This brief presents a novel approach to extend the zero voltage switching (ZVS) range in the current-fed parallel resonant converter for wireless power transfer in an automated guided vehicle (AGV). Unlike previous methods that focus on tuning capacitors or inductors, the proposed method is to resonate the matching capacitor with a lumped inductor to enable ZVS in the region where the ZVS condition is not met, which is an LC resonance approach. The power dissipation due to ZVS failure is analyzed, and the proposed method to guarantee ZVS operation is described in detail. The simulated and measured results verified that the proposed method extends the range of ZVS by approximately 242% and achieves an efficiency improvement of up to 10.69% under the same load conditions compared to the conventional method.

This study investigated the feasibility of double-effect absorption refrigeration systems (DEARS) using hydrofluoroolefin (HFO) refrigerants and ionic liquid (IL) absorbents as working fluid pairs. Enthalpy and vapor-liquid equilibrium (VLE) correlation equations were developed to facilitate thermodynamic modeling and system analysis. Among the examined pairs, R1234ze(Z) + [BMIM][SCN] and R1336mzz(Z) + [OMIM][BF4] were identified as promising candidates due to their significant concentration differences between weak and strong solutions (0.0998 and 0.0565, respectively). Performance evaluations demonstrated high coefficients of performance (COP), reaching 1.24 for R1234ze(Z) + [BMIM][SCN] and 1.46 for R1336mzz(Z) + [OMIM][BF4]. Further analysis of COP variations under different operating conditions reveals that both working fluid pairs exhibit performance improvements with increasing generator temperatures. The absorber temperatures significantly influenced system efficiency, where lower temperatures enhanced refrigerant separation and improved COP. Similarly, increasing the evaporator temperature improved COP by raising the saturation pressure, which enhanced refrigerant separation in the generator and overall system performance. These findings expanded the selection of environmentally friendly refrigerants for DEARS by incorporating ILs, contributing to the sustainable development of absorption refrigeration systems.

Prussian blue (PB) is a promising low‐cost cathode material for sodium‐ion batteries (SIBs), but the impact of crystal water on performance degradation remains unclear. This study explores how PB's crystal water interacts with different electrolyte salts—NaClO 4 and NaTFSI—affecting solvation structure and interfacial stability. Based on the Hofmeister series, it is demonstrated that the strong hydration of ClO 4 – sustains water reactivity, promoting Fe oxidation and solvent decomposition at high voltages. In contrast, the weakly hydrated TFSI – suppresses water‐induced side reactions and facilitates the formation of stable interphases on both cathode and anode. Electrochemical analysis at 4.0 V and 4.2 V revealed that NaTFSI consistently improves reversibility, particularly at 4.2 V, achieving 77.1% capacity retention over 500 cycles—56.8% for NaClO 4 . The results highlight the crucial role of electrolyte‐dependent water coordination in determining PB electrode stability, offering valuable insights for designing electrolytes and interphases for long‐life PB‐based SIBs.

In vanadium redox flow batteries (VRFBs), vanadium ion crossover contributes to performance degradation and a reduced system lifespan. Polybenzimidazole (PBI) membranes have been proposed as an effective solution to minimize ion crossover. In this study, PBI was used to achieve low vanadium ion permeability, while the addition of 1-ethyl-3-methylimidazolium dicyanamide (EMIM-DCA) created microstructures in the polymer, increasing ion pathways. Furthermore, a 10 mu m thin PBI-EMIM-DCA 45 wt % (PED 45) membrane was fabricated to minimize membrane resistance. PED 45 exhibits a vanadium ion permeability of 1.4 x 10-8 cm2 min-1 and a proton selectivity of 34.2 x 107 mS min cm-3. This results in 71- and 22-fold lower permeability compared to Nafion N115 and Fumatech FAP-450 membranes, respectively, while providing 4- and 14-fold higher proton selectivity, respectively. PED 45 demonstrates a Coulombic efficiency (CE) of up to 99.6% and an energy efficiency (EE) of 77.8% at a current density of 100 mA cm-2. Its self-discharge (SD) times are 6-9 times longer than those of other membranes, and its long-term stability shows over 5% higher efficiency across 100 cycles. PED 45 has proven to be a high-performance membrane for VRFB applications.

