Interfacial Kinetics Research Articles

Microstructural evolution and corrosion behavior of deformed GH3536 alloy fabricated by laser metal deposition for bipolar plates in PEMFC

The influences of cold rolling deformation on the microstructures and corrosion behavior of laser metal deposition processed GH3536 alloy were investigated through electron backscattered diffraction and electrochemical tests. The results indicate that the deformed sample within a 15 % of reduction exhibits an excellent corrosion resistance in the simulated PEMFC solution, which can be mainly attributed to a small amount of deformation providing more nucleation sites for Cr to form compact Cr2O3 passive films. In addition, an appropriate compressive residual stress reduces point defect concentrations in passive films and limits interfacial reaction kinetics. In comparison, the corrosion resistance of GH3536 alloy obviously decreases with an increase in deformation reduction from 15 % to 50 %. Apart from a strong increase in activation energy, high-density dislocations after a severe deformation will enhance the surface activity and result in the lattice distortion in the passive film, which deteriorates the corrosion resistance of cold-rolled GH3536 alloy samples.

Construction of MoS2/NiS2 heterostructure with fast interfacial reaction kinetics for ultrafast sodium storage

Constructing heterostructure is a valid method to reinforcing sodium storage performance of transition metal chalcogenides materials. Herein, a simple, safe and controllable one step hydrothermal method is proposed to synthesize MoS2/NiS2 heterostructure. Due to the difference in band gaps and work functions of MoS2 and NiS2, the charges are redistributed at the MoS2/NiS2 heterointerfaces, thereby accelerating the migration of electrons and Na+. The heterointerfaces provide extra active sites for storing Na+, thus increasing the sodium storage capacity of the heterostructure. Furthermore, the distinct redox potentials of NiS2 and MoS2 promote the structural stability of MoS2/NiS2 heterostructure during the electrochemical reaction processes. Consequently, the obtained MoS2/NiS2 heterostructure exhibits superior rate properties (339.4 mAh g−1 at 10 A g−1) and ultra-stable cycling stability (480.5 mAh g−1 after 350 cycles at 1 A g−1). This paper presents a valid strategy for creating heterostructure anodes with excellent sodium storage properties.

Interfacial tribochemical kinetics: A new perspective on superlubricity of diamond-like carbon films

Interfacial tribochemical kinetics: A new perspective on superlubricity of diamond-like carbon films

Enhancing interfacial kinetics and stability of LiMn2O4 cathode by fabricating an artificial cathode electrolyte interphase of LiNbO3

LiMn2O4 (LMO) cathode material has received continuous attention due to its low price, environmental friendliness, high voltage platform, and high safety. However, the structure distortion is usually caused by the Jahn-Teller effect of Mn3+ in LMO, in which Mn3+ undergoes disproportionation reaction, resulting in the dissolution of Mn element and leading to the problems of fast capacity decay and short cycle life of battery. In this study, a thin (∼3 nm) artificial cathode electrolyte interphase (CEI) of LiNbO3 (LNO) is uniformly covered on the surface of LMO powder (LMO@LNO) by magnetron sputtering method. Compared with the bare LMO, LMO@LNO delivers a higher discharge capacity and better cycling stability. The capacity retention rate of bare LMO/Li cell reaches 80 % in 150 cycles, while LMO@LNO/Li cell can cycle up to 700 cycles, greatly prolonging the cycle life of battery. According to the experimental tests, it is found that the CEI layer of LNO not only improves the interfacial kinetics of electrode, but also inhibits the dissolution of Mn element and side reactions between electrolyte and electrode, thus effectively enhances the rate capability and cycling stability of batteries even at 55 °C and high-voltage of 4.8 V.

Unveiling the Inhibition of Enzymatic Hydrolysis of Cellulose by Lignin-Derived Phenolics: Interfacial Kinetics and Molecular Simulations

Unveiling the Inhibition of Enzymatic Hydrolysis of Cellulose by Lignin-Derived Phenolics: Interfacial Kinetics and Molecular Simulations

Quantifying Interfacial Ion Transfer at Operating Potassium-Insertion Battery Electrodes within Highly Concentrated Aqueous Solutions.

