High Electric Potential Research Articles

Effect of Electric Fields on the Decomposition of Phosphate Esters.

Phosphate esters decompose on metal surfaces and form protective polyphosphate films. For many applications, such as in lubricants for electric vehicles and wind turbines, an understanding of the effect of electric fields on molecular decomposition is urgently required. Experimental investigations have yielded contradictory results, with some suggesting that electric fields improve tribological performance, while others have reported the opposite effect. Here, we use nonequilibrium molecular dynamics (NEMD) simulations to study the decomposition of tri-n-butyl phosphate (TNBP) molecules nanoconfined between ferrous surfaces (iron and iron oxide) under electrostatic fields. The reactive force field (ReaxFF) method is used to model the effects of chemical bonding and molecular dissociation. We show that the charge transfer with the polarization current equalization (QTPIE) method gives more realistic behavior compared to the standard charge equilibration (QEq) method under applied electrostatic fields. The rate of TNBP decomposition via carbon-oxygen bond dissociation is faster in the nanoconfined systems than that in the bulk due to the catalytic action of the surfaces. In all cases, the application of an electric field accelerates TNBP decomposition. When electric fields are applied to the confined systems, the phosphate anions are pulled toward the surface with high electric potential, while the alkyl cations are pulled to the surface with lower potential, leading to asymmetric film growth. Analysis of the temperature- and electric field strength-dependent dissociation rate constants using the Arrhenius equation suggests that, on reactive iron surfaces, the increased reactivity under an applied electric field is driven mostly by an increase in the pre-exponential factor, which is linked to the number of molecule-surface collisions. Conversely, the accelerated decomposition of TNBP on iron oxide surfaces can be attributed to a reduction in the activation energy with increasing electric field strength. Single-molecule nudged-elastic band (NEB) calculations also show a linear reduction in the energy barrier for carbon-oxygen bond breaking with electric field strength, due to stabilization of the charged transition state. The simulation results are consistent with experimental observations of enhanced and asymmetric tribofilm growth under electrostatic fields.

Laser Printer Printed Ion Sources for Ambient Ionization Mass Spectrometric Analysis of Volatiles and Semivolatiles.

In this study, we demonstrated a facile method to fabricate ion sources using a laser printer for ambient ionization mass spectrometry (MS). Toner spots printed by a printer can readily facilitate ionizing volatile and semivolatile compounds derived from solid or liquid samples for MS analysis. The experimental arrangement involved positioning the toner-printed paper near the inlet of a mass spectrometer, which was subjected to a high electric potential (e.g., -6 kV). Volatile or semivolatile compounds deriving from the sample positioned below the metal inlet of the mass spectrometer were promptly ionized upon activating the mass spectrometer. No direct electrical connection or voltage application was required on the paper substrate. An electric field was established between the toner spot on the paper and the inlet applied with a high voltage to induce the dielectric breakdown of the surrounding air and water molecules. Consequently, ionic species, including electrons and cationic radicals, were generated. Subsequent ion-molecule reactions facilitated the production of protons for ionizing analytes present in the gas phase proximal to the inlet of the mass spectrometer. Deprotonated analytes were detected in the resultant mass spectra when employing the method in negative ion mode. This methodology presents a straightforward approach for analyzing analytes in the gas phase under ambient conditions utilizing an exceptionally uncomplicated experimental setup. In addition, the developed method can be used to detect trace 2,4-dinitrophenol, an explosive, with a limit of detection as low as ∼30 pg.

Coating Titanium Transport Layers for Enhanced Short and Long Term Performance in PEM Water Electrolysis Cells

