Increase In Voltage Research Articles

Maximizing Output Energy via Suppressing Charge Loss and Increasing Load Voltage in Charge Extraction Process.

The effective collection of interfacial tribo-charges and an increase in load voltage are two essential factors that improve the output energy of triboelectric nanogenerators. However, some tribo-charges are hardly collected through one or multiple integrated side electrodes based on corona discharge, and their load voltages are limited by air breakdown in adjacent electrodes. In this study, a dynamic quasi-dipole potential distribution model is proposed to systematically reveal the mechanisms of interfacial tribo-charge loss. Based on this model, an optimization route is designed to reduce the interfacial charge loss stepwise, achieving a 15-fold improvement in charge collection from the tribo-interface.A potential difference enhancement strategy is used for the first time to increase the air breakdown threshold between the inner electrodes and increase the output voltage under a large load. By effective increase in charge collection efficiency and load voltage, a historical record output energy density of 5.03 J m-2 is obtained. This study refined and optimized the interfacial charge loss mechanisms and provided advanced guidance for efficiently extracting energy during the triboelectrification process.

Study on the crack propagation morphology and initiation law of coal rock under the action of underwater electric pulse

Based on the symmetric initiation mechanism of double-wing cracks in coal rock mass induced by high-pressure electro-recoil water pressure, fracturing experiments have been performed on coal rock mass under different water pressures and discharge conditions using high-voltage electric pulse hydraulic fracturing devices. Combined with CT scans, the crack spatial distribution inside the post-break coal rock mass was analyzed and found that the edge of the water injection hole is prone to produce double-wing cracks along the drilling hole diameter. ABAQUS is used to verify the physical test and extend the test conditions, the geometric parameter change, morphological expansion rule and crack initiation mechanism of double-wing crack in coal rock mass under different discharge conditions and ground stress conditions are studied. The results show that the cracks around the borehole of coal rock mass crack symmetrically under the action of high-voltage electric pulse in water. When the impact load of the high-voltage electric pulse is small(3 MPa hydrostatic pressure, 7 kV discharge voltage), cracks crack symmetrically around the drilling hole, and when the impact load is large(3 MPa hydrostatic pressure, 13 kV discharge voltage), most of the cracks inside the specimen crack symmetrically along the radial or tangential wings of the drilling hole, and the cracks change from multiple pairs of double-wing cracks to a pair of double-wing cracks with the weakening of the shock wave energy until only one single wing crack remains. With the increase of discharge voltage, the length, width, area and complexity of the cracks in both wings will increase in different degrees. With the increase of in-situ stress difference, the crack is more inclined to the direction of the maximum principal stress and eventually expands along the direction of the maximum principal stress. The results further shed light on the initiation and propagation laws of double-wing crack during high-voltage electrical pulse fracturing of coal rock in water and provide theoretical support for efficient extraction of coalbed methane from high-voltage electrical pulse fracturing of coal rock mass in water in China.

Flexible and Robust Piezoelectric Chitosan Films with Enhanced Bioactivity.

Chitosan (CHT) is a known piezoelectric biomacromolecule; however, its usage is limited due to rapid degradation in an aqueous system. Herein, we prepared CHT film via a solvent casting method and cross-linked in an alkaline solution. Sodium hydroxide facilitated deprotonation, leading to increased intramolecular hydrogen bonding and mechanical properties. The CHT film remained intact for 30 days in aqueous environments. A systematic study revealed a gradual increase in the output voltage from 0.9 to 1.8 V under external force (1-16 N). In addition, the CHT film showed remarkable antibacterial and anti-inflammatory activities under ultrasound stimulation and inhibition of inflammatory cytokines. The CHT films also displayed enhanced cellular proliferation and ∼5-fold faster migration of NIH3T3 cells under US stimulation. Overall, this work presents a robust, biocompatible, and wearable CHT device that can transform biomechanical energy into electrical pulses for the modulation of cell fate processes and other bioactivities.