Electrode/electrolyte interfacial ion transfer is a fundamental process occurring during insertion-type redox reactions at battery electrodes. The rate at which ions move into and out of the electrode, as well as at interphase structures, directly impacts the power performance of the battery. However, measuring and quantifying these ion transfer phenomena can be difficult, especially at high electrolyte concentrations as found in batteries. Herein, we report a scanning electrochemical microscope method using a common ferri/ferrocyanide (FeCN) redox mediator dissolved in an aqueous electrolyte to track changes in alkali ions at high electrolyte concentrations (up to 3 mol dm-3). Using voltammetry at a platinum microelectrode, we observed a reversible E1/2 shift of ∼60 mV per decade change in K+ concentrations. The response showed high stability in sequential measurements and similar behavior in other aqueous electrolytes. From there, we used the same FeCN mediator to position the microelectrode at the surface of a potassium-insertion electrode. We demonstrate tracking of local changes in the K+ concentration during insertion and deinsertion processes. Using a 2D axisymmetric, finite element model, we further estimate the effective insertion rates. These developments enable characterization of a key parameter for improving batteries, the interfacial ion transfer kinetics, and future work may show mediators appropriate for molar concentrations in nonaqueous electrolytes and beyond.

Imide-pillared covalent organic framework protective films as stable zinc ion-conducting interphases for dendrite-free Zn metal anodes

The notorious growth of zinc dendrite and the water-induced corrosion of zinc metal anodes (ZMAs) restrict the practical development of aqueous zinc ion batteries (AZIBs). In this work, a zinc metallized, imide-pillared covalent organic framework (ZPC) protective film has been engineered as a stable Zn2+ ion-conducting interphase to modulate interfacial kinetics and suppress side reactions for ZMAs. Compared to bare Zn, ZPC@Zn exhibits a higher Zn2+ ionic conductivity, a larger Zn2+ transference number, a lower electronic conductivity, a smaller desolvation activation energy and correspondingly a significant suppression of corrosion, hydrogen evolution and Zn dendrites. Impressively, the ZPC@Zn||ZPC@Zn symmetric cell obtains a cycling lifespan over 3000 h under 5 mA cm−2 for 1 mA h cm−2. The ZPC@Zn||NH4V4O10 coin-type full battery delivers a specific capacity of 195.8 mA h g−1 with a retention rate of 78.5% at 2 A g−1 after 1100 cycles, and the ZPC@Zn||NH4V4O10 pouch full cell shows a retention of 70.1% in reversible capacity at 3 A g−1 after 1100 cycles. The present incorporation of imide-linked covalent organic frameworks in the surface modification of ZMAs will offer fresh perspectives in the search for ideal protective films for the practicality of AZIBs.

On the kinetics of electrodeposition in a magnesium metal anode

Magnesium (Mg) metal batteries are promising for next-generation energy storage due to Mg’s abundance and potential for improved energy densities through two-electron redox in cathodes and thin film anodes supporting high current densities. However, reversible and uniform electrodeposition of Mg necessary for high-energy-density Mg batteries continues to be plagued by challenges traceable to energy barriers to desolvation in liquid electrolytes, the stabilization of passivation layers that impede Mg diffusion at electrified interfaces, and deleterious high-asperity electrodeposition morphologies. Thus, the specific impact and coupling of factors such as (i) composition of the salt solution, (ii) electrode overpotential, and (iii) reversible stripping/plating on the interfacial kinetics of electrodes remains an area of intense interest. This study investigates the effects of overpotential time-transients and electrolyte concentration using experimentally-guided phase-field methods and compares them with an electrochemical spherical cap model. Complex dynamics at the electrode/electrolyte interface involve transient changes in overpotential, influencing nucleation, diffusion, and crystallization, ultimately altering surface evolution. We find that the Damkohler number converges to approximately one for a symmetric Mg-Mg cell using 0.1 M Mg[TFSI]2 in 1:1 v/v diglyme/dimethoxyethane suggesting a subtle balance between reactive and diffusive forces. The results indicate the formation of dendritic structures is primarily driven by limitations in electrolyte transport. In addition, we determine the limiting current density of this cell under various electrolyte concentrations, which is an essential step in successful battery design and operation. Our findings underscore the critical role of overpotentials in underpinning reaction kinetics and non-equilibrium growth dynamics during metal electrodepositon.