The ageing of titanium porous transport layers (PTL) affects the longevity of polymer electrolyte membrane water electrolysis systems by the formation and thickening of a weakly conductive oxide layer. The evolving oxygen on the anode in combination with the high electrical potential provides a challenging environment in which a low electrical contact resistance to the catalyst layer (CL) needs to sustain over a long period. One previous approach is a precious metal coating of the PTL with platinum or iridium [1], which can prevent oxidation of the titanium. A cost-effective alternative is a hydrochloric acid treatment, which forms titanium hydride (TiH). [2] Titanium nitride (TiN) promises better electrical conductivity with similar corrosion resistance, but has not yet been tested as a coating. The same is true for niobium, which performed well as a coating for stainless steel bipolar plates. [3] In our studies, all these candidates face the same conditions aside an untreated PTL in one unique series of measurements. All types are repeated three times to ensure reproducibility. The mean polarization curves (figure 1 left) show that the two precious metals, iridium and platinum, significantly improve the cell voltage at a current density of 2A/cm² by 80mV and 95mV, respectively. Titanium hydride achieves an even higher reduction of 100mV without the use of precious metals. The high frequency resistance plots in figure 1 right determine that the improvement of up to 20% or 30mΩ∙cm² is attributable to a reduced contact resistance to the CL. This assumption is proven by the fact that a PTL that is only coated with iridium on the side facing the CL behaves identically to a PTL that is coated on both sides. The ohmic losses in contact with the BPP are therefore negligible in these experiments. Titanium nitride and niobium coated PTLs behave in the same way as the reference measurement. In addition to the measurements shown, long-term experiments (>1000 hours) are currently running for all types of coating, and corrosion measurements in sulphuric acid are being carried out in parallel. The joint results will determine the suitability of the various coatings for long-term use in electrolysers.[1] Liu, C., Shviro, M., Gago, A. S., Zaccarine, S. F., Bender, G., Gazdzicki, P., Morawietz, T., Biswas, I., Rasinski, M., Everwand, A., Schierholz, R., Pfeilsticker, J., Müller, M., Lopes, P. P., Eichel, R.-A., Pivovar, B., Pylypenko, S., Friedrich, K. A., Lehnert, W., Carmo, M., Exploring the Interface of Skin-Layered Titanium Fibers for Electrochemical Water Splitting. Adv. Energy Mater. 2021, 11, 2002926. https://doi.org/10.1002/aenm.202002926[2] Bystron, T., Vesely, M., Paidar, M. et al. Enhancing PEM water electrolysis efficiency by reducing the extent of Ti gas diffusion layer passivation. J Appl Electrochem 48, 713–723 (2018). https://doi.org/10.1007/s10800-018-1174-6[3] Stiber, S., Hehemann, M., Carmo, M., Müller, M., Ayers, K.E., Capuano, C., Danilovic, N., Morawietz, T., Biswas, I., Gazdzicki, P., Heger, J.-F., Gago, A.S. and Friedrich, K.A. (2022), Long-Term Operation of Nb-Coated Stainless Steel Bipolar Plates for Proton Exchange Membrane Water Electrolyzers. Adv. Energy Sustainability Res., 3: 2200024. https://doi.org/10.1002/aesr.202200024 Figure 1

Effect of applied electrical potential and humidity on friction of Graphene-Based thin films

Understanding the nanofrictional characteristics of thin films in various conditions is important for fabricating nanoelectronic devices and micro-/nanoelectromechanical systems with high functionality and reliability. This study investigated the nanofrictional characteristics of composite thin films of graphene oxide (GO) and cellulose nanocrystals (CNCs) and of reduced graphene oxide (rGO) and CNCs, namely GO/CNC and rGO/CNC thin films, under an applied electrical potential and humidity by using a conductive atomic force microscope (AFM). For all films, the coefficient of friction (CoF) was affected by the applied electrical potential and enhanced mechanical properties resulting from strong interactions of GO and rGO with CNCs. Furthermore, the friction force increased with the electrical potential at low humidities (relative humidity (RH) < 40 %) because of the electrostatic force effect, while for RH>40 %, the friction force sensitively increased with the electrical potential because of the puckering effect. At high humidities (RH>40 %) and high electrical potentials (>4 V), the friction force decreased as the electrical potential increased, owing to the electron leakage phenomenon. This study also characterized the altered nanofrictional behavior influenced by interfacial phenomena in the films under an electrical potential and humidity, and it provides design guidelines for fabricating nanoelectronic devices and micro/nanoelectromechanical systems.

Transformation of sedimentary dissolved organic matter in electrokinetic remediation catalogued by FT-ICR mass spectrometry

