with ANFIS Controllers which are trained as per the data generated by the CC and CV control using an optimization technique that controls the duty ratio of the switches. The proposed ANFIS-based and PI-based control strategy provides an adaptive and flexible approach to control the battery voltage and current by intelligent adjustment of Constant Current (CC) and Constant Voltage (CV) operation modes and the passive elements switching across specific ranges of State-Of-Charge (SOC) to enhance the performance and safety of the charging system. MATLAB Simulation results demonstrated that the proposed ANFIS-based control reduces current ripple content compared to PI-based control. The ANFIS Controller improves overall battery performance, reliability, and stability, which makes it a better choice for next-generation EV charging systems.

Modeling the Dynamics of Supercapacitors by Means of Riemann–Liouville Integral Definition

The application of fractional calculus to obtain dynamic models for supercapacitors represents an alternative approach to obtaining simpler and more accurate models. This paper presents a model for the supercapacitor in the time domain, based on the use of the fractional or non-integer order integral. This fractional model is compared with the conventional simple model, which is typically used in industrial applications. This fractional integral-based model provides satisfactory fits in relation to the number of parameters used in the model. Furthermore, an interpretation of the effect of the application of fractional integration is presented for constant current charging and discharging processes at constant current, using the Riemann–Liouville definition for the non-integer order integral. Supercapacitors are devices that exhibit non-linear behavior, with a distinct charging and discharging operation. There are several methods of dynamic analysis for the characterization of supercapacitors. The information extracted from these methods is essential for understanding the behavior of supercapacitors and, thus, ensuring that processes involving supercapacitors are as efficient as possible. This paper presents a dynamic analysis based on charge and discharge operations with constant currents. The conclusion is that the fractional model provides fairly accurate fits.

Assessment of Hysteresis Models for LiFePO4

The selection of the cathode material is an important task in the design phase of batteries for mobile applications. One material of increasing interest is LiFePO4 (LFP) due to its improved energy density, good thermal stability and durability. In contrast to other commonly used cathode materials, LFP features a clear phase separation between the lithium rich and the lithium poor phase, leading to a pronounced voltage plateau over wide ranges of state of charge (SOC). The level of this plateau also changes for charge and discharge operation, even at very low C-rates. This voltage hysteresis in combination with the wide plateau gives some ambiguity to the correlation between voltage and SOC, which is a challenge for battery management systems. Thus its correct description is crucial if a cell model is meant to serve as virtual twin supporting control function development and calibration. Beyond that, a highly dynamic battery development process requires models that run significantly faster than real-time and parametrization processes which allow for accurate validation and easy adaptation to modified electrodes. A simulation approach complying with these requirements is the electrochemical pseudo-two dimensional (P2D) model, though adaptions to the core model are needed to appropriately capture hysteresis-affected voltage plateau characteristics for phase-separating materials such as LFP.The goal of this study is to extend an existing P2D framework with two approaches capable of describing hysteresis effects and analyzing these extensions regarding result plausibility, computational cost and effort of parametrization. The first model of interest is based on the one-state hysteresis model proposed by Plett. This approach allows for fast simulation and accurate reproduction of the charge and discharge voltages at low C-rates but lacks deeper physical consideration of the phase-separating origin of the hysteresis and thus might lose accuracy to predict system responses on dynamic pulses. In this approach, the voltage hysteresis is not a simulation result, it is due to the input of two separate open circuit voltages for charge and discharge. The second model of interest applies variable solid diffusion (VSSD) featuring a reduced Fickian diffusion coefficient in the plateau region. Lower diffusion at a given C-rate leads to steeper concentration gradients between lithium rich and lithium poor phase. With this approach, effective phase boundaries within the representative particles can be obtained. In the limiting case, when the Fickian diffusion coefficient becomes zero or even negative at some lithium concentration, phase separation persists also when no current is applied. In this setting, the voltage hysteresis at low C-rates is an emergent phenomenon, it is not an input. The physical basis of the approach also allows to consider mechanical stresses and their impact on the voltage gap between charge and discharge. Concentration gradients cause a mismatch of volume demands and thus lead to local stresses, which in turn alter the chemical potential.Results emphasizing advantages and disadvantages of the two hysteresis models are presented. Charge and discharge simulations are performed for several C-rates and the voltage hysteresis is extrapolated to infinitely small currents. Furthermore, the effect of resting phases with zero current as in Galvanostatic Intermittent Titration Technique measurements is discussed. As hysteresis models are often tested only on charge/discharge cycles with constant currents over large SOC regions, the responses of the simulation models are also assessed in pulse tests and dynamic profiles giving a realistic picture of automotive applications. Here special focus is put on energetical aspects of the one-state model and on intra-particle concentration profiles for the VSSD model.

