Effect Of Electrical Double Layer Research Articles

(Invited) Modeling the Charge Transfer Reactions at Li/SEI/Electrolyte Interfaces in Lithium-Ion Batteries

Two kinds of charge transfer reactions are critical for the performance and life of lithium battery: the desired ion transfer reaction occurring during each charge/discharge cycle, , and the undesired electron transfer reactions leading to the parasitic chemical decomposition of the electrolyte and solid electrolyte interphase (SEI) formation/growth. The heterogeneous multi-component nature of SEI dominates its ionic and electronic transport properties and controls these two charge transfer reactions. Density Functional Theory (DFT)-informed multiscale modeling has been providing valuable insights under the scarcity of quantitative experiments. For example, the LiF/Li2CO3 interface was demonstrated to increase the ionic conductivity of mixed SEI nanocomposite by forming an ionic space charge region near the interface and promoting more Li-ion interstitials in Li2CO3, although LiF itself has low Li-ion conducting carriers and conductivity. To form a LiF-rich SEI layer, the electrolyte compositions need to be designed. Since the SEI formation occurs on the charged surface, the electric double layer (EDL) structure near the charged surfaces needs to be incorporated into the modeling. Here interactive classical molecular dynamics (MD), DFT, and data statistical analysis were combined to illustrate the effect of EDL on SEI formation in two essential electrolytes, the carbonate-based electrolyte for Li-ion batteries and the ether-based electrolyte for batteries with Li-metal anodes. It was found the effectiveness of adding fluoroethylene carbonate (FEC) to form the beneficial F-containing SEI component (e.g., LiF) varies with the electrolyte and temperature, because of the interplay of ion-solvent interactions with the surface charge. These integrated modeling provided quantitative guidance for electrolyte/SEI/Li-metal interface design.

Basalt mineral surface charge and the effect of mineralization on its colloidal stability: Implications of subsurface CO2 storage

Global concern over climate change caused by greenhouse gas emissions has received and is still receiving a lot of attention. Companies and nations have committed to reducing their carbon footprint to halt the consequences, and work is being done to create long-term strategies for CO2 usage. One of these goals is to use the CO2 that has been captured to make chemicals or to use it to make waste that can be buried or safely disposed of. One such endeavours is CO2 mineralization, which has been suggested as a method of CO2 utilization. It entails the creation of carbonates by the interaction of a fluid that contains CO2 with cations that are found in brines or rocks. However, the mineralization process is a protracted one, and until recently it was not believed that it could be completed in less than two years. Furthermore, little research has been done on how mineralization affects the electrokinetic and surface chemistry of cation-bearing rocks like basaltic rocks. Therefore, this study assesses how mineralization (carbonate precipitation) affects the colloidal and electrokinetic characteristics of basaltic rock.According to the study's findings, the electrical double layer (EDL) effect and protonation of the silanol group function as the two main controlling mechanisms of charge formation in the basaltic rock. More so, the rock sample is negatively charged over a range of pH and colloidally stable in freshwater. However, its colloidal stability is decreased in brines, and the EDL effect and potential determining ions (H+ and OH–) dominate its charge development. Additionally, different precipitates have distinct effects on the electrokinetic characteristics of basaltic rock, with the MgCO3 and FeCO3 precipitation having a more notable impact than the CaCO3 precipitation. Furthermore, at pH values of 3 – 4 (CO2 storage pH) in both freshwater and sweater environments, basaltic rocks exhibit near zero or low surface charge values indicating weak adhesion force. Thus, the question of if the near pH values of 2, can be considered as higher values of surface charge is observed in some cases. These findings raise questions about the structural integrity of basaltic rock, which has been touted as a prime candidate for the mineralization process due to its reactive nature, particularly in the case of colloidal stability after the mineralization process. The results of this study further provide new insight into the optimization of the mineralization process, which is dependent on the structural and petrophysical characteristics of the rocks and reservoirs that provide the cations for the process.

A Comparative Study of Electrical Double Layer Effects for CO Reduction Reaction Kinetics

A Comparative Study of Electrical Double Layer Effects for CO Reduction Reaction Kinetics

Low-Voltage Solution-Processed Zinc-Doped CuI Thin Film Transistors with NOR Logic and Artificial Synaptic Function.

