Anodic Layer Research Articles

Effect of anodizing on high cycle fatigue behaviour of cast AlSi8Mg-T6 alloy

The work investigates the effect of anodizing on the high cycle fatigue behaviour of a high-quality cast Aluminium (AlSi8Mg-T6) alloy. Tensile and fatigue tests are carried out on both non-anodized and anodized specimens in order to highlight the differences in tensile and fatigue responses. In addition, roughness measurements, fracture surfaces analyses, metallography, instrumented micro-indentation and scanning electron microscope (SEM) inspections are performed in order to investigate the interplay between the presence of an anodic layer and the fatigue life of anodized specimens.It is demonstrated that, after anodizing, AlSi8Mg-T6 specimens shows a deterioration of the fatigue performance at medium–low stress amplitudes (130 and 110 MPa). In addition, fracture surface analysis reveals that the presence of the anodic layer modifies the fatigue crack initiation and early growth mechanisms. The manuscript paves the way for an accurate fatigue design of anodized, cast AlSix components.

Overlithiation lithium-rich Mn-based oxide as cathode pre-lithiation agent towards high-energy-density batteries

Huge active Li+ loss in the initial cycle owing to the formation of solid electrolyte interface (SEI) layer of anode restrict the enhancement of high-energy–density lithium-ion batteries (LIBs). Here, a method by reducing surface oxygen vacancies of lithium-rich manganese-based oxide (LRMO) to obtain huge number of irreversibly active Li+ for the application of cathode pre-lithiation, which is highly adaptive to electrode preparation process with excellent air stability, is proposed. Through modulating different lithium ratios, Li2-x(Mn2/3Ni1/3)xO2 (x = 0.67, LR-2) with fewer oxygen vacancies is synthesized. By simply adjusting cell voltage, it exhibits different electrochemical properties to match the requirements of different LIB cathode. When used as an agent to a LiFePO4 cathode, LR-2 can further enhance the capacity of cells, due to its “donor” lithium-ion capacity (244.1 mAh/g) and exceptional cyclic performance. By coupling with LiNi0.5Mn1.5O4, LR-2 provides high lithium compensation efficiency (320.0 mAh/g), while also releasing reversible capacities of 98.5 mAh/g, achieving a balance between pre-lithiation capacities and reversible discharge capacities. As a consequence, the LiNi0.5Mn1.5O4|graphite full cell containing LR-2 exhibits a reversible capacity of 123.3 mAh/g, 47% greater than the counterpart without LR-2, and significantly better cyclic performance. This study introduces a novel approach to design cathode pre-lithiation agent with Li-rich oxides for high-energy–density LIBs.

Numerical analysis of the relation between the porosity of the fuel electrode support and functional layer, and performance of solid oxide fuel cells using computational fluid dynamics

The development of the hydrogen industry brings new technological challenges. Solid oxide fuel cells (SOFCs) seem to be one of the leading devices for hydrogen conversion and its production while operating in its reverse mode (as an electrolyser). Fine-tuning of SOFC microstructure might extend cells life and boost their performance. The article presents original numerical studies of the performance of solid oxide fuel cells, based on the OpenFuelCell model, extended by fuel and oxidant concentration loss equations. Transport phenomena in the porous structure of the anode functional layer (AFL) and the anode support layer (ASL) were simulated using the modified Fick's law (MFL) and the Knudsen diffusion coefficient. The presented research focuses on the influence of fuel distribution in fuel electrode of SOFC together with reacting zones and on the influence of AFL and ASL microstructure characteristics on cell performance. The studies included porosity in the range of 30%–60% for both types of anode layers. The obtained results showed a significant impact of the porosity characteristics on the SOFC performance and indicated the possible direction for further improvement. Numerical studies have shown that an increase in anode layers porosity of 30% allows for an increase in cell efficiency of even 15%. Experimental, as well as numerical results, showed that above a porosity of 49%, further increasing the porosity has no strong effect on the results. Also, a novelty in the work and an important part of it is the comparison of the impact of microstructure manipulation of the two anodic layers. Improvement of ASL microstructure allows to better, more homogeneous, fuel distribution inside the anode. Additionally, it increases the concentration of the fuel in the functional layer by up to 8%, which leads to increase in SOFC performance.

