Interfacial Kinetics Research Articles

Building Organic-Inorganic Robust Interphases from Deep Eutectic Solution for Highly Stable Mg Metal Anode in Conventional Electrolyte.

Magnesium metal batteries (MMBs) currently face challenges suffering from severe Mg metal passivation and extremely high overpotential in conventional electrolytes. Herein, a strategy of using a low-cost deep eutectic solution (DES) is proposed to modify Mg anode with the monolithic and compact coating of a MgCl2-Al-MgCl2 sandwich structure, enabling the stable and reversible Mg plating-stripping behavior. An organic/nanocrystal hybrid interphase is in-situ built through a facile Mg-Al displacement reaction between aluminum-chloro clusters and Mg in AlCl3/Et3NHCl solution, and it can effectively minimize the adverse interfacial passivation reaction and surface diffusion barrier, affording the high ion-conduction and electronic insulation. This DES-assisted method guarantees a highly reversible cycling of Mg metal anode (over 5000h at 0.1mA cm-2 and 400h at 2.0 mAh cm-2) in Mg(TFSI)2/DME electrolyte with the improved interfacial kinetics and low overpotential. Even at a much higher current density of 1mA cm-2, the overpotential only undergoes a slight increase from 0.2V (at 0.1mA cm-2) to 0.23V. The corresponding full cells with CuS and phenanthraquinone cathodes deliver satisfactory cyclic performance. The DES modification strategy provides a new solution to the design of robust and conductive solid electrolyte interphase for achieving high-voltage and durable MMBs.

The growth and morphological stability of a precipitate in a multi-component solution

The growth and morphological stability of a precipitate in a multi-component solution with cross diffusion between solute species is studied by using the asymptotic method. The resulting asymptotic solution for the dynamics model of the precipitate reveals the relationship between precipitate growth and solute diffusion, and the absolute and relative stability criteria of the precipitate in the multi-component solution with cross diffusion between solute species. The absolute and relative stability radii of the precipitate are determined. It is demonstrated that the growth velocity and size of the precipitate in the multi-component solution are controlled by a growth factor that is determined by the solute diffusion coefficients. In the multi-component solution with cross diffusion between solute species, via the co-action between cross diffusion of solute species and interface kinetic undercooling, the precipitate enhances or reduces the morphological stability by changing the growth factor. In the multi-component solution, the interface kinetics decreases the growth velocity of the precipitate, and enhances the stability of the precipitate. When the interface kinetic undercooling is neglected, the absolute and relative stability criteria of the precipitate remain the same whether the diffusion of solute species is intrinsic or cross diffusive.

Potassium-Based Dual-Ion Batteries Operating at -60 °C Enabled By Co-Intercalation Anode Chemistry.

Battery performance at subzero is restricted by sluggish interfacial kinetics. To resolve this issue, potassium-based dual-ion batteries (K-DIBs) based on the polytriphenylamine (PTPAn) cathode with anion storage chemistry and the hydrogen titanate (HTO) anode with K+ /solvent co-intercalation mechanism are constructed. Both the PTPAn cathode and the HTO anode do not undergo the desolvation process, which can effectively accelerate the interfacial kinetics at subzero. As revealed by theoretical calculations and experimental analysis, the strong K+ /solvent binding energy in the dilute electrolyte, the charge shielding effect of the crystal water, and the uniform SEI layer with high content of the flexible organic species synergically promote HTO to undergo K+ /solvent co-intercalation behavior. The special co-intercalation mechanism and anion storage chemistry enable HTO||PTPAn K-DIBs with superior rate performance and cycle durability, maintaining a capacity retention of 94.1% after 6000 cycles at -40 °C and 91% after 1000 cycles at -60 °C. These results provide a step forward for achieving high-performance energy storage devices at low temperatures.