Low-voltage Zn-doped CuI thin film transistors (TFTs) gated by chitosan dielectric were fabricated at a low temperature. The Zn-doped CuI TFT exhibited a more superior on/off current ratio than CuI TFT due to the substitution or supplementation of copper vacancies by Zn ions. The Zn-doped CuI films were characterized by scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The Zn-doped CuI TFTs exhibited an on/off current ratio of 1.58 × 104, a subthreshold swing of 70 mV/decade, and a field effect mobility of 0.40 cm2V-1s-1, demonstrating good operational stability. Due to the electric-double-layer (EDL) effect and high specific capacitance (17.3 μF/cm2) of chitosan gate dielectric, Zn-doped CuI TFT operates at a voltage below -2 V. The threshold voltage is -0.2 V. In particular, we have prepared Zn-doped CuI TFTs with two in-plane gates and NOR logic operation is implemented on such TFTs. In addition, using the ion relaxation effect and EDL effect of chitosan film, a simple pain neuron simulation is realized on such a p-type TFTs for the first time through the bottom gate to regulate the carrier transport of the channel. This p-type device has promising applications in low-cost electronic devices, complementary electronic circuit, and biosensors.

In situ growth of 1T-MoS2 nanosheets on NiS porous-hollow microspheres for high-performance potassium-ion storage

In this study, a two-step route was adopted to in situ grow 1T-MoS2 nanosheets on NiS porous-hollow microspheres. It was found that the tiled MoS2 sheets tightly wrapped NiS spheres through coherent attachment via lattice-plane rotation, which would fully activate inert sulfur atoms on the basal plane of 1T-MoS2. This unique structure resembled a concentric spherical capacitor, which was able to store a large quantity of K+ ions with a capacity of 273.1 mAh/g at 5 A/g and deliver a stable capacity of 472.1 mAhg−1 after 1000 cycles at 0.2 A/g. In these multilevel hollow spheres, NiS phase mainly acted as a dielectric material to boost K-storage capability of MoS2 lamellae, and this electrical double-layer effect is more prominent either at high current densities or upon long-term cycling. It was anticipated that this work would shed new light on designing heterostructures of transition-metal dichalcogenides for high-performance potassium-ion storage.

Effect of electrodialysis on colloidal geometry and dynamics: Why my membrane stack was clogged even after a fine pretreatment?

As a long-standing problem, electrodialysis (ED) clogging is believed a consequence of colloids. However, its blocking causation and clogging mechanism have not been verified. In this study, electrodialysis was used to treat a colloidal saline solution, aiming to answer the question from the “nature” of ED by investigating the influence of ED parameters such as laminar flow, salt concentration, current density and pH on colloid geometry and dynamics during the desalting process. The results revealed that: (i) laminar and membrane electrostatic repulsion and adsorption could not significantly increase the particle size (maximum 2.28 times), while the applied electric field elevated the particle size by 54.52 times (119.9 ± 13.66 to 6537.5 ± 64.35 nm); (ii) when the initial feed concentration elevated 10 times (0.1 to 1 mol/L NaCl), the particle size upsurged 149-fold (5.99 ± 0.57 to >150 μm), and flocs were generated. This enhancement was mainly attributed to the compressive electric double layer effect, and the Debye length was trimmed from 0.96 to 0.30 nm; (iii) The low current density (25 A/m2) had a profound aggregation effect on small BSA particles (roughly 10 nm); (iv) The change of pH causes the conformational transition of BSA. In the strong acidic (pH = 3.0) environment, the colloidal particle size expanded by 13 times. This study confirmed that the aggregation of colloids was the culprit of spacer clogging during electrodialysis at higher salt concentrations (>1 mol/L). Furthermore, experimental data were substituted into the simulation formula to summarise the geometry and dynamic variation of BSA in ED.

The effect of electric double layers, zeta potential and pH on apparent viscosity of non‐Brownian suspensions

AbstractWe carried out 3D simulations of monodisperse particle suspensions subjected to a constant shear rate with the view to investigate the effect of electrical double layers around the particles on apparent suspension viscosities. To this end, expressions for Debye length, zeta potential, and ionic strength (pH) of the liquid were incorporated into our in‐house lattice Boltzmann code that uses the immersed boundary method and includes subgrid lubrication models. We varied the solids concentration and particle radius, keeping the particle Reynolds number equal to 0.1. We report on results with respect to the effect of pH in the range 9 through 12 and of Debye length on apparent viscosity and spatial suspension structures, particularly at higher solids volume fractions, and on the effect of flow reversals.