Tailoring Electric Double Layer by Cation Specific Adsorption for High‐Voltage Quasi‐Solid‐State Lithium Metal Batteries

AbstractThe interfacial instability of high‐nickel layered oxides severely plagues practical application of high‐energy quasi‐solid‐state lithium metal batteries (LMBs). Herein, a uniform and highly oxidation‐resistant polymer layer within inner Helmholtz plane is engineered by in situ polymerizing 1‐vinyl‐3‐ethylimidazolium (VEIM) cations preferentially adsorbed on LiNi0.83Co0.11Mn0.06O2 (NCM83) surface, inducing the formation of anion‐derived cathode electrolyte interphase with fast interfacial kinetics. Meanwhile, the copolymerization of [VEIM][BF4] and vinyl ethylene carbonate (VEC) endows P(VEC‐IL) copolymer with the positively‐charged imidazolium moieties, providing positive electric fields to facilitate Li+ transport and desolvation process. Consequently, the Li||NCM83 cells with a cut‐off voltage up to 4.5 V exhibit excellent reversible capacity of 130 mAh g−1 after 1000 cycles at 25 °C and considerable discharge capacity of 134 mAh g−1 without capacity decay after 100 cycles at −20 °C. This work provides deep understanding on tailoring electric double layer by cation specific adsorption for high‐voltage quasi‐solid‐state LMBs.

Tailoring Electric Double Layer by Cation Specific Adsorption for High-Voltage Quasi-Solid-State Lithium Metal Batteries.

The interfacial instability of high-nickel layered oxides severely plagues practical application of high-energy quasi-solid-state lithium metal batteries (LMBs). Herein, a uniform and highly oxidation-resistant polymer layer within inner Helmholtz plane is engineered by in situ polymerizing 1-vinyl-3-ethylimidazolium (VEIM) cations preferentially adsorbed on LiNi0.83Co0.11Mn0.06O2 (NCM83) surface, inducing the formation of anion-derived cathode electrolyte interphase with fast interfacial kinetics. Meanwhile, the copolymerization of [VEIM][BF4] and vinyl ethylene carbonate (VEC) endows P(VEC-IL) copolymer with the positively-charged imidazolium moieties, providing positive electric fields to facilitate Li+ transport and desolvation process. Consequently, the Li||NCM83 cells with a cut-off voltage up to 4.5 V exhibit excellent reversible capacity of 130 mAh g-1 after 1000 cycles at 25 °C and considerable discharge capacity of 134 mAh g-1 without capacity decay after 100 cycles at -20 °C. This work provides deep understanding on tailoring electric double layer by cation specific adsorption for high-voltage quasi-solid-state LMBs.

Hole scavenger effect on hexagonal ZnO nanostructures decorated with SnO2 nanoparticles for generating high current densities via photoelectrochemical activity

This study investigated the effects of the heterostructure and interface kinetics on the photocurrents generated by ZnO-coupled SnO2 nanostructures. Electrochemical impedance spectroscopy was utilized to understand the nanostructure heterostructure and interface charge kinetics in a 0.1 M NaOH under a ON/OFF state; the lowest charge kinetic resistance of 370.84 Ω was attained for ZnO sample decorated with SnO2 particles in the light state, which is ten times lower than that of ZnO structures, with a current density of 0.94 mA cm−2. In addition, the effect of the applied potential on the charge production of all the electrodes was examined at an applied voltage of 0.55 V vs. reference electrode, which showed the maximum generation of induced-current density for ZnO nanostructures decorated with SnO2 particles compared with other pristine electrodes. Furthermore, the hole scavenger effect on the interface kinetics and photocurrent generation for all the photoelectrodes was investigated under similar conditions, such as without a scavenger and in the same electrolyte. All electrodes in the presence of the scavenger exhibited better resistance, charge transfer kinetics, and photocurrent densities than the electrodes without a scavenger. The maximum current density of 8.96 mA cm−2 was attained for ZnO nanostructures decorated with SnO2 nanoparticles. This was higher compared with other pristine electrodes with scavengers, owing to better charge migration and reduced recombination due to the hole scavenger.

