Aluminum Anode Research Articles

Electrokinetics-Driven Anodic Oxide Pore Formation: Linear and Weakly Nonlinear Analysis

Abstract Anodization of aluminium in an acidic medium facilitates the formation of well-ordered nanoporous anodic oxide films. The mechanism of pore formation is investigated as a morphological instability using a simplified model. The model accounts for the high field conduction law and field-assisted reactions (oxide formation/dissolution) only at the oxide-solution interface. The role of Butler–Volmer electrokinetics, electrolyte pH, anodic efficiency, and interface curvature on reaction kinetics are taken into account. Linear stability analysis suggests that the oxide film is unstable to well-defined wavelengths in specific ranges of parameters such as anodizing efficiency, applied voltage and electrolyte pH. Subsequently, a weakly nonlinear analysis is carried out to determine the nature of bifurcation beyond the stability threshold. Our findings indicate that the instability exhibits a subcritical nature, well in agreement with experimental observations.

Structural and Hydrophilic Properties of Nanoporous Aluminium Oxide Film as a Function of Voltage Anodization

Abstract The impact of voltage on the formation of nanopores through electrochemical anodization of high-purity aluminum was examined. The electrochemical bath was carefully prepared with oxalic acid electrolyte, while a 99.5% pure aluminum electrode served as the cathode and an aluminum template as the anode. The anodization process was conducted at room temperature, with voltage increments ranging from 20V to 65V, which was made possible by the in-house electrochemical cell. Notably, each incremental increase in voltage yielded a significant surge in current density, accompanied by a marked expansion in nanopore size, growing from approximately 35 nm to 125 nm. X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Rutherford backscattering spectrometry were used to characterize the films. A slight phase change was observed in the aluminum substrate's FCC structure after the anodization process, transitioning to a monoclinic structure at 39° and 45° for all applied potentials. The stoichiometry of the films was determined through RBS analysis. The nano pores' resulting morphology and phase composition were further examined using SEM and EDS, providing insights into their structural characteristics. Furthermore, the water contact angle of the anodized aluminum oxide samples was measured, revealing a range of approximately 85.16 to 61.01 degrees.

Exploring the Impact of In Situ-Formed Solid-Electrolyte Interphase on the Cycling Performance of Aluminum Metal Anodes.

Unwanted processes in metal anode batteries, e.g., non-uniform metal electrodeposition, electrolyte decomposition, and/or short-circuiting, are not fully captured by the electrolyte bulk solvation structure but rather defined by the electrode-electrolyte interface and its changes induced by cycling conditions. Specifically, for aluminum-ion batteries (AIBs), the role of the solid-electrolyte interphase (SEI) on the Al0 electrodeposition mechanism and associated changes during resting or cycling remain unclear. Here, we investigated the current-dependent changes at the electrified aluminum anode/ionic liquid electrolyte interface to reveal the conditions of the SEI formation leading to irreversible cycling in the AIBs. We identified that the mechanism of anode failure depends on the nature of the counter electrode, where the areal capacity and cycling current for Al0 electrodeposition dictates the number of successful cycles. Notwithstanding the differences behind unstable aluminum anode cycling in symmetrical cells and AIBs, the uniform removal of electrochemically inactive SEI components, e.g., oxide-rich or solvent-derived organic-rich interphases, leads to more efficient cycling behavior. These understandings raise the importance of using specific conditioning protocols for efficient cycling of the aluminum anode in conjugation with different cathode materials.

Lithium-ion comb—artificial self-regulating lithium-storage film on aluminum anode enabling long cycles of batteries

