Electrode Separation Research Articles

Assessment of Bedrock Depth Utilizing Vertical Electrical Sounding (DDBR)

This study is aimed at evaluating the depth to bed rock around Liji area of Gombe Northeastern Nigeria. The area covers 18𝒌𝒎𝟐and lies between Latitudes 11°11ʹ20.4ʺ, and 11°14′ 37.4″Eand Longitudes 10°16′ 20.8″, and 10°19′ 16.0″N, (Gombe N.W Sheet 152). The study area consists of Basement rocks (Coarse grained Biotite Granite,), Aptian-Albian indurated Bima Sandstone, Gombe Formation and Mudrock. Ten (10) Vertical Electrical Sounding (VES) were profiled around Liji and environs, employing Schlumberger array with a maximum electrode separation of AB/2 = 100m to determine the depth to bedrock. The data obtained were processed and interpreted using WinResist program. The results showed that seven (7) VES points (VES 1, 2, 3, 5, 6, 7 and 10) displayed three layers while the remaining (VES 4, 7 and 9) had four layers. The Geo-electric sections along profiles A-A’ and B-B’ revealed that the area is underlain dominantly bythree layers, (top soil, weathered sandstone and basement). Thefirst layer has a resistivity value ranging from 2.3 to 193.5Ωm witha thickness that ranges from 0.4 to 7.1m. The second layer isweathered Sandstone with a resistivity range of 2.8 to 4607.6Ωmand thickness of 0.8 to 7.3m while the third layer is Basement withresistivity value of 93.6 to 37356.9Ωm with an infinite thickness.VES 4, 7 and 9 had four layers and the third layer represent thefresh Sandstone with resistivity ranges of 290.2Ωm to 4607.6Ωmand a thickness of 3.3m to 17.3m while the forth layer in therespective three VES points is basement, having resistivity rangesof 3.1Ωm to 15717.4Ωm with an infinite thickness. At the end ofthe study, the results revealed that Basement rocks are present atVES 1, 2, 4, 5, 6, 7 and 10 at the depth of 10m, 9.3m, 19.7m, 6.5m,5.7m, 14.7m and 24.0m respectively with an infinite thickness,therefore these serves as the depths to be removed to reached thetop of the basement for the construction of a sound foundation.

Charged atomization characteristics and influencing factors analysis of aviation kerosene/ethanol blended fuel

ABSTRACT In this study, an experimental apparatus for charged atomization was established to explore the charged atomization modes of blended aviation kerosene/ethanol fuels and the corresponding evolution of atomization modes for E0 (100% aviation kerosene), E10 (10% ethanol + 90% aviation kerosene), E30 (30% ethanol + 70% aviation kerosene), and E50 (50% ethanol + 50% aviation kerosene) blends with varying applied voltages. Furthermore, the influence of the ethanol blending ratio, electrode separation distance, fuel flow rate, nozzle diameter, and other influencing factors on the charged atomization characteristics was investigated. Experimental results within the 0 to 10 kV voltage range revealed that as the voltage increased, the E0 fuel transitioned from droplet formation to spindle shape without exhibiting atomization, while the E10, E30, and E50 fuels displayed a sequential progression of atomization modes including droplet, micro-droplet, pulsed-jet, cone-jet, deflected-jet, and multi-jet configurations. As the ethanol blending ratio increases, the critical voltage required for the transition to atomization mode decreases, while the atomization cone angle gradually increases. The average atomization cone angles are 38.98°, 49.97°, and 66.83° for E10, E30, and E50, respectively. When the nozzle diameter is reduced from 1.05 mm to 0.3 mm, the charged atomization cone angle does not change significantly. With increasing fuel flow, the critical voltage for the atomization mode transition increases progressively, and the charged atomization cone angle also increases. The average atomization cone angles are 65.80°, 88.45°, 93.04°, 103.63°, and 110.97°, respectively.

A 3D printed dual screen-printed electrode separation device for twin electrochemical mini-cell establishment.