(Digital Presentation) Experimental Techniques for Parameterization of a Commercial 21700 Lithium-Ion Cell for Multiscale Battery Models

Lithium-ion batteries have gained huge attention in the past few decades. Since its commercialization, a steady improvement in cost, and performance over the last 25 years has surfaced many new applications such as EV, HEV, etc., and growing popularity for military and aerospace applications [1, 2]. However, developing a safer, longer life, high energy, power-dense, and cheaper Lithium-ion battery requires a concerted research effort from various disciplines. For a long time, research was focused on developing the chemistry, but in the recent past, the improvement in the battery performance has been realized by reengineering the manufacturing processes and model innovation that help to understand the battery performance during the charging-discharging process. Battery models employed to optimize and predict battery performance are useful tools to design and manage batteries to ensure safe and efficient utilization. To understand the underlying physical, chemical, and electrochemical properties and precisely capture the cell dynamics in EVs application, the model should be based on fundamental governing equations of diffusion and migration processes as well as the kinetics of species intercalation.The physicochemical model requires precisely evaluated model parameters for the materials under consideration. Accurately measured kinetics and transport parameters will hold the key to deriving reliable conclusions about the internal state of a Lithium-ion battery. Parameter’s quantification is a challenging and time-consuming process that requires a range of characterization and analytical methods as shown in Figure. The battery modelling community usually borrowed the parameters list from the literature, with their origins not essentially being traced [3]. In literature, parameterizations have been reported for both high-energy and high-power cells for a physicochemical model [4-7]. This work employed several characterization techniques to parametrize a commercial Lithium-ion cell model. Also, various analytical methods were employed to determine the geometrical, chemical, and electrode microstructure as suggested in Figure. To determine the thermodynamic, kinetics, and transport properties of the extracted electrode materials different electrochemical tests, e.g., galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), constant current constant voltage (CC-CV) charge and constant current (CC) discharge were employed. The parameter’s accuracy would be investigated by validating the mathematical modelling simulation results with the experimental charge-discharge curves at different currents of the commercial 21700 cell at room temperature.

Fabrication of Na+-Conducting Ionic Liquids Na[((FSO2)2n) x ((CF3SO2)(FSO2)N)1-X ], and Its Physical and Electrochemical Properties

