Transfer Resistance Research Articles

A biomacromolecular additive based on pullulan polysaccharide to enhance the life of lead-acid battery packs in DC systems

Abstract With the rapid growth in demand for mobile power, lead-acid batteries still occupy a large market share due to their excellence in energy storage. However, their lifespan is affected by various factors, which limits the application efficiency and environmental friendliness. In this regard, this paper proposes a method to enhance the service life of lead-acid battery packs by applying biomacromolecule additives. A lead-acid battery pack modification method is investigated by introducing chitosan, a natural macromolecule with excellent electrical conductivity and biodegradation properties, into lead-acid batteries. So that the chitosan-modified material forms a stable and protective film on the surface of the battery electrode plate, thereby reducing the analysis of sulphate crystals on the electrode surface. The method of modification of lead-acid battery packs has been studied. Comparative analysis of the experimental data shows that the modified battery pack exhibits lower charge transfer impedance and better electrochemical stability than the traditional lead-acid battery during the cyclic charge/discharge test. Through the cycle charge/discharge test, the energy loss of the battery with biomolecules is 30% lower than that of the unmodified battery, and the number of charge/discharge cycles increases by 60%, which effectively prolongs the service life of the lead-acid battery. The progress of this paper not only has guiding significance for the performance improvement of traditional lead-acid batteries but also provides a significant theoretical and experimental basis for the development and application of environmental friendly battery materials.

Analysis of a passive frequency mixer with current control by using protective intervals of heterodyne signals

A generalized technique for analyzing a current-controlled passive frequency mixer circuit using guard intervals between adjacent heterodyne signal pulses is proposed. The results of calculations and simulations in the Micro-Cap environment are presented for two cases of mixer input impedance: RLC circuit, RC circuit. The dependences of the modulus of the transfer impedance of the mixer for various durations of protective intervals are considered.

Effect of micromechanical properties of commercial grade electrolytic copper foils on lithium-ion batteries

As the carrier and electrical conduction component of positive and negative electrode materials, current collector plays an important role in lithium-ion batteries(LIBs). With the industrial application of silicon-doped anode materials with higher gram capacity, the huge volume change of silicon-doped anode materials puts forward higher requirements for the mechanical properties of copper foils(CFs). It is of great significance to study the effect of micromechanical properties on LIBs for the application screening of CFs. In this article, the effects of micromechanical properties of conventional tensile strength(CTS), high tensile strength(HTS) and ultra-high tensile strength(UHTS) commercial grade electrolytic CFs on LIBs were studied. The tensile strength of CTS, HTS and UHTS was 316.88 MPa, 464.74 MPa and 673.43 MPa, respectively; the elongation were 6.49 %, 5.38 % and 4.47 %, respectively. The surface morphology and XRD tests show that the microstructure such as grain size and dislocation density are the key factors affecting the mechanical properties of CFs. And under the same conditions, the main factors affecting bonding strength of electrode are microstrain and residual stress of CFs rather than surface roughness. The larger the microstrain and residual stress of CFs, the worse the interface bonding strength between CFs and coating materials, and the larger the corresponding interface charge transfer impedance, which is well confirmed by DCR and EIS. The charge-discharge test results show that the mutual stress between CFs and coating materials also have a great influence. The lower elastic modulus and microscopic stress of CFs can better eliminate the expansion pressure and contraction tension of coating materials, thereby reducing the resistance and overpotential in the process of lithium-ion diffusion, and achieving higher capacity under high rate system. The retention rates of three CFs after 500 cycles at 25℃ and 45℃ were 25-CTS(92.64 %), 25-HTS(90.63 %) 25-UHTS(89.11 %), and 45-CTS(82.17 %), 45-HTS(82.14 %), 45-UHTS(80.77 %), respectively, which indicates that the difference in mechanical properties of CFs have an important influence on long-term application of LIBs. The primary cause of the variation in electrochemical performance, aside from copper foil’s conductivity, is the phase interface shift brought on by the microstress of the material; and the overpotential caused by the phase interface force cannot be ignored.

