Diffusion Channels Research Articles

Highly Stable Aqueous Zn‐Ion Batteries Achieved by Suppressing the Active Component Loss in Vanadium‐Based Cathode

AbstractAqueous zinc–ion batteries (AZIBs) hold significant promise for large‐scale energy storage due to their inherent safety and environmental benefits. However, their practical application is often limited by rapid capacity loss from the dissolution of active cathode materials. Here, an effective strategy is proposed to suppress the active component loss by doping high‐valence Sn4+ in V3O7·H2O (Sn–V3O7·H2O) cathode material to achieve highly stable AZIBs. An impressive capacity retention of 89.3% over 6000 cycles at 5.0 A g−1 and a high specific capacity of 408 mAh g−1 at 0.1 A g−1 are attained. The Sn4+ doping thermodynamically lowers the formation energy of Sn–V3O7·H2O and increases the dissolution energy of VO2+ ions, thereby reinforcing the structural stability and suppressing the vanadium dissolution. Besides, Sn4+ doping enhances electrical conductivity and broadens Zn2+ diffusion channels, significantly accelerating Zn2+ intercalation and deintercalation kinetics. The experimental results are integrated with mechanism analysis and density functional theory calculation to elucidate the dissolution dynamics of V‐based cathodes, and employ X‐ray absorption spectroscopy to reveal the local electronic structures and chemical valences of vanadium during charge/discharge processes, thereby providing comprehensive insights into high‐performance cathode materials for AZIBs.

Vertically Aligned Ultrathin CoNi-LDH@NiS@MXCF Core-Shell Heterostructure for Flexible Supercapacitor Electrodes and Oxygen Evolution Reaction.

A multilayer core-shell heterostructure with CoNi-LDH as the core and NiS nanosheets as the shell is deposited on MXene-coated carbon nanofibers by electrospinning and electrochemical deposition. This unique structure not only combines highly conductive and hydrophilic one-dimensional carbon nanofibers but also exposes abundant two-dimensional reactive sites and multiple ion diffusion channels to maximize material utilization, enhance electron transfer kinetics, accelerate Faraday reaction, high capacitance and strong stability. The CNNS@MXCF electrode exhibits outstanding electrochemical characteristics, including a capacity of 1441.8 F g-1 at a current density of 1 A g-1 and excellent cycling stability. The CNNS@MXCF//VN@MXCF device shows a high energy density of 84.4 Wh kg-1 at 0.8 kW kg-1 power density, with nearly 92% capacitance retention after 10,000 cycles (30 A g-1). In addition, the oxygen evolution reaction (OER) shows a small overpotential of 128 mV, confirming the versatility and large potential of the materials and strategy.

Probing a solid electrolyte interphase layer with sub-nanometer pores using redox mediators

The solid electrolyte interphase (SEI) layer is crucial for lithium-ion batteries and has a significant impact on the electrochemical performance of negative electrodes, particularly for conversion-type materials with large volume changes and metallic lithium anode. However, the SEI layer has not yet been well understood. In this work, we used redox mediators of various sizes to probe the SEI layer that formed in carbonate-based electrolytes. The SEI layer has diffusion channels that allow the mediators smaller than benzoquinone (5.7 Å) to pass, suggesting that lithium ions have to partially de-solvate to pass through. Additionally, due to partial desolvation, the diffusion coefficient in the diffusion channels was higher than that in the bulk electrolytes. Both lithium salts and solvents influenced the size and areal density of channels. Herein, we aim to enhance comprehension of SEI structure and provide a method to study porous SEI layers using mediators, which can be extended to other electrochemical systems.

Tribo-oxidation mechanism of gradient nanostructured Inconel 625 alloy during high-temperature wear