Intercalated hydrates stabilize bulky MoS2 anode for Lithium-Ion battery

Bulky molybdenum disulfide (MoS2) has rarely been considered as a promising anode for lithium-ion battery due to the high volume strain and structural collapse caused by conversion reaction. In this work, a bulky K(H2O)MoS2 is rationally designed by intercalating hydrated potassium into commercial 2H MoS2, which exhibits a high volumetric capacity of 1566.7 mAh cm−3 along with an extremely enhanced capacity retention from 16% to 102% after 400 cycles at 1 A/g. Moreover, the assembled LiCoO2//K(H2O)MoS2 full cell delivers an energy density of 223.2 Wh/kg and a capacity retention of 89.6% after 100 cycles at 0.5 A/g. Based on the results of in situ X-ray diffraction (XRD) and Raman spectrum, differential electrochemical mass spectrometry (DEMS), time-of-flight secondary mass spectrometry (TOF-SIMS), and theoretical calculations, the stable lithium storage of K(H2O)MoS2 benefits from the buffer interlayers composed of “confined Li-O species and S-H bonds”, which limit the complete conversion reaction and preserve the layered structure. The proposed strategy of introducing intercalated hydrates for improving the cycling stability of bulky MoS2 raises the prospect of practical applications in layered metal chalcogenides anodes.

Ce nanoparticles and sol-gel hybrid organic-inorganic coatings maximize corrosion protection in the anodized AA2024-T3

We demonstrate that the corrosion resistance of the AA2024-T3 alloy can be maximized with the application of top protective sol-gel hybrid organic-inorganic coatings. Samples combining Ce nanoparticles within the pores of the anodic layer with the top sol-gel coatings were observed to outperform samples featuring only the coating. This research unravels the self-healing capability against corrosion of the sol-gel coating when Ce nanoparticles are present, as well as a good coverage of defective regions within the oxide by the hybrid layer. This research opens a paradigm aiming at maximizing the corrosion resistance for non-ferrous anodized alloys.

High-zeta-potential accelerates interface charge transfer in lithium anodes via MXene-graphdiyne heterojunction layers

Lithium (Li) metal anodes are a crucial part of lithium-based batteries and are highly regarded as a top contender for achieving high-energy–density lithium batteries. However, the development of dendrites and other related issues have significantly impeded their practical applications. Here, we fabricated a MXene (Ti3C2Tx)-graphdiyne heterostructure layer anode with high-zeta-potential (−90 mV) using an electrostatic self-assembly method. The high-zeta-potential can accelerate the interface charge transfer in the lithium deposition process, facilitating the uniform Li nucleation on the surface of anodes. Theoretical simulations further reveal that the high-zeta-potential can not only reduce the lithium ion concentration gradient but also homogenize the electric field in the anodes. Besides, based on first-principles computation, the adsorption energy of lithium atoms on MXene-graphdiyne heterostructure is − 3.4 eV. As a result, a low overpotential of 12.4 mV has been achieved by MXene-graphdiyne layers at 0.05 mA cm−2. Additionally, MXene-graphdiyne-Li anodes display an ultralong cycle life upto 1400 h and good rate capability upto 8 mA cm−2 in symmetric cells. Full cells consisting of MXene-graphdiyne-Li anodes and LiFeO4 cathodes also show stable cyclic properties (300 cycles at 5C).