Tuning the pH value of electrospinning precursor to synthesize Fe2O3/MoO2/Fe2(MoO4)3 as anode for lithium-ion batteries to boost the reaction kinetics and energy/power density performance

In this work, a simple strategy for the synthesis of Fe2O3/MoO2/Fe2(MoO4)3 anode material was proposed, which controls the surface tension and viscosity of electrospinning precursor by adjusting its pH value, and optimizes the structure and morphology of the product. Compared with the Fe2(MoO4)3, the Fe2O3/MoO2/Fe2(MoO4)3 heterostructure not only effectively reduces the deactivation of the electrode material, but also increases the insertion sites of lithium-ions. Meanwhile, the built-in electric field generated near the heterointerface increases the diffusion coefficient of lithium-ions and improves the interfacial reaction kinetics. The sample obtained at a pH value of 1.85 exhibits the best electrochemical performance. The battery maintained a high reversible capacity (1014.2 mAh·g−1) after 480 cycles at 1000 mA·g−1, with an average specific capacity decrease rate of only 0.035 % per cycle. The mechanism of improving reaction kinetics and lithium storage performance by heterostructures has been proposed. Based on the interfaces confined effect of heterostructures and the formation of built-in electric fields, this work provides a strategy to adjust the spinning behavior by changing the pH value of precursors to achieve product structure optimization and electrochemical performance improvement, which will provide strong support for the research of high power/energy densities LIBs.

Functional Roles of N-Terminal Domains in Pullulanase from Human Gut Lactobacillus acidophilus.

Pullulanases are multidomain α-glucan debranching enzymes with one or more N-terminal domains (NTDs) including carbohydrate-binding modules (CBMs) and domains of unknown function (DUFs). To elucidate the roles of NTDs in Lactobacillus acidophilus NCFM pullulanase (LaPul), two truncated variants, Δ41-LaPul (lacking CBM41) and Δ(41+DUFs)-LaPul (lacking CBM41 and two DUFs), were produced recombinantly. LaPul recognized 1.3- and 2.2-fold more enzyme attack-sites on starch granules compared to Δ41-LaPul and Δ(41+DUFs)-LaPul, respectively, as measured by interfacial kinetics. Δ41-LaPul displayed markedly lower affinity for starch granules and β-cyclodextrin (10- and >21-fold, respectively) in comparison to LaPul, showing substrate binding mainly stems from CBM41. Δ(41+DUFs)-LaPul exhibited a 12 °C lower melting temperature than LaPul and Δ41-LaPul, indicating that the DUFs are critical for LaPul stability. Notably, Δ41-LaPul exhibited a 14-fold higher turnover number (kcat) and 9-fold higher Michaelis constant (KM) compared to LaPul, while Δ(41+DUFs)-LaPul's values were close to those of LaPul, possibly due to the exposure of aromatic by truncation.

Boosting Low Temperature Performance of Lithium Ion Batteries at −40°С Using a Binary Surface Coated Li3V2(PO4)3 Cathode Material

AbstractSevere capacity degradation at low temperatures (<−20°С) hampers wide applications of lithium‐ion batteries (LIBs) in consumer electronics and electric vehicles. Existing works are dedicated to electrolyte modification because that electrolyte controls both Li+ transportation and interfacial reaction. However, the efforts on electrolytes are always hard to balance rate performance and low‐temperature capacity due to their high viscosity. Herein, a binary coating layer for Li3V2(PO4)3 cathode material without changing electrolyte formulation is proposed, which significantly improves the high‐rate capability and low‐temperature performance of batteries. YPO4 nanoparticles are in situ formed in the amorphous surface carbon layer under the reaction between Li3V2(PO4)3 and Y(NO3)3 during post‐thermal treatment. The C+YPO4 binary coating reduces the side reactions of Li3V2(PO4)3 at high voltage. In addition, the binary surface coating also improves the interfacial kinetics of the electrode at low temperatures. Benefiting from these advantages, the Li3V2(PO4)3 cathode material can cycle stably at ultra‐high rates up to 50 C. In addition, the capacity retention at −20 and −40 °С are improved to 89.1% and 75.7%, respectively. This binary surface‐coated Li3V2(PO4)3 cathode material shows promising application potential in low‐temperature LIBs.