To achieve low-carbon society in near future, it’s imperative to research and develop high-performance and low-cost batteries. Therefore, sodium-ion batteries (SIBs) are attracting attention owing to their possibility to be composed of elements with no resource scarcity and low cost.To solve the challenge of low energy density in SIBs, it is essential to focus on developing electrodes of the 4V to 5V class. Simultaneously, electrolytes with wide electrochemical window are crucial from in terms of electrolyte decomposition at high operating voltages. Molten salt electrolytes exhibit relatively high ionic conductivity and electrochemical stability. On the other hands, there is an issue that the electrolyte must be heated to a high temperature to maintain molten state of the electrolytes. In this study, with the goal of expanding the melting temperature range of molten salt electrolytes, we precisely mixed relatively low-melting sodium salts Na(FSO2)2N (NaFSA) and Na(CF3SO2)(FSO2)N (NaFTA) and found a composition with a melting point below 100 ℃. As a result, we successfully fabricated novel single-sodium cationic salt ionic liquid. In this presentation, we will report on its bulk properties and electrochemical characteristics. All mixed sodium salts were mixed NaFSA and NaFTA in each molar ratio and stirred during gradually cooling after uniformly melting at 170 ℃ in Ar-filled grove box. The thermal properties of the mixed sodium salts were evaluated by differential scanning calorimetry (DSC). The samples were stored at room temperature for 2~3 days to reach equilibrium state, and then sealed in a high-pressure SUS pan. Ionic conductivity (σ) of the mixed sodium salts were also measured from 60 ℃ to 135 ℃ at each temperature. Symmetrical cells were constructed by put the mixed sodium salt between two SUS or sodium metal electrodes. Ionic conductivity of mixed sodium salts was evaluated by electrochemical impedance spectroscopy (EIS) with SUS electrodes symmetric cells. Na+ transference number was measured by potentiostatic polarization and EIS with sodium metal symmetric cells at 90℃. The binary phase diagram of NaFSA and NaFTA were shown in Fig.1. In the NaFTA-rich composition range (0.1 < x < 0.4), the phase diagram resembles a simple eutectic phase diagram, while, in the NaFTA-rich composition range (0.5 < x < 0.9), the mixed sodium salts exhibited pseudo-single-phase behavior, and the lowest liquid-phase transition temperature (T L) was observed at 90℃ of Na[(FSA)0.8(FTA)0.2].(1) Additionally, in this composition range, glass transition points (T g) were also confirmed, indicating the supercooled behavior.The Arrhenius plot of the ionic conductivity (σ) for Na[(FSA)0.8(FTA)0.2] was shown in Fig.2. At the T L around 90℃, σ was observed to 0.69 mS cm-1. This is attributed to the strong interactions between Na+ and anion in the absence of solvents, causing high viscosity and decreasing mobility. Below the T L, there was no remarkable decrease in σ and Nyquist plots remained non-divergent to 55℃, allowing for the attribution of σ. Moreover, below the T L, the glass transition and crystallization of Na[(FSA)0.8(FTA)0.2] were not observed. The temperature dependence of σ was analyzed by the Vogel-Fulcher-Tamman (VFT) equation.(2) In addition, the σ(T g) at the observed T g from DSC were calculated by VFT equation. Also, the decoupling index (R τ), representing the ratio of ionic conductive relaxation time (τ σ) to structural relaxation time (τ s), were calculated.(3) The value of logR τ value for Na[(FSA)0.8(FTA)0.2] was -0.62 and the low value indicates that τ s is coupled with τ σ.To investigate the Na+ conduction behavior in Na[(FSA)0.8(FTA)0.2], chronoamperograms with an applied potential of 500 mV to the sodium metal symmetric cells were shown in Fig.3(a). Fig.3(b) shows Nyquist plots before and after direct current polarization. The steady current was observed after 8h. Furthermore, there was slightly changes of Nyquist plots before and after direct current (DC) polarization, stable interface between sodium metal and Na[(FSA)0.8(FTA)0.2] was also confirmed. The Na+ transference Number (t Na+) in the Na[(FSA)0.8(FTA)0.2] was estimated to be 0.86. Tatara et al. reported the t Na+ of 0.18 in the 1M NaPF6/PC+0.5vol% FEC.(4) Since molten salts consisting of only cations and anions should not be occurred concentration polarization, it exhibited a considerably higher t Na+ in Na[(FSA)0.8(FTA)0.2] compared to the t Na+ in dilute non-aqueous sodium electrolyte. In the presentation, we will discuss the cycle characteristics obtained by constant current charge-discharge tests of both half-cell and full-cell configurations using generic positive and negative electrode materials.(1) K. Kubota et al., J. Chem. Eng. Data, 55, No. 9, 2010, 3142–3146.(2) H. Vogel., Phys. Z. 1921, 22, 645.(3) C. A. Angell, Annu. Rev. Phys. Chem. 1992, 43, 693.(4) R. Tatara et al., Electrochemistry, 89(6), 2021, 590–596. Figure 1

Aqueous Lithium-Ion Battery with Dual Electrolytes at Equilibrium across Cation-Exchange Membrane Separator