Al anode can increase battery energy density, but its non-wettability and high Li nucleation hindrance cause uneven Li nucleation to deteriorate the anode structure. Herein, we present a novel in-situ synthesis method for the deposition of molybdenum oxide nanospheres (NMO) onto the surface of Al foil, that is, molybdenum oxide/aluminum (M-Al), which demonstrates a two-stage propulsion effect on Li-ion migration to address the issue at hand. The high wettability and low Li nucleation hindrance of the NMO layer drive the first stage of Li-ion migration. NMO acted as a comb to deliver Li ions uniformly with minor volume expansion. Subsequently, the formation of Li2O-rich solid electrolyte interphase (SEI) film with exceptional desolvation capability, facilitated by the NMO layer and electrochemically activated M-Al to Li molybdate/aluminum (Li-M-Al), represents the second stage in the advancement of Li−ion migration. The embedding of lithium ions makes molybdenum oxide evolve into lithium molybdate, thereby enabling Mo to regulate the storage of Li ions through the valence state. Hence, the Li nucleation overpotential of M-Al is decreased by 0.32 V, leading to a significant enhancement in the cycling performance of the Li-M-Al||LiFePO4 (LFP) battery, with a capacity retention rate of 78.5 % after 400 cycles at 1C.

Effects of ion mass transport on electrochemical reaction pathways in aluminum-anthraquinone batteries

Aluminum anodes and quinone-based organic cathodes couple as earth abundant, sustainable, and safe battery electrodes. However, different numbers of galvanostatic discharge plateaus have been observed in aluminum-quinone cells depending on the experimental conditions, a phenomenon that has not yet been explained and furthermore affects cell energy density. Here, in aluminum-anthraquinone batteries, we show that ion mass transport affects the electrochemical reaction pathway and controls the occurrence of either one or two reduction plateaus during galvanostatic discharge. The effects of electrode mass loading, porosity, rest periods, and cycling rates were analyzed on the reduction potential and relative specific capacity of the galvanostatic plateaus. When AlCl2+ cations charge compensate the electrochemically reduced carbonyl groups concurrently, a single reduction plateau is observed. When ion mass transport is limiting, sequential reduction and charge compensation of each carbonyl group results in two distinct reduction plateaus. The second plateau occurs at a potential approximately 0.3 V lower than the first, thus decreasing the cell energy density. The potential of the electrochemical oxidation reaction where AlCl2+ cations dissociate, however, is not affected. Ion mass transport is thus shown to be a critical variable that can control the electrochemical reaction pathway, redox potentials, and practical energy densities of aluminum-quinone batteries.

Progresses, Challenges and Prospects for Aluminum Anode in Aqueous Secondary Batteries

Progresses, Challenges and Prospects for Aluminum Anode in Aqueous Secondary Batteries

Aluminum Foil Surface Etching and Anodization Processes for Polymer 3D-Printing Applications

Extrusion-based polymer three-dimensional (3D) printing, specifically fused deposition modeling (FDM), has been garnering increasing interest from industry, as well as from the research and academic communities, due to its low cost, high speed, and process simplicity. However, bed adhesion failure remains an obstacle to diversifying the materials and expanding the industrial applications of the FDM 3D-printing process. Therefore, this study focused on an investigation of the surface treatment methods for aluminum (Al) foil and their applications to 3D printer beds to enhance the bed adhesion of a 3D-printed polymer filament. Two methods of etching with sodium hydroxide and anodization with phosphoric acid were individually used for the surface treatment of the Al foil beds and then compared with an untreated foil. The etching process removed the oxide layer from the Al foil and increased its surface roughness, while the anodizing process enhanced the amount of hydroxide functional groups and contributed to the formation of nano-holes. As a result, the surface-anodized aluminum foil exhibited a higher affinity and bonding strength with the 3D-printed polymers compared with the etched and pristine foils. Through the increase in the success rate in 3D printing with various polymers, it became evident that utilizing surface-treated Al foil as a 3D printer bed presents an economical solution to addressing bed adhesion failure.

Study of burst mode for enhancing the ps-laser cutting performance of lithium-ion battery electrodes

The demand for lithium-ion batteries (LIBs) has increased significantly, leading to an increased focus on high quality production methods. In response to this growing demand, laser technology has been increasingly used for electrode notching and cutting. In addition, the advent of high-power ultrashort lasers equipped with burst mode capabilities represents a promising option for electrode cutting of LIBs. On the other hand, these types of lasers for this purpose are relatively unexplored in the literature. This study investigates the effect of various parameters, including the number of pulses per burst (ranging from 1 to 8), the pulse repetition rate (200.0, 550.3, and 901.0 kHz), and the burst shape (equal pulse peak and increasing pulse peak), on the laser cutting process of aluminum foil, cathode, copper foil, and anode. The results indicate that increasing the number of pulses per burst and the pulse repetition rate improves productivity and quality for all materials, with a more significant effect observed for metal foil than for cathode and anode materials due to the different laser-material interactions for metal foil and active material. The burst shape with equal pulse peaks was found to be a more suitable temporal distribution for cutting all materials compared to an increasing pulse peak distribution. The ablation efficiency was evaluated as a function of the peak fluence of a single pulse within the burst. The results emphasize that higher productivity at higher average power can be achieved by increasing the pulse repetition rate toward the MHz range with moderate pulse energies.