Research on the Influence of Coating Technologies on Adhesion Anti-Corrosion Layers in the Case of Al7175 Aluminum Alloy

A key element in ensuring the service life and strength of aluminum alloys in many industrial applications is the adhesion of anti-corrosion coatings. The aim of this study is to analyze how coating processes affect the adhesion of anti-corrosion coatings on aluminum alloy 7175. In other words, the influence of the nature of the elementary layers that form the anti-corrosion coating was studied for the following: the anodic layer, the primer, and the topcoat. To learn more about the different coating technologies and how they affect adhesion, a thorough literature review was carried out. In addition, a case study using electrocoating and thermal spraying was conducted to show the impact of coating processes on adhesion. The results showed that electrodeposition, as opposed to thermal spraying, improved the adhesion of anti-corrosion coatings. In the case of the aluminum alloy analyzed, there is a significant difference in terms of the adhesion strength of the anti-corrosion coatings. This resistance is influenced by both the anodic coating (BSA TSA SAA) and the type of primer and topcoat used (water-based or solvent-based). The correct choice of anode coat and primer and topcoat can lead to an increase (or decrease) in the adhesion strength of the paint coat by 20%. In conclusion, this study highlights how crucial it is to select the best coating process to maximize the adhesion and durability of aluminum alloys under corrosion conditions.

Experimental analysis of anodic coating process parameters of Al 5754 alloy by response surface method

Aluminum 5754 alloy appears as a candidate material for many engineering applications in terms of its lightness and strength values. The surface properties of this alloy need to be improved for applications where there is surface damage such as friction and wear. In this study, Central composite design was applied to investigate the influences of anodic coating process parameters (voltage, coating time and grit size) on the response (i.e. surface roughness and coating thickness). The competence of the mathematical models recognized, and the importance of the regression coefficients were studied by ANOVA. The initial surfaces of the samples were sanded with 400, 800 and 1200 grit size and surfaces with 3 different roughnesses were obtained. Al 5754 specimens were anodic coated at 8 V, 12 V and 16 V voltages and combinations of time parameters of 10, 20 and 30 min The ANOVA results show that the designed models by RSM for average coating thickness and surface roughness are statistically important at the confidence level of 95%, and 80%, respectively. Maximum anodic coated layer of 29 μm was obtained at surface prepared with 1200 grit size, at 16 V of voltage and used for 30 min of anodizing time. The lowest roughness value of 0.676 μm was obtained at the surface was prepared with 1200 grit size, 8 V of voltage and anodizing time of 10 min.

P‐124: Efficiency Enhanced Top Emitting OLED‐on‐Silicon Microdisplay with Aluminum Anode

A top emitting organic light emitting diode‐on‐silicon (OLEDoS) panel with aluminum (Al) anode for high‐resolution microdisplays was proposed and fabricated. The low work function of the Al anode increases the energy barrier of the interface between the anode and hole injection layer (HIL), and has poor hole‐injection properties, which causes the low efficiency of the device. To enhance the hole‐injection characteristics of the Al anode, we applied optimized HIL and hole transportation layer (HTL) materials. The proposed single stack structure white OLED display panel with Al anode was fabricated on CMOS backplane and the white OLED device improved efficiency by up to 20 cd/A at 1000 nit, which is 90% of the level of conventional OLEDs with indium tin oxide (ITO) anode.

Effect of multiple discharges on accumulated damage to the DLC anode layer of a resistive Well Electron Multiplier

A prototype of the WEM (Well Electron Multiplier) detector with an active area of 10 × 10 mm2 and a resistive DLC anode was tested in terms of robustness to electrical discharges induced by highly ionizing particles (241Am alpha source). The perforated structure of the WEM detector was produced from a 500 μm thick FR4 with drilled holes of 200 μm in diameter and 500 μm in pitch. The resistive anode was made of 100 nm thick DLC layer with 30 MOhm/square sheet resistance deposited on the anode grid electrode. The anode grid electrode is used to distribute voltage to the resistive layer and provide fast charge evacuation. The detector was operated in Ar:CO2 (90:10) gas mixture at gas gain of 3,500. The alpha source was placed in the drift gap. The WEM detector with intrinsic capacitance of 34 pF did not show visible damage and changes in performance after 1 million accumulated discharges. To simulate a large area detector, we added a capacitance up to 1 nF in parallel with the test device. The results of the experiments with an additional capacitance revealed that a small WEM prototype can't be directly scaled to the dimensions more than 60 × 60 mm2 without losing the robustness to discharges. We assume that the observed damage could be caused by the design features of the prototype. The grid anode electrode with a thickness of 35 μm results in a gap between the perforated FR4 board and the resistive anode board. Simulations of the electric field distribution with Comsol Multiphysics software revealed a significant electric field strength in this gap. This could lead to electric discharge path bypassing the protective resistive DLC layer. A possible solution to this problem could be additional insulation of the anode grid electrode with a coverlay similar to that used in bulk MicroMegas production.