Coexistence of five domains at single propagating interface in single-crystal Ni[sbnd]Mn[sbnd]Ga shape memory alloy

Coexistence of both austenite and martensite during phase transformation is a common feature of all Shape Memory Alloys (SMAs). The martensite has different variants featuring characteristic deformations rotationally linked to each other due to the symmetries of the austenite parent phase, and the martensite variants can form twins with different mean characteristic deformations. Multiple-domain microstructures (consisting of austenite, martensite twins and individual martensite variants) evolve collectively within an SMA sample during the phase transformation, contributing thus to the material's macroscopic response (e.g., its global deformation). Particularly, the multiple domains can exist at the diffuse austenite-martensite interface nucleating and propagating in a single crystal in certain conditions. This implies an energy barrier for this interfacial structure, influencing the interface kinetics and the driving force (energy dissipation) of the phase transformation. In this paper, we report an experimentally observed interface consisting of five domains (austenite, one martensite variant and three twins) in a Ni–Mn–Ga single-crystal initially consisting of one martensite variant and subjected to a uniaxial thermal gradient. The compatibility analysis (performed from the characteristic strains of the three martensite variants having approximately a tetragonal symmetry) reveals that the five-domain interface is not a perfectly compatible pattern like the basic habit plane (consisting of only one twin compatible with austenite). However, its level of non-compatibility is similar to that of the quite common X-interface (four-domain coexistence) which is observed in many SMAs. Further, the significant effects of the thermal loading path and the material initial state (the initial martensite variant) on the domain pattern formation are demonstrated and analyzed. The experimental observation and the theoretical analysis of the domain patterns can provide hints to better understand diffuse interface kinetics and phase transformation hysteresis.

Ion recognition enables fast Mg–Cl bond dissociation kinetics and better Mg plating/stripping reversibility

Rechargeable Mg-metal batteries hold considerable promise for renewable energy storage and utilization. However, the Mg stripping/plating processes suffer from sluggish ion pairs dissociation kinetics, resulting in poor rate and cycle properties. In this work, an efficient skeleton host containing dissimilar coupling elements with varied electronegativity has been designed to promote interfacial reaction kinetics by accelerating the Mg–Cl bond dissociation process. As a proof-of-concept prototype, the N/O-doped cobalt nanoparticles embedded in carbonaceous polyhedrons has been synthesized via facile high temperature annealing of zeolitic imidazolate framework-67 (ZIF-67). The exposed electron-rich N/O sites and electron-deficient Co sites can regulate the adsorbing structure configuration of [Mg-Cl]+ complex ions by selectively bonding with the Mg2+ and Cl– through chemical coordination linkage, respectively. The elongated bond length from 2.596 Å to 2.679 Å and the weakened bond strength are beneficial for the complex ions dissociation, leading to better charge transfer kinetics. In addition, the better magnesiophilic property accompanied by the conductive and porous permeable three-dimensional architecture realizes the homogeneous electrodeposition of Mg and improved electrode kinetics. The decreased overpotential has been verified in both magnesium organohaloaluminates electrolyte (from 290 mV to 189 mV) and conventional Mg(TFSI)2-based electrolyte (from 600 mV to 200 mV). The designed skeleton host also exhibits excellent long cycle lifespan above 2300 h and extra-high average Coulombic efficiency of 99.65 % within 700 cycles. The accelerated bond splitting strategy enables improved metal-anode reversibility, which is also insightful to high concentrated or other electrolyte systems that contain abundant ion pairs or aggregates.