Investigating the Current-Carrying Friction Mechanism of n-Type and p-Type Two-Dimensional TMD under a Positive Electric Field.

Nanofriction plays an important role in the performance and lifetime of n-type or p-type TMD-based semiconductor nanodevices. However, the mechanism of nanofriction in n-type and p-type TMD semiconductors under an electric field is still blurry. In this paper, monolayers of n-MoSe2 and p-WSe2 materials were prepared by chemical vapor deposition (CVD), and their nanofriction behavior under positive electric field was investigated. Atomic force microscopy (AFM) was used to analyze the nanofriction by the positive voltage applied through the needle tip: both the friction and the friction coefficient of MoSe2 increased with the increase of the applied voltage, while the friction and the friction coefficient of WSe2 decreased with the increase of the applied voltage. As the applied voltage increases, the friction force and energy dissipation exhibit corresponding trends in relation to the surface potential. The accumulation and dissipation of carriers represent significant factors influencing friction change. The diverse types of carriers give rise to variations in the friction laws. Our experiments have revealed the differences and mechanisms of friction in TMD materials dominated by different carrier types at positive voltages. It provides guidance for the application and modulation of n- and p-type two-dimensional semiconductor materials in the field of friction.

Precise Synthesis of 4.75 V-Tolerant LiCoO2 with Homogeneous Delithiation and Reduced Internal Strain.

The rapid advancements in 3C electronic devices necessitate an increase in the charge cutoff voltage of LiCoO2 to unlock a higher energy density that surpasses the currently available levels. However, the structural devastation and electrochemical decay of LiCoO2 are significantly exacerbated, particularly at ≥4.5 V, due to the stress concentration caused by more severe lattice expansion and shrinkage, coupled with heterogeneous Li+ intercalation/deintercalation reactions. Herein, employing the molten-salt synthesis technique, we propose a universal morphology-shaping strategy to attain bulk reaction homogeneity and reduce internal strains, even at extremely high charge voltages. The newly designed flattened polygon prismlike LiCoO2 (P-LCO) particle, featuring a regular symmetrical arrangement along the c-axis, demonstrates a more homogeneous Li+ extraction/insertion reaction, which results in a restrained transformation to detrimental O1 phase and reduced variation in lattice volume throughout the (de)lithiation processes. This benefits the mitigation of the local stress accumulation misfit dislocations and particle cracking, ultimately maintaining the mechanical stability of the cathode. Consequently, P-LCO is capable of breaking the voltage ceiling and exhibits exceptional long-term cycling capability at an ultrahigh voltage of 4.75 V. This work offers a brand-new perspective for the rational design of cathode morphology to address capacity deterioration caused by inhomogeneous delithiation and internal strain, thus inspiring the development of high-energy-density cathodes with improved durability.

Pyridine polymer tubular structures connected with polyoxometalates as bifunctional electrocatalysts for water splitting.

In this work, we successfully prepared four POM-based organic-inorganic hybrids, namely, [(C5H6N)2(C4H5N2)][PMo12O40] (1), [(C5H6N)3(C5H5N)][PMo12O40] (2), [(C3H6N8)3][PMo12O40]·4H2O (3), and [(C2H5N4)3][PMo12O40] (4) (where C5H6N = pyridine, C4H5N2 = pyrazine, C3H6N8 = 2,7-diamino-1,3,4,6,8,9-hexaazaspiro[4.4] nonane, and C2H5N4 = 3-amino-1,2,4-triazole), using a hydrothermal method. Compounds 1 and 2 exhibited a lamellar three-dimensional structure. Compared to compound 1, compound 2 contained only one ligand, pyridine, which formed a pyridine polymer tubular structure that was further connected to a [PMo12O40]3- anion, creating a pyridine-PMo12-pyridine stacking-like structure. Compounds 3 and 4 showed a stereostructure, where organic ligands were wrapped around polyacid spheres. Unlike compound 3, compound 4 maintained a similar three-dimensional structure but had a hexagonal astral ligand configuration. However, ligands formed hexagonal boxes that were smaller than those in compound 3, with shorter distances between the ligands. The overpotential values for compound 2 were 143 mV (HER) and 136 mV (OER) at 10 mA cm-2, which were significantly lower than those of the other compounds, the H3[PMo12O40] precursor, and the organic ligands. Given the relatively outstanding HER/OER catalytic properties of compound 2, a dual-electrode water-splitting device was assembled. The compound 2/CC∥compound 2/NF system achieved a low cell voltage of 1.48 V at 10 mA cm-2, which was significantly lower than that of the commercial Pt/C/CC∥RuO2/NF setup (1.5 V). In addition, compound 2/CC∥compound 2/NF exhibited rapid response capabilities and showed no significant increase in voltage after 6000 s of operation.