The tribo-oxidation layer is typically formed at the contact interface of high temperature wear, which exhibits a significant effect on the friction behavior of gradient nanostructured (GNS) materials. This study systematically investigated the wear resistance, near-surface microstructure, and compositional changes of ultra-thick GNS Inconel 625 alloy subjected to surface mechanical rolling treatment (SMRT) under high-temperature sliding wear conditions. The experimental results indicated that as the temperature increased to 500 °C, a tribo-oxidation layer was formed on the surface of the GNS sample, thereby resulting in an abnormal increase in the coefficient of friction (COF) and a rapid decrease in the wear rate. The gradient nanostructures facilitated oxidation diffusion channels, promoting the formation of a protective Cr2O3 film and spinel oxides, reducing the wear rate. At lower temperatures, a rapidly formed Cr2O3 film shielded the matrix, forming a tribo-oxidation layer composed of Cr2O3 and nickel. At 800 °C, the tribo-oxidation layer exhibited complex structures, including glaze, spinel oxide, Cr2O3, and Cr2O3/Ni mixed layers. This complexity was attributable to the oxidation diffusion rate of the gradient nanostructures and tribo-oxide layers. The findings not only elucidated the tribo-oxidation mechanism of GNS nickel-based superalloys but also offered valuable insights for designing wear-resistant materials.

In-situ growth of series-connected CoNi2S4 hollow nanocages strung by carbon nanotubes for high-performance hybrid supercapacitors

For supercapacitors (SCs), there is an urgent need to develop positive materials with excellent electrochemical performance. In this work, in-situ growth of series-connected CoNi2S4 hollow nanocages derived from zeolitic imidazolate framework-67 (ZIF-67) and strung by carboxylated carbon nanotubes (C-CNTs) were successfully synthesized through a two-step ordered ion etching/exchange procedure. The special connection structure and synergistic effect between CoNi2S4 nanocages and C-CNTs greatly improve the electrochemical performance of the hybrid (CoNi2S4/C-CNTs), in which porous CoNi2S4 hollow nanocages offer electrochemical active sites and fast ion diffusion channels, while C-CNTs provide electron transport paths. The optimized hybrid, CoNi2S4/C-CNTs20, exhibits excellent electrochemical performance with a high specific capacity (1314.6C g−1 at 1 A g−1) and an impressive rate capability (72.1 % retention at 20 A g−1). Furthermore, the hybrid supercapacitor (HSC) using CoNi2S4/C-CNTs20 and active rice husk carbon (ARHC) as the positive and negative electrodes, respectively, demonstrates an outstanding energy density of 47.9 Wh kg−1 at a power density of 800 W kg−1 and remarkable cycling stability of 90 % at 5 A g−1 after 8500 cycles. Our work will open up a brand-new strategy to oriented design electrode materials for various energy storage devices.

Perovskiet-like BaZrO3 nanocatalyst with rich oxygen vacancies on boosting hydrogen storage property of MgH2

Magnesium hydride (MgH2) as a promising solid hydrogen syorage material has been extensively researched. but the higher separating temperature and sluggish kinetics hinder its large-scale practical application. To solve this problem, a BaZrO3 nanocatalyst with abundant oxygen vancies is manuscripted, exerts significant improvement to the hydrogen storage performance of MgH2. Impressively, the onset dehydrogenation temperature of MgH2-10 wt% BaZrO3-Ov composite is reduced markedly from 390 °C(for pure MgH2) to 260 °C. Additionally, the composite can discharge 4.22 wt% H2 with 10 min at 275 °C and a total dehydrogenation amouut of 5.88 wt% is achieved at 300 °C. For hydrogen absorption, the composite can rapidly recharge hydrogen at a low temperature of 150 °C and approximately 5.08 wt% H2 can be absorbed at 275 °C within 10 min. The dehydrogenation activation energy of BaZrO3-Ov-added MgH2 is as low as 92.61 kJ mol−1 compared to pure MgH2 (164.78 kJ mol−1). Meantime, the composite presents unexceptionable reversible kinetic performance with a retention rate of 97.35 % after 10 cycles. The excellent catalytic effects can be attributed to the in-situ generation of ZrO2-Ov, BaO-Ov and ZrH2 from BaZrO3-Ov during the first de-/rehydrogenation cycle, which function as nanosized active sites on MgH2 matrix to accelerate electron transfer and provide abundant hydrogen diffusion channels. Density functional theory calculations results verify that the Mg–H length and dehydrogenation energy barrier are ameliorated through BaZrO3-Ov. This work provides a unique perspective on modification MgH2 by perovskiet-like BaZrO3-Ov nanocatalyst.