Accelerating Li+/Li redox through the regulation of the electric double layer for efficient lithium metal anodes

High performance lithium metal anode is of great importance to achieve batteries with high energy density. Due to the intrinsic high reactivity of Li metal anode and the insufficient understanding of lithium redox at the Li/electrolyte interface, the fast and dendrite-free Li metal deposition still remains a grand challenge. In this work, we accelerate Li+/Li redox through the regulation of the electric double layer (EDL), in which 2-Mercaptopyridine (2-MP), a conjugated weak-base molecule with stable electrochemical properties, can be specifically adsorbed on Li metal surface and promote charge transfer. It fundamentally avoided the formation of Li metal dendrites and enabled fast Li plating/stripping process, leading to uniform Li deposition as well as superior cycling performances of batteries. This work provides a significant contribution to the understanding of battery chemistry at the electrode/electrolyte interface.

Direct-Fed Ethanol Metal-Supported Solid Oxide Fuel Cell System with Regeneration Process by Air Pulsing

A Metal-Supported-SOFC (MS-SOFC) has been modified by infiltrating a non-noble metal ceria-zirconia supported cobalt (Co/CZ) internal reforming catalyst to improve its reforming activity and inhibit the carbon deposition or coking under ethanol steam reforming conditions. Non-noble metal catalysts can still be deactivated during long-term cell operation in a severe coking-inducing environment. Therefore, an in-situ regeneration procedure was performed by pulsing air into the anode surface to burn the deposited carbon on the anode and catalyst layer during the cell operation. Upon the cell regeneration steps, the cell voltage was recovered to its initial condition at ~0.8 V, while the peak power density of the cell showed up to 116% recovery under H2 and 111% recovery under ethanol. These data show that the air pulsing regeneration steps in the MS-SOFC can improve the lifetime by removing the coking deposit within the anode and further enhancing its electrochemical and catalytic activity.

A Comprehensive Investigation on the Direct-Ammonia Thin-Film Solid Oxide Fuel Cells (TF-SOFCs) and the Effect of Porosity-Control of the Anode Support Layer

Ammonia is highly regarded as a hydrogen storage and transportation medium due to its various advantages. Solid oxide fuel cells (SOFCs) can achieve high synergy by using ammonia directly as fuel without the ammonia decomposition reactor and filtration devices. We confirmed the distribution of hydrogen produced by the decomposition of ammonia through 2D multi-physics numerical modeling and predicted the decomposition rate and maximum current density according to the tortuosity. Based on the results, we adjusted the pore volume of the anode-support layer using PMMA to reduce tortuosity and facilitate hydrogen supply and produced anode support layer-anode functional layer substrate. We then manufactured a Thin-film SOFC and tested using hydrogen and ammonia fuel, and achieved high performance of 1897 and 1357 mW/cm2 at 650 °C.