Numerical Study on Thin Film Lubrication Performance with Imperfect Coating under the Effect of the Electrical Double Layer in Point Contact

Revealing the interface effect on lubrication is great significance for designing high performance water-based lubricating friction pairs. In this study, a new thin film lubrication numerical model considering the electrical double layer (EDL) effect with an imperfect coating in point contact is proposed, and the validity and effectiveness of the model is verified. The numerical results show that increasing the zeta potential increases the film thickness, which indicates that the EDL effect can improve the firm lubricated film formation. However, the effect of the zeta potential on the von Mises stress is very small because the liquid film pressure remains constant at different surface potentials. On the other hand, with an increase in coating thickness, the effects of the coating on the film thickness and pressure gradually become evident, but the von Mises stress is affected by the imperfectly bonded interface and coating thickness. Finally, the effect of surface roughness on thin film lubrication was analyzed. The liquid film thickness slightly decreased and the occurrence of stress concentration on the surface coating was evident. The proposed model was expected to provide a calculation basis for solving the thin film lubrication problem of coatings affected by the EDL.

Justification of a New Original Homogenized Model for Ionic Diffusion in Porous Media

Abstract In this work, a new original justification of an homogenized model for ionic diffusion in porous media is proposed. The approach used enables to specify clearly the domain of validity of this homogenized model, involving a source term characterizing the electrical double layer effect at the macroscale. This homogenized model is obtained from the formal periodic homogenization of a Nernst–Planck–Poisson system at the pore scale accounting for conductivity of the solid phase which is generally neglected. The Poisson equation is defined in both fluid and solid phases and the discontinuity of fluxes at the solid–fluid interface is modeled by a jump of the electrical field, linked to the surface electrical charge of the solid interface. Numerical simulations are carried out at the scale of the unit cell to underscore the influence of the contrast on the electrical permittivity between fluid and solid phases. The comparison of the concentrations and the electrical potential given at the macroscale by the homogenized model and by a direct pore scale model reveals the accuracy of the homogenized model which is very simple to use.

Surface Carbonized Natural Wood via Hydrogen–Oxygen Flame for Electricity Generation from Water Evaporation

Water evaporation-induced power generation technologies based on the interaction between water and nanomaterials have received wide attention over the years. Herein, a natural wood-based water evaporation-induced power generator (EIPG) via the surface carbonization technique under high-temperature hydrogen–oxygen flame was developed. The unique surface carbonization strategy made the internal layer (uncarbonized layer) maintain high hydrophilicity to satisfy the stable and continuous capillary flow for the transport of ions. The internal layer possessed a higher surface charge density, promoting the establishment of the electric double layer (EDL), which ensured high selectivity of the wood channels for positive ions. Meanwhile, the external carbonized layer could effectively adsorb positively charged ions through strong cation−π interactions to strengthen the EDL effect. The carbonized layer also provided an electrical charge transportation channel, lowering the resistance of the device. The device could continuously generate power with an open-circuit voltage (Voc) of ∼170 mV and a short-circuit current (Isc) of ∼730 nA over 24 h, exhibiting excellent stability. Moreover, a higher electric output was generated by the water EIPG through assembling several devices in series or parallel and applied successfully in charging capacitors and powering a commercial digital calculator. This work provides a different strategy for developing an environment-friendly and low-cost water EIPG utilized in harvesting green energy, with no chemical treatment.

Toward High Bias‐Stress Stability P‐Type GaSb Nanowire Field‐Effect‐Transistor for Gate‐Controlled Near‐Infrared Photodetection and Photocommunication

AbstractThe bias‐stress instability of nanowires (NWs) field‐effect‐transistors (FETs), originated from the surface trappings, are challenging greatly the functionalization of III‐V group semiconductors in next‐generation electronics and optoelectronics. In this study, the solution‐processed high‐κ oxide dielectric shell is configured uniformly onto the surface of GaSb NWs, contributing to the excellent bias‐stress stability of as‐constructed p‐type NWFETs. Owing to the interdiffusion between Al and Ga, the oxide dielectric shell is Ga‐AlOx. With an optimal oxide dielectric shell, the as‐constructed p‐type GaSb NWFETs show an insignificant attenuation of on‐state current (within 10%) and a negligible negative shift of threshold voltage under 60 min continuous gate bias, which is far better than that of pristine GaSb NWFETs, resulting from the electric double layer effect. Benefiting from the excellent bias‐stress stability, when configured into the near‐infrared photodetector, NWFET exhibits desirable stability and gate‐controlled photodetection behaviors. Idark and Ilight are effectively modulated by gate voltage, resulting in gate‐controlled responsivity and gain under the illumination of 1550 nm laser. In the end, the as‐constructed bias‐stress stability NWFET demonstrates expected gate‐controlled photodetection imaging and photocommunication ability. The strategy of solution‐processed oxide dielectric shell promises high bias‐stress stability NWFETs for gate‐controlled photodetection and photocommunication.