This study evaluates a proton exchange membrane water electrolysis (PEMWE) system for dual functionality in wastewater treatment and hydrogen production. Feedwater containing organic compounds-humic acid (HA), bovine serum albumin (BSA), and effluent organic matter (EfOM)-is supplied to the anode, with sodium chloride (1-10 g/L) added in situ to generate free chlorine oxidants. Linear sweep voltammetry shows that chloride addition increases overpotentials due to side reactions, yet free chlorine production rises proportionally. Dissolved organic carbon removal efficiencies reach 34.6 % for HA, 51.5 % for BSA, and 49.8 % for EfOM without notable loss of hydrogen yield. Excitation-emission matrix fluorescence spectroscopy indicates the breakdown of organic molecular structures, evidenced by decreases in humification, biological, and fluorescence indices. Size exclusion chromatography confirms the degradation of high-molecular-weight fractions in treated samples. Hydrogen production remains stable at 6.45-7.67 mL/min during 8 h of continuous operation despite a gradual 17 % voltage increase. These findings demonstrate PEMWE as a promising dual-purpose system for decentralized water treatment and energy generation.

Solid polymer electrolytes (SPEs)-based lithium metal batteries (LMBs) are at the forefront of next-generation energy storage, offering remarkable energy density and safety. Despite their high potential, the practical use and commercialization of LMBs encounter two significant challenges: inadequate interfacial stability and low critical current density (CCD). One promising approach to tackle the problems is by designing an advanced SPE that simultaneously ensures uniform and high lithium-ion transport. Achieving uniform ion transport is key to minimizing concentration gradients that lead to dendrite formation, while selective lithium-ion conduction prevents anion accumulation, thereby improving interfacial stability. This review comprehensively examines recent progress in the development of uniform lithium-ion transporting polymer electrolytes (ULPEs) and high lithium-ion conducting polymer electrolytes (HLPEs). By combining the structural uniformity of ULPEs with the enhanced conductivity of HLPEs, uniform-high lithium-ion transporting polymer electrolytes (UHLPEs) have emerged as a promising class of materials capable of simultaneously ensuring high interfacial stability and supporting elevated CCD in practical LMBs. Key molecular design strategies, along with insights into ionic conductivity, electrochemical performance, and interfacial behavior, are systematically reviewed to provide a comprehensive understanding of the way to achieve high CCD, enhanced safety, and extend cycle life.

In this study, a serial electrochemical hydrogen compressor (EHC) stack was designed to compress hydrogen gas to hundreds of bars. The operating parameters were examined to analyze optimal performance. First, a serial stack was designed to enable the EHC to operate at pressures exceeding hundreds of bars. The circular design of the stack was chosen specifically to prevent hydrogen leakage. A 127-mu m-thick membrane was selected owing to its relatively good pressure resistance and performance. Through a serial EHC stack of 3 cells, hydrogen was pressurized over 120 bar. A parametric study showed that the pressure-ratio across the membrane barely affected the performance. Additionally, the higher the temperature and relative humidity, the better the performance. By increasing the temperature to 70 degrees C, the power consumption was reduced by 40 %. At 100 % relative humidity, the EHC exhibited the lowest power consumption. Finally, the performance of the serial stack was analyzed under optimal operating conditions, wherein it demonstrated an efficiency over 64 % for below 0.03 kg/day mass-flow rate of compressed hydrogen. However, efficiency decreased to 12 % at a mass-flow rate over 0.17 kg/ day.

This study analyzes the growth of the solid electrolyte interphase (SEI) layer and lithium plating under various charging conditions. By examining the thermal-electrochemical effect on degradation, the proper charge conditions for alleviating degradation can be understood. First, we analyzed the degradation mechanism during the charging process. After 100 cycles, the SEI layer increased by 30%, resulting in an increase in ohmic loss. The growth of lithium plating increased to approximately 5.2 x 10_2 nm, causing concentration loss. Then, we analyzed the effect of charge rate (C-rate) on degradation. When the C-rate increased from 1C to 1.5C, the charge capacity decreased by 80% at the 100th cycle because a large number of lithium ions reacted at the high C-rate, resulting in a thick SEI layer and lithium plating. The effect of temperature was analyzed as well. When the temperature was 5 degrees C, the charge capacity decreased by 75% owing to low diffusivity in the electrolyte. Finally, thermal-electrochemical effect on degradation was analyzed. By lowering the C-rate and increasing temperature, 0.3 V of the overpotential can be lowered. In order to mitigate the degradation of the battery, it is recommended to lower the C-rate and higher the temperature as charging proceed.