Effects of layered walnut NiS@NTA on hydrogen storage performance of MgH2

To investigate the effects of NiS concentration in NiS/C composites on catalytic performance and hydrogen storage performance of MgH2 particles, we synthesized nitrilotriacetic acid (NTA) chelating agent–derived composites with various NiS proportions via a hydrothermal process, labeled as NiS@NTAx (x = 0.065, 0.078, 0.091, 0.107, and 0.119, respectively). The composites exhibited a layered walnut morphology. After ball milling 5 wt% NiS@NTAx with MgH2, the resulting MgH2–5 wt%NiS@NTA0.078 composite (NiS: 83.5 wt% and C: 16.5 wt%) demonstrated the excellent performance, which could absorb 3.0 wt% of H2 at 353 K and released 3.5 wt% of H2 at 573 K within 60 min, and the intital dehydrogenation temperature was decreased to 508 K.. Undergoing 20 hydrogen absorption/desorption cycles, the composite maintained hydrogenation/dehydrogenation capacity retention rates of 97.4 % and 96.4 % with activation energies of 24.1 and 67.3kJ/mol, respectively. The in situ formation of MgS and Mg2Ni catalysts promoted electron transfer during Mg and MgH2 transformation. Moreover, as a prominent transition metal, Ni Ni element reacts with the hydrogen absorption and desorption of Mg to form Mg2Ni/Mg2NiH4, which is like a “hydrogen pump” and provides additional hydrogen diffusion channels due to more interfaces. MgS additionally functioned as a catalyst in the reaction system, improving overall reaction kinetics. Carbon additives reduced particle agglomeration, stabilized the particle size, and moderately improved hydrogen diffusion during hydrogen absorption/desorption cycles. The in situ adjustment of NiS concentration in NiS/C samples and its impacts on MgH2 hydrogenation/dehydrogenation offer insights for designing high-performance sulfide catalysts.

Ordered and Expanded Li Ion Channels for Dendrite‐Free and Fast Kinetics Lithium–Sulfur Battery

AbstractThe uncontrolled polysulfide shuttling and lithium dendrite growth greatly impede the practical implementation of Li–S batteries. These issues can be alleviated by constructing an artificial layer that immobilizes soluble polysulfides and regulates Li+ flux. Here, a layer‐expanded lithium montmorillonite is fabricated through molecular intercalation to serve as a dual regulator for Li–S batteries. The lithiophilic montmorillonite, with its ordered and expanded Li+ diffusion channels, exhibits a high transference number, and promotes homogeneous Li deposition. Additionally, its moderate adsorption of polysulfides, combined with favorable Li diffusion behavior, enhanced the redox kinetics of sulfur species. This unique structure enables a prolonged lifespan of 1000 cycles at 0.5C with a low capacity decay of 0.04% per cycle for practical Li–S batteries.

Chromite Pellet Prereduction by Methane‐Containing Gas: Influence Factors and Consolidation Mechanism

Prereduction process of chromite is an effective method for saving energy and reducing emissions during ferrochrome alloy production. This study investigates the factors affecting the reduction and strength levels of chromite pellets reduced in a CH4–H2 atmosphere. Thermodynamic calculations indicate that carbon from methane pyrolysis is highly active, and chromium oxide can be converted to metal chromium and carbide at lower temperature of 1100 °C. The experimental results show that extending the reduction time can increase the pellet metallization rate without sacrificing strength at 1100 °C in 10% CH4. As the reaction progressed, the carbon from methane cracking diffused into the pellet through the metallic iron, creating observable diffusion channels. Continuous methane input further facilitates this mechanism, leading to iron carbide precipitation and ultimately compromising the pellet strength. The consolidation mechanism of pellets in CH4–H2 = 10:90 atmosphere is analyzed using X‐ray diffraction, scanning electron microscopy‐energy dispersive X‐ray spectroscopy, and chemical analysis. The consolidation process of the pellets can be divided into four stages—namely, liquid phase formation, phase transition, strengthening, and carbonization stages.