Enhanced hydrogen evolution performance of Co/CoP in electrolysis of water by interfacial regulation of crystal plane orientation

Modulating the heterojunction interface is an effective way to improve the electrocatalytic efficiency of water electrolysis, and the metal centers with preferred crystal plane orientation offer the potential to enhance the interfacial charge transfer and electrode reaction kinetics. In this study, a Co/CoP modified hydrogen evolution electrode with selective exposure of the metal-centered Co(002) crystal face was prepared using a one-step electrodeposition method by adjusting the P/Co molar ratio. Results demonstrate that the preferential orientation of Co(002) crystal face in Co/CoP leads to an increased electrochemical active surface area, significantly reduced interfacial impedance and Tafel slope. Moreover, it brings the d-band center closer to the Fermi level, which is thermodynamically favorable for hydrogen evolution reaction (HER). Under optimized conditions, Co/CoP exhibits overpotentials of 85 mV and 183 mV at 10 mA cm−2 and 100 mA cm−2, respectively. After long-term and cyclic stability tests, no significant activity decay is observed, demonstrating excellent hydrogen evolution activity and cyclic stability.

Regulated Ion‐Conductive Electrode–Electrolyte Interface by In Situ Gelation for Stable Zinc Metal Anode

AbstractDendritic growth and severe side reactions remain challenging problems for advancing aqueous zinc‐ion batteries. Those critical issues are closely related to the interfacial chemistry, solvation structure, and transportation kinetics of zinc ions. Herein, a regulated ion‐conductive electrode–electrolyte interface (PVA‐Zn(CF3SO3)2‐Si3N4, denoted as PZS) on Zn metal has been in situ constructed, which simultaneously solves the above‐mentioned issues. PZS can effectively accelerate ion transportation and extrude interfacial water, thus endowing dendrite‐free Zn deposition and eliminating side reactions. Benefiting from these features, the PZS‐Zn exhibits stable and reversible Zn stripping/plating with an ultralong cycling life of 3800 h, and an ultrahigh Coulombi efficiency of 99.8%. The full cell paired with the NH4V4O10 cathode runs stably over 1000 cycles at 5 A g−1 with near 100% capacity retention and is demonstrated to cycle up to 200 times along with 71.94% capacity retention in a practical cathode‐anode coupling configuration pouch cell. With this interfacial design, the assembled zinc batteries display excellent cycling stability, paving a practical way for aqueous Zn‐storage systems.

Construction of an ultra-stable mixed conductive layer to stabilize the solid-state electrolyte/Na interface by in-situ interface chemistry

The quest for high energy density, essentially safe, and cost-effective energy storing systems is powering the evolution of solid-state sodium metal batteries (SSSMBs). However, insufficient Na/solid-state electrolyte (SSE) interface contact leads to the formation of sodium dendrites, causing premature cell failure and safety issues that limit their practical application. Here, a novel ultra-stable mixed conductive layer (MCL) composed of Na15Sn4 and NaF is introduced at the Na|Na3Zr2Si2PO12 (NZSP) interface through in-situ interface chemistry. Such an MCL not only enables the transformation of the NZSP surface from sodiophobic to sodiophilic to achieve intimate contact with Na but also homogenizes the Na+ flux without dendritic sodium. Benefiting from the construction of the multifunctional interface, a high critical current density (CCD) of 1.3 mA cm−2 and an exceptionally long cycle life of 6000 h at 0.3 mA cm−2 are achieved for the Na|SnF2@NZSP|Na cell at room temperature (RT). Furthermore, the Na|SnF2@NZSP|Na3V2(PO4)3 full cell shows excellent cycling performance (91 % of maintained capacity for over 500 cycles at 1 C) and rate capability (101.4 mAh/g at 5 C) at RT. This work presents a validated method for the coordinated regulation of interfacial transfer kinetics and inhibition of sodium dendrite growth.

Organic-inorganic p-type PEDOT:PSS/CuO/MoS2 photocathode with in-built antipodal photogenerated holes and electrons transfer pathways for efficient solar-driven photoelectrochemical water splitting