Aqueous lithium-ion batteries (ALIBs) have been investigated as a promising safe and low-cost storage device for sustainable energy. For the stability of ALIBs, it is important to expand the electrochemical stability window of aqueous electrolytes. Although “Water-in-salt” electrolytes [1] containing significant amounts of lithium salts have been reported as an effective approach, cost reduction of the aqueous electrolyte remains a major challenge for the industrialization of such ALIBs.Controlling the pH of the aqueous electrolyte is another approach to widen the electrochemical window with a smaller use of lithium salts. The 2 V-class ALIB of Zn-coated Li4Ti5O12/LiMn2O4 was demonstrated using dual aqueous electrolytes having different pH separated by a lithium-ion conductive inorganic solid electrolyte.[2] However, lithium-ion conductive inorganic solid electrolytes may often be unstable in alkaline solutions. A perfluorinated sulfonic acid cation-exchange membrane (CEM) is one of the possible alternatives for separating two different aqueous electrolytes. In principle, the concentration of the entire electrolyte does not change during lithium-ion battery operation where lithium ions shuttle between the cathode and anode. Therefore, the specific compositions of the cathode and anode electrolytes are selected to achieve the Donnan equilibrium across the CEM, and stable battery operation is expected as long as the electrolyte equilibrium is maintained. In this study, the feasibility of this concept was investigated using ALIB cell of the anatase-TiO2/spinel-LiMn2O4.A stable combination of cathode and anode electrolytes was investigated experimentally. Several compositions of cathode and anode electrolytes were prepared, and equal volumes of the cathode and anode electrolytes were faced across the CEM, stored for 10 days at room temperature, and the composition of each electrolyte were determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). After repeating this procedure, a stable combination of cathode and anode electrolytes was found as 27 g/L of Li and 8 g/L of K for an anode electrolyte, and 24 g/L of Li, 36 g/L of K, 41 g/L of P, and 68 g/L of S for a cathode electrolyte prepared using LiOH, KOH, Li2SO4, and KH2PO4. The pH was 4 and 11 for the cathode and anode electrolytes, respectively.The battery test was demonstrated for the TiO2/LiMn2O4 cells assembled with the cathode/anode electrolyte and the same 2 mol/kg Li2SO4 electrolyte in both sides for comparison. The initial charge/discharge profiles are shown in Fig. 1. The profiles were obtained by constant current of 15 mA/g regarding the weight of the cathode active material with the cutoff voltage of 2.8 V and 1.5 V in charge and discharge processes, respectively. The Coulombic efficiency was reached to 96% in the cells with electrolytes having the pH difference, whereas it was 69% in the cell with the 2 mol/kg Li2SO4. The alkaline anode electrolyte suppressed hydrogen generation sufficiently for the lithiation/delithiation of anatase TiO2, which leads to an excellent reversibility over 2 V operation with an improvement in the Coulombic efficiency of the cell with dual aqueous electrolytes.To further investigate the stability of the aqueous battery, a cycle test was conducted on the cell with the dual electrolytes. Figure 1(b) shows the discharge capacity during 100 charge-discharge cycles obtained by the constant current of 75 mA/g-cathode. The Coulombic efficiency reached >99%, and the capacity retention was calculated to be 75% at 100 cycles, which indicates that the suitable pH of the cathode and anode electrolyte was maintained during repeated charge/discharge cycles.In the presentation, we will discuss the details of the battery operation, including a role of perfluorosulfonated CEM and issues to improve the battery performance.

A Novel Method for Determining the Threshold Plating Current in Li-Ion Batteries via Electrical Measurements