The role of Nb in enhancing the corrosion resistance of U-Nb alloy to hydrogen

The corrosion resistance of uranium to hydrogen has been significantly enhanced by niobium addition while its mechanism remains unknown. To better understanding the underlying effect of niobium addition, behaviours of hydrogen in α-U, dilute U-Nb alloy and concentrated U-Nb alloy have been systematically explored by ab-initio calculations and experimental observations. Our findings suggest that Nb atoms play distinct roles in the dilute and concentrated single-phase U-Nb alloys, shifting from hydrogen traps to rapid hydrogen diffusion channels. Moreover, the dominant mechanisms enhancing hydrogen corrosion resistance differ between dilute and concentrated U-Nb alloys.

Synthesis and Characterisation of iron doped manganese oxides for thermal energy storage

Iron-doped manganese oxides were synthesized using a co-precipitation method and thermodynamically characterized to demonstrate their potential as a thermochemical energy storage medium. Thermochemical energy storage, via chemical bonds that employ reversible redox reactions, is a promising approach to tackle solar thermal energy storage. Hysteresis loops observed confirm that the pore network consisted of mesopores that were not filled with pore condensate, and the narrow loop indicates a narrow size distribution. Barrett-Joyner-Halenda (BJH) studies of all the synthesized materials showed that they have a high mesoporous and specific area, essential for supplying reduced diffusion channels over the Mn oxides, Good conductivity through electron transfer, with the presence of active sites allow the study thermochemical approaches. The BJH studies showed the material MnOFe2 (2.5:1) to have a higher pore area, which is effective in the adsorption process of the material.

Vertical spillovers and the energy intensity of European industries

The prior literature has argued that inter-sectoral supply chain links provide an important channel for technology diffusion and productivity spillovers across industries, but whether such vertical spillovers influence industrial energy use has remained unexplored thus far. This study analyzes how the energy intensity of European industries is affected by vertical technology and energy productivity spillovers along the industrial supply chain. The analysis combines international input-output tables, energy use and patent data. Panel data from 2000 to 2014 for 27 industries in 29 countries is analyzed using panel fixed effects and instrumental variable estimation methods. The findings reveal that supply-use links channel significant vertical spillovers that promote a decline in energy intensity in downstream industries. These spillovers appear to be more strongly associated with overall energy intensity changes in upstream industries and, to some degree, with patented green innovations in upstream industries.

Orientation-Selective Memory Switching in Quasi-1D NbSe3 Neuromorphic Device for Omnibearing Motion Detection.

Intelligent neuromorphic hardware holds considerable promise in addressing the growing demand for massive real-time data processing in edge computing. Resistive switching materials with intrinsic anisotropy and a compact design of non-volatile memory devices with the capability of handling spatiotemporally reconstructed data is crucial to perform sophisticated tasks in complex application scenarios. In this study, an anisotropic resistive switching cell with a planar configuration based on lithiated NbSe3 nanosheets is demonstrated. Benefitting from the highly aligned diffusive channel associated with a quasi-1D van der Waals structure, the memristor patterned along NbSe3 atomic chains presents robust memory switching behavior with superior stability, particularly the low set/reset voltages (0.4V/-0.36V) and extremely small standard deviation (0.041V/0.051V), among the best compared to state-of-the-art devices. More importantly, unlike traditional resistive switching materials, anisotropic ion migration in NbSe3 crystals leads to a high orientation selectivity in the conductance update. Custom-designed neuromorphic hardware contributes to the implementation of omnibearing motion recognition for automatic pilot applications, yielding a high accuracy of 95.9% considering variations. This article presents a new strategy based on NbSe3 crystals to develop a neuromorphic computing system with intelligent application scenarios.

Conceptualizing Surface-Like Diffusion for Ultrafast Ionic Conduction in Solid-State Materials.

Surface-like diffusion is a recently proposed concept to explain the mechanism of ultrafast ionic conduction in high-rate oxide (e. g., niobium oxides and their alloys with TiO2 and WO3) and framework materials (e. g., Prussian blue analogs). This perspective seeks to illustrate the structural origin, theoretical foundation, and experimental evidences of surface-like diffusion. Unlike classical lattice diffusion, which typically involves ionic hopping between adjacent interstitial sites in solids, surface-like diffusion occurs when ions-that are significantly smaller than the interstitials-migrate along the off-center path in the diffusion channel. This mechanism results in an exceptionally low activation energy (Ea) down to 0.2 eV, which is crucial for achieving high-rate performance in electrochemical devices such as lithium-ion and sodium-ion batteries. This concept review also discusses the criteria to identify materials with potential surface-like diffusion and outlines theoretical and experimental tools to capture such phenomenon. Several candidates for further investigation are proposed based on the current understanding of the mechanism.