Reaction Gas Pressure, Temperature, and Membrane Water Content Modulate Electrochemical Process of a PEMFC: A Simulation Study

Proton exchange membrane fuel cells (PEMFC) are widely used in transportation systems owing to their desirable characteristics such as high efficacy and low operating temperature. However, the fuel cell systems exhibit load changes as well as voltage and power losses so as to reduce dependence on the battery. The aim of the present study was to explore the composition and basic working principle of PEMFC. A PEMFC electrochemical reaction model was then established according to the electrochemical reaction principle of fuel cell to evaluate the effects of Nernst electromotive force, activation overvoltage, Ohmic overvoltage, concentration overvoltage, and electric double layer. The effects of activation loss, concentration loss, and Ohmic loss on the fuel cell were evaluated through simulation analysis. The effect of various factors on the dynamic output of a 60 kW PEMFC was explored through dynamic simulations. The findings showed that a change in current modulated a change in voltage through the Ohmic loss equivalent resistance. The activation loss equivalent resistance and the concentration loss equivalent resistance decreased the voltage loss owing to the presence of the capacitor. The output voltage of the fuel cell decreased with an increase in load current, whereas the output power increased with an increase in load current. Increase in partial pressure of oxygen caused an increase in output power and output voltage of the cell. The internal chemical reaction rate and the voltage output of the fuel cell increases with an increase in the working temperature. The findings of this study provide a basis for conducting further studies to produce efficient fuel cells for application in various systems.

Cilia–Driven Flow in a Symmetric Elliptical Duct with Electric Double Layer and Thermal Effects: Exact Solutions

Cilia–Driven Flow in a Symmetric Elliptical Duct with Electric Double Layer and Thermal Effects: Exact Solutions

Chloride penetration and binding behavior in unsaturated alkali-activated slag mortars

A comprehensive study from detailed microstructure analyses to mass transport investigations was implemented to explore chloride penetration of unsaturated alkali-activated slag (AAS) mortars accounting for chloride binding behaviors. Unsaturated chloride penetrations reflected from diffusion cases of instantaneous plane source and sorption cases of wetting-drying exposure were elaborated in relation to solid hydrates and pore structure features. It is found that the specimen with lower saturation has a slower chloride diffusion but a larger chloride penetration under wetting-drying cycles. Slag mortars with sodium hydroxide activation exhibit higher chloride binding capacity owing to more hydrotalcite-like phases and higher Ca/Si ratio of C-(N-)A-S-H gels in the outer product zones as compared to sodium silicate activated slag mortars, regardless of the saturation. Accelerations of the chloride penetration under the wetting-drying exposure are limited in saturated AAS specimens while for unsaturated AAS specimens more wetting-drying cycles result in the inner layers to be gradually diffusion-controlled. The chloride binding capacity of AAS specimens follows Langmuir's isotherm and clearly decreases with a lower saturation. It is advised to consider the electrical double layer effect within narrow pores when applying rapid chloride migration tests for AAS systems.

Regulation of electrical double layers promotes electrochemical reduction of carbon dioxide

The electrochemical CO2 reduction reaction is an effective approach to alleviate global energy shortage and environmental problems by converting CO2 to high value-added products. The rational design of nanostructured electrocatalysts requires an understanding of the interplay between mass transfer and reaction in a confined environment. Here, local pH and CO2 concentration are considered as the typical descriptors of reaction environment, which are modelled using the reaction-coupled modified Poisson-Nernst-Planck equations in an isolated nanopore. The effect of nanoconfinement, steric hindrance and electrical double layer on the CO2RR as well as the competitive hydrogen evolution reaction are investigated. An optimal local reaction environment with high Faradaic efficiency and selectivity is found when the pore radius is comparable to the Debye length. Our work provides microscopic insights into the interplay between diffusion, migration, and reaction under the nanoconfinement of nanopores.

Regulation of thermo-electro-magneto dynamics in course of peristalsis

The effect of heat transfer on Couple-Stress fluid’s unsteady peristaltic motion is theoretically studied in this paper using applied electric and magnetic fields. Thermal analysis is carried out in the presence of fluid friction-induced viscous dissipation and Joule heating. The potential distribution is examined using the Debye-Huckel linearization approximation. The governing equation’s complexity is decreased using the lubrication theory. The dynamics of electroosmosis and peristaltic pumping are examined for the velocity field, temperature field, pressure distribution, and streamlines. The effects of electrical double layer (EDL) on flow, pumping, and thermal properties have been calculated. Numerical computations have been done to provide the graphical depiction and to explain the model’s outcomes. This model can be used to design a variety of microfluidic gadgets and intelligent micropumps for combining chemicals and ionic liquids.