Acoustic properties of perforates - experimental data and empirical models

Sound reducing treatment in for instance aircraft engine and IC engine applications often involve the use of perforates. In these applications they are exposed to fluid flow and high-level acoustic excitation, and this influences the acoustic properties of the perforate, as is well known from many published papers. The acoustic properties are usually described using a transfer impedance. The transfer impedance of a perforate sample has been studied using both a conventional impedance tube (two-port) setup and an innovative three-port setup. The three-port configuration made it possible to study both the effect of grazing flow and high-level excitation effects separately as well as jointly. In the present paper these recent experimental results are presented and comparisons are made with results from previously published papers and empirical models.

Acoustic characterization of a bi-directional turbine

A thermoacoustic engine converts thermal energy into acoustic energy, which can then be converted into electricity using an alternator. The conversion of acoustic-to-electric energy in thermoacoustic electricity generators usually relies on electromagnetic transducers. A bi-directional turbine coupled to a DC motor offers a plausible alternative due to its simplified mechanical design, cost-effectiveness, and relatively good performance. Efficient coupling of a bi-directional turbine with a thermoacoustic engine requires a comprehensive understanding of its operating behavior. This study aims to extend existing research by carrying out experimental characterization of a bi-directional turbine. This will involve measuring its transfer matrix and impedance under various acoustic conditions. The experimental results are then analyzed and compared with the predictions of an electro-acoustic model.

An experimental study on three-port measurements for acoustic characterisation of the perforate reactance

The usage of perforated plates in passive noise-control systems in e.g. aircraft liners and mufflers involves the standard operating conditions of grazing flow and high-amplitude acoustic incidence. This study focuses on the usage of the three-port experiment technique for the experimental passive acoustic characterisation of a perforated plate. Expanding on the previous paper about the resistance of the perforate, the influence of operating conditions on the imaginary part of the transfer impedance, i.e., the reactance is discussed here. The relationship between the end correction in the linear range, without the presence of grazing flow, and the frequency of acoustic excitation is demonstrated. The reduction in the value of the mass end correction under the individual effects of grazing flow, and high-amplitude excitation is presented. Additionally, depending on the excitation wavelength, the partial recovery of the reduced value of the end correction under simultaneous exposure is also shown. Using the experimental results, models for the end correction, and by extension the reactance are proposed. These models take into account the geometrical parameters of the perforate, and the dimensionless Mach, Shear and Strouhal numbers.

Efficient photocatalytic H2 evolution over CuCo2S4 decorated ZnIn2S4 with S-scheme charge separation way

The construction of an S-scheme heterojunction can facilitate the separation and utilization of photogenerated charges, as well as reserve the reducing power of electrons to induce proton reduction for H2 evolution. In this study, CuCo2S4 nanoparticles and ZnIn2S4 nanoflowers were both synthesized via a hydrothermal method, and then CuCo2S4 was employed to decorate ZnIn2S4 to form CuCo2S4/ZnIn2S4 heterojunction through a simple physical solvent evaporation strategy. The experiment result shows that the rate of photocatalytic H2 evolution (rH2) over 10 wt% CuCo2S4/ZnIn2S4 can reach up to 20421.3 μmol g−1 h−1, which is 4.0 times that of ZnIn2S4 (5062.5 μmol g−1 h−1) and 144.6 times that of CuCo2S4 (141.2 μmol g−1 h−1). The improved activity results from the establishment of an S-scheme charge transfer way between CuCo2S4 and ZnIn2S4, which facilitates efficient charge separation while preserving active e− and h+. Besides, the formation of the heterojunction broadens the range of light absorption, promotes charge carrier generation, reduces charge transfer impedance, and increases electrochemically active surface area, these together lead to faster H2 evolution kinetics. The present study demonstrates the potential of bimetallic sulfides as a promising catalyst for construction ZnIn2S4-based photocatalysts for efficient solar conversion.

The enhanced properties of ZnCoNi-S electrode by magnetron sputtering of Au nanoparticles for high performance supercapacitors