Electrochemical performance of YMg2Ni9 hydrogen storage electrode alloy in-situ coated with Ni3S2

The YMg2Ni9 hydrogen storage alloy in-situ coated with Ni3S2 was successfully prepared by hydrothermal sulfurization treatment and investigated as the anode material in nickel-metal hydride (Ni-MH) batteries for the first time. Owing to the high electronic conductivity and electrocatalytic activity of Ni3S2 nanoflake coating, the electrochemical performance of the YMg2Ni9 alloy electrode is significantly enhanced. The alloy electrode treated in 0.3 M Na2S solution exhibits the highest discharge capacity of 230.8 mAh/g and superior cycling stability, maintaining a capacity retention rate of 85.1 % after 100 cycles. The increase in the discharge capacity of the electrode is credited to the Ni3S2 coating on the surface of the alloy, which possesses a nanoflake structure, facilitating the surface electrochemical reaction and providing more channels for hydrogen diffusion. In addition, Ni3S2 nanoflakes wrapped around the surface of the alloy can stabilize the reaction interface between the alloy and the electrolyte and slow down the alkali erosion, thus improving the cycle life of the electrode. The present study offers beneficial information for investigating a potential anode material for Ni-MH batteries.

Metal‐Organic Framework‐Derived Elastic Solid Polymer Electrolytes Enabled by Covalent Crosslinking for High‐Performance Lithium Metal Batteries

AbstractThe key issue in utilizing solid polymer electrolytes for high‐energy‐density lithium metal batteries is to balance the conflicting demands of superior processability, adequate ionic conductivity, and mechanical stability. Inspired by molecular structure design, a metal‐organic framework‐derived polyether poly(urethane urea) solid polymer electrolyte (denoted as ePU@H SPE) has been synthesized via a facile polycondensation method involving covalent crosslinking. The reduced crystallinity and numerous polar groups in ePU@H SPEs enhance Li salt dissociation and create efficient Li+ ion diffusion channels, yielding remarkable ionic conductivity (1.48 × 10−4 S cm−1). The polymer backbones, incorporating covalent bonds and dynamic hydrogen bonds, provide superb mechanical strength (5.12 GPa), high toughness (1240%), and excellent resilience, which suppress lithium dendrite growth and buffer electrode volume fluctuations during cycling. Leveraging these attributes, the well‐designed ePU@H SPE enables ultra‐high durability in lithium plating/stripping over 2300 h. Moreover, the integrated LFP|ePU@H|Li batteries, generating delicate electrode/electrolyte interfacial contact, deliver an exceptionally long lifespan (86% retention over 500 cycles at 1 C). Moreover, the LFP|ePU@H|Li pouch cell operates reliably even under severe deformation and external damage. Impressively, the stable cycling performance of full batteries incorporating high‐voltage LCO and high‐capacity S cathodes further verifies the significant potential of advanced ePU@H SPEs for practical applications.

In‐Situ Self‐Respiratory Solid‐to‐Hydrogel Electrolyte Interface Evoked Well‐Distributed Deposition on Zinc Anode for Highly Reversible Zinc‐Ion Batteries

AbstractThe aqueous zinc‐ion batteries (AZIB) have emerged as a promising technology in the realm of electrochemical energy storage. Despite its potential advantages in terms of safety, cost‐effectiveness, and inherent safety, AZIB faces significant challenges. Issues attributed to unsupported thermodynamics and non‐uniform potential distribution and deposition, present formidable obstacles that necessitate resolution. To tackle these challenges, a novel strategy adapting hybrid organic–inorganic in situ derived solid‐to‐hydrogel electrolyte interface (StHEI) has been developed from coordination reactions and self‐respiratory process, establishing uniform diffusion channels by ion bridges and accelerating ion transport. Self‐respiratory pattern of StHEI realized through in situ inorganic component conversion further prolongs the protecting duration, which effectively mitigates corrosion and passivation but enhance the mechanical properties of the StHEI measured through Young's modulus. This novel StHEI promotes well‐distributed potential lines within the Helmholtz regions. Zn2+ are finally induced to deposit and nucleate in a compact, fine, and uniform manner. Asymmetrical batteries assembled with the modified Zn electrode and bare Zn exhibit exceptional stability over 3000 h (1 mA cm−2–0.5 mAh cm−2). The asymmetrical Cu//Zn cell achieved an outstanding average Coulombic efficiency (CE) of 99.6 % over 1200 cycles.