Organic PEDOT:PSS thin film and n-type MoS2 flakes were incorporated on CuO photocathode as the underlying layer and surface co-catalysts, respectively, establishing a rationally-designed novel integrated structure of PEDOT:PSS/CuO/MoS2. The organic-inorganic interface of PEDOT:PSS/CuO effectively shuttles photogenerated holes towards the FTO/PEDOT:PSS junction. Furthermore, the surface MoS2 co-catalysts form a p-n junction with CuO, which accelerates the transport of photogenerated electrons towards the photocathode/electrolyte junction, in addition to providing more reactive sites for the H2 evolution reaction. These synergistically formed antipodal charge transfer pathways have led to improved charge separation, rapid interfacial charge transfer kinetics and impeded electron-hole recombination in the PEDOT:PSS/CuO/MoS2 photocathode, which can achieve a photocurrent density of – 2.26 mA/cm2 at −0.6 V vs Ag/AgCl (2.1 times higher than that of the bare CuO photocathode). Analytical characterisations, electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS), also provide supporting evidence for its dramatically enhanced PEC water splitting performance.

Phase regulation enabling dense polymer-based composite electrolytes for solid-state lithium metal batteries

Solid polymer electrolytes with large-scale processability and interfacial compatibility are promising candidates for solid-state lithium metal batteries. Among various systems, poly(vinylidene fluoride)-based polymer electrolytes with residual solvent are appealing for room-temperature battery operations. However, their porous structure and limited ionic conductivity hinder practical application. Herein, we propose a phase regulation strategy to disrupt the symmetry of poly(vinylidene fluoride) chains and obtain the dense composite electrolyte through the incorporation of MoSe2 sheets. The electrolyte with high dielectric constant can optimize the solvation structures to achieve high ionic conductivity and low activation energy. The in-situ reactions between MoSe2 and Li metal generate Li2Se fast conductor in solid electrolyte interphase, which improves the Coulombic efficiency and interfacial kinetics. The solid-state Li||Li cells achieve robust cycling at 1 mA cm−2, and the Li||LiNi0.8Co0.1Mn0.1O2 full cells show practical performance at high rate (3C), high loading (2.6 mAh cm−2) and in pouch cell.

Kinetic partitioning of trace cations between zoned clinopyroxene and a variably cooled-decompressed alkali basalt: Thermodynamic considerations on lattice strain and electrostatic energies of substitution

We present kinetic partitioning data for trace cations measured in zoned clinopyroxene crystals obtained from a variably cooled and decompressed olivine basalt erupted at Mt. Etna volcano in Italy. Supersaturation effects and compositional heterogeneities at the interface melt lead to the development of sector zoning, concentric zoning, and patchy zoning in clinopyroxene crystals. Apparent partition coefficients between compositionally different growth layers and adjacent melts (Di) for isovalent groups of trace elements are tested for internal consistency on the thermodynamic basis of lattice strain (ΔGstrain) and electrostatic (ΔGelec) energies of substitutions. The excess energy of partitioning (ΔGpartitioning) for trace cations in zoned crystals accounts for a kinetic incorporation control leading to large enthalpic effects through distortion of the lattice and changes in the electrostatic forces. ΔGpartitioning depends upon the complementary relationship between ΔGstrain and ΔGelec, which is the most appropriate thermodynamic description for the accommodation of rare earth elements and high field strength elements in the lattice site of zoned crystals. Polyhedral sectors, skeletal forms, and overgrowth zones have Di values settled by the number of charge-balanced and -imbalanced configurations taking place in the lattice site as a function of aluminium in tetrahedral coordination, and crystal structural changes produced by heterovalent cation substitutions. In an energetically unstable macroscopic system ruled by cooling and decompression, thermodynamic requirements for the crystallochemical control of Di encompass the attainment of local equilibrium at the crystal-melt interface via the establishment of small-volume reaction kinetics. The requisite of local interface equilibrium is however susceptible to the anisotropic growth velocity of each specific clinopyroxene surface, thereby giving reason to different energetic properties of the crystallographic site. This axiomatic control requires that transition metal cations partition also in consideration of electronic effects related to the crystal field stabilization energy. The overriding implication is that Di values for trace cations having different size, charge, and electronic configuration serve as sensitive probes of the different crystal growth mechanisms, surface incorporation sites, and arrangements of atoms at the lattice-scale. In this perspective, fractional crystallization modeling of 2011–2013 bulk rock data from lava fountains indicates that the compositional evolution of magmas erupted at Mt. Etna cannot be described by a unique equilibrium value of Di for a given clinopyroxene-melt interface. The leverage of interface kinetics is distinctively dominant along the subvolcanic plumbing system, thereby requiring that values of Di differ for structurally and compositionally distinct zones in clinopyroxene phenocrysts. To successfully interpret the trace element signature of Etnean magmas, the archetypal constancy of partition coefficient at bulk thermodynamic equilibrium must be in some measure reappraised in favor of the establishment of a local interface equilibrium upon highly dynamic crystallization and growth conditions.

