Protective Surface Layer Research Articles

Stabilization Strategies of Lithium Metal Anode Toward Dendrite-Free Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered as a most promising rechargeable lithium metal batteries because of their high energy density and low cost. However, the Li-S batteries mainly suffer the capacity decay issue caused by the shutting effect of lithium polysulfides and the safety issues arising from the Li dendrites formation. This review outlines the current issues of Li-S batteries. Furthermore, we comprehensively summarized the challenges encountered by Li anode in Li-S batteries, such as the heterogeneous deposition of the Li anode, the unstable solid electrolyte interface (SEI) layer, and volume expansion. Moreover, research progresses in the stabilization strategies of Li anodes (physical approaches, optimization of electrolyte, surface protection layer, and design of current collector) is discussed in detail. Lastly, the remaining challenges and future research directions of Li metal anode stabilization in Li-S batteries are also present.

Synthesis, Characterization, Theoretical, and evaluation of Eco-Friendly benzimidazolylmethyl-pyrazole carboxylate Schiff Bases corrosion inhibitors for mild steel

In this study, benzimidazolylmethyl-pyrazole carboxylate derivatives were synthesized via a 1,3-dipolar cycloaddition reaction and characterized using IR, HRMS and NMR spectroscopy. Three derivatives, namely ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1-phenyl-1H-pyrazole-3-carboxylate (Ph-BPC), ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro- 1H-benzo[d]imidazol-1-yl)methyl)-1-(p-tolyl)-1H-pyrazole-3-carboxylate (CH3Ph-BPC), and ethyl 1-(4-chlorophenyl)-5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1H-pyrazole-3-carboxylate (ClPh-BPC), were evaluated as corrosion inhibitors for mild steel (MS) in a 1 M HCl solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements revealed high inhibition efficiencies of 98.5 %, 98.2 %, and 97.7 % for ClPh-BPC, Ph-BPC, and CH3Ph-BPC, respectively, at a concentration of 10-4 M. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed the formation of protective surface layers, significantly reducing corrosion rates. Thermodynamic analysis indicated that the adsorption of these inhibitors follows the Langmuir isotherm model with adsorption energies of −50.12 kJ/mol for ClPh-BPC, −50.52 kJ/mol for Ph-BPC, and −51.62 kJ/mol for CH3Ph-BPC, suggesting chemisorption. Computational studies, including Monte Carlo (MC), density functional theory (DFT), and molecular dynamics (MD) simulations, showed strong agreement with experimental results, further validating the adsorption behavior and corrosion inhibition mechanisms of these compounds.

WO2–N co-doped 2D Carbon nanosheets as multifunctional additives for enhancing the electrochemical hydrogen storage performance of Co2B

Co2B, with its high theoretical hydrogen storage capacity, is a potential solid-state hydrogen storage material. However, its poor cycling life limits its practical application. In this work, in order to improve the cycling stability and reversibility of hydrogen absorption and desorption of Co2B, we propose to use WO2–N–C nanosheets as dopants to mix with Co2B, thereby enhancing its practical performance. Two-dimensional tungsten oxide-nitrogen-carbon (WO2–N–C) nanosheets was syntheized via a liquid-phase approach, using a tungstenate-polydopamine precursor followed by thermal treatment. Subsequently, these WO2–N–C nanosheets were compounded with cobalt boride (Co2B) particles through ball milling at various ratios of 1%, 3%, and 5%, which were confirmed by XRD (X-ray diffraction) and SEM (Scanning Electron Microscope) methods. Employing a comprehensive suite of electrochemical analyses, including corrosion potential measurements, polarization curves, step voltammetry, and electrochemical impedance spectroscopy (EIS), we found that the incorporation of WO2–N–C significantly enhances the corrosion resistance and electrochemical activity of Co2B. Furthermore, cyclic life tests revealed that the WO2–N–C-doped Co2B composites exhibit superior discharge capacities and capacity retention rates compared to pristine Co2B. Notably, the 3% WO2–N–C-doped Co2B composite demonstrated the optimal electrochemical performance, achieving a maximum discharge specific capacity of 555 mAh g−1 and maintaining 82% of its initial capacity after 50 cycles. Our findings underscore the dual role of WO2–N–C in not only augmenting the surface electrochemical activity of Co2B but also providing a protective surface layer, thereby enhancing its overall electrochemical performance.