In electrokinetic remediation (EKR), the sedimentary dissolved organic matter (DOM) could impede remediation by scavenging reactive species and generating unintended byproducts. Yet its transformation and mechanisms remained largely unknown. This study conducted molecular-level characterization of the water-extractable DOM (WEOM) in EKR using negative-ion electrospray ionization coupled to 21 tesla Fourier transform ion cyclotron resonance mass spectrometry (21 T FT-ICR MS). The results suggested that ∼55 % of the ∼7,000 WEOM compounds identified were reactive, and EKR lowered their diversity, molecular weight distribution, and double-bond equivalent (DBE) through a combination of electrochemical and microbial redox reactions. Heteroatom-containing WEOM (CHON and CHOS) were abundant (∼ 35% of the total WEOM), with CHOS generally being more reactive than CHON. Low electric potential (1 V/cm) promoted the growth of dealkylation and desulfurization bacteria, and led to anodic CO2 mineralization, anodic cleavage of -SO and -SO3, and cathodic cleavage of -SH2; high electric potential (2 V/cm) only enriched desulfurization bacteria, and differently, led to anodic oxygenation and cathodic hydrogenation of unsaturated and phenolic compounds, in addition to cathodic cleavage of -SH2. The long-term impact of these changes on soil quality and nitrogen-sulfur-carbon flux may be need to studied to identify unknown risks and new applications of EKR.

A fast-switching low-loss field-stop IGBT with dual control gate of SIPOS material

A fast-switching low-loss field-stop insulated gate bipolar transistor with a dual control gate (DIGBT) of a semi-insulating polycrytalline silicon (SIPOS) material is proposed in this paper. Because the SIPOS has uniform high resistance, it has an approximate linear electric potential distribution. When DIGBT conducts, the higher electric potential on SIPOS causes the P-type drift region (P-drift) to generate an inversion layer of electrons, adjusting the number of carriers and making the generation of non-equilibrium carriers no longer dependent on the doping concentration in P-drift (Nd) but on the electric potential distribution on SIPOS. Therefore, it can solve the contradiction among the breakdown voltage, forward voltage drop [VCE(sat)], turn-off time (toff), and turn-off loss (Eoff) caused by the Nd. Through Technology Computer Aided Design (TCAD) simulation, the VCE(sat) of DIGBT is 30.6% lower than that of SJFS IGBT. Meanwhile, DIGBT reduces the toff by 62.8% while reducing the Eoff by 83.0% compared to SJFS IGBT. In addition, the static latch-up I–V and the forward biased safe operating area of the DIGBT have been significantly improved. This paper adjusts the number of carriers through the characteristics of SIPOS material, enabling the above-mentioned physical phenomena to be applied in insulated gate bipolar transistor power devices and achieving device performance breakthroughs.

Development of Low-Cost c-Si-Based CPV Cells for a Solar Co-Generation Absorber in a Parabolic Trough Collector

Concentrator photovoltaics (CPVs) have demonstrated high electrical efficiencies and technological potential, especially when deployed in CPV–thermal (CPV-T) hybrid absorbers, in which the cells’ waste heat can be used to power industrial processes. However, the high cost of tracking systems and the predominant use of expensive multi-junction PV cells have caused the market of solar co-generation technologies to stall. This paper describes the development and testing of a low-cost alternative CPV cell based on crystalline silicone (c-Si) for use in a novel injection-molded parabolic hybrid solar collector, generating both, photovoltaic electricity and thermal power. The study covers two different c-Si cell technologies, namely, passive emitter rear contact (PERC) and aluminum back surface field (Al-BSF). Simulation design and manufacturing are described with special attention to fingerprinting in order to achieve high current carrying capacities for concentrated sunlight. It was determined that Al-BSF cells offer higher efficiencies than PERC for the considered use case. Solar simulator tests showed that the highly doped 4 cm2 cells (50 ohm/sq) reach efficiencies of 16.9% under 1 sun and 13.1% under 60 suns at 25 °C with a temperature coefficient of −0.069%(Abs)/K. Finally, options to further improve the cells are discussed and an outlook is given for deployment in a field-testing prototype.

Recent Advances in the Development of Nanocarbon-Based Electrocatalytic/Electrode Materials for Proton Exchange Membrane Fuel Cells: A Review

The global issue for proton exchange membrane fuel cell market development is a reduction in the device cost through an increase in efficiency of the oxygen reduction reaction occurring at the cathode and an extension of the service life of the electrochemical device. Losses in the fuel cell performance are due to various degradation mechanisms in the catalytic layers taking place under conditions of high electric potential, temperature, and humidity. This review is devoted to recent advances in the field of increasing the efficiency and durability of electrocatalysts and other electrode materials by introducing structured carbon components into their composition. The main synthesis methods, physicochemical and electrochemical properties of materials, and performance of devices on their basis are presented. The main correlations between the composition and properties of structured carbon electrode materials, which can provide successful solutions to the highlighted issues, are revealed.