We describe a tiny 3D-printed polymethyl-methacrylate-based plastic sleeve that houses two disposable screen-printed electrodes (SPE) and enables each of the working electrodes (WEs) to work independently, on a different side of a thin barrier, in its own electrochemical (EC) mini-cell, while the SPE counter and reference units are shared for electroanalysis. Optical and EC performance tests proved that the plastic divider between WE1 and WE2 efficiently inhibited solution mixing between the mini-cells. The two neighboring, independently operating mini-cells enabled matched differential measurements in the same sample solution, a tactic designed for elimination of electrochemical interference in complex samples. In a proof-of-principle glucose biosensor trial, a glucose oxidase-modified WE2 and an unmodified WE1 delivered the EC data for the removal of anodic ascorbic acid (AA) interference simply by subtracting the WE1 (background) current from the analyte-specific WE2 current (from buffered sample solution supplemented with glucose/AA), at an anodic H2O2 detection potential of +1 V. The microfabricated SPE accessory is cheap and easy to make and use. For the many dual electrode SPE strips on the market for multiple analytical targets the new device widens the options for their exploitation in assays of biological and environmental samples with complex matrix compositions and significant risks of interference.

Development of novel ionization chambers for reference dosimetry in electron flash radiotherapy

AbstractBackgroundReference dosimetry in ultra‐high dose rate (UHDR) beamlines is significantly hindered by limitations in conventional ionization chamber design. In particular, conventional chambers suffer from severe charge collection efficiency (CCE) degradation in high dose per pulse (DPP) beams.PurposeThe aim of this study was to optimize the design and performance of parallel plate ion chambers for use in UHDR dosimetry applications, and evaluate their potential as reference class chambers for calibration purposes. Three chamber designs were produced to determine the influence of the ion chamber response on electrode separation, field strength, and collection volume on the ion chamber response under UHDR and ultra‐high dose per pulse (UHDPP) conditions.MethodsThree chambers were designed and produced: the A11‐VAR (0.2–1.0 mm electrode gap, 20 mm diameter collector), the A11‐TPP (0.3 mm electrode gap, 20 mm diameter collector), and the A30 (0.3 mm electrode gap, 5.4 mm diameter collector). The chambers underwent full characterization using an UHDR 9 MeV electron beam with individually varied beam parameters of pulse repetition frequency (PRF, 10–120 Hz), pulse width (PW, 0.5–4 µs), and pulse amplitude (0.01–9 Gy/pulse). The response of the ion chambers was evaluated as a function of the DPP, PRF, PW, dose rate, electric field strength, and electrode gap.ResultsThe chamber response was found to be dependent on DPP and PW, and these dependencies were mitigated with larger electric field strengths and smaller electrode spacing. At a constant electric field strength, we measured a larger CCE as a function of DPP for ion chambers with a smaller electrode gap in the A11‐VAR. For ion chambers with identical electrode gap (A11‐TPP and A30), higher electric field strengths were found to yield better CCE at higher DPP. A PW dependence was observed at low electric field strengths (500 V/mm) for DPP values ranging from 1 to 5 Gy at PWs ranging from 0.5 to 4 µs, but at electric field strengths of 1000 V/mm and higher, these effects become negligible.ConclusionThis study confirmed that the CCE of ion chambers depends strongly on the electrode spacing and the electric field strength, and also on the DPP and the PW of the UHDR beam. A significant finding of this study is that although chamber performance does depend on PW, the effect on the CCE becomes negligible with reduced electrode spacing and increased electric field. A CCE of ≥95% was achieved for DPPs of up to 5 Gy with no observable dependence on PW using the A30 chamber, while still achieving an acceptable performance in conventional dose rate beams, opening up the possibility for this type of chamber to be used as a reference class chamber for calibration purposes of electron FLASH beamlines.