Reconstructing Solvation Structure by Steric Hindrance‐Coordination Push‐Pull of Dipolymer‐H2O‐Zn2+ toward Long‐life Aqueous Zinc‐Metal Batteries

AbstractAqueous zinc‐metal batteries are prospective energy storge devices due to their intrinsically high safety and cost effectiveness. Yet, uneven deposition of zinc ions in electrochemical reduction and side reactions at the anode interface significantly hinder their development and application. Here, we propose a solvation‐interface attenuation strategy enabled by a frustrated tertiary amine amphiphilic dipolymer electrolyte additive. The configuration of superhydrophilic segments with covalently bonded lipophilic spacers enables coupled steric hindrance/coordination, which establishes a balanced push‐pull dynamic of dipolymer‐H2O‐Zn2+. Such interplay reconstructs the solvation structure of Zn2+ and allows the formation of a stable dipolymer‐inorganic hybrid solid electrolyte interface (SEI) layer. This SEI layer effectively shields the zinc‐metal anode from water and anions, significantly reducing side reactions. In addition, the dipolymer adsorbed at the zinc‐metal anode interface regulates the interfacial electrochemical reduction kinetics and ensures uniform zinc deposition. As a result, the Zn−Zn symmetric cells with dipolymer‐containing electrolyte exhibit remarkable cycling stability exceeding 5800 h (242 days). The Zn‐NVO batteries and Zn‐AC hybrid ion supercapacitors also deliver stable cycling for up to 1440 h (60 days) with high‐capacity retention over 80 %. This research demonstrates the potential to facilitate the development and commercialization of zinc‐based energy storage devices.

Reconstructing Solvation Structure by Steric Hindrance-Coordination Push-Pull of Dipolymer-H2O-Zn2+ toward Long-life Aqueous Zinc-Metal Batteries.

Aqueous zinc-metal batteries are prospective energy storge devices due to their intrinsically high safety and cost effectiveness. Yet, uneven deposition of zinc ions in electrochemical reduction and side reactions at the anode interface significantly hinder their development and application. Here, we propose a solvation-interface attenuation strategy enabled by a frustrated tertiary amine amphiphilic dipolymer electrolyte additive. The configuration of superhydrophilic segments with covalently bonded lipophilic spacers enables coupled steric hindrance/coordination, which establishes a balanced push-pull dynamic of dipolymer-H2O-Zn2+. Such interplay reconstructs the solvation structure of Zn2+ and allows the formation of a stable dipolymer-inorganic hybrid solid electrolyte interface (SEI) layer. This SEI layer effectively shields the zinc-metal anode from water and anions, significantly reducing side reactions. In addition, the dipolymer adsorbed at the zinc-metal anode interface regulates the interfacial electrochemical reduction kinetics and ensures uniform zinc deposition. As a result, the Zn-Zn symmetric cells with dipolymer-containing electrolyte exhibit remarkable cycling stability exceeding 5800 h (242 days). The Zn-NVO batteries and Zn-AC hybrid ion supercapacitors also deliver stable cycling for up to 1440 h (60 days) with high-capacity retention over 80%. This research demonstrates the potential to facilitate the development and commercialization of zinc-based energy storage devices.

Weak Solvation Chemistry in Fluorinated Nonflammable Electrolytes Achieves Stable Cycling in High-Voltage Lithium Metal Batteries.

High-voltage (>4.35 V) lithium nickel-cobalt-manganese batteries are star candidates due to their higher energy density for next-generation power batteries. This poses higher demands for electrolyte design, including compatibility with lithium metals, stability on high-voltage cathodes, speedy interfacial ion transport kinetics, and appropriate concentration. However, electrolytes at the current level of research struggle to balance these demands. Here, we took advantage of the reduced affinity with Li+ and enhanced oxidative stability of three fluorinated linear carbonates to design a series of weakly solvating electrolytes (WSEs) at a low salt concentration of 1 M, which contain abundant ionic cluster structures, leading to the optimization of interfacial chemistry. As a result, WSEs can support the stable cycling of 4.6 V high-voltage Li||NCM811 cells for 300 cycles with a capacity retention of nearly 80%. Moreover, benefiting from the lower desolvation energy of Li+, WSEs achieve superior cycling stability and low polarization under -20 °C. Our work extends the application of WSEs for high-voltage LMBs, providing a promising solution in electrolytes for high-specific-energy lithium batteries.