Effect of Fabrication Processes on Electrochemical Performance of Metal-Supported Solid Oxide Fuel Cells

In this study, MSCs were fabricated on the sintered porous metal substrates by wet coating with high temperature sintering in reduced atmosphere. The electrochemical performance of MSCs strongly depended on the process conditions. The relationship between the electrochemical performance and the structural property were investigated. In order to obtain dense electrolyte, the shrinkage behavior of porous metal substrates is quite important. Large shrinkage of substrate can assist the densification of electrolyte in the sintering process. It was found that the degrease and sintering temperature affected the shrinkage behavior, and existence of H2O in the atmosphere also affect it. It was considered that the oxidation of metal particles in substrate affected on the shrinkage. When the sintering temperature were high to obtain the dense electrolyte, Fe and Cr diffused from the substrate to the anode layer. This metal elements diffusion strongly deteriorated the performance of the anode. When the MSCs are prepared by wet process with high temperature sintering, controlling the sintering behavior of all components by adjusting the process parameter was quite important to low polarization resistance.

Interface stress calculation and failure behavior of TBCs on the surface of aluminum alloy with anodic oxidation

Aluminum protective coatings have poor performance due to the significant difference in coefficient of thermal expansion (CTE) between the substrate and the coating. In this study, porous anodic aluminum layer, which have high bonding, well matching and grew in situ on the substrate of aluminum alloy (4032) using anodic oxidation, and then thermal barrier coatings were produced on the surface by laser surface modification and atmospheric plasma spraying (APS). The aim of this way is to improve the interface thermal shock resistance (TSR) of the coatings. The results showed that the coatings with anodic aluminum layer (highest group average of 444 cycles) have a much higher number of thermal shock cycles than metallic bond coatings. Furthermore, the failure analysis suggested that the bonding stability of the coatings is influenced by the surface state, surface mosaic structure, as well as such as CTE and surface roughness. Eventually, a double-layer mismatch stress model was developed to characterize the residual stresses caused by deformation mismatch in the coatings. After performing calculations，from a force perspective τa≈10τb, and from a work perspective Wfa≈3.34Wfb.

Effect of Functional Nanoporous TiO2 Film Obtained on Ti6Al4V Implant Alloy to Improve Resistance in Biological Solution for Inflammatory Conditions.

The metallic titanium-based biomaterials are sensitive to corrosion-induced degradation in biological fluids in the presence of inflammatory conditions containing reactive oxygen species (ROS). Excess ROS induces oxidative modification of cellular macromolecules, inhibits protein function, and promotes cell death. In addition, ROS could promote implant degradation by accelerating the corrosive attack of biological fluids. The functional nanoporous titanium oxide film is obtained on titanium alloy to study the effect on implant reactivity in biological fluid with reactive oxygen species such as hydrogen peroxide, which are present in inflammations. The TiO2 nanoporous film is obtained by electrochemical oxidation at high potential. The untreated Ti6Al4V implant alloy and nanoporous titanium oxide film are comparatively evaluated for corrosion resistance in biological solution by Hank's and Hank's doped with hydrogen peroxide by electrochemical methods. The results showed that the presence of the anodic layer significantly improved the resistance of the titanium alloy to corrosion-induced degradation in biological solutions under inflammatory conditions.

Bioderived Freestanding Film as a Robust Interfacial Protective Layer for Advanced Lithium Metal Anodes

Lithium metal is a potential candidate for anode material in next‐generation rechargeable batteries with high energy and power densities. However, the huge volume change caused by the uneven deposition of metallic Li leads to the cracking of the solid electrolyte interphase (SEI), which cannot prevent the reaction of inner fresh Li with electrolyte, resulting in severe dendrite growth and electrochemical degradation. Herein, a freestanding protein film derived from eggshell is reported as the protective layer on the electrode surface to form a robust artificial SEI layer. Benefiting from its 3D interconnected fiber framework along with good mechanical stiffness and softness, the Li‐ion flow is uniformly modulated, leading to the suppression of Li dendrite growth. The electrochemical performance of corresponding symmetric, asymmetric, and full cells is significantly enhanced. A high coulombic efficiency above 95% for nearly 700 cycles is achieved for the modified Cu/Li asymmetric cell at a current density of 3 mA cm−2 (with a capacity of 1 mAh cm−2). This study indicates a SEI reinforcement approach for the stabilization of the Li metal anode based on the freestanding structure derived from biomaterials.