Recovery of lithium from oxalic acid leachate produced from black mass of spent electric vehicle Li-ion batteries

Lithium (Li) demand is surging due to the adaptation of Lithium-ion batteries (LIBs) in electric vehicles (EV). To ease the supply from virgin sources and meet new legislative recycling targets it's imperative to secure supply from secondary sources. Recently oxalic acid leaching has been reported for early-stage recovery of Li from black mass (BM) of spent EV LIBs. Such processes often face challenges in electrodes separation, thermal treatment of cathode material, and leachate up-concentration. Herein, the synergistic application of benzoyltrifluoroacetone (HBTA) and trioctylphosphine oxide (TOPO) to extract Li from oxalate streams of an industrial BM has been demonstrated for the first time. Under optimum conditions, ∼92 % Li was extracted from the leachate in 6mins, aqueous/organic (A/O) phase ratio 1, and pH 11. McCabe Thiele diagram indicated two counter-current stages for the complete extraction of Li at A/O 1. The slope analysis method indicated equal moles of HBTA required to extract Li and FT-IR spectroscopy confirmed the synergism of the extractants. The organic phase was scrubbed with Li salt and stripped with hydrochloric acid (HCl) resulting in a concentrated (Li ∼4 mol/L) solution precipitated as lithium carbonate (>99 % pure). The transition metals during oxalic acid leaching were reduced and precipitated as respective oxalates due to low solubility. They were successfully recovered using a second leaching step with HCl. The excess acid was recovered as oxalic acid by cooling crystallization, not reported earlier for BM recycling streams, facilitating a closed-loop process. The developed flowsheet significantly advances the early-stage Li recovery processes from BM.

Impedimetric detection of chloride ions using two symmetric Ag/AgCl electrodes

The suitability of Ag/AgCl electrodes for specific detection of chloride ions in aqueous gels is investigated. In contrast to potentiometric sensors, we use an impedimetric approach and avoid the need for a separate reference electrode through a symmetric two-electrode configuration. As such, electrochemical impedance spectroscopy is employed to characterise the response of the Ag/AgCl electrodes in contact with gels at various hydration levels containing different types as well as concentrations of salt. In order to extract quantitative information related to e.g. the ion concentration and mobility from the impedance spectra, an equivalent circuit model is fitted to the data. Here, we develop a simple equivalent circuit model related to the physical parameters of the system, which can be reduced to a modified Randles circuit with only few circuit elements. Importantly, even though the equivalent circuit model contains the same elements as a Randles circuit, their physical origin is different. Systematic variations of ion mobility, ion concentration, and type of ions allow us to evaluate the relationship between those physical properties and the resulting fitting parameters of the modified Randles circuit. This finally enables us to determine chloride concentrations in complex liquids, containing other salts and long chain molecules.

Electrically driven cavity plasmons in Au nanowire over Au film

Light emission via inelastic tunneling electrons is appealing for integrated optoelectronic devices due to its femtosecond time scale that can in principle allow terahertz modulation bandwidth. It has gained renewed interest since 2015 due to the improved quantum efficiency, highly tunable emission wavelength, linewidth, or directionality once the electrodes are designed as a plasmonic nanocavity. However, efficient construction of stable tunnel junctions with desired plasmonic resonances is still technically challenging because of the subnanometer precision required in the electrical and optical design. Here, we demonstrate an easily accessible electrically driven cavity plasmon in metal-insulator-metal (MIM) tunnel junctions, comprised by a Au nanowire (NW) across two separate ultrasmooth Au electrodes. Two layers of self-assembled thiol molecule defines a reliable tunneling barrier. The contribution from the localized cavity plasmons to the total light emission is found to be dominant over that from the propagating surface plasmon polariton in the MIM waveguide, different from the traditional explanations. This work introduces a simplified method for constructing electrically driven cavity plasmons using crystalline metals, which holds promise for applications in in situ chemical or biosensing and the development of flexible light-emitting metasurfaces.

Novel Conductive and Redox-Active Molecularly Imprinted Polymer for Direct Quantification of Perfluorooctanoic Acid.