In this work, the distinctive effect of Au nanoparticles on shape preservation and properties enhancement during the preparation of transition metal sulfides is explored for the first time. After zeolitic imidazolate framework-67 (ZIF-67) is uniformly covered on nickel foam (NF), ZnCo layered double hydroxides (ZnCo-LDH) are compounded with ZIF-67 via hydrothermal method. The surface of compound is then coated with Au by magnetron sputtering. The final electrode is produced through sulfidation reaction. Benefiting from the excellent inertness and electrical conductivity of Au, the flake structure remains stable during the following sulfidation, and transfer impedance of the obtained Au/ZnS@Co3S4@Ni3S2 (Au/ZCN-S) electrode decreases significantly. In contrast, magnetron sputtered Ag or Cu nanoparticles react to Ag2S or CuS2 and cannot protect the refined structure of electrode as Au does. The Au/ZCN-S electrode shows a low transfer impedance of 0.0785 Ω and enables a specific capacity of 302.6 mAh g−1. Furthermore, the asymmetric supercapacitor constructed by Au/ZCN-S and activated carbon (AC) achieves a remarkable energy density of 104.09 Wh kg−1 with a high capacitance retention rate of 91.184 % after 10000 cycles. This work provides a new approach to optimize the morphology and performance of transition metal sulfides electrode for supercapacitors.

Development of novel plasma process for modification of solid and liquid interfaces for high-energy-density Cu-MnOx supercapacitor electrodes

Supercapacitors are known for their fast-charging capabilities and high-power density, though their energy density is lower compared to common batteries. Modifying the interface of manganese oxide (MnOx) electrodes by incorporating copper (Cu) is a promising method to enhance the energy density of supercapacitors, though it is not yet fully implemented due to the high electrical resistance inherent to MnOx. This work addresses this challenge by incorporating copper oxide into MnOx. A custom-designed atmospheric-pressure plasma device is used to induce super-hydrophilicity in the carbon cloth substrate, thereby improving MnOx electrodeposition. The copper sulfate precursor solution is also treated with direct plasma discharge to increase the copper doping rate in MnOx. The resulting Cu-MnOx supercapacitor electrodes, with copper oxide incorporated into the material, exhibit significantly lower charge transfer resistance and impedance, indicating an improved electrolyte/electrode interface. The assembled asymmetric supercapacitor, featuring Cu-MnOx as the cathode and activated carbon as the anode, demonstrates a specific capacitance of 92.3 F/g at 1 A g-1, a power density of 700 W/kg, and an energy density of 25.13 Wh/kg. This approach is promising for developing next-generation plasma processing technologies and energy storage materials and devices, as well as easy-to-implement surface modifications for improved wettability.

Photo-Assisted Chemical Self-Rechargeable Zinc Ion Batteries with High Charging and Discharging Efficiency.

Chemical self-recharging zinc ion batteries (ZIBs), which are capable of auto-recharging in ambient air, are promising in self-powered battery systems. Nevertheless, the exclusive reliance on chemical energy from oxygen for ZIBs charging often would bring some obstacles in charging efficiency. Herein, we develop photo-assisted chemical self-recharging aqueous ZIBs with a heterojunction of MoS2/SnO2 cathode, which are favorable to enhancing both the charging and discharging efficiency as well as the chemical self-charging capabilities under illumination. The photo-assisted process promotes the electron transfer from MoS2/SnO2 to oxygen, accelerating the occurrence of the oxidation reaction during chemical self-charging. Furthermore, the electrons within the MoS2/SnO2 cathode exhibit a low transfer impedance under illumination, which is beneficial to reducing the migration barrier of Zn2+ within the cathode and thereby facilitating the uniform inserting of Zn2+ into MoS2/SnO2 cathode during discharging. This photo-assisted chemical self-recharging mechanism enables ZIBs to attain a maximum self-charging potential of 0.95 V within 3 hours, a considerable self-charging capacity of 202.5 mAh g-1 and excellent cycling performance in a self-charging mode. This work not only provides a route for optimizing chemical self-charging energy storage, but also broadens the potential application of aqueous ZIBs.

Photo‐Assisted Chemical Self‐Rechargeable Zinc Ion Batteries with High Charging and Discharging Efficiency