Functional Aerogel Driven Synchronous Modulation of Zn2+ Interfacial Migration Behavior and Electrolyte Microenvironment Enables Highly Reversible Zn Anodes

AbstractUncontrolled dendrite growth and electrolyte‐induced intricate parasitic reactions are two great challenges that hinder the commercial applications of aqueous zinc‐ion batteries. Herein, a synchronous modulation strategy for Zn2+ interfacial migration behavior and electrolyte microenvironment is proposed by constructing a functional lanthanum hydroxide aerogel (LAG) interface layer on Zn anode surface. The in situ derivation of ion‐conducting zinc hydroxide sulfate (ZHS) from LAG layer results in the spontaneous generation of a hierarchic interface layer during the plating process, where the high Zn2+ selectivity of the upper dense ZHS layer can limit SO42− migration and allow for fast Zn2+ interfacial migration kinetics, while the aerogel layer with well‐defined nanochannels near the anode side can homogenize Zn2+ distribution, thus leading to the effective suppression of both dendrites and side reactions. Additionally, the pH microenvironment of the acidic electrolyte can be synchronously regulated by slightly soluble La(OH)3 aerogel, further inhibiting electrolyte corrosion and HER. Consequently, the modified Zn anode delivers highly reversible Zn plating/stripping and low‐voltage hysteresis, and the high areal‐capacity Zn||MnO2 full cells demonstrate considerable electrochemical performances under high Zn utilization conditions. This functional aerogel‐driven synchronous modulation strategy of Zn2+ migration behavior and electrolyte microenvironment provides new insight for stabilizing Zn metal anodes.

Interfacial kinetics reveal enzymatic resistance mechanisms behind granular starch with smooth surfaces

Heterogeneous (interfacial) enzyme catalyzed hydrolysis of starch granules occurs in various biological systems, including plants, animal/human digestion, and microorganisms. Factors such as granular size, surface area, pores, and smoothness play crucial roles in influencing this process. However, limited understanding persists regarding the high enzymatic resistance of starch granules with smooth surfaces. In this study, we investigated the hydrolysis mechanism of glucoamylase (GA) on three different types of starch granules with smooth surfaces, extracted from Curcuma zedoaria (zedoary) rhizomes, Solanum tuberosum (potato) tubers, and Manihot esculenta (tapioca or cassava) roots. We compared the Langmuir adsorption, interfacial kinetics, and the multi-level structure of the three starches. Our data demonstrate that the lower enzymatic resistance observed in tapioca starch stems from the higher density of enzymatic attack sites (kinΓmax) recognized by GA on tapioca starch (1.0 nmol/g) compared to potato (0.6 nmol/g) and zedoary (0.3 nmol/g) starch granules. The high kinΓmax for tapioca starch was significantly influenced by its relatively lower B-type crystallinity, which is disrupted by the presence of short fa chains (degree of polymerization (DP) < 12) and long amylose chains. Furthermore, the relatively higher proportion of longer chains (fb1 and fb2 chains) on the surface of tapioca starch also contributed to higher kinΓmax for GA, resulting in lower enzymatic resistance. These findings enhance our understanding of how the structure of starch granules affects enzymatic catalysis, particularly in granular starches with smooth surfaces devoid of pores. Such insights are crucial for elucidating the digestion and utilization of starch granules.