Effects of gravity on the cell performance of proton exchange membrane water electrolyzer

Hydrogen is of great significance for building a low-carbon and safe energy system. The proton exchange membrane water electrolyzer (PEMWE) is considered a highly promising hydrogen production device. However, due to the complex physical and chemical processes within the cell, and the impact of gravity effect on the cell characteristic is unclear. Analyzing the impact of gravity on cell performance is critical. In this study, the three-dimensional two-phase flow models are developed for the PEMWE, the models couple many physical fields, including the hydrodynamics, electrochemical reaction kinetics, mass transfer, heat transfer, two-phase flow based on Euler model, and gravity effect. The simulation model is verified through experiment results. The effect of gravity on the cell performance is investigated, the influences of gravity under different placement directions are compared, and the impact of the cell voltage on the transport characteristics is discussed under the gravity effect. Results show that the gas transport and heat transfer are enhanced under the gravity, the active sites in the catalytic layer can be timely released due to the accelerated bubble removal, the polarization performance is accordingly improved. The cell performance with the gravity effect under vertical placement is higher than that with the gravity effect under horizontal placement because of the improved mass transfer, but the mixture velocity at anode flow channel is decreased. Moreover, as the cell voltage increases, the electrochemical reaction rate is enhanced, the heat transfer is increased, and the volume fraction of disperse phase in anode flow channel is accordingly increased. This study provides a theoretical reference for further investigating transport characteristics and optimising the cell performance.

Mechanically robust, highly toughened, corrosion and impact resistant epoxy/silica nanocomposites by UV curing 3D printing technology

In this paper, a photosensitive resin was successfully synthesized using epoxy as a matrix and the effect of nanosilica on its properties was investigated. Micromorphology analyses show that the nanosilica has good dispersion and strong interaction with the matrix. Additionally, a finite element model was developed to predict the tensile performance of the nanocomposite under high-strain loads. Molecular dynamics simulations demonstrated a favorable binding energy between nanosilica and epoxy resin. The effects of nanosilica on the fracture toughness and energy release rate of photosensitive resins were investigated using load-enhanced tensile test method. The results showed that the addition of 1.0 wt.% nanosilica particles increased the toughness of the resin from 0.45 MPa m1/2 to 0.79 MPa m1/2, and the energy release rate from 248.3 J/m2 to 555.7 J/m2; compared with the neat photosensitive resins, the incorporation of nanosilica increased the tensile and impact strengths of the resins by 26.8% and 49.2%, respectively. The nanosilica was used to improve the tensile strength and impact strength of the resin by 26.8% and 49.2% respectively compared with the neat photosensitive resin. Electrochemical corrosion analysis showed that the photosensitive resin/nanosilica composites have excellent corrosion resistance. Under different corrosion environments of acid, alkali, and salt, the addition of 1 wt.% nanosilica in the photosensitive resin composite led to an increase in corrosion voltage by 0.023 V, 0.004 V, and 0.1 V respectively compared to neat photosensitive resin. Additionally, the corrosion current density decreased by 1.39 × 10−6 A/cm2, 0.525 × 10−4 A/cm2, and 2.57 × 10−6 A/cm2, respectively. On this basis, the independently synthesised photosensitive resin has excellent strength and 0.01 mm printing accuracy.