Studies on the effects of preheated β-lactoglobulin on the physicochemical properties of theaflavin-3,3′-digallate and the interaction mechanism

Teaflavin-3,3′-digallate (TFDG) is a sensory and health benefit substance in tea beverage, but is usually eliminated during processing due to the formation of tea cream by binding with proteins. In order to retain the TFDG, β-lactoglobulin (β-LG) was used to bind with TFDG and avoid the formation of tea cream. The results of physicochemical tests and entropy weight-TOPSIS showed that the best β-LG-TFDG dispersion (TFDG concentration: 0.468 g/L) had low particle size (37.29 nm), high electrical potential (−32.43 mv), high transmittance (88.52%), and strong antioxidant activity (84.82%), when the preheated temperature of β-LG was 85 °C and the molar ratio was 1:2. The multispectral experiment results showed that TFDG interacted with β-LG via static quenching, and preheated treatment of β-LG enhanced the interaction between β-LG and TFDG. CD spectroscopy suggested that TFDG induced slight changes in the secondary structure of β-LG. The results of molecular dynamics showed that preheated treatment leading in the changes in tertiary structure of β-LG, opening of key ring region of β-LG and exposing the active cavities of β-LG, which enhances the intermolecular forces between TFDG and β-LG. What's more, molecular docking was proved that preheated treatment of β-LG enhances the hydrophobic interactions and hydrogen bonds, which dominated the interaction between TFDG and β-LG. The results proposed in this research could further reducing tea cream formation and improving the healthy and sensory performances of tea beverage by using preheated β-LG without preserving both the tea pigments and the active nutrients.

Conformal Silver Films for EMI Shielding of SiP Architectures

Electrospray printing is an additive manufacturing technique where a precursor solution composed of a solute material in a compatible solvent is subjected to a high electric potential, generating a spray of charged, solvent-encapsulated particles. Due to the high surface area to volume ratio, the solvent rapidly evaporates to deposit dry or semi-dry solute material onto a target surface. Over time, a thin continuous film is formed. Material emitted by electrospray is highly charged and will follow the electric field lines established between the emitter and a grounded target. As a result, this process is best suited for deploying material onto (grounded) conductive surfaces and can be used to create conformal coatings, even on non-line-of-sight surfaces. In contrast, delivering material to insulating surfaces is more difficult due to the accumulation of charge on the target, inhibiting the deposition of the solute and preventing the formation of a continuous film. We report on a new approach to improve deposition on dielectric (insulating) targets by manipulating the electric field and distribution of charge in the vicinity of the target surface. Colloidal silver in triethylene glycol monomethyl ether is deployed to create a conformal coating on packages consisting of a (i) broadband radiator encapsulated in epoxy molding compound and (ii) a model silicon flip-chip assembly. We seek to replace board level shielding and provide electromagnetic interference protection for System-in-Package at frequencies from 100 MHz to 6 GHz, with a target of 60 dB of isolation at 1 GHz.

A novel annular slit-type emitter developed for multi-jet electrospray propulsion

Electrospray thrusters employ ionization in the liquid phase to produce and propel streams of molecular ions or highly charged droplets at significant velocities. In this study, we developed a novel annular slit-type emitter for electrospray and investigated its operational modes under varying applied potentials in both open atmosphere and vacuum conditions. To assess the performance of the annular slit-type emitter in comparison to the conventional capillary-type emitter, benchtop electrospray experiments were conducted using water and glycerin as working fluids for both emitter types. The study examined the formation of the Taylor cone, cone-to-jet transition, stable jet, whipping jet, and multi-jet, along with their dependence on fluid viscosity and electric potential for both emitter designs. Clear distinctions in hydrodynamic mode, drop-to-cone mode, and cone-to-jet transition mode were observed between the two emitters. As the electric potential increased, the capillary-type emitter exhibited a whipping and pulsating water jet, while glycerin displayed a steady tilted jet. In contrast, the annular slit-type emitter demonstrated a pulsating water jet followed by a distinctive dripping mode at higher electric potentials, while glycerin formed multiple steady jets around the annular slit. Notably, the annular slit-type emitter, when subjected to an 18.5 kV potential, produced seven electrospray jets for glycerin, a phenomenon attributed to the novel design of the emitter and the viscosity of glycerin enabling the generation of multiple cone-jets at a specific electrostatic potential around the slit peripheral meniscus. Vacuum chamber tests of the annular-type emitter using liquid indium as an ion source at 1 × 10−5 Torr revealed an ion-current density of 0.3 mA/mm, resulting in a thrust of 290 μN.