Design method of immiscible dissimilar welding (Mg/Fe) based on CALPHAD and thermodynamic modelling

Joining dissimilar metals is a major challenge in joining technology; the weldability of immiscible systems is especially challenging. In this study, a design methodology for dissimilar welding is suggested. The Miedema model and Toop model are developed to calculate the thermodynamics of quaternary alloy systems (Mg-Fe-Al-Cu). Finite element modelling (FEM) of temperature fields and the calculation of phase diagrams (CALPHAD) are combined to provide prerequisite information for modelling. As a test subject, laser welded lap configuration joints of AZ31B magnesium alloy and DP590 steel with a copper coating were put into the design scheme. The interfacial elemental diffusion and formation of intermetallics (IMCs) along the interface during the welding process are predicted. This simulation design scheme predicts the interfacial reaction kinetics and identifies whether the intermediate element works or not. The effects of the Cu coating thickness on the weld constitution, interfacial microstructures and mechanical properties were studied. Cu coating promotes the weld formation fostering the metallurgical reaction of the fusion zone (FZ) with the steel brazing interface. The mechanism of interfacial reactions during the welding-brazing process has been clarified. The Vickers hardness distribution across the interface shows that the Cu-IMCs are ductile.

Studies of indium nanostructures growth models on A3B6 layered templates

This article explores the surface architecture formation on layered A3B6 semiconductors, such as In4Se3, InSe, and InTe, focusing on kinetics of surface roughness parameters, such as RMS, skewness and kurtosis, and power spectral density (PSD) under indium deposition studied through large-scale 1 × 1 µm2 and 150 × 150 nm2 scanning tunneling microscopy (STM) images analysis. Our findings reveal common kinetics of surface parameters across different crystals, suggesting fundamental similarities in their interface kinetics. Particularly, PSD analysis elucidates the role of low-frequency spatial structures, underscoring their significance in surface roughness kinetics to some extent independent of the specific layered crystal surface structure.

From Fundamental Interfacial Reaction Kinetics to Macroscopic Current–Voltage Characteristics: Case Study of Solid Acid Fuel Cell Limitations and Possibilities

AbstractThe unique properties of solid acid electrolytes, in particular CsH2PO4, are in many ways ideal for fuel cell operation. However, the technology is constrained by high cathode overpotentials. Here a simplified cathode geometry is employed to obtain the fundamental electrochemical parameters (exchange current density and charge transfer coefficient) describing the oxygen reduction reaction (ORR) at the CsH2PO4‐Pt‐gas interface. The parameters are incorporated into a 1D model of the voltage–current characteristics of realistic SAFC cathodes, which reproduced the measured polarization behavior of such cathodes without recourse to fitting adjustable parameters. Following this validation, the model is utilized to evaluate the impact of changes to cathode properties, microstructure, and operating conditions. Of these, the charge transfer coefficient, measured to have a value of ≈0.6 for ORR on Pt in the SAFC cathode environment, is found to have the greatest impact on power output. Nevertheless, even without material modifications, a combination of microstructural and operational modifications are identified with projected performance metrics meeting Department of Energy targets (0.8 V at 300 mA cm−2, and peak power density of 1 W cm−2), albeit at high Pt loadings. However, the analysis indicates that truly meaningful advances will likely necessitate the discovery of alternative ORR catalysts.

Duodecuple H‐Bonded NH4+ Storage in Multi‐Redox‐Site N‐Heterocyclic Cathode for Six‐Electron Zinc–Organic Batteries

AbstractDesigning multiple redox sites in electroactive organic cathodes that allow more electron transfer is a permanent target for energy storage. Here, six‐electron zinc–organic batteries are reported accessed by duodecuple H‐bonded NH4+ storage in N‐heterocyclic dipyrazino[2,3‐f:2′,3′‐h]quinoxaline‐2,3,6,7,10,11‐hexacarbonitrile (DQH) cathode. DQH features an extended π‐conjugated aromatic planarity enriched with super electron delocalization routes and dodecahedral‐active imine/cyano motifs, achieving a high capacity up to 385 mAh g−1 at 0.5 A g−1. Besides, DQH cathode redox‐exclusively couples with small‐hydration‐size and low‐desolvation‐energy‐barrier NH4+ ions (0.33 nm and 0.19 eV vs 0.86 nm and 0.36 eV of Zn2+) via flexible H‐bonding interactions. NH4+ topo‐coordination enables DQH anti‐dissolution in aqueous electrolytes to avoid common capacity decay of small organic molecules, and solves the instability and low interfacial reaction kinetics issues caused by rigidly and sluggishly repeated insertion of Zn2+ ions. This gives zinc–organic battery high‐rate ability (30 A g−1) and high lifespan (30 000 cycles at 10 A g−1).