Themismatch between switching frequency and receiver (RX) resonance occurs in frequency-modulated spread-spectrum application. The conventional resonance tuningmethods for parallel-compensated RX are not effective because they require additional power components, which increase power loss and system volume. Other switched-capacitor or active rectifier-based reactance tunings cannot be applied to parallel-resonant RX due to the opposite waveform nature of series-resonant and parallel-resonant circuits. To solve these issues, we propose a parallel-resonant tuning rectifier (RTR) which can fix the resonance mismatch of parallel-compensated RX during spread-spectrum frequency modulation. The proposed design does not need extra power components such as capacitor or switch as well as complex control logic. Rather, the tuning is achieved simply by synchronizing the rectifier MOSFET's turn-OFF with the zero-crossing of primary current. Moreover, the proposed tuning MOSFETs achieve zero voltage switching (ZVS) turn-ON and low dv/dt turn-OFF, which avoids switching loss. A 2.2 kW prototype is fabricated and tested. The measurement results show that the proposed RTR can achieve constant output power and improve the overall efficiency by 3.5%-8.1% point when the operating frequency is detuned ranging 80-90 kHz.

A hydrogen-based energy system will be the backbone of a future energy grid using renewable energies. It is widely accepted that polymer electrolyte membrane fuel cells (PEMFCs) are promising converters of chemical energy stored as hydrogen into electrical energy. An increase of the operation temperature from below 80 degrees C to above about 160 degrees C is considered beneficial, as it would allow for much simpler water management and the use of waste heat. Here, we are investigating protic ionic liquids (PILs) immobilized in a polybenzimidazole polymer as electrolytes for high-temperature PEMFCs. Ionic liquids are promising for fuel cell applications as they provide high thermal and chemical stability and high proton conductivity. In contrast to aqueous electrolytes, ionic liquids form a dense layered structure at the electrode-electrolyte interface that depends on the potential and on the content of residual water in the electrolyte. We investigate how PILs interact with the host polymer of the membrane revealing that porous polymer structures can be formed by solution casting, which allows for an encapsulation of the ionic liquid within the pores. After doping the polymer with small amounts of phosphoric acid, the membranes showed reasonable conductivity and fuel cell performance.

Facile adjustment of the behavior of dual cross-linked polymer-ionic liquid composites (PICs) for stretchable electronics was achieved via solution blending of two copolymers having the same monomer pairs. Two poly(docosyl acrylate-r-tert-butyl acrylate) (poly(A22-r-tBA)) copolymers with different molar ratios were synthesized and solution-cast with ionic liquids (ILs) to fabricate ternary PICs. The phase behavior and the thermal and structural properties of the composites were investigated by varying the mixing ratio, providing insights into the cross-linking mechanisms. The observed changes enabled systematic modulation of the stretchability, thermal stability, and self-healing capability of PICs, which are crucial attributes of wearable devices. Mechanically tough and conductive PICs were utilized in fabricating strain sensors capable of detecting human motion.

The power transfer efficiency of a wireless power transfer is degraded by mismatch between LC resonant frequency and TX switching frequency. One of the drawbacks of conventional resonance tuning methods is that only increment of capacitor is allowed. Even if some conventional tunings allow both increment and reduction of capacitance, they fail zero-voltage switching (ZVS) at the increment of capacitance, which practically limits their tuning range. To solve the issue, we propose an automatic tuning resonant capacitor (ATRC), which can both increase and decrease the resonant capacitor. The tuning mosfet s achieve zero-voltage turn- on (ZVS) both at the capacitor-reduction mode and the capacitor-increment mode. These two (decrement/increment both are possible, and ZVS for both modes) are the advantages compared to conventional autotuning methods. Additionally, low dv/dt turn- off is achieved at capacitor-increasing mode in proposed method. Hence, the delivered power and overall efficiency is improved. The proposed method is suitable for any LC network to solve the detuning problem. A 200 W prototype is fabricated and tested experimentally. The measurement results show that the proposed ATRC can improve the overall PTE by 25%–63% point when the operating frequency is detuned ranging 75–125 kHz for 100 kHz nominal LC resonant frequency.

In this study, we analyze gas accumulation in a polymer electrolyte membrane water electrolyzer by considering two-phase flows in the porous transport layer on the anode and cathode sides. First, effect of mass flow rate on gas accumulation is analyzed. The transport of liquid water occurred differently on the anode and cathode sides. While the transport of liquid water on the anode side decreased in the high current density region, that on the cathode side increased with current density. The limiting current density increased by 1.2 A/cm 2 when the mass flow rate was increased. Next, we study the effect of contact angle of the porous transport layer. When the contact angle was decreased from 75 degrees to 30 degrees , gas saturation decreased by 0.04. The use of a hydrophilic porous layer on the cathode side, however, hindered the transport of liquid water into the channel because the porous transport layer tended to retain liquid water. Finally, we study the effect of porosity of the porous transport layer. When the porosity was 80%, the mass flow rate of liquid water into the porous layer was 0.1 g/s, and gas saturation was approximately 0.25 at 0.8 A/cm 2 .