1D Spatially Resolved Model of Alloyed Catalyst Degradation in LT-PEMFC

Low-temperature fuel cells with proton exchange membrane (LT-PEMFC) are among the most promising energy devices for future decarbonizaion of heavy-duty long-distance transport. Fuel cells use hydrogen as the energy source and air as oxidizer to produce electricity in catalyzed electrochemical process, with only side-products being heat and water. Despite some clear advantages over other energy sources, i.e. batteries, their adoption is still somewhat limited by some prominent factors such as high price and limited durability. Both of these factors are closely related to the use of specific catalyst materials needed to ensure high efficiency and power density of hydrogen fuel cells. Due to its high catalytic activity, Pt is traditionally used as a catalyst material, dispersed in form of nanoparticles on a highly porous carbon matrix ensuring good accessibility of hydrogen and air to the catalyst surface and efficient removal of water.Due to harsh local conditions in the catalyst layer, i.e. high temperatures of up to 80° C, high humidity and high electric potentials, catalyst nanoparticles are exposed to various degradation processes. Electrochemical corrosion of carbon support can result in detachment of particles and their consequent agglomeration, which results in a decrease of specific area suitable for electrochemical reactions. Despite high redox potential of Pt (1.115 V vs. SHE), high electric potential in fuel cell cathode can also lead to electrochemical dissolution of catalyst particles, which is additionally accelerated by their small size. Dissolved catalyst can either redeposit to larger particles, resulting in net growth of catalyst particles (so-called Ostwald ripening), or diffuse in proton exchange membrane, where it is reduced by crossover hydrogen. Both processes result in a loss of electrochemically active surface area in the catalyst layer.To reduce the amount of Pt used and thus lower the price, new types of catalyst materials are being developed, using alloys of Pt with other metals, such as Co, Cu or Ni, which also increases the specific electrochemical activity of the material. [1] Since alloying metals have lower redox potential compared to Pt, alloyed catalyst are more susceptible to dissolution, which represents a significant challenge in their wider adoption. Degradation is somewhat mitigated by preconditioning of catalyst nanoparticles during which Pt shell is formed around alloy particle core, resulting in higher stability of core-shell catalysts. Despite clear advantages, the use of alloyed catalyst might introduce some new risks in terms of fuel cell durability. Dissolution of alloying metal introduces ions of transition metals into the membrane, where they could serve as a catalyst in chemical reactions leading to the chemical degradation of the membrane [2]. Metal ions can also block the active sites in proton exchange membrane and thus reduce its proton conductivity, while diffusion from cathode to anode catalyst layer and deposition on catalyst surface can present a risk of anode catalyst surface passivization [3].To improve the understanding of aforementioned processes, we propose a 1-dimensional spatially and temporally resolved degradation model of alloyed catalyst degradation in the membrane-electrode assembly (MEA). The model describes the changes of cathode core-shell catalyst structure as a redistribution of particle core sizes and shell thicknesses due to electrochemical surface oxidation, dissolution and redeposition. To provide realistic internal states of the fuel cell during operation, the degradation model is coupled with advanced spatially and temporally resolved model of the fuel cell operation [4]. Dissolution model represents a source of Pt and alloying ions in the catalyst layer, which is coupled to 1D model of ion diffusion in the catalyst layer and the membrane, taking into account the specifics of transport in different MEA components. The transport model is further coupled with potential ion sinks, such as reduction in the presence of hydrogen, interaction with the proton exchange membrane and redeposition on the anode.Preliminary results indicate that Pt ions diffusion results in spatial inhomogeneities of catalyst layer degradation. The location and mechanism of metal ion deposition depends on the redox potential of metal and can occur in either membrane or anode catalyst layer. The model shows great promise in developing a better understanding of degradation processes of alloyed catalyst materials and could in future guide a development of better operation strategies for fuel cell use, mitigating their degradation and improving their lifetime.[1] E. Antolini et al., J. Power Sources. 160 (2006) 957–968.[2] M. Strlič et al., Acta Chim. Slov. 50 (2003) 619–632.[3] A. Han et al., Int. J. Hydrogen Energy. 45 (2020) 25276–25285.[4] A. Kregar et al., Appl. Energy. 263 (2020) 114547