Corrosion Resistance and Structure of Cr−O−N Coatings Formed in Vacuum Arc Plasma Fluxes With PIIID

ABSTRACTCr−O−N‐based vacuum arc coatings are very promising for the wear and corrosion protection of various steel parts. The aim of the work was to determine the effect of frequency and amplitude of the pulsed bias voltage (UB) on the elemental and phase composition, mechanical, and corrosion properties of Cr−O−N coatings. They have an amorphous structure with embedded nanosized solid solution crystallites based on CrN with a cubic structure and Cr2O3 with a rhombohedral structure. The increase in the bias voltage results in a reduction in the grain size of the Cr2O3 and CrN phases by about four times to about 5 nm, as well as a change in the CrN phase content in the coating. The lattice parameter increases slightly for the Cr2O3 phase but decreases for the CrN phase. The increase in the pulse frequency results in an increase in the CrN phase content in the coating and the lattice constant of both phases and a slight decrease in the crystallite size. The hardness of Cr−O−N coatings slightly increased with the UB from 26 ± 1 GPa (DC) to 28 ± 1 GPa (−300 V, pulsed), and the elastic modulus ranges from 290 to 310 GPa. The greatest changes were observed in corrosion resistance. With an increase in the bias voltage and pulse frequency, the corrosion current of Cr−O−N coatings on steel in 3% NaCl solution decreased by three orders of magnitude compared to coatings deposited at DC voltage and by five orders of magnitude compared to the base steel. Therefore, the use of a pulsed bias voltage with a frequency of at least 10 kHz and an amplitude of 700 V can significantly increase the corrosion resistance of Cr−O−N coatings on steel substrates.

Effect of Bias Voltage on the Microstructure and Photoelectric Properties of W-Doped ZnO Films.

W-doped ZnO (WZO) films were deposited on glass substrates by using RF magnetron sputtering at different substrate bias voltages, and the relationships between microstructure and optical and electrical properties were investigated. The results revealed that the deposition rate of WZO films first decreased from 8.8 to 7.1 nm/min, and then increased to 11.5 nm/min with the increase in bias voltage. After applying a bias voltage to the substrate, the bombardment effect of sputtered ions was enhanced, and the films transformed from a smooth surface into a compact and rough surface. All the films exhibited a hexagonal wurtzite structure with a strong (002) preferred orientation and grew along the c-axis direction. When the bias voltage increased, both the residual stress and lattice parameter of the films gradually increased, and the maximum grain size of 43.4 nm was achieved at -100 V. When the bias voltage was below -300 V, all the films exhibited a high average transmittance of ~90% in the visible light region. As the bias voltage increased, the sheet resistance and resistivity of the films initially decreased and then gradually increased. The highest FOM of 5.8 × 10-4 Ω-1 was achieved at -100 V, possessing the best comprehensive photoelectric properties.

Conjugated Polymer-Based Multilayer Thin-Film Triboelectric Nanogenerators via Continuous Layer-By-Layer Coating Process.

