Al Foil Research Articles

Multilayer bonding of A1N30H foils to A1050 plates using cold spot forge welding

The cold spot forge-welding method, recently developed to achieve high-productivity and high-strength dissimilar material joining, was applied to multiple solid-phase joining of aluminum (Al) foils simulating tab-lead electrodes. Fifty Al foils of 12-μm thickness were sandwiched between 0.5 and 0.8 mm A1050 Al alloy plates and pressurized with 6-mm diameter punch for 1 s. The effect of bonding temperature (330–420 °C) and the reduction ratio (R, 1.4–3) on the tensile shear load of the joint was investigated. A lower R value at a higher bonding temperature resulted in base metal fracture (i.e., plug fracture) of the Al alloy plate. The maximum load reached 410 N using a reduction ratio of higher than 2.1 and bonding temperature of 420 °C. The processed foils were properly stretched in the plane without breakage, and a total of 51 sound layered bonded interfaces were formed. The results also confirmed that the oxide film became more rarefied with increasing R. These results are expected to be applicable to high-throughput, high-reliability bonding of secondary battery electrodes.

<i>In Situ</i> TEM Observation of the Ultrasonic Bonding Process

In the ultrasonic bonding process, oxides existing on the metal surfaces are removed, and bonding is achieved by bringing clean surfaces to be in contact with each other. However, the bonding process with microstructure variation is not well understood due to experimental difficulties. In this study, using a newly developed sample holder, which enables ultrasonic bonding in a TEM, we directly observed the bonding process at the nanoscale. The bonding process of Au foils with a clean surface was investigated and compared to that of Al foils with a stable oxide film, a bonding inhibitor, on the surface. During the Al ultrasonic bonding process, the nanoparticles generated dispersed over the entire bonding interface and finally formed a fine grain region at the interface. In contrast, in Au bonding, the nanoparticles generated tended to accumulate at the local area of the Au surface and form bridge-like connections between Au foils. It was considered that these differences in bonding behavior were caused by the surface conditions of the materials to be bonded.

Asymmetrical Schottky Junction Built by Metal/Conducting Polymer Targeting Efficient Flexible Direct Current Tribovoltaic Generator

Direct current (DC) from mechanical energy built on the tribovoltaic effect is promising for the development of self‐powered flexible electronics. A semiconductor triboelectric generator is one of the optimized solutions for DC output. However, it remains underutilized because of its low output power and insufficient insight into the fundamental principles of charge generation and transport at dynamic interfaces. Herein, a flexible fabric‐based DC generator that relies on a metal–semiconducting polymer interface constructed by an asymmetric Schottky junction between a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS)‐coated fabric and an aluminum (Al) foil is reported. The dependence of the electrical output performance of the device on the doping carrier concentration using different types of PEDOT:PSS to modulate the Schottky barrier height, validating both the work function and conductivity of the triboelectric material, which plays a fundamental role in DC generation, is explored. A large work function difference is required to create a high built‐in electric field for efficient separation of electron–hole pairs. Decent conductivity also fulfills an integral role in the innate carrier‐transport capability. Accordingly, an open‐circuit voltage (Voc) of 800 mV, a short‐circuit current (Isc) of 80 μA, and a power density of 6.7 mW cm−2 are yielded simultaneously.

Qualification of laser-weld interconnection of aluminum foil to back-contact silicon solar cells

Laser welding can be used to interconnect high-efficiency back-contact silicon solar cells with low-cost Al foil. This interconnection approach is relatively new and, thus, requires detailed vetting of its reliability before being adopted commercially. In this study, we weld 50-μm-thick Al foil to Sunpower back-contact cells and observe that the laser-weld adhesion, module fill factor, and reliability through thermocycling are all highly correlated to each other. A JMP statistical model built from adhesion data reveals that the statistically significant parameters to improve laser-weld adhesion are the laser pulse energy, pulse density, and pattern. Increasing the laser pulse energy and density improves the foil adhesion to the cell metallization, which is likely because of the improved melting of the Sn capping layer on the Cu electrode of the cells, as identified by cross-sectional microscopy. 94.4% of the modules fabricated using laser welds with a mean adhesion above 0.8 mJ lost less than 5% of their initial maximum power after 200 thermocycles, which is the IEC 61215 criterion for any single accelerated stress test. Additionally, 90.0% of modules fabricated with an as-fabricated module series resistance below 1.9 Ω cm passed thermocycling. Thus, laser-weld adhesion and the as-fabricated module series resistance can be used in the further development of new laser-weld settings and as quality control parameters in the manufacturing of these modules.

N-doped carbon quantum dots as corrosion inhibitor for ultra-high voltage etched Al foil

In this work, the N-doped carbon quantum dots (N-CQDs) were synthesized by hydrothermal method, and introduced into the preparation process of ultra-high voltage etched Al foil as corrosion inhibitor, in order to alleviate its over-etching (tunnels clustering and overall thinning), thus to increase its specific capacitance. N-CQDs were characterized by ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS). The effects of N-CQDs on etched tunnels, cross section of tunnel tunnels and electrochemical behavior of etched Al foil were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), open circuit potential (OCP), cyclic voltammetry curve (CV), potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS). As a result, when 100 mg·L−1 N-CQDs is added, the over-etching on etched Al foil surface is obviously modified, together with the extended depth, the relieved tunnels clustering, and the lowed Al foil weight loss ratio. Meanwhile, compared with the sample without N-CQDs, the specific capacitance of the ultra-high voltage formed foils prepared by anodizing at 600 V increased by 30 % from 0.49 μF·cm−2 to 0.64 μF·cm−2.

Modification of