Emerging current-voltage plateaus caused by high internal electric potentials in interband cascade photodetectors

Emerging current-voltage plateaus caused by high internal electric potentials in interband cascade photodetectors

An experimental study on the role of electrical conductivity in the steady cone-jet electrospray

In present work, the effect of the electrical conductivity on the steady cone-jet electrospray are experimentally investigated, where the operating diagram and the jet breakup instability are extensively examined. A hemispherical tube is employed as spraying nozzle severed as high electric potential electrode in a needle-plated electrode configuration compared to the common and sheathed tubes. The cone-jet electrospray is visualized by a high-resolution camera and extensively analyzed offline. The aqueous solution in ethanol, Diethyleneglycol (DEG) and Ethylene glycol (EG) are atomized with varied electrical conductivity under different high electric potentials and flowrates. Experimental results indicate that the cone-jet electrospray can operate in the certain ranges of operating parameter for all types of capillaries. The operating diagram for the hemispherical tube is significantly broader than other tubes because of various electric field strength distribution. The onset electric potential to determine a steady cone-jet electrospray gradually increases and the termination value also increases as the electrical conductivity increasing. The lower and upper flowrate to form a steady cone-jet electrospray also increase as the electrical conductivity increases. The jet breakup instability can transit from varicose to whipping due to low the reference flow rate as electrical conductivity increasing, which is agreement with theoretical analysis. In particular, for EG, the transition from whipping to similar micro-dripping is observed as the electrical conductivity increasing, while the transition also occurs as flowrate increases for EG with higher electrical conductivity. The increase in the electrical conductivity and flowrate elongates the cone due to EHD body force, which causes the electric field vary, further resulting in the difference in jet breakup instability. Moreover, the electrical conductivity also plays an important role in jet breakup length.

Electroosmotic flow and heat transfer of a hybrid nanofluid in a microchannel: A structural optimization

In microchannels where there is a change in the direction of flow, the difference in path length between the inner and outer walls or boundaries can play an effective role in dispersion. This research focuses on studying the fluid flow and heat transfer of a hybrid nanofluid in a microchannel under electroosmotic flow. A structural optimization is applied to reduce dispersion, and the results of the optimized geometry are compared with the original geometry. The results show that the heat transfer is improved due to the new geometry configuration. If only the study of heat transfer is considered, it is recommended to use the optimal geometry with a low volume fraction and a high electric potential. Although the nanofluid's performance in increasing heat transfer is failed due to the low flow rate, the enhanced heat transfer can be achieved through optimized geometry or high electric potential. The results of this research can be applied to the design of more advanced and efficient microfluidic devices with multifaceted objectives.

Role of dielectric force and solid extraction in electrohydrodynamic flow assisted melting

A numerical study of non-isothermal solid-liquid phase change process in a differentially heated square cavity aided with an electrohydrodynamic (EHD) flow is reported. Melting of a phase change material (PCM) subjected to an electric field with different charge injection strengths is studied. The study aims to numerically demonstrate the solid extraction phenomenon and its role in accelerating the melting process. The EHD flow modifies the flow structure and notably alters the solid–liquid interface morphology. The dielectric force extracts the semi-solid PCM from the melt interface into the liquid bulk with high electric field intensity. The dielectric force causes melting-rate enhancement during the initial stages of melting. While, the later stages of melting are influenced by the combined action of Coulomb and dielectric forces. The role of the Coulomb force is weaker in the weaker charge-injection regimes. Higher electric potential and stronger charge injection generally lead to increased melting rates. Up to 62.12 % decrease in total time taken for melting is achieved within the parameters considered herein.

Lithium plating induced by anode tab tearing in lithium-ion batteries: An experimental and modeling study

Manufacturing defects are potential causes of thermal runaway in batteries, which poses serious safety risks in electric vehicles and energy storage systems. Tab tearing, one common defect that can occur during battery manufacturing process, can result in battery safety hazards. However, there has been little research on the impact of tab tearing defects on battery safety. This study compares the impact of different types of tab tearing defects, and concludes that complete tearing of the anode tab poses the most significant hazard to battery safety. Specifically, the study investigates the lithium plating phenomenon caused by the anode tab tearing defect, and identifies its corresponding mechanisms. The study finds that the complete tearing of anode tab causes lithium plating at the anode edge, which is more likely to occur at low charging currents. This result is unexpected, as it had been previously thought that high charging currents cause lithium plating. The study analyzes the mechanism behind the lithium plating phenomenon and identifies two main factors: (1) high electrolyte-phase electrical potential at the anode edge during charging, and (2) gradual accumulation of the amount of lithium intercalation at the anode edge during cycling. The study's results broaden the understanding of the impact of tab tearing defects and the causes of lithium plating.