AbstractChemical self‐recharging zinc ion batteries (ZIBs), which are capable of auto‐recharging in ambient air, are promising in self‐powered battery systems. Nevertheless, the exclusive reliance on chemical energy from oxygen for ZIBs charging often would bring some obstacles in charging efficiency. Herein, we develop photo‐assisted chemical self‐recharging aqueous ZIBs with a heterojunction of MoS2/SnO2 cathode, which are favorable to enhancing both the charging and discharging efficiency as well as the chemical self‐charging capabilities under illumination. The photo‐assisted process promotes the electron transfer from MoS2/SnO2 to oxygen, accelerating the occurrence of the oxidation reaction during chemical self‐charging. Furthermore, the electrons within the MoS2/SnO2 cathode exhibit a low transfer impedance under illumination, which is beneficial to reducing the migration barrier of Zn2+ within the cathode and thereby facilitating the uniform inserting of Zn2+ into MoS2/SnO2 cathode during discharging. This photo‐assisted chemical self‐recharging mechanism enables ZIBs to attain a maximum self‐charging potential of 0.95 V within 3 hours, a considerable self‐charging capacity of 202.5 mAh g−1 and excellent cycling performance in a self‐charging mode. This work not only provides a route for optimizing chemical self‐charging energy storage, but also broadens the potential application of aqueous ZIBs.

Study on low-mid-frequency broadband sound absorption properties of bending acoustic metamaterials with embedded porous materials

With the rapid development of the traffic industry, noise issues are becoming increasingly serious, and the traditional noise control technologies have the problems of poor low-frequency noise absorption and narrow bandwidth. This study proposes a variable-section bending acoustic metamaterial with an embedded porous material (VS_BAMP). A theoretical model of the VS_BAMP unit is developed based on the Johnson-Champoux-Allard (JCA) model and the impedance transfer method. The sound absorption unit with a thickness of 48 mm exhibits a quasi-perfect (α = 0.98) at 736 Hz, and an efficient sound absorption (α > 0.8) in the range of 574 Hz–966 Hz. Based on the complex frequency plane method, this work designs sound absorption units that exhibit perfect sound absorption at discrete frequencies. By connecting two different absorption units (PVS_BAMP) in parallel, efficient sound absorption from 424 Hz to 1500 Hz is achieved. Finally, the accuracy of the theoretical model is verified by experiments and simulations, confirming the effective sound absorption of PVS_BAMP structure in the middle and low frequency bands. The prepared PVS_BAMP is highly adjustable, has a wide bandwidth, and can be prepared through a simple manufacturing process. Our results can provide a theoretical basis for the design of compact low-mid-frequency broadband noise reduction structures for practical application.

Two-phase magnetohydrodynamic blood flow through curved porous artery

Blood arteries are important part of our cardiovascular system. A comprehensive study of shape and anatomy of blood arteries allows to elucidate the dynamics of blood flow in these arteries. Typically, the arteries are a curved-tube like structure, with arterial walls exhibiting a composition of various porous layers. The current study embarks on a theoretical exploration of a two-fluid model of blood flow and heat transfer through the curved artery under an influence of a magnetic field. The artery walls are composed of Brinkman and Darcy layers. The blood flows through a curved artery exerts centrifugal forces on the arterial walls that leads to change the blood flow patterns. The significant effects of curvature along with the intensity of an applied magnetic field on the blood flow patterns, heat transfer, and resistance impedance in curved artery have been investigated in the present work. The mathematical model of the proposed work is tackled by the homotopy analysis method using physically relevant boundary and interface conditions. The significant outcome of the present work is that the heat transfer rate increases with the increase in the curvature parameter, and it reduces on raising the couple stress parameter and Hartmann number. The novelty of this work lies in the consideration blood flow and heat transfer in inner endothelial layers of curved porous artery. The result presented in this work is vital to assess the condition of atherosclerosis, aneurysms, vasculties, blood clot, etc.; beyond this, the present model can be extended for medical diagnostics, treatment planning, medical device design, drug delivery optimization, and biomedical engineering research. This study can ultimately contribute for improved patient care and outcomes in cardiovascular medicine.

Acoustic measurement of super-small-particle-filtering stainless steel wire cloths

The super-small-particle-filtering stainless steel (SSPFSS) wire cloth can serve as a front cover on resonators in mufflers, offering a broader noise reduction bandwidth compared to the resonators themselves. Like micro-perforated panels (MPPs), the SSPFSS wire cloth provides flexibility in resonator design and manufacturing. In this study, we conduct measurements of the transfer impedance of SSPFSS cloths and sound absorption coefficients of absorbers covered by SSPFSS cloths. For comparison purposes, we also calculate the sound absorption coefficient of foam and various absorbers covered by MPPs, traditional perforated panels, and fabric using referenced empirical equations.