This study introduces a flexible and scalable charge-trapping intermediate layer of conjugated polymeric film comprising [PANI/PEDOT:PSS]n between the [PVA/PDDA]n triboelectric layer and graphene-based [PVA/GNP-PSS]n electrode using the layer-by-layer (LbL) assembly method. By varying the deposition layers, the optimal coating layout was identified as 2 and 8 bilayers of intermediate and triboelectric layers, respectively. The triboelectric nanogenerator (TENG) fabricated with this optimal configuration achieved peak output voltage and current of 180 V and 9 μA, respectively, at 3 Hz and 5 N against PDMS. This represents a 63.6% increase in output voltage and a 20% increase in output current compared to the TENG without the intermediate charge-trapping layer, owing to the surface charge density reaching 61.5 μC/m2. Furthermore, an ultrathin, free-standing PANI-PEDOT:PSS film was encapsulated in a free-standing PVA-PDDA film, which resulted in a significant TENG output performance of 315 V. Inspired by these TENG results, we investigated the flame-retardant properties of the LbL [PANI/PEDOT:PSS]n coating on polyurethane foam (PUF) and demonstrated, through the open flame test, that the presence of the flame-retardant coating prevented flame flashover, melting, and dripping of the burning PUF. The coated PUF exhibited a lower heat release capacity of 402 J/g·K compared to neat PUF, and the thermal degradation of coated PUF resulted in the formation of 10.95 wt % residue in the TGA test. In addition, the TENG fabricated using the coated foam achieved a significant output performance. Therefore, this study contributes to future flame-retardant energy harvesting materials via sustainable LbL assembly.

Analisis Nilai CT Number (CTN) dan Kualitas Citra dari Pengaruh Variasi Tegangan dan Arus Tabung Menggunakan Pesawat CT Simulator

Background: The CT simulator is an integral part of radiotherapy treatment that can determine the target location and dose planning in images. Exposure factors such as tube voltage and current are important components that affect the resulting images. This study compares the effects of varying exposure factors on CT numbers (CTN) and image quality (spatial resolution, uniformity, SNR, and CNR). Methods: This study used a Catphan®604 phantom with helical image acquisition on a CT simulator to obtain images. The voltage variations were 80, 100, 120, and 135 kV. Additionally, current variations of 50, 100, 150, and 200 mA were applied at both their maximum and minimum values. Results: The study results indicate that variations in voltage tend to decrease CTN values and improve image quality. Conversely, variations in current do not result in significant changes in CTN values but tend to enhance the quality of the image. The optimal values for CTN and image quality were found at 100 kV and 200 mA. Conclusions: The exposure factor of voltage significantly affects changes in CTN and image quality. Conversely, tube current does not have a significant impact on CTN. As the voltage and current increase, the image quality improves, but the resulting noise also becomes greater.

Water Activation: The Effect of an Electric Field on the Properties of a Liquid

The article discusses the process of obtaining activated water based on an electric field. Activated water obtained as a result of electrolysis demonstrates unique physico-chemical properties that differ from ordinary water, which opens up new possibilities for use in various sectors of the national economy. The mechanisms of water activation and their effect on the acid-base balance, as well as the stability of activated properties, have been studied. The experimental part presents data on the dependence of the pH of the water on the activation time and the voltage between the electrodes. The results show that an increase in activation time and voltage leads to significant pH changes near the anode and cathode. The problems related to the instability of activated properties and the influence of the composition of the source water are discussed. The work highlights the need for further research to optimize activated water production technology and develop standards for its application.

Influence of Substrate Bias Voltage on Structure and Properties of (AlCrMoNiTi)N Films.

(AlCrMoNiTi)N high-entropy alloy nitride (HEAN) films were synthesized at various bias voltages using the co-filter cathodic vacuum arc (co-FCVA) deposition technique. This study systematically investigates the effect of bias voltage on the microstructure and performance of HEAN films. The results indicate that an increase in bias voltage enhances the energy of ions while concomitantly reducing the deposition rate. All synthesized (AlCrMoNiTi)N HEAN films demonstrated the composite structure composed of FCC phase and metallic Ni. The hardness of the (AlCrMoNiTi)N HEAN film synthesized at a bias voltage of -100 V attained a maximum value of 38.7 GPa. This high hardness is primarily attributed to the synergistic effects stemming from the formation of strong metal-nitrogen (Me-N) bonding formed between the target elements and the N element, the densification of the film structure, and the ion beam-assisted bombardment strengthening of the co-FCVA deposition technique. In addition, the corrosion current density of the film prepared at this bias voltage was measured at 4.9 × 10-7 A·cm-2, significantly lower than that of 304 stainless steel, indicating excellent corrosion resistance.