Newton-GMRES-Method for the Scritinization of electric double layer and surface roughness on EHL line contact problem

The electric double layer phenomenon exists on the solid interface under the water-liquid condition. The water molecules are ionized and adhered in the interface forming the sturn layer is a diffused layer in which molecules can move with the movement of bulk of molecules. Because of these two characteristics, the boundary layer of water molecules is called the electric double layer. The aim of present study is to explore the impact of two fraction surfaces of electric double layer (EDL) on a thin water lubricating film on an elastohydrodynamic lubrication (EHL) line contact problem with a sinusoidal surface roughness. The governing modified Reynolds and film thickness equations are based on mathematical model of electro-viscosity of asymmetrical electrical double layer is analyzed numerically. The viscosity-pressure relation of water and theoretical evaluation pertaining to the effect of electric double layer on film-thickness and pressure distribution of EHL with water film of line contact problem is discussed in detail. The effect of zeta potential on film thickness and pressure is determined using Newton’s-GMRES method with Daubechies D6 wavelet as a pre-conditioner. The results predict that, EDL has less impact on pressure distribution and significant impact on film thickness. The obtained results are compared with results of Dowson and Higginson which are comparable.

Microstructure-based modelling of chloride diffusivity in non-saturated cement paste accounting for capillary and gel pores

Accurate prediction of chloride diffusivity in non-saturated cement paste is crucial for durability design of concrete. This paper presents an integrated framework for modelling chloride diffusivity in non-saturated cement paste considering 3D microstructure, water-gas distribution in pore network and electrical double layer effect. Results indicate that the chloride diffusivity in C-S-H pore solution is dominantly influenced by surface electric potential regardless of water saturation level, porosity of C-S-H and chloride concentration of bulk solution. With the decrease of water saturation level, the relative chloride diffusivity in cement paste experiences sharp, slow and slight decrease stages, followed by a non-diffusive stage, corresponding to connected capillary water, combination of capillary water and saturated C-S-H network and non-saturated C-S-H network as the main diffusion channel, and pore depercolation. The relative chloride diffusivity in cement paste at a given water content decreases with increasing water-to-cement ratio. The simulation results show good agreement with experimental data.

Assessing the unsaturated transport and adsorption properties of ions in nanopores of realistic hydrated-calcium-silicate gel using molecular dynamics simulations

The unsaturated transport of water and ions in concrete structures accelerates the corrosion of reinforcing steel bars. Unfortunately, previous macroscopic and microscopic experimental studies have provided little clarity on the transport mechanisms of ions in calcium-silicate-hydrate (C-S-H) gels. This paper presents molecular dynamics simulations performed to investigate the effect of ion species and concentration during unsaturated transport processes. The transport rate of NaCl solutions at any given concentration significantly exceeds that of CaCl2 solutions because of desorption of intralayer calcium ions in the substrate. Additionally, the electric double layer effect of the realistic C-S-H gel substrate is more pronounced in NaCl solution than in CaCl2 solution and becomes stronger as the concentration increases in both cases. These insights into the effects of ion species and concentration on unsaturated ion transport and adsorption in realistic C-S-H gel nanopores will help guide the development of cement-based materials with improved corrosion resistance.

Insights into the mechanism involved by electric double layer on phosphate removal of metal-bearing environmental remediation agent: Taking tricalcium aluminate as representative

Metal-bearing materials are known to be desirable environmental captures for phosphate removal, yet few studies focus on understanding the reaction process, especially formed a special phenomenon, i.e., electric double layer (EDL), which might influence the phosphate removal. To fill in this gap, we fabricated metal-bearing tricalcium aluminate (C3A, Ca3Al2O6) as representative, to remove phosphate and unveil the impact by electric double layer (EDL). Specifically, a preeminent removal capacity of 142.2 mg·g−1 was achieved at the initial phosphate concentration below 300 mg·L−1. Following thorough the characterizations, the process was that the released Ca2+ or Al3+ of C3A formed positive charged stern layer attracted phosphate to generate Ca or Al-precipitation. At high phosphate concentration (>300 mg·L−1), C3A exhibited inferior removal capability for phosphate (<45 mg·g−1), due to the aggregation of C3A particles with low water permeability under the EDL effect, obstructing Ca2+ and Al3+ to release for phosphate removal. In addition, the feasibility application of C3A was evaluated based on response surface methodology (RSM), highlighting its prospective phosphate treatment. This work not only provides a theoretical guidance for the application of C3A to remove phosphate, but also deepens the understand of phosphate removal mechanism by metal-bearing materials, shedding light on environmental remediation.