In this paper, a method for power distribution control in communication-free multiple-input and multiple-output (MIMO) wireless power transfer (WPT) through load impedance and mutual inductance estimation is proposed. The proposed method intentionally adjusts the resonant frequency of the secondary side to introduce a reactance, utilizing this information to estimate the load impedance and mutual inductance for power distribution control without the need for communication. The principle of the power transmission algorithm proposed in this paper is designed to be effective regardless of whether the power or frequency is high or low. Therefore, the experimental setup is not designed by specifying the coil size, system frequency, or separation distance between the transmitting (Tx) and receiving (Rx) coils to match specific real applications. To verify the proposed method, four Tx coils and two Rx coils of arbitrary sizes are fabricated, and a MIMO-WPT environment is implemented using LC matching. In the experiment, since the circuit designed for the Tx is not capable of withstanding high currents, power is intentionally transmitted at a low range of less than 1 W to validate the feasibility of the method. Because the transmission power range is set low, the distance between the Tx and Rx coils is set close to approximately 2 cm. Consequently, it is verified that the algorithm for parameter estimation and power transmission to multiple Rx coils is effective as long as the environment allows for the current flowing through the Tx coil to change due to the presence of the Rx coils. All experiments for uniform and non-uniform power distribution to two Rx coils showed good agreement between the desired power and the actual received power.

An analysis of various system configurations of hydrogen refueling stations and the types of failures that can occur in these stations is presented herein. Although the major components (compressor, storage tank, dispenser and chiller) are the same across various configurations, the numbers of compressors and storage tanks, as well as the system layouts, are different. Because compressors are operated at high pressure, leakage from valves and malfunctioning of lubricant oil pumps occur frequently (−50

Ethylene oxide (EO) is a pivotal intermediate in the chemical industry owing to its versatility and high demand. Currently, direct oxidation is the most important technical process to produce EO. This conventional process, in which ethylene is partially oxidized with air or oxygen, has limited selectivity for EO of 65-90%, leading to significant CO2 emissions. This study explores an alternative method involving the electrochemical selective oxidation of ethylene powered by renewable electricity. The electrochemical oxidation technology is expected to reduce CO2 emitted during EO production. Process models were developed based on existing literature data. A techno-economic evaluation and sensitivity analysis focusing on the electrochemical cell variables were conducted. In this assessment, the investment and production costs of the electro-oxidation process for EO production were compared with those of the conventional process. This assessment also compared processes producing of mono-ethylene glycol and ethylene carbonate from EO. These analyses reveal that the separation energy has a significant impact on the carbon footprint. While current economic and environmental benefits are not favorable, this study identifies key descriptors of the technology for further reducing the carbon footprint. Based on the evaluation results, this study demonstrates the potential to cut CO2 emissions in half compared to conventional plants by utilizing the electro-oxidation of ethylene via a direct route.

This paper presents a wireless power transfer (WPT) system for an automated guided vehicle (AGV). Our WPT system proposes an AC-AC converter located in a transmitter, which integrates AC-DC and DC-AC converters in a conventional structure. As a result, the WPT efficiency can be increased as well as the size. Additionally, the proposed structure allows for the WPT power capacity to be raised up to 3.3 kW. The proposed WPT system is theoretically analyzed using a lumped circuit model and verified with waveforms.

Manganese ferrite (MnFe2O4) nanoparticles initially fabricated using a solvothermal process were coated with conducting polyaniline (PANI) to produce core/shell-structured MnFe2O4/PANI nanoparticles. An electro/magnetorheological (E/MR) fluid was prepared by suspending MnFe2O4/PANI particles in silicone oil, and the rheological properties under either electric or magnetic fields were investigated. Scanning electron microscope and transmission electron microscope provided the particle morphology and size information. X-ray diffraction and Fourier transform infrared spectroscopy were used to analyze the crystal structure and chemical composition of the particles. Chain formation in E/MR fluids under electric or magnetic fields was observed by optical microscopy, and the rheological properties were evaluated using a rheometer. Steady shear and dynamic oscillatory tests were conducted to confirm the effective E/MR characteristics while varying the electric/magnetic field strength. The dielectric properties of the particles measured using an LCR meter were analyzed based on the Cole-Cole model. The E/MR fluids composed of MnFe2O4/PANI showed a reversible and fast electro/magnetic response.