Mechanical properties and corrosion behavior of biodegradable Mg-Cu alloys

Mechanical properties and in vitro corrosion behavior of Mg-Cu alloys in the simulated body fluid solution were investigated. Copper addition led to grain refinement and formation of α–Mg/Mg2Cu eutectics, resulting in the best combination of mechanical properties for the as-cast Mg-0.5Cu alloy, for which the values of the yield stress, ultimate tensile strength, total elongation, and tensile toughness were obtained as 71 MPa, 164 MPa, 5.8%, and 7.5 MJ/m3, respectively. Hot deformation by extrusion led to fine grain sizes via dynamic recrystallization and breaking up the eutectics. Accordingly, the extruded Mg-0.1Cu alloy showed tensile toughness of ∼30 MJ/m3 and good corrosion resistance; while Mg-1.2Cu alloy with a distinct protective surface layer was also considered as a viable alternative for biomedical applications.

Investigations on the Structure, Mechanical Property, Wear and Oxidation Resistances of TiAlSiN Coatings by Tailoring Al/(Al + Ti) Ratios

Previous studies have broadly dealt with TiAlSiN coatings that exhibit promising characteristics as surface protective layers for antiwear and antioxidation applications. In this regard, revealing the correlations among coating composition, structure, and properties is vitally important for developing advanced TiAlSiN coatings. The present work addresses the issue by studying the structure and properties of TiAlSiN coatings by tailoring Al/(Al + Ti) ratios. To this end, TiAlSiN coatings are produced by arc deposition with the Al/(Al + Ti) ratios of 0.31, 0.42, 0.51, and 0.62, respectively. The results show that, when the Al/(Al + Ti) ratio ranges from 0.31 to 0.51, the phase structure is mainly TiN phase, and the hardness, wear resistance and oxidation resistance of the films are increased with the rise in the Al/(Al + Ti) ratio. When the Al/(Al + Ti) ratio reaches 0.62, the oxidation resistance of the coating does not improve significantly, while the mechanical and wear properties of the coating are deceased due to the formation of w‐AlN phase. Therefore, the appropriate Al/(Al + Ti) ratio at 0.51 provides overall improvements including mechanical properties, and wear and oxidation resistances under operation conditions. These findings show that optimizing the Al/(Al + Ti) ratio is a promising way to develop TiAlSiN coatings with advanced structure and properties.

Corrosion behavior and mechanical integrity of Zn-based guided bone generation (GBR) membrane subjected to U-bending deformation

To study the effect of pre-strain on corrosion behavior of pure Zn strip/membranes, the U-bending treatment, immersion and mechanical tests were conducted. The pre-strain accelerated the corrosion rates of both pure Zn strips or membranes with an elevated ratio of 78.02 % (strips), 27.33 % (300 μm), 32.09 % μm/yr (600 μm) and 52.77 % μm/yr (1000 μm). Besides, the finite element simulation results indicated that stress concentration occurred at the maximum deflection sites, leading to the rupture of surface protective layer and formation of micro cracks. Moreover, the applied strain would accelerate the mechanical integrity decay of pure Zn membranes.

Mechanism of Formation of Surface Protective Layer in Heat-Resistant HP40NbTu Alloys during High-Temperature Oxidation

Mechanism of Formation of Surface Protective Layer in Heat-Resistant HP40NbTu Alloys during High-Temperature Oxidation

Lithium borates as a surface protective layer for lithium-manganese spinel

Lithium borates as a surface protective layer for lithium-manganese spinel

Fully carbonate‐electrolyte‐based high‐energy‐density Li–S batteries with solid‐phase conversion

AbstractCarbonate‐electrolyte‐based lithium–sulfur (Li–S) batteries with solid‐phase conversion offer promising safety and scalability, but their reversible capacities are limited. In addition, large‐format pouch cells are paving the way for large‐scale production. This study demonstrates the in situ formation of a solid‐electrolyte interphase (SEI) as a protective layer using vinylene carbonate (VC), highlighting its industrial adaptability. A high reversible capacity is achieved by the lithiated poly‐VC SEI formed inside the cathode particles as a nanoscale ionic conduction path, along with the traditional surface protective layer. Furthermore, the severe dissolution of poly‐VC is mitigated by LiF derived from fluorine ethylene carbonate as a co‐solvent, enabling high rate performance and a long cycle life. A large 8 Ah pouch cell is successfully developed, which shows a high energy density of 400 Wh kg−1 based on the cell weight. This work demonstrates the high performance of large‐scale Li–S batteries with the in situ formation of a protective layer as a scalable technique for future applications.