Lithium-ion (Li-ion) batteries play a vital role in our daily lives by powering essentials like smartphones, electric vehicles, and energy storage systems. One of the main factors that lead to accelerated aging of Li-ion batteries is the lithium plating effect. An improved understanding of lithium plating holds the potential to extend lifespan, enhance performance, and reduce cost of lithium-ion batteries. Lithium plating occurs while charging in low temperatures or with high currents, as lithium-ions accumulate on the anode.Lithium plating can be separated into two parts, a reversible and an irreversible part. During relaxation, when the battery sits idle, or while discharging, reversible plating is stripped from the anode. Typically, when plating is stripped, a voltage plateau can be observed. In contrast, irreversible plating consists of lithium deposits that cannot be stripped during discharge, therefore causing a loss of capacity.In this work, we present a novel non-destructive method for determining a cell's threshold plating current using only electrical measurements. The method is validated using commercial 3.2Ah Panasonic NCR18650B cells at varying low temperatures and charging currents. The designed method requires the use of two identical cells, a reference and a test cell. After completely discharging both batteries at room temperature to reach 0% depth of discharge (DOD), the same plating tests at low temperatures are conducted on both cells. Once the cells are fully charged with a constant current of 0.5C, the reference cell experiences relaxation for 10 minutes. Simultaneously, a sine wave current is applied to the test cell, leading to small charging and discharging cycles. During the positive half-wave of the sine, plating occurs and during the negative half-wave reversible plating is stripped again. As plating only occurs, once the threshold plating current is exceeded, the sine amplitude must be greater than this threshold. It is important to note that, the charging current consists of intercalation current and plating current.Intercalation is the insertion of Li-ion into the layered structure of graphite during charging. As charging progresses, the surface concentration of intercalated lithium increases, but simultaneously, the number of vacancies for lithium intercalation at the graphite surface decreases. When the anode potential falls below 0V, thermodynamically allowing lithium plating, the intercalation current decreases and the plating current increases. With continued charging, the plating current continues to increase, while the intercalation current gradually diminishes.We assume that only the part of the sine exceeding this threshold is responsible for the lithium plating, while the portion below this threshold contributes to intercalation. In contrast, the negative half-wave is completely responsible for stripping. After 10 minutes, both cells are discharged with a low current while the remaining reversible plating is stripped. From the voltage and current measurements during discharge, we can compute how much reversible plating was stripped during the sine phase and during the discharge. To determine the plating current, the plated charge amount dQ on the positive sine half-wave is calculated by the difference between the stripped charge amount on the sine negative half-wave and the difference between the stripped charge amount of the reference cell and the test cell (c.f. attached figure). With the known plated charge amount dQ, the sine is integrated to find the threshold plating current.To validate the precision of this method, we subject an additional cell to charging at the same low temperature as the other cells. The charging involved varying currents from 0.04C to 0.4C in 10 steps, with a 1.5-hour interval between each step for the cell to cool down. To determine the threshold plating current, a differential voltage analysis (DVA) was conducted at each step, thus identifying the lowest current where a voltage plateau occurred, as the threshold plating current. Further refinement involves smaller steps to achieve a more accurate plating current. We assume this result is the true threshold plating current. Comparing with our novel method, in the worst case we achieve an error of less than 100mA. To ensure the reliability and reproducibility of this method across varying cells, additional plating tests, involving various cell chemistry types, are planned. Figure 1

Sulfur-Phosphorus Doped Metal Composites As Superior Catalyst for Electrolytic Hydrogen Production in Real Seawater