This study developed a novel molecularly imprinted polymer (MIP) that is both conductive and redox-active for directly quantifying perfluorooctanoic acid (PFOA) electrochemically. We synthesized the monomer 3,4-ethylenedioxythiophene-2,2,6,6-tetramethylpiperidinyloxy (EDOT-TEMPO) for electropolymerization on a glassy carbon electrode using PFOA as a template, which was abbreviated as PEDOT-TEMPO-MIP. The redox-active MIP eliminated the need for external redox probes. When exposed to PFOA, both anodic and cathodic peaks of MIP showed a decreased current density. This observation can be explained by the formation of a charge-assisted hydrogen bond between the anionic PFOA and MIP's redox-active moieties (TEMPO) that hinder the conversion between the oxidized and reduced forms of TEMPO. The extent of the current density decrease showed excellent linearity with PFOA concentrations, with a method detection limit of 0.28 ng·L-1. PEDOT-TEMPO-MIP also exhibited high selectivity toward PFOA against other per- and polyfluoroalkyl substances (PFAS) at environmentally relevant concentrations. Our results suggest electropolymerization of MIPs was highly reproducible, with a relative standard deviation of 5.1% among three separate MIP electrodes. PEDOT-TEMPO-MIP can also be repeatedly used with good stability and reproducibility for PFOA detection. This study provides an innovative platform for rapid PFAS quantification using redox-active MIPs, laying the groundwork for developing compact PFAS sensors.

Surface State Modulation via Electrochemical Heterogeneous Redox Reactions for Full-Color Emission Carbon Dots.

Carbon dots (CDs) still suffer from unclear surface state fluorescence mechanism for fine modulation. Here, redox reactions for cathode and anode within electrochemical method are firstly employed to construct differentiated strategy for surface-state modulation, so as to obtain CDs with controllable emission in separated electrodes simultaneously. The fluorescence peaks of CDs from blue to red centered at 425 nm (mCDs-), 530 nm (mCDs+), 580 nm (oCDs-) and 665 nm (oCDs+) are mainly originated from the different bombardment effects of the ions and reaction tendencies of modifier during the electrolysis process. The phenylenediamine (as modifier) tends to introduce the amino groups on the surface of CDs- while introduced nitrogen atoms into the carbon nucleus skeleton around the anode, thus leading to much larger size and the formation of the graphite N for CDs+. It is the different surface states formed by phenylenediamine and the absorption redshift triggered by graphite N that ensures the tunable emission. The improved electrochemical method is of great significance for finely spectra modulation and efficient synthesis.

Streamlined integrated protein isoelectric focusing using microfluidic paper-based device

An innovative integrated paper-based microdevice was developed for protein separation by isoelectric focusing (IEF), allowing for robust design thanks to a 3D-printed holder integrating separation channel, reservoirs, and electrodes. To reach robustness and precision, the optimization focused on the holder geometry, the paper nature, the reservoir design, the IEF medium, and various focusing parameters. A well-established and stable pH gradient was obtained on a glass-fiber paper substrate with simple sponge reservoirs, and the integration of the electrodes in the holder led to a straightforward system. The separation medium composed of water/glycerol (85/15, v/v) allowed for reducing medium evaporation while being an efficient medium for most hydrophobic and hydrophilic proteins, compatible with mass spectrometry detection for further proteomics developments. To our knowledge, this is the first report of the use of glycerol solutions as a separation medium in a paper-based microdevice. Analytical performances regarding pH gradient generation, pI determination, separation efficiency, and resolution were estimated while varying the IEF experimental parameters. The overall process led to an efficient separation within 25 min. Then, this methodology was applied to a sample composed of saliva doped with proteins. A minimal matrix effect was evidenced, underscoring the practical viability of our platform. This low-cost, versatile and robust paper-based IEF microdevice opens the way to various applications, ranging from sample pre-treatment to integration in an overall proteomic-on-a-chip device.

Collection efficiencies of cylindrical and plane parallel ionization chambers: analytical and numerical results and implications for experimentally determined correction factors