Effect of the Atmosphere on the Properties of Aluminum Anodizing

This study aims to quantify the effect of process parameters on the anodizing of Al6061 aluminum. To achieve this, studies on layer thickness, the porosity of the anodized surface, electrochemical techniques, X-ray diffraction, grain size estimation, and statistical analysis were conducted for three different atmospheres (without air, air, and oxygen). Parameter levels were established as follows: temperature (30 °C, 45 °C, and 60 °C), time (20 min, 40 min, and 60 min), electrolyte concentration (0.5 M), voltage (9 V), and current intensity (0.600 A). A 33 experimental design (three factors, three levels) was proposed, and mathematical models were obtained using general factorial design. The experimental design was used to determine the three most important variables in the optimal condition. A total of 27 tests were conducted using sulfuric acid electrolytic solutions, of which 12 samples were selected by the factorial design method, which simultaneously evaluates the effects of factors and their interactions in a single experiment. Measurement of porosity and oxide layer thickness was performed using scanning electron microscopy. The purity of the anodic layer formed was characterized using X-ray diffraction techniques with a vertical goniometer X-ray diffractometer. The electrochemical behavior is presented through potentiodynamic polarization curves for the anodic layer. A general factorial design and an analysis of variance (ANOVA) were conducted to establish the significant factors for layer thickness, grain size, and reaction rate. Finally, the best results and their parameters for each response are presented.

Interfacial activation of anode in aluminum-air battery through incorporating 5-carboxyl benzotriazole@β-cyclodextrin assembly in synthetic seawater electrolyte

Neutral electrolyte, such as synthetic seawater (SW), is a promising candidate for aluminum-air (Al-air) battery due to the alleviated hydrogen evolution along with anode self-corrosion. However, aluminum surface passivation in SW poses a serious challenge for battery's power generation. Following molecular self-assembly theory, 5-carboxylate benzotriazole (CB) was incorporated into β-cyclodextrin (β-CD), which (CB@β-CD) was utilized as an interfacial activator for aluminum anode in SW. CB could be released from β-CD, and activated aluminum surface, facilitating anode discharge. The specific capacity and energy density of Al-air battery were achieved as 2607.4 mAh/gAl and 2.37 kWh/kgAl, respectively, at an optimal CB@β-CD concentration of 120 mg/L. Density functional theory calculations revealed that the overwhelming adsorption energy of guest molecule (CB) on Al (111) plane over its binding energy inside host (β-CD) accounted for the release of CB on anode surface, and the ensuing interfacial activation effect.

Formation mechanism of nanopores in dense films of anodic alumina

Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films. Through comparative experiments, nanopores are found in the anodic films formed in the electrolytes after high-temperature storage (HTS) at 130 °C for 240 h. A comparison of the voltage−time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes. FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures. Combining the electronic current theory and oxygen bubble mold effect, the change in electrolyte composition could increase the electronic current in the anodizing process. The electronic current decreases the formation efficiency of anodic oxide films, and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films. The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model.

Modern Conversion Layers as High-Performance Alternatives to Aluminum Anodizing and Its Alloys

Modern Conversion Layers as High-Performance Alternatives to Aluminum Anodizing and Its Alloys

The effect of Artemisia capillaris leaf extract as a benign corrosion inhibitor on the performance of Al–air batteries