An application and discussion of wide-band signal processing technology in the primary calibration for hydrophones

Abstract Wide-band signals are potentially available in the measurement of transducers, which can obtain wide-band responses of electroacoustic parameters of them directly. The hydrophone of B&K 8103 is calibrated in a Φ 1.2 m×1.8 m small water vessel by wide-band signal processing technology in the frequency range of 3.15 kHz to 100 kHz. A thin pellicle co-vibrates with acoustic particle in the free-field, and its oscillation can be detected by a laser Doppler vibrometer, which can estimate the acoustic pressure distribution. The transfer function model is established in a small water vessel, and the wide-band frequency responses of the transfer impedance of transducer and hydrophone as well as the transfer impedance of transducer and pellicle in the small water vessel are calculated respectively. The wide-band signal processing technology of frequency domain filter process are used, which can isolate the reflecting acoustic wave from the boundaries and the surface of the water vessel. To verify the accuracy of the wide-band calibration measurements, the calibration results are compared with that using tone-burst signals in the water vessel and using free-field reciprocity method in the large water tank. The comparisons show that their calibration results are in a good agreement with each other, and the maximum deviation is 0.7 dB. All these demonstrate that the wide-band signal processing technology described is accurate and stable.

Comparative electrocatalytic behavior of mesoporous FeP and FeS2 for the hydrogen evolution reaction

FeP nanoparticles and FeS2 nanospheres with mesoporous surface are synthesized, and their performance is compared for the hydrogen evolution reaction under identical electrochemical conditions. The activity-determining characteristics of the electrodes, such as specific and electrochemically active surface area, electrochemical impedance and charge transfer resistance, Tafel slopes, number of catalytic active sites, and turnover frequency (TOF) are studied and correlated to their activity. Because of its larger surface area and reduced charge transfer resistance, the FeS2 showed superior HER performance than the FeP, despite the latter’s higher intrinsic catalytic activity. The electrocatalytic stability of the electrocatalysts are also compared.

Multi-dimensional carbon modification strategy for lithium-ion battery anodes: Carbon-covered TiP2O7 supported by 3D carbon skeleton

Carbon coating is a beneficial method for improving surface capacitive behavior, electron transfer kinetics and cyclic stability of three-dimensional lattice lithium-embedded anode materials. Herein, we adopt one-step pyrolysis to achieve carbon-covered TiP2O7 supported by a three-dimensional carbon skeleton utilizing phytic acid and glucose as carbon sources. The two-dimensional amorphous carbon layer on TiP2O7 surface improves the initial Coulombic efficiency and rate capacity by inhibiting the irreversible embedding of lithium ions and reducing the interfacial charge transfer impedance. The three-dimensional carbon skeleton not only forms a conductive pathway between the carbon-covered TiP2O7, but also its large specific surface area, randomly oriented and defective carbon layer provide extra lithium storage sites and capacitive contribution. In addition, the specific capacity of the TiP2O7/C composite is still as high as 314.5 mA h g−1 after 1000 cycles at 1 A g−1. A TiP2O7/C//LiFePO4 full cell delivers a high energy density of 273.96 Wh kg−1 at 0.153 kW kg−1, and retains 114.43 Wh kg−1 even at the power density of 4.086 kW kg−1. The multi-dimensional carbon modification strategy has improved the electrochemical performance of TiP2O7-based anode materials, providing a model for synthesizing other high-performance anode materials.

(Battery Student Slam 8 Award Winner) Multi-Clustered Lithium Diffusion in Single-Crystalline NMC Battery Particles