Improving the Performance of LiNi0.9Co0.05Mn0.05O2 via Atomic Layer Deposition of ZnxOy Coating

AbstractNickel‐rich cathode materials such as LiNi0.9Co0.05Mn0.05O2 (NMC90) have gained attention due to their ability to deliver high energy densities while being cost‐effective for Lithium‐ion battery manufacturing. However, NMC90 cathodes suffer irreversible parasitic reactions such as electrolyte decomposition, severe capacity fading and impedance build‐up upon prolonged cycling. Herein, we synthesize a conformal ultrathin, surface protection layer on NMC90 powder using ZnxOy via atomic layer deposition technique (ZnxOy@NMC90). Prolonged electrochemical investigation of full cells at high discharge rates of 2 C shows that ZnxOy@NMC90 cells yielded ~31 % improvement in discharge capacity compared to pristine NMC90. Furthermore, operando electrochemical mass spectroscopy studies show that the ZnxOy@NMC90 cells have significantly suppressed electrolyte decomposition as compared to pristine NMC90 cells. Post‐cycling electrochemical impedance spectroscopy studies show that the ZnxOy@NMC90 full cells have significantly reduced impedance compared with pristine NMC90 cells. Additionally, post cycling manganese dissolution studies show that ZnxOy@NMC90 cells have greatly enhanced chemo‐mechanical integrity thereby contributing to improved electrochemical performances. Our results underscore the potential of tailored ZnxOy surface coatings on nickel‐rich cathode materials to address critical challenges in advanced energy storage systems, offering promising prospects for the development of high‐energy‐density lithium‐ion batteries.

Enhanced Oxidation Resistance of ZrB2–SiC–WC Composite below 1800 °C

The effect of 3.6 vol% WC addition to ZrB2–20 vol% SiC (ZSW) on oxidation resistance is studied over a broad range of oxidation temperatures, 1000–1800 °C. Non‐WC‐containing samples (ZS) show significant surface damage and degradation during oxidation, losing protective B2O3 and SiO2‐based surface layers and exposing a porous ZrO2 layer and base material for further oxidation. ZSW samples preserve their surface protective layers during oxidation up to 1800 °C while the underlying ZrO2 scale remains dense. The appearance of convection cells on the surface of ZSW samples during oxidation above 1600 °C is reported. This confirms the presence of boron‐rich phases, suppressing oxygen permeation into the material and enhancing oxidation resistance of ZSW samples. During exposure of the samples to 1800 °C for 15 min, ZS and ZSW samples gain 11.1 ± 1.5 and 7.8 ± 0.3 mg cm−2, respectively, due to oxidation. Exposure of the composites for 5 h at 1600 °C results in weight gains of 10.5 and 7.0 mg cm−2 for ZS and ZSW samples, respectively. Cross sections of oxidized samples at 1800 °C show a tight zirconia layer below a glassy surface in ZSW and complete loss of surface glass in ZS, demonstrating the effectiveness of WC addition.

Structure and replication cycle of a virus infecting climate-modulating alga Emiliania huxleyi.

The globally distributed marine alga Emiliania huxleyi has cooling effect on the Earth's climate. The population density of E. huxleyi is restricted by Nucleocytoviricota viruses, including E. huxleyi virus 201 (EhV-201). Despite the impact of E. huxleyi viruses on the climate, there is limited information about their structure and replication. Here, we show that the dsDNA genome inside the EhV-201 virion is protected by an inner membrane, capsid, and outer membrane. EhV-201 virions infect E. huxleyi by using fivefold vertices to bind to and fuse the virus' inner membrane with the cell plasma membrane. Progeny virions assemble in the cytoplasm at the surface of endoplasmic reticulum-derived membrane segments. Genome packaging initiates synchronously with the capsid assembly and completes through an aperture in the forming capsid. The genome-filled capsids acquire an outer membrane by budding into intracellular vesicles. EhV-201 infection induces a loss of surface protective layers from E. huxleyi cells, which enables the continuous release of virions by exocytosis.

Experimental Investigation on the Effects of Mineral Water Composition on the Leaching of Cement-Based Materials.

The common phenomenon observed for concrete in aggressive water is leaching, which involves the dissolution of cement hydration products. Many studies have focused on leaching in demineralised water or acid attacks, but mineral water still deserves further investigation. In most standards, the aggressiveness of a given water body is determined by its pH and not its composition. The effect of the calcium content of the water on degradation is yet to be determined. In this paper, the leaching of Portland cement-based mortar was induced by two types of drinking water with different calcium contents and buffer capacity in controlled conditions. The Langelier saturation index (LSI) was used to describe water aggressiveness based on the calco-carbonic equilibrium. The studied waters had the same pH but LSIs of +0.5 and -1.0 corresponding to scaling with respect to aggressive water; demineralised water was used as a reference. Microstructural damage was checked by TGA and X-ray microtomography. Macroscopic measurements were used to monitor global degradation. The soft water caused a 53% deeper deterioration of the mortar sample than the hard water. Soft water-induced leaching was found to be similar yet slower to leaching via demineralised water (with a mass loss of -2.01% and -2.16% after 200 days, respectively). In contrast, hard water induced strongly time-dependent leaching, and the damage was located close to the surface. The roughness of leached specimens was 18% higher in hard water than in soft water. The formation of calcite on the sample surface not only affects the leaching rate by creating a protective surface layer, but it could also act as a calcium ion pump.