Understanding the electric field dependent channel migration for shorter channel length of multilayer rhenium disulfide (ReS2) FETs

Multilayer rhenium disulfide (ReS2) has attracted considerable attention due to the decoupled van der Waals interaction between its adjacent layers, leading to significantly higher interlayer resistance compared with other layered materials. While the carrier transport in multilayer materials can be well described by the interlayer resistance (RInt) and Thomas-Fermi charge screening length (λTF) in resistor network models, the electric field scaling of the channel with the back gate voltage (VBG) and the drain voltage (VD) is limited in two-dimensional (2D) multilayer materials. In this report, we present the effects ofVBGandVDon the channel migration of ReS2field effect transistors (FETs) with channel lengths of 0.25, 2.4, and 4.4μm. For shorter channels, theVBG-dependent conductance (G= (drain current (ID)/VD)) increases with increasingVD, different from the longer channels. Based on the resistor network model, the different behaviors with channel lengths were analyzed by considering the interlayer resistance (RInt) versus the channel resistance and the Thomas-Fermi charge screening length (λTF). Lower back gate voltage (VBG) in shorter channels builds the channel near the bottom layer close to the oxide, while highVBGshifts the conductive channel to the top sheet exposed to ambient condition. In longer channels, due to the increased channel resistance (Rch), the conductive channel forms near the bottom side close to the oxide. The increase of the threshold voltage (Vth) was observed at higher drain-source voltages (VD), but in opposite for the top side channel, i.e. the decrease of threshold voltage with increasingVD. This study will give a hint on establishing the electric field scaling of 2D material-based FETs with channel lengths and applied voltages ofVBGandVD.

Enhanced Performance and Durability of Pore-Filling Membranes for Anion Exchange Membrane Water Electrolysis.

Four distinct pore-filling anion exchange membranes (PFAEMs) were prepared, and their mechanical properties, ion conductivity, and performance in anion exchange membrane water electrolysis (AEMWE) were evaluated. The fabricated PFAEMs demonstrated exceptional tensile strength, which was approximately 14 times higher than that of the commercial membrane, despite being nearly half as thin. Ion conductivity measurements revealed that acrylamide-based membranes outperformed benzyl-based ones, exhibiting 25% and 41% higher conductivity when using crosslinkers with two and three crosslinking sites, respectively. The AEMWE performance directly correlated with the hydrophilicity and ion exchange capacity (IEC) of the membranes. Specifically, AE_3C achieved the highest performance, supported by its superior IEC and ionic conductivity. Durability tests showed that AE_3C outlasted the commercial membrane, with a delayed voltage increase corresponding to its higher IEC, confirming the importance of increased ion-exchange functional groups in ensuring longevity. These results highlight the critical role of hydrophilic monomers and crosslinker structure in optimizing PFAEMs for enhanced performance and durability in AEMWE applications.

Study on the Optimization of Process Parameters for Submerged Arc Welding of Hydrogen Production Reactor Material

In a hydrogen production reactor based on the principle of coal-to-hydrogen, the welds, which are considered the weak points, must exhibit a good impact resistance property and high hardness under special operating conditions. This paper investigates the influence of submerged arc welding (SAW) process parameters on the hardness and the impact resistance property of welds in the steel used for a hydrogen reactor. It establishes the relationship between the microstructure of the welds and their hardness and impact resistance property under varying welding parameters. Based on orthogonal welding experiments and a comprehensive balance method, the welding parameters were optimized to obtain the best combination of parameters. The results indicate that as the current and voltage increase, the average hardness of the welds first decreases and then increases, while the impact resistance property initially improves before declining. As the welding speed increases, the average hardness of the welds initially increases and then decreases, while the impact resistance property gradually declines. After optimization under specific experimental conditions, the best welding parameters are determined to be a current (I) of 320 A, a voltage (U) of 34 V, and a welding speed (v) of 33 cm/min. Compared to the base metal, the hardness of the weld increased by 36.1%, and the impact resistance property improved by 71.5%.