The self-corrosion of the aluminum anode reduces largely the performance of Al-air batteries. Herein, we report on the effect of Artemisia capillaris leaf extract (ACLE) as a benign corrosion inhibitor on the performance of Al-air batteries in 4 M NaOH electrolyte. The hydrogen evolution tests, electrochemical measurements, and surface analysis show that ACLE can markedly reduce the corrosion current density of the Al electrode in 4 M NaOH, which is due to the adsorption of the active components in ACLE inhibitor on the Al electrode surface. The presence of ACLE in 4 M NaOH greatly reduces the self-corrosion of the Al anode, and thus improves the utilization rate of the Al electrode. Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) are employed to determine the chemical composition of the adsorption layers on the surface of the Al electrode. When the concentration of ACLE in 4 M NaOH is 5 g/L, the Al-air battery has a high practical capacity density of 3545 Wh kg−1, and the fuel efficiency also increases to a high value of 44 % from 14 % without ACLE. This work presents a novel approach to enhance the performance of Al-air batteries through the utilization of natural product extracts as corrosion inhibitors.

A Mixed Ionic/Electronic Conductor Interphase Enhances Interfacial Stability for Aluminium‐Metal Anode

AbstractMetallic aluminium (Al) anodes are considered to be a promising alternative for large‐scale energy storage due to their inherent low cost, high safety and ideal weight/volume capacity (2980 mAh g−1/8040 mAh cm−3). However, aluminum‐ion batteries (AIBs) based on room‐temperature ionic liquid electrolytes have encountered challenges in practical applications, such as side reactions and slow sluggish kinetics. The anode/electrolyte interface has attracted considerable attention for addressing the aforementioned challenges. Here, an AlCl3/Sn‐based mixed ionic/electronic conductor interface (MCI) is designed through a facile displacement reaction. The stability of the modified Al metal anode has been significantly enhance by superior charge transfer, excellent corrosion resistance and dense deposition morphology. Consequently, in symmetric cell, the Al@Sn electrode with MCI offers a lifespan for about 700 h (350 cycles) at 0.1 mA cm−2. Moreover, combined with the graphite cathode, the pouch cells based on this novel anode present outstanding cycling performance, demonstrating a maintained capacity of 87.1 mAh g−1 after 450 cycles. This research presents an innovative Al‐metal anode for ionic liquid‐based Al‐ion batteries.

An Aluminum Anode with Superior Discharge Characteristics Prepared via Grain Refinement

AbstractAs Electric Vehicles became more important in the field of energy, the disadvantages of lithium‐ion batteries became apparent. This led to an increased interest in metal‐air batteries, particularly aluminum‐air batteries, as alternatives to lithium‐ion batteries. However, aluminum‐air batteries also have their own deficiencies, with one of the main areas of research being the improvement of anode characteristics. Improving anode characteristics is a crucial area of research in this field. Aluminum alloys have traditionally been used to overcome obstacles in creating batteries with favorable electrochemical properties. However, recent studies suggest that reducing the grain size of aluminum anodes can have positive effects. In this study, we investigated the electrochemical behavior of three aluminum alloys that were grain‐refined by Al‐5Ti‐1B and compared the results to a commonly used aluminum alloy as an anode in aluminum‐air batteries. We chose Al−Ti alloys with variable amounts of titanium (0.01, 0.05, and 0.1 wt.%) for evaluation. We selected a 4 molar potassium hydroxide solution as the test electrolyte due to the merits of alkaline electrolytes. Our study found that the alloy with 0.05 wt.% of titanium is the best anode choice. This anode has promising discharge characteristics at high current density (50 mA/cm2) and is an appropriate choice for electric vehicles.

New insights into aluminium anodizing in phosphonic acid

Aluminium anodizing in phosphonic acid is known to produce anodic aluminium oxide (AAO) honeycomb structures with large interpore distances. However, detailed information on two-stage anodizing in phosphonic acid and annealing conditions required for the crystallization of AAO cell walls have not been reported yet. Here, the kinetics of aluminium anodizing in 1 M phosphonic acid and the thermal behaviour of the resulting AAO have been studied in detail. The apparent activation energy of aluminium anodizing is 65 kJ mol–1 and the AAO growth rate reaches 15 µm h–1 before oxide “burning”. A universal approach for stable two-stage anodizing at high voltages allowing to prevent porous structure rearrangement in the upper part of AAO is proposed. It involves the preliminary formation of a dense barrier alumina layer by anodizing in a weak acid electrolyte before the second anodizing step in phosphonic acid. The crystallization pathways of AAO obtained in phosphonic acid electrolyte are revealed based on differential scanning calorimetry, X-ray diffraction, and solid-state nuclear magnetic resonance techniques. The designed annealing program allows one to preserve the honeycomb porous structure after the crystallization of AAO in corundum at 1310 °C for 60 h. AAO obtained in phosphonic acid possesses high thermal stability and, thus, is promising as a support for gas sensors and fuel cells.