Single‐molecule fluorescence microscopy for imaging chemical reactions: Recent progress and future opportunities for advancing polymer systems

AbstractSingle‐molecule fluorescence (smFL) imaging techniques have evolved greatly over the past two decades to encompass the ability to monitor chemical reactions, providing unique advantages of non‐invasive sample preparation and characterization, labeling specificity, and high spatial and temporal resolutions. This work summarizes the recent progress in this important area by first providing a brief overview of different smFL techniques, including their common optical setups and working principles. We then introduce recent developments of smFL to characterize various model chemical reaction systems, such as biochemical synthesis, catalyzed systems, and nanomaterial assembly. Furthermore, several representative areas of using smFL to understand polymer reactions are discussed, including understanding interfacial phenomenon and polymerization kinetics, as well as characterizing electrochemical reactions. We also highlight the outlook of this exciting field and potential opportunities for further development and application of smFL to enable advances in polymer chemistry and physics.

Probing nanopore surface chemistry through real-time measurements of nanopore conductance response to pH changes.

We developed a flow cell apparatus and method for streamlined, real-time measurements of nanopore conductance (G) in response to pH changes. By time-resolving the measurements of interfacial kinetics, we were able to probe nanopore surface coating presence and properties more thoroughly than in our previous work. Nanopores have emerged as a prominent tool for single-molecule sensing, characterization, and sequencing of DNA, proteins, and carbohydrates. Nanopore surface chemistry affects analyte passage, signal characteristics, and sensor lifetime through a range of electrostatic, electrokinetic, and chemical phenomena, and optimizing nanopore surface chemistry has become increasingly important. Our work makes nanopore surface chemistry characterizations more accessible as a complement to routine single-pH conductance measurements used to infer nanopore size. We detail the design and operation of the apparatus and discuss the trends in G and capacitance. Characteristic G vs pH curves matching those obtained in previous work could be obtained with the addition of time-resolved interfacial kinetic information. We characterized native and chemically functionalized (carboxylated) silicon nitride (SiNx) nanopores, illustrating how the method can inform of thin film compositions, interfacial kinetics, and nanoscale chemical phenomena.

Diffusion-Reaction-Deformation Coupled Modeling of Large-Deformed Germanium Thin Film Anodes

Germanium is known as a high-capacity material that reversibly stores large amounts of lithium, whereas the inevitable volume changes lead to mechanical failures and unstable reaction interfaces. According to the finite deformation theory, we establish a theoretical framework to capture the viscoplastic flow and the interfacial transfer kinetics during lithiation and delithiation under coupled diffusion-reaction-deformation environments. Many microcracks on the surface of germanium electrodes are observed by previous experiments, and we take this effect into consideration by associating the parameters of Li-Ge alloy with the degree of lithiation, such as the concentration-dependent elasticity modulus and yield stress. Subsequently, the framework is used to calculate the mechanical and electrochemical response of thin film electrodes during charge and discharge under the rigid substrate constraint. The results suggest that charge rate and electrode thickness determine the performance of thin film battery, which is in accordance with the experimentally observed phenomenon. The Cauchy stress in the thin film electrode is also subject to the effect of the inhomogeneous spatial distribution of stress, and the stress drop at the ends of the electrodes is the main source of material fracture failure.