In-Situ Self-Respiratory Solid-to-Hydrogel Electrolyte Interface Evoked Well-Distributed Deposition on Zinc Anode for Highly Reversible Zinc-Ion Batteries.

The aqueous zinc-ion batteries (AZIB) have emerged as a promising technology in the realm of electrochemical energy storage. Despite its potential advantages in terms of safety, cost-effectiveness, and inherent safety, AZIB faces significant challenges. Issues attributed to unsupported thermodynamics and non-uniform potential distribution and deposition, present formidable obstacles that necessitate resolution. To tackle these challenges, a novel strategy adapting hybrid organic-inorganic in situ derived solid-to-hydrogel electrolyte interface (StHEI) has been developed from coordination reactions and self-respiratory process, establishing uniform diffusion channels by ion bridges and accelerating ion transport. Self-respiratory pattern of StHEI realized through in situ inorganic component conversion further prolongs the protecting duration, which effectively mitigates corrosion and passivation but enhance the mechanical properties of the StHEI measured through Young's modulus. This novel StHEI promotes well-distributed potential lines within the Helmholtz regions. Zn2+ are finally induced to deposit and nucleate in a compact, fine, and uniform manner. Asymmetrical batteries assembled with the modified Zn electrode and bare Zn exhibit exceptional stability over 3000 h (1 mA cm-2-0.5 mAh cm-2). The asymmetrical Cu//Zn cell achieved an outstanding average Coulombic efficiency (CE) of 99.6 % over 1200 cycles.

Effect of Synthesis Temperature on Performance of Phenazine-Based Cathode for Sodium Dual-Ion Batteries.

Organic materials have attracted much attention in the field of electrochemical energy storage due to their ecological sustainability, abundant resources and structural designability. However, low electrical conductivity and severe agglomeration of organic materials lead to poor discharge capacity and reaction kinetics in batteries. Herein, the morphology of the phenazine-based organic polymer poly(5,10-diphenylphenazine) (PDPPZ) was modified by varying the synthesis temperature. PDPPZ-165 °C with an exceptional porous structure provides abundant reaction channels for rapid charge transfer and diffusion that improves the reaction kinetics in sodium dual-ion batteries. Therefore, PDPPZ-165 °C cathode possesses excellent rapid charge-discharge capability delivering a specific capacity of 119.2 mAh g-1 at 40 C. Furthermore, a high specific capacity of 124.7 mAh g-1 can be provided even at a high loading of 16 mg cm-2 at 0.5 C with a capacity retention of 86.4 % after 500 cycles. This work could afford new insights for optimizing the performance of organic cathode materials in sodium dual-ion batteries.

Electron Transport and Ion Diffusion in Hydrogen-Bonded Interlayer Cross-Linked Graphene/MXene for Wearable Micro-Sensors.

2D graphene and MXene have attracted much attention in the field of energy storage devices and wearable sensors due to their excellent electrical conductivity and mechanical properties. However, the capacitance of their composites is limited by low electron transport and sluggish ion diffusion due to the lack of electron transport and ion diffusion channels between stacked interlayers. Herein, this work reports the possibility of using disodium terephthalate as an auxiliary conductive bridge to cross-link the interlayer interaction between graphene and MXene from theoretical analysis and experimental verification. The cross-linker with a dicarboxyl group and a conjugated structure forms hydrogen bonds with the hydroxyl groups on the surface of graphene and MXene to provide a pathway for interlayer electron transfer, while inhibiting interlayer stacking and ensuring an effective ion diffusion process. To verify the actual effect of this approach, micro-sensors are assembled by the integration of micro-supercapacitors. The assembled micro-sensors demonstrate real-time monitoring of body movements and temperature signals. This work provides a feasible strategy to promote electron transport and ion diffusion in layered composites to design next-generation multifunctional micro-devices.