Understanding the diffusion dynamics of lithium within solid-state electrodes is pivotal for developing high-performance batteries. In this context, layered oxides were utilized as a promising cathode material due to their high energy density and fast intraparticle lithium diffusivity. Despite advancements in material composition, coating, and doping, the understanding of intraparticle lithium diffusion has long been described by Fick's law. Conventionally, lithium diffusion is assumed to generate a monotonic lithium concentration gradient within solid-solution single-crystalline battery materials during cycling. This raises fundamental questions about diffusion in layered oxides; (1) Can the diffusion of Li in solids be interpreted as Fickian diffusion, similar to diffusion in gases or liquids, even though it involves structural and phase evolution throughout the battery cycle? and, (2) Does the fast diffusivity (10-11-10-9 cm2/s) support the homogenization of Li?In this study, we address these questions surrounding lithium diffusion in layered oxide by utilizing operando scanning transmission X-ray microscopy. We revealed the formation of mobile Li-dense/-dilute nano-domains within individual single-crystalline LiNi1/3Mn1/3Co1/3O2 (scNMC) during battery cycles. We term this phenomenon ‘multi-clustered lithium diffusion’, distinguishing our findings from the conventionally suggested Fickian diffusion model in solid-solution materials. These domains persist for at least 4 hours during relaxation, accompanied by locally residing strained domains, as confirmed by Bragg coherent diffraction imaging (BCDI), within a single particle. We believe these domains arise due to the compensation of localized chemical potential gradients that are generated by the sustained presence of strain within the battery particles during cycling.While maintaining integrity of Li-dense/-dilute domain at various C-rates, STXM result further show that Li-dilute domains maintain during the discharging. Given the lower concentration of Li at insertion boundaries, which could lower the surface charge transfer impedance of the system, Li-dilute domains facilitate lithium transport by functioning as low-resistance pathways. Through a comprehensive analysis of electrical impedance spectroscopy (EIS), STXM imaging and finite element analysis (FEA), we showed that controlling the local domain fraction is crucial for controlling the overpotential during subsequent charging. Our study introduces new insights into nanoscale solid-state diffusion, thereby enabling the fabrication of high-performance batteries. Figure 1

Optimizing Silicon Nanostructures for Enhanced Li-Ion Storage: Microstructure, Binder and Production Technology

The utilization of silicon nanostructures as anodes in lithium-ion batteries (LIBs) presents a promising avenue for improving device performance. However challenges related to prolonged cycling, energy density, and costs need to be addressed. This presentation outlines three strategies employed within the E2MC framework to overcome these challenges: (a) By incorporating high-quality graphene nanosheets, produced through a low-cost and scalable molten salt method, common silicon nanoparticles (generated by commercially available pyrolysis-based methods) can be enveloped in graphene layers with a controllable chemical composition. The graphene-encapsulated silicon nanoparticles exhibit stable electrochemical lithiation/delithiation performance, showcasing significantly improved energy density, even after numerous Li-insertion and extraction cycles, outperforming bare Si nanoparticles; (b) Thermally modified polyimide (PI) is introduced as an efficient binder to enhance the Li-ion storage performance of silicon nanoparticles. An optimized thermal treatment of the electrodes containing Si nanoparticles and PI binder produces an effective charge transfer complex (CTC) structure, improving the electrochemical performance by forming a compact structure that reduces charge transfer impedance. This enhancement significantly boosts the cycling performance of the silicon anode; (c) An ultra-fast shock-wave combustion synthesis approach is introduced for the rapid and low-cost preparation of Si nanostructures using naturally available SiO2 as the silicon feedstock. Completed at an ignition temperature of approximately 550 °C, this method requires virtually no dwell time. The resulting nanostructured Si product exhibits a mesoporous integrated sheet-like morphology, demonstrating excellent and stable Li-ion storage performance. This approach contributes to a more sustainable and cost-effective utilization of elemental Si nanoparticles in LIB applications.

Micrometer long bimetallic Nickel-cobalt schiff base MOF as supercapacitor electrodes

Nickel and Nickel-cobalt [Ni1/3Co2/3(HL)2].3H2O Schiff base complexes were synthesized from 2-(methoxycarbonyl-hydrazono)-pentanedioic acid, H2L ligand with metal salts. The structural analysis reveals that the prepared samples were endowed with well crystalline nature. The electrodes of Nickel-cobalt Schiff base complex (Ni-Co) exhibits Faradaic peaks indicating the diffusion controlled charge transfer mechanism. As a supercapacitor electrode, the Ni-Co exhibits higher specific capacitance of 683 F g−1 at a current rate of 1 A g−1, which is higher than the Nickel complex. Further the bimetallic material possesses better cyclic stability and very less charge – transfer resistance. An asymmetric device was fabricated using Ni-Co complex as the positive electrode material and activated carbon as the negative electrode. The as fabricated device displays a specific capacitance of 239 F g−1 with energy density of 69 Wh kg−1 and power density of 1385 W kg−1. This device demonstrated preservation of 91 % of initial capacitance after 2000 cycles. These attractive features demonstrate Ni-Co complex is a better candidate for supercapacitor electrode applications.