Ionomer film structure under a constant electric potential in proton exchange membrane fuel cells

ABSTRACT Ionomer electrolyte covering Pt/C electrode provides the sites of electrochemical reactions and plays a significant role in the performance of proton exchange membrane fuel cells. The nanoscale ionomer films have been explored by many molecular dynamics (MD) simulations. However, the significant electric field formed in the electrode–electrolyte interface was usually ignored. In this study, MD simulations integrated with the constant electric potential method are carried out to explore the ionomer film structure on the charged Pt electrode. Pt atoms in the electrode have various and changing charges under the constant electric potential, which thus affects the ionomer film structure on the Pt electrode. Specifically, the perfluorosulfonic acid side chains become more stretched and tend to arrange on the location with positively charged Pt atoms. The water molecules rotate toward a preferred orientation and their diffusivity increases under a higher electric potential. In addition, the multilayered structure of ionomer film on the Pt electrode remains unchanged, whereas the water molecules closely on the negatively charged Pt electrode increases. This study provides an approach for the investigation of the electrode–electrolyte interface with a constant electric potential, and the findings can help better understand the complex ionomer film structure on a Pt electrode.

Electric field forward osmosis (EFFO) fouling mitigation in algae harvesting

Efficient microalgae harvesting is crucial for sustainable biofuel production. Forward osmosis (FO) membranes offer a cost-effective solution for algae separation but are prone to membrane fouling. To address this, a bench-scale FO membrane unit was created, utilizing an aquaporin thin film composite FO membrane. The unit was combined with an electric field in both continuous and pulsing modes, employing stainless steel (SS) meshes to mitigate fouling during Chlorella vulgaris dewatering. Generally, applying higher electric potentials in continuous mode demonstrated improved water flux and flux recovery. The electric field forward osmosis (EFFO) configuration achieved significantly higher fluxes at applied potentials of −0.1, −0.4, and −1.0 V compared to the control. An electric potential as high as −10 V effectively removed fouling by inducing H2 gas formation on the SS cathode. Additionally, the application of high electric potential led to increased settling velocity, possibly due to electrocoagulation and the release of metals. Conversely, carbon fiber electrodes had no impact on algal cell morphology. Both higher salinity levels and increased potential enhanced lipid contents in algal biomass. Overall, EFFO technology in algae harvesting offers improved efficiency by reducing membrane fouling and increasing water flux, enabling cost-effective and sustainable biofuel production from microalgae.

Strategic enhancement of oxygen defects in ZnO from ZnS for water splitting to generate green electricity by hydroelectric cell

The green energy produced by the material device Hydroelectric Cell possesses a huge potential to transform the energy generation by water splitting. It is an efficient, clean and green electricity generating device accomplishing the ambitious Net Zero target. The present study reports a facile and unique process to obtain highly defective and nanoporous ZnO for water splitting at room temperature by strategic heat treatment of ZnS and lithium substituted ZnS. The creation of defects enhanced microstrain and dislocation density in ZnO has been confirmed by X-ray diffraction analysis. Surface and lattice defects presence have been distinctly evidenced by photoluminescence (PL) spectroscopy. The oxygen vacancy in ZnO and Li-ZnO has been also confirmed by the g value of 2.06 and 2.09 calculated from electron paramagnetic resonance (EPR) measurements. As soon as water is sprinkled on the Hydroelectric cell, the surface defects chemidissociate water into H3O+ and OH− ions. Hydronium ions trapped in nanopores create a high electric potential that sustains water splitting. Due to redox reactions at electrodes of Hydroelectric cell, voltage and electric current is generated. The fabricated hydroelectric cells (4 cm2 area) of pristine ZnO, ZnS converted ZnO, and Li-ZnO exhibited short circuit current, ISC 5.6 mA, 15 mA and 53 mA respectively by instant water splitting. Innovative method of oxygen defects creation in ZnO by heat treatment of bulk ZnS is an environment friendly, novel and simple non-photocatalytic technique to generate green electricity by water splitting at room temperature.