Preferred crystal plane electrodeposition of aluminum anode with high lattice-matching for long-life aluminum batteries

Aluminum batteries have become the most attractive next-generation energy storage battery due to their advantages of high safety, high abundance, and low cost. However, the dendrite problem associated with inhomogeneous electrodeposition during cycling leads to low Coulombic efficiency and rapid short-circuit failure of the aluminum metal anode, which severely hampers the cycling stability of aluminum battery. Here we show an aluminum anode material that achieves high lattice matching between the substrate and the deposit, allowing the aluminum deposits to maintain preferred crystal plane growth on the substrate surface. It not only reduces the nucleation barrier of aluminum and decreases electrode polarization, but also enables uniform deposition of aluminum, improving the cycling stability of aluminum batteries. Aluminum anode with (111) preferred crystal plane can stably 25000 cycles at the current density of 5 A·g−1, with a capacity retention rate of over 80%.

Influence of 3D printed porous aluminum anode structure on electrochemical performance

Aluminium-air (Al-air) batteries have been considered as one of the most promising next-generation energy storage devices. In this study, we investigated the effect of structural changes in the main body of porous aluminium anode on the electrochemical performance under the constraints of the 3D printing process using both simulation and experimental methods. By analysing the simulation results under the constraint of 3D printing process, we found that the variation of the base fillet radius affects the dimensional deviation of the porous aluminium anode. As the radius of the fillet increases, the degree of warpage deformation gradually decreases. For this reason, we experimentally verified the self-corrosion rate, electrochemical and discharge properties of aluminium anodes under the same process parameters. The test results are consistent with the simulation analysis. With the increase of fillet radius, the self-corrosion rate of anode gradually decreases and the electrochemical activity gradually increases. Meanwhile, the discharge voltage was as low as 1.55 V in the periphery without rounded corners, and increased by 1.3 % and 3.2 % when the periphery radius was 1 mm and 2 mm, respectively. This research result provides a new method for other researchers to further improve the overall performance of aluminium-air batteries.

Unraveling the Role and Impact of Alumina on the Nucleation and Reversibility of β‐LiAl in Aluminum Anode Based Lithium‐Ion Batteries

AbstractAluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium‐ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α‐phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al‐based batteries. The native passivation layer, Al2O3, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β‐LiAl is found to be 40.5 kJ mol−1, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol−1). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium‐ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones.

The Enhancement Discharge Performance by Zinc-Coated Aluminum Anode for Aluminum–Air Battery in Sodium Chloride Solution

The main drawback of seawater batteries that use the aluminum (Al)–air system is their susceptibility to anode self-corrosion during the oxygen evolution reaction, which, in turn, affects their discharge performance. This study consist of an electrochemical investigation of pure Al, 6061 Al alloy, and both types coated with zinc as an anode in a 3.5% sodium chloride (NaCl) electrolyte. The electrolyte solution used for the deposition of zinc metal contained citrate, with and without EDTA as a complexing agent. Subsequently, the performance of the anode was tested in a seawater battery, using a carbon@MnO2 cathode and a 3.5% NaCl electrolyte. The performance of Al–air batteries has been significantly enhanced by applying a process of electrodepositing zinc (Zn) with a citrate deposition electrolyte solution in both pure aluminum and alloy 6061. The performance of the battery was further enhanced by adding EDTA as a chelating agent to the citrate-based electrolyte solution. The Al–air battery with aluminum alloy 6061 with Zn electrodeposition with an additional EDTA as the anode, carbon@MnO2 as the cathode, and NaCl 3.5% solution as the electrolyte has the highest battery performance, with a specific discharge capacity reaching 414.561 mAh.g−1 and a specific energy density reaching 0.255 mWh.g−1, with stable voltage at 0.55 V for 207 h.