Objectives. To derive a collection efficiency formula, fGauss , for cylindrical ionization chambers in pulsed radiation beams from a volume recombination model of Boag et al (1996 Phys. Med. Biol. 41 885–97) including free electrons. To validate fGauss and a parallel plate chamber formula fexp using an ion transport code and calculate changes in collection efficiencies caused by electric field charge screening at 0.1–100 mGy doses-per-pulse. And to determine collection efficiencies CE∞ predicted at infinite voltage in the absence of avalanche effects by fitting scaled formulae to efficiencies computed for 100–400 V chamber voltages and 10 and 100 mGy doses-per-pulse. Approach. Calculations were performed for an idealized parallel plate chamber with 2 mm electrode separation d , and for an idealized cylindrical chamber with 0.5 and 2.333 mm inner and electrode radii rin and rout . Main results. fGauss and fexp predict the same collection efficiencies for cylindrical and parallel plate chambers satisfying d2=(rout2−rin2)ln(rout/rin)/2 , an equivalence condition met by the chambers studied. Without charge screening, efficiencies computed using the code equalled fGauss and fexp . With screening, efficiencies changed by ⩽0.03%, ⩽1.1% and ⩽21.3% at 1, 10 and 100 mGy doses-per-pulse, and differed between the chambers by ⩽0.9% and ⩽19.6% at ⩽10 and 100 mGy dose-per-pulse. For fits of fexp and fGauss , CE∞ values were ⩽1.2% and ⩽17.6% from unity at 10 and 100 mGy per pulse respectively, closer than for other formulae tested. Significance. Allowing for screening, fGauss and fexp described computed collection efficiencies to within 0.03%, 1.1% and 21.3% at doses-per-pulse ⩽1, 10 and 100 mGy. Equivalence of the two chambers broke down at 100 mGy per pulse. Departures of CE∞ values from unity suggest that collection efficiencies determined experimentally by fitting fGauss or fexp to readings made at multiple voltages will be accurate to within 1.2% and 17.6% at 10 and 100 mGy per pulse respectively.

Interpenetrated Structures for Enhancing Ion Diffusion Kinetics in Electrochemical Energy Storage Devices

HighlightsA new and compact device configuration was created with two interpenetrated, individually addressable electrodes, allowing precise control over the geometric features and interactions between the electrodes.The interpenetrated electrode design improves ion diffusion kinetics in electrochemical energy storage devices by shortening the ion diffusion length and reducing ion concentration inhomogeneity.The device with interpenetrated electrodes outperformed the traditional separate electrode configuration, enhancing both volumetric energy density and capacity retention rate.

Design of electrical energy harvesting devices utilizing air bubbles sliding along a fluoropolymer immersed in water

Recent research has shown that it is possible to utilize contact electrification combined with electrostatic induction to harvest electrical energy from the mechanical motion of air bubbles sliding along a charged solid surface immersed in water. The working principle of these devices is simple, but the design is usually complicated as transduction efficiency depends on a number of interdependent parameters. Here we propose a simple analytical model and demonstrate how it can be used to determine the optimal energy per bubble for a given resistive load. The model allows one to estimate the optimal energy harvested per bubble in terms of polymer thickness, electrode separation and load resistance. It is shown that the model provides a good fit to experimental data. The model may be used as an initial step when designing energy harvesting devices utilizing air bubbles sliding along a solid surface.

Comprehensive Experimental Database and Model Fitting for Electric Arc Behavior in Aircraft Environments

The More Electric Aircraft (MEA) paradigm advocates weight reduction by transitioning to electrical components, resulting in increased system voltage and higher arc fault risk. This paper presents a methodology for creating a database of nearly one thousand tests simulating parallel arc faults, using Andrea's arc model for accurate representation. Objectives include the creation of a robust experimental database and the use of a simplified model to analyze arcing behavior. The setup follows the UL 746A standard and considers various pressure and electrode separation conditions. The database includes 960 experiments with PVC and PTFE materials, and model fitting ensures accurate representation of arc currents and voltages. Error analysis shows consistent model performance across materials and highlights sensitivity to electrode spacing, pressure, and source voltage. The paper concludes with a clear 30% error threshold for model validity, enhancing the understanding of the applicability of Andrea's model under various experimental scenarios in aircraft environments.