In the face of the increasingly severe global energy crisis and challenges posed by climate change, promoting energy transition has become an international consensus. Among various renewable energy sources, hydrogen is considered an ideal energy carrier due to its clean and efficient characteristics. The electrolysis of seawater for hydrogen production has garnered widespread attention for its ability to fully utilize abundant seawater resources and the advantage of zero carbon dioxide emissions. However, achieving efficient, stable, and economically viable hydrogen production in seawater still faces many challenges, with catalyst design and optimization being recognized as key issues.Firstly, NiFe-LDH was synthesized using a simple one-pot solvothermal method. Subsequently, phosphorization, sulfurization, and sulfur-phosphorus co-doping were conducted to obtain samples namely NiFe-P, NiFe-S and NiFe-SP, respectively. Various electrochemical tests, including hydrogen evolution reaction (HER), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were firstly performed in simulated seawater to evaluate the electrochemical performance of the synthesized catalysts. The overall seawater splitting reaction was conducted with the same catalysts for both anode and cathode sides.After comparing the electrochemical activity of four different catalysts, it was found that NiFe-SP performs superior HER activity in alkaline simulated seawater. NiFe-SP required merely -0.143 V to deliver 100 mA cm-2 current density, which was 95 mV lower than NiFe-LDH to achieve the same current density. In EIS tests, NiFe-SP exhibited a smaller charge transfer resistance than NiFe-LDH, and NiFe-SP had the largest double-layer capacitance (Cdl) value in ECSA measurements, indicating that NiFe-SP possessed and lowest reaction resistance and the maximum electrochemically active surface area.X-ray Diffraction (XRD) and Raman spectroscopy analyses indicate that the catalyst, after sulfur-phosphorus doping, does not exhibit a pure-phase LDH structure but transforms into a heterogeneous structure of Ni3S2 and FeS2. Scanning Electron Microscopy (SEM) observations suggest that sulfur-phosphorus co-doping causes the original spherical structure of NiFe-LDH to aggregate, with the appearance of some lamellar structures on the surface. Energy Dispersive Spectroscopy (EDS) also confirms the successful doping of sulfur and phosphorus elements into NiFe-LDH, with uniform distribution on the material's surface.Finally, the catalyst underwent a 2000-hours continuous stability test at a constant current of 100 mA cm-² in real seawater. The results indicate that the potential of NiFe-SP increased by only 5%, demonstrating that the doping of sulfur and phosphorus not only reduces the catalytic overpotential but also significantly sustains potential retention. This suggests that the metal composite structure obtained after sulfur-phosphorus co-doping is well-formed and stable. The systematic electrochemical tests and stability evaluation in this study highlights the potential of sulfur-phosphorus co-doped metal composite NiFe-SP as an efficient and stable catalyst for real seawater electrolysis. This not only contributes to a deeper understanding of the fundamental principles governing catalyst behavior but also opens new possibilities for the practical application of hydrogen production technology. Figure 1

Analysis and design of a three‐coil IPT system with independent dual output ports

AbstractIndustrial applications tend to involve a substantial assemblage of electronic devices, and it is imperative to consider diverse charging requirements while charging these devices. This paper proposes a three‐coil single‐input‐and‐dual‐output (SIDO) inductive power transfer (IPT) system to meet the charging requirements of different devices. The system includes two independent output ports, providing constant voltage (CV) output and constant current (CC) output for different loads, respectively. In addition, the zero‐phase angle (ZPA) operation can be achieved, thus avoiding injection of reactive power and improving energy transfer efficiency. Unlike previous related studies, the receiver of the proposed SIDO IPT system only includes one receiving coil to pick up energy, eliminating unnecessary cross‐coupling and complex decoupling circuits in traditional IPT systems with multiple outputs. This study first analyzes the CC/CV output theory of the proposed SIDO IPT system in detail, and designs and optimizes the parameters by establishing an equivalent model. Then, the conditions for achieving zero‐voltage switching (ZVS) operation of the inverter are obtained by analyzing the sensitivity of CC/CV performance to the variation of the compensation capacitors. Finally, a verification experimental prototype with 2.5A CC output and 72 V CV output is established to verify the effectiveness of the proposed IPT system.

Advanced control and energy management algorithm for a multi-source microgrid incorporating renewable energy and electric vehicle integration

This paper presents a comprehensive study on advanced control and energy management in a multi-source/multi-load microgrid. The microgrid integrates solar panels, a wind turbine system, a Li-ion battery-based storage system, an electric vehicle (EV), and a DC load, all inter-connected through power electronic converters to a DC bus and linked to the AC grid via a DC/AC inverter. The study outlines the primary control objectives: DC bus voltage regulation, optimization of photovoltaic and wind energy conversion, and maintaining high-quality energy injection into the grid. Given the intermittent nature of solar and wind energy and the varying energy demands that affect battery life and performance, a novel energy management algorithm is introduced. This algorithm addresses different operating modes, such as Constant Current (CC) and Constant Voltage (CV), to enhance network stability, energy quality, and optimize energy distribution between the various sources and the EV. The proposed fuzzy logic controllers, known for their robustness to uncertainties, flexibility, and ease of implementation, are employed to achieve these objectives. The Particle Swarm Optimization (PSO) is used to fine-tune the fuzzy logic control parameters, ensuring optimal performance. This optimization process included minimizing Integral Absolute Error (IAE), Integral Square Error (ISE), and Integral Time-weighted Square Error (ITSE) as objective functions. Extensive simulations under various operating scenarios demonstrated significant improvements in control accuracy, stability, and system performance.