Revealing the Electrochemical Kinetics of Electrolytes in Nanosized LiFePO4 Electrodes

Lithium-ion battery rate performance is ultimately limited by the electrolyte, yet the behaviors of electrolytes during high-rate (dis)charge remain elusive to electrochemical measurement. Herein, we develop and study a nanosized LiFePO4 model system in which the electrolyte completely controls the electrochemical kinetics of the porous electrode. Impedance spectroscopy, cyclic voltammetry, and rate performance testing prove that ion transport in the electrolyte is the sole rate-limiting process, even in thin electrodes. A novel pseudo-steady-state extrapolation (S3E) method for Tafel analysis shows that LiFePO4 obeys Butler-Volmer kinetics with a transfer coefficient of 3. The combination of these unexpectedly rapid interfacial kinetics and an activation barrier for phase transformation causes extreme reaction heterogeneity, which manifests as a moving reaction zone. Resistance versus capacity analysis enables direct measurement of electrolyte resistance growth during high-rate (dis)charge, revealing how the interaction between concentration polarization and a moving reaction zone controls electrolyte rate performance in LiFePO4 electrodes. This work elucidates the profound impacts of the electrolyte on electrochemical measurements in porous battery electrodes: when the active material is not rate limiting, it is impossible to directly measure the intrinsic kinetics of the active material, but conversely, it becomes possible to directly measure the kinetics of the electrolyte.

Boosting interfacial kinetics in extremely fast rechargeable Li-ion batteries with linear carbonate-based, LiPF6-concentrated electrolyte

Amidst the surging demand for battery-powered automobiles, it is crucial to tackle the safety risks of Li plating triggered by high cell polarization to achieve extremely fast charging (XFC) of Li-ion batteries. This study explores the impact of Li+ desolvation and solid-electrolyte interphase (SEI) chemistry on cell polarizations by utilizing linear carbonate (LC)-based, LiPF6-concentrated electrolytes (LPCEs). In the LC family, dimethyl carbonate (DMC) is thermodynamically preferred to facilitate desolvation kinetics, thereby lowering the charge-transfer barrier at the graphite anode. For effective graphite passivation and faster Li+ diffusion crossing the SEI, fluoroethylene carbonate (FEC) can help build up a thin and fluorinated SEI and reinforce the XFC cycling stability of graphite||NMC622 full cells (3.0 mAh cm−2; N/P ratio = 1.1), exhibiting 94.3% capacity retention over 500 cycles under a 10-min charging condition. The excellent XFC performance is practically validated using a 1.2-Ah pouch cell, demonstrating three times higher capacity retention over 200 cycles while suppressing Li plating-triggered cell swelling compared to conventional electrolytes. Unraveling the cell polarization governed by electrolyte chemistry provides valuable insights regarding future electrolyte designs for improving the XFC capabilities of Li-ion batteries.

Synergizing Spatial Confinement and Dual-Metal Catalysis to Boost Sulfur Kinetics in Lithium-Sulfur Batteries.

Sluggish kinetics and parasitic shuttling reactions severely impede lithium-sulfur (Li-S) battery operation; resolving these issues c ould enhance the capacity retention and cyclability of Li-S cells. Therefore, an effective strategy featuring core-shell-structured Co/Ni bimetal-doped metal-organic framework (MOF)/sulfur nanoparticles is reported herein for addressing these problems; this approach offers unprecedented spatial confinement and abundant catalytic sites by encapsulating sulfur within an ordered architecture. The protective shells exhibit long-term stability, ion screening, high lithium-polysulfide adsorption capability, and decent multistep catalytic conversion. Additionally, the delocalized electrons of the MOF endow the cathodes with superior electron/lithium-ion transfer ability. Via multiple physicochemical and theoretical analysis, the resulting synergistic interactions are proved to significantly promote interfacial charge-transfer kinetics, facilitate sulfur conversion dynamics, and inhibit shuttling. The assembled Li-S batteries deliver a stable, highly reversible capacity with marginal decay (0.075% per cycle) for 400 cycles at 0.2C, a pouch-cell areal capacity of 3.8 mAh cm-2 for 200 cycles under a high sulfur loading, as well as remarkably improved pouch-cell performance. This article is protected by copyright. All rights reserved.