Ingress of municipal solid waste into water resources: an environmental assessment and monitoring tool near dumpsites in Akwa Ibom State, Nigeria

ABSTRACT Municipal solid waste (MSW) dumping sites are only used for trash discarding. Beyond the reek that the dumpsites generate, which defiles the milieu, the primary issue is the spreading of fluid from the landfills. The thrust of this research is to utilize the contiguous data from geophysics and laboratory analysis of groundwater samples to decipher the influence of MSW on aquifer systems in Uyo and Eket Counties. Geo-electrical studies featured vertical electrical sounding (VES) and constant electrode separation techniques to generate 1D and 2D electrical resistivity models. The analyzed field data were integrated with water sample analysis to deduce the influence of leachate on groundwater. The VES curve types conformed to A (7.1%), HK (21.4%), Q (21.4%), and K (50.0%). The created 2D image maps for MSW locations lay bare the fact that leachate dispersal between source and sink obeys the inverse square rule. The heavy ions, which were all higher than the approved standards have, chromium as the highest and nickel as the least. The anionic average relative abundance has hydrogen trioxocarbonate ion concentration as the highest and fluoride ions as the least. The survey demonstrates that leachate has a considerable impact on groundwater.

A biocompatible triboelectric nanogenerator-based edible electronic skin for morse code transmitters and smart healthcare applications

Skin-inspired electronic devices have gained immense interest due to their application in prosthetics, healthcare, robotics, and humanmachine interactions. Mimicking human skin and incorporating multifunctional properties such as stretchability, flexibility, biocompatibility, biodegradability, and paving the way for self-powered electronic skin (e-skin) is highly desirable. The present work reports the fabrication of biocompatible triboelectric nanogenerator (TENG)-based edible electronic skins made of a biocompatible chitosan film. The fabricated chitosan film was engineered using plasticizers to enhance its flexibility and mechanical strength. To make the entire device biocompatible, edible gold leaf, which is used as a decorative layer in the sweets of the Indian subcontinent, has been used as an electrode. Both the chitosan film and the edible gold electrode were studied for their biocompatibility by immersion in acetic acid and H2O2, where the films were completely dissolved in 1 h and 50 h, respectively. The e-skins were used as the active layer in the triboelectric nanogenerator by working under both vertical contact separation and single electrode modes of triboelectrification. Furthermore, the fabricated device has been used for real-time applications in self-powered sleep monitoring systems as well as for wearable Morse code transmitters. The electrical response and performance in real-time applications prove that the developed e-skin-based device is a promising candidate for future wearable applications in health care, humanmachine interactions and haptics.

CREATION OF A CHEMICAL CURRENT SOURCE USING REDOX REACTIONS IN THE "IODINE-IODIDE" SYSTEM

Chemical current sources play an important role in energy supply systems that are closely related to everyday life. The ever-increasing dependence on electricity creates a huge demand for appropriate energy storage devices. The purpose: The aim of the work is to create a chemical current source based on the use of the "red – ox" iodine-iodide system and to determine the patterns of formation of electromotive force (EMF) and short-circuit current (short-circuit current) in water solutions depending on the concentration of ions. Objects. The experiments are carried out by measuring the EMF formed between graphite electrodes and SCC. A special installation has been assembled, consisting of an electrolyzer with separated electrode spaces, an ammeter, a voltmeter and graphite electrodes. Solutions of iodine and potassium iodide served as the electrolyte. Results. In an electrolyzer, the electrode spaces of which are separated by an anionite membrane, when one of the spaces is filled with a solution of iodine and the other with potassium iodide, an EMF is formed between the graphite electrodes. Under optimal conditions, the EMF and SCC values will be higher than 135 mV and 10 mA, respectively. Conclusion. The possibility of forming a chemical current source using the "red – ox" iodine-iodide system is shown. The patterns of EMF and SCC formation and their changes depending on ion concentrations are revealed. The results of the study show that "red – ox" systems of alternating valent elements can be used to create flowing chemical current sources with increased electrical capacity.

Reduced graphene oxide nanosheets as electron sink for MnFe2O4 nanoparticles: A synergistically boosted supercapacitance