Modelling the effects of areal capacity on mass transport in liquid metal batteries

Liquid metal batteries (LMBs) are formed from three molten layers, and the interaction of thermal, compositional and electromagnetic forces influences their performance and stability. The coupled behaviour of these forces in LMBs remains uncharacterised, so in this study, a three-layer numerical model was developed to investigate this interaction in lab-scale to grid-scale batteries; areal capacities 0.9–7.5 Ah/cm2. Thermal convection was modelled first, and Rayleigh-Bénard convection, a flow observed in the anode, only developed in batteries larger than current grid-scale batteries. Electro-vortex flow was introduced and found to suppress thermal convection in the anode and electrolyte layers. Thermally stratifying temperature gradients in the cathode had some effect on electro-vortex flow, but compositional effects from mass transport were dominant. Finally, a background magnetic field was used to induce swirl flow, and the coupled effects of this flow with thermal gradients was studied. Swirl flow also suppressed thermal convection, and stratifying temperature gradients had little effect on the flow; however, compositional gradients in the cathode decelerated the poloidal velocity of swirl flow during discharge. These results show that electromagnetic flows are dominant in LMBs, and mixing compositional gradients in the cathodes of large areal capacity batteries remains a challenge in the field.

Decrypting the growth of anodic TiO2 nanotube layers in eco-friendly fluoride-free nitrate-based electrolyte for enhanced photocatalytic degradation of organic pollutants

Anodic TiO2 nanotube (TNT) layers were prepared in eco-friendly fluoride-free organic-aqueous-based electrolytes containing cerium ammonium nitrate. Nanotubes with controllable morphology (tube diameter and tube length) and surface features (porosity and surface roughness) were obtained by varying percentual ratios of ethylene glycol (Ex%) and water (Wy%) in the electrolyte (Ex%Wy%). Obtained TNT layers were studied for photocatalytic degradation of methylene blue (MB) under UVA irradiation. The most promising, TNT layers were prepared in E75%W25% electrolyte with a thickness of approx. 1.9 μm with a tube diameter of approx. 33 nm, and exhibited the highest photocatalytic degradation rate (k = 0.0151 min−1).

Ag-modification argyrodite electrolytes enable high-performance for all-solid-state lithium metal batteries

Solid-state batteries combined with high-voltage layered cathode and lithium metal anode display good safety and high energy density, showing great potential as next-generation energy storage devices. However, the low ionic conductivity and poor stability with lithium metal of most solid electrolytes inhibit the development of solid-state lithium metal batteries. Herein, Ag+ is successfully integrated into Li5.5PS4.5Cl1.5 structure with improved ionic conductivity and better lithium metal stability for the yielded Li5.5-xAgxPS4.5Cl1.5 (x = 0, 0.02, 0.05, 0.10) electrolytes. Ag+ dopant is carefully tailored to achieve the optimal Li5.45Ag0.05PS4.5Cl1.5 electrolyte with a high Li-ion conductivity of up to 9.1 mS cm−1 and a large CCD value of 1.8 mA cm−2. The corresponding battery with LiNi0.6Mn0.2Co0.2O2 cathode and Li-In anode delivers a high initial discharge capacity of 154.9 mAh g−1 at 1.0C and maintains 94.5% of this value after 100 cycles. However, the same cathode shows low discharge capacities and fast degradation of capacities with bare lithium metal anode in solid-state batteries. A facial 3D host lithium metal with Ag and LiNO3 particles on the surface is designed as the anode for this battery, showing much higher capacities and superior cyclability at different C-rates. The corresponding battery delivers discharge capacities of 140.6 mAh g−1 and 105.4 mAh g−1 when cycled at 0.1C and 0.5C. These superior electrochemical performances are attributed to the dual modification of Ag+ both in solid electrolytes and lithium metal anodes.