Radiation resilience of β-Ga2O3 Schottky barrier diodes under high dose gamma radiation

A systematic investigation of the electrical characteristics of β-Ga2O3 Schottky barrier diodes (SBDs) has been conducted under high-dose 60Co gamma radiation, with total cumulative doses reaching up to 5 Mrad (Si). Initial exposure of the diodes to 1 Mrad resulted in a significant decrease in on-current and an increase in on-resistance compared to the pre-radiation condition, likely due to the generation of radiation-induced deep-level acceptor traps. However, upon exposure to higher gamma radiation doses of 3 and 5 Mrad, a partial recovery of the device performance occurred, attributed to a radiation annealing effect. Capacitance–voltage (C–V) measurements showed a decrease in net carrier concentration in the β-Ga2O3 drift layer, from ∼3.20 × 1016 to ∼3.05 × 1016 cm−3, after 5 Mrad irradiation. Temperature-dependent I–V characteristics showed that 5 Mrad irradiation leads to a reduction in both forward and reverse currents across all investigated temperatures ranging from 25 to 250 °C, accompanied by slight increases in on-resistance, ideality factors, and Schottky barrier heights. Additionally, a slight increase in reverse breakdown voltage was observed post-radiation. Overall, β-Ga2O3 SBDs exhibit high resilience to gamma irradiation, with performance degradation mitigated by radiation-induced self-recovery, highlighting its potential for radiation-hardened electronic applications in extreme environment.

INFLUENCE OF BOUNDARY CONDINIONS ON THE PLASMA POTENTIAL IN A HELICON DISCHARGE WITH PLANAR ANTENNA

In a helicon discharge excited by a flat inductive antenna, situated at the discharge chamber end, distributions of plasma parameters have been measured by a thermo-emissive probe. The aim of the work was to define an influence producing by the bias potential of the surface being processed on plasma parameters in discharge chambers with either the dielectric or with conducting side walls. It was found that in the dielectric chamber application of a positive voltage and taking electron current to the surface under treatment causes increasing the plasma potential because the opposite sine current can not flow to the insulating wall. In the metal chamber increase of positive voltage on the surface leads to the discharge instability and break off for considerable taking electrons away from the discharge volume.

Theoretical analyses of the performance parameters of PEM fuel cells at various operating temperatures and pressures

In the present study, the performance parameters for a single-cell PEM fuel cell with 50 cm2 active surface area and 0.0178 cm polymer membrane thickness at 4 different operating temperatures (303, 323, 343, and 363 K) and 4 different operating pressures (3, 6, 9, and 12 atm) was investigated by theoretical analysis. Hydrogen and oxygen partial pressures, membrane resistivity, internal resistance, activation, ohmic and concentration losses, cell voltage, power density, and thermal efficiency were calculated using this analysis. It has been observed that the augmentation of temperature and pressure in the fuel cell leads to a favorable increase in cell voltage, power density, and thermal efficiency. The thermal efficiency values were found to be 23% and 39%, respectively at the following conditions: temperatures of 303 K and 363 K, current density of 1 A/cm2, and constant pressure. At the same current density, the thermal efficiency is 29% and 32% at 3 atm and 12 atm operating pressures at a constant temperature. When operated under constant current density and temperature conditions, an increase in the operating pressure of the PEMFC from 3 atm to 12 atm results in a corresponding increase in cell voltage, from 0.4422 V to 0.4755 V, respectively. It was observed that the influence of temperature on the thermal efficiency of the PEM fuel cell was led to be higher than the influence of pressure.