Explosion characteristics of wood dust and its suppression in typical powder-related environments

To reduce the explosion hazard caused by wood dust, the effects of dust concentration and ammonium polyphosphate (APP) on the explosion of wood dust were carried out in a vertical combustion pipeline and the suppression mechanism was revealed. The explosion intensity of the wood dust increased and then decreased with increasing concentration, and the bottom of the pipeline remained bright due to continuous ignition. APP could effectively suppress the propagation of wood dust explosion flame. When the mass fraction of APP was 10%, there was no obvious flame, and the flame pressure dropped by up to 98%. The effect of APP on wood dust pyrolysis was analyzed using TG-DSC, and the explosion products were characterized by physicochemical analysis using EDS. The results showed that APP could improve the stability of the carbon layer on the surface of wood dust particles, and its decomposition products could enhance the thermal shielding and oxygen isolation effects of the particle surface protective layer. In addition, the APP significantly suppressed wood dust explosion by absorbing heat from the reaction zone, capturing and consuming free radicals, and reducing the oxygen concentration per unit volume.

Self-healing polymer materials: Basic concepts and applications

Since the past few decades, the trend of researching self-healing materials such as ceramic, concrete, and self-healing polymer has always been a very hot topic in materials science. Considering polymer self-healing materials (and their composites), several hundred new articles are published yearly. What is the self-healing feature? This is the ability of materials, thanks to some special mechanisms, to self-recover from damage (scratches, cuts...) returning to an almost intact state. This ability is achieved by adding external healing agents (the specialized term is "healing agent"), or based on dynamic interactions between internal components in the material. If in the past, self-healing polymer materials thanks to the addition of foreign materials (extrinsic self-healing) were of interest in development, in recent times, intrinsic self-healing polymer materials (intrinsic self-healing) have been developed and received more attention. Whether self-healing internally or externally, self-healing polymer materials have many applications such as raw materials for manufacturing sensors, electronic components, surface protection layers, and medical implants... With the ability of application, self-healing polymer materials are an area that attracts a large number of research facilities and technology companies around the world.

(Invited) Nanomembrane Coating for Advanced Electrocatalysis

Advanced electrocatalysis that possesses higher selectivity and durability is more and more important for the electrification of chemical processes, which is expected in the renewable energy society in the future. Electrochemical reactions are often determined by the competition between the thermodynamic redox potential and the applied potential. Because the redox potential is characteristic for determining the product, it is often difficult to adjust the selectivity just by surface chemistry. Against this background, surface modification of electrodes is a well-studied field. Surface modification improves membrane functionality and selectivity, resulting in electrocatalysts with higher productivity and selectivity. Surface protective layers are also associated with material durability, as they prevent toxic and harmful substances from approaching the surface and prevent dissolution of the electrode material into the electrolyte. We are investigating the use of "nanomembrane" coatings on electrodes to achieve better selectivity and durability.Electrochemical reduction deposition of ultrathin layers of Cr and Mo on Pt cathodes has been shown to yield O2-tolerant hydrogen-evolving electrodes in the appropriate pH range. Electrochemical measurements indicate that these surface layers act as a membrane film. Many bulky ions and O2 molecules cannot pass through these surface layers, but H2 molecules can, consistent with electrochemical and spectroscopic measurements. First, the electrochemical properties of Pt modified with other elements such as Cr and Mo were investigated and monitored for catalytic activity under different atmospheres. Next, in-operando X-ray absorption spectroscopy (XAS) was used to investigate the working state of the material: electrochemical measurements in H2 and O2 confirmed that the oxygen reduction reaction (ORR) was severely suppressed and the hydrogen evolution reaction (HER) was maintained. XAS results also showed that the oxidation state of Pt can be freely changed by a potential sweep with or without a coating layer. We extended this work to nanofilm coating on oxygen-evolving anodes for water splitting, and succeeded in anodic deposition of a thin Ce layer on Ni-Fe electrodes; the Ce layer not only prevents unwanted ions from reaching the electrode surfaces, but also prevents Fe ions from leaching from the electrodes, thus improving the durability of the electrodes. In this presentation, key findings of these nanomembrane coatings and future prospects for selective and durable electrodes will be discussed.