Spinel ferrite structures have shown promise for energy storage. However, they are insulators and need a conductive substrate for better charge transfer. Here, we utilized a simple hydrothermal technique to in-situ coat a nickel foam with few-layer nanosheets of reduced graphene oxide (rGO) decorated with manganese ferrite (MnFe2O4) nanoparticles. We then studied the supercapacitance/pseudocapacitance properties of the rGO/MnFe2O4 composite. X-ray diffraction patterns, energy-dispersive X-ray maps, and X-ray photoelectron spectra of the composite were investigated to confirm its structural, elemental, and surface chemical composition, respectively. Scanning electron microscopy and transmission electron microscopy images demonstrated the decoration of rGO nanosheets with MnFe2O4 nanoparticles. In a three-electrode setup, the rGO/MnFe2O4 nanocomposite exhibits a specific capacitance per loaded material mass (2446 F/g at 1 A/g) which is higher than the sum of rGO (304 F/g) and MnFe2O4 (1084 F/g) electrodes, suggesting a synergistic effect between rGO and MnFe2O4. The energy density and power density of the rGO/MnFe2O4 electrode were also calculated 58.24 Wh/kg and 260.82 W/kg (at 1 A/g), respectively. We found that the resistance of the rGO/MnFe2O4 electrode (2.53 Ω) is much lower than the MnFe2O4 electrode (6.15 Ω), and the interfacial resistance of the rGO/MnFe2O4 electrode with electrolyte was found low, confirming the rGO role as a conductive substrate for insulating MnFe2O4 nanoparticles. We also showed that surface-related capacitance, rather than pseudocapacitance, is more dominant in the rGO/MnFe2O4 composite electrode than in the separate rGO and MnFe2O4 electrodes. We also demonstrated the practical performance of the rGO/MnFe2O4 electrode in a two-electrode setup. Finally, density functional theory calculations showed the considerable potential drop (16.5 eV) between MnFe2O4 and graphene that leads to a strong built-in electric field from graphene towards MnFe2O4. This indicates the role of graphene as a wide electron sink for MnFe2O4 nanoparticles that results in better charge distribution and storage.

Integrating Aperiodic 3D Porous Electrodes into 3D Batteries through Spray‐Deposited Polymer Electrolytes

AbstractDue to their exceptional energy and power densities, 3D micro‐batteries emerge as highly promising candidates for miniaturized power sources. However, fabricating a complete and uniform electrolyte/separator membrane to separate 3D electrodes in assembled 3D batteries remains a significant challenge. Herein, the study presents a straightforward approach to preparing 3D electrolyte membranes via a modified spray‐deposition method. This 3D electrolyte membrane effectively isolates the 3D porous LiFePO4 cathode from the Li anode with a ionic conductivity of 9.6 × 10−4 S cm−1, facilitating the creation of an integrated aperiodic 3D battery. The 3D battery exhibits a specific capacity of up to 8.8 mAh cm−2 (29.1 mWh cm−2) and attains a maximum power density of 12.7 mW cm−2. The characteristic time is 0.17 s for 3D battery while 0.73 s for traditional 2D batteries. The enhanced rate performance with thick electrode is primarily attributed to the reduced ionic diffusion pathway. These results represent the highest peak power and energy density among all reported aperiodic 3D batteries. The utilization of spray‐deposited electrolytes for 3D electrode separation promises significant advancements in developing 3D batteries and demonstrates great potentials for practical applications.

Effect of hydroxy-terminated hyperbranched polymer coated separator on the lithium-ion battery performances

Abstract The hydrophobicity of polyolefin separators causes poor compatibility with the internal environment of lithium-ion batteries and thus elevates lithium-ion migration barriers. In this research, hydroxy-terminated hyperbranched polymer (HTHP) coated separators are fabricated successfully based on the simple and easy-on impregnation method. Abundant hydroxyl groups in HTHP reinforce separator electrolyte affinity, generating the much lower contact angle and higher electrolyte uptake. Accordingly, HTHP-coated separators show broader electrochemical window and superior ionic conductivity and Li+ transport number, which facilitate the Li+ migration within porous pathways and hence maximally weaken counteranions-induced polarizations. The lower interfacial resistances also guarantee the Li+ accelerated diffusion via the separator–electrodes interfaces. Therefore, batteries containing modified separators exhibit optimized C-rate capacity and cycling stability. However, immoderate HTHP coating blocks partial pores and thus restricts Li+ transference, which deteriorates C-rate capacity and cycling durability in turn. This separator modification scheme possesses advantages of simple preparation, environment-friendly, and low manufacturing cost, providing practical guidance for low-cost and high-performance separator manufacture.