High cycle fatigue and corrosion behaviors of Mg3Zn/HA biodegradable composite

In this study, the effects of adding sub-micron hydroxyapatite (HA) particles were investigated on high cycle fatigue (HCF) and corrosion behaviors of Mg3Zn magnesium alloy. To this end, the Mg3Zn alloy and Mg3Zn/2.5 wt%HA bio composite were fabricated using mechanical-electromagnetic stir casting method followed by hot extrusion process. The results of the microstructural evaluation showed that grain refinement occurred in the composite by 48 % and Vickers microhardness increased approximately by 12 %. According to the results of the pH and weight loss measurements during the immersion tests, the presence of sub-micron HA particles increased the pH of the simulated body fluid (SBF) containing the composite specimens because of the micro-galvanic corrosion between the primary phase and the secondary phase of Ca2Mg6Zn3 in the matrix. However, a thicker protective surface layer formed on the composites, which may lead to a more desirable protection in the longer immersion time, compared to those of the monolithic alloy. Under the tensile monotonic load, the composite exhibited a moderate increase in the yield stress and a reduction in the ultimate tensile strength and the maximum strain at fracture, while the yield stress amelioration is more considerable under the compressive monotonic load. In comparison to the monolithic alloy, an improvement was observed in the high cycle fatigue behavior of the composite, which could be attributed to the yield stress enhancement, retarding the crack initiation under the same stress amplitudes.

Realizing primary/secondary particle co-coating with CoxB for lithium-rich cathodes in high-performance lithium-ion batteries

The construction of a surface protection layer is an important way to improve the cycling stability of lithium-rich manganese-based cathode materials. However, the protection for the primary particles inside is usually neglected compared with the secondary particles, which increases the corrosion risk of the electrolytes. In view of this, amorphous CoxB coated Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) was rationally designed and prepared. Nano CoxB not only completely coated the surface of the secondary particles but also penetrated between the grain boundaries of the primary particles to achieve the protection of the primary particles. Thus, the cycling stability of the LMNCO is improved significantly. After 200 cycles at 1C and 25°C, the capacity loss rate of CoxB-LMNCO is 8.9%. Even at 2C and 40°C, the value is only 13.4%. As a result, this work provides a new idea to improve the electrochemical performances of the LMNCO cathode materials in high-performance lithium-ion batteries.

Solid-state polymeric coating as regulating deposition layer for dendrite-free and stable rechargeable aqueous Zn metal anode

The growth of dendrites and self-corrosion issues of Zn anodes in aqueous energy storage systems cause poor stability and cycling life. Hence, poly-quinol-phenylenediamine (PQA) is synthesized and constructed as the surface protective layer of bare Zn by blade coating, promoting the even dispersion of the electric field, inducing the uniform nucleation and growth of Zn. Consequently, PQA coated Zn (PQA@Zn) electrode demonstrates the improved cycling life of 450 h at 1 mA cm-2 and 220 h even at 5 mA cm-2 with the symmetric cells, superior rate capability and relatively lower overpotential at different current densities, far more than bare Zn foil. The surface morphology after cycles indicates that PQA coating restrains dendrites by leading to the deposition of Zn dendrites and decreasing the side effects by capturing the Zn2+. In brief, the PQA@Zn anode exhibited remarkable improvement in service life, cycling stability and rate capability, providing more possibilities for advanced energy systems.

Ni-based coating on 5083 aluminum alloy with Cu-Ni interlayer fabricated by ultra-high-speed laser directed energy deposition

Through the innovative design of interlayer connection materials, a high-performance wear-resistant and corrosion-resistant composite protective coating was successfully prepared on the surface of 5083 aluminum alloy using ultra-high-speed (0.5 m/s) laser energy deposition technology. By conducting orthogonal experiments and analyzing the coating morphology and non-destructive testing results, the optimal process parameters for preparing the Cu-Ni25 alloy interlayer and nickel-based alloy surface protection layer were determined. The bond strength and friction resistance of the composite coating and the substrate were tested by shearing and scratch tests. Furthermore, the wear and corrosion resistance of the nickel-based alloy protective layer and substrate were comparatively assessed using an abrasive wear tester, electrochemical workstation, and salt spray test chamber. The results show that the Cu-Ni25 alloy interlayer plays a good bridge role and realizes metallurgical bonding with the aluminum alloy matrix. Additionally, the addition of the nickel-based alloy surface protection layer yields a significant improvement in deformation resistance, wear resistance, and seawater corrosion resistance compared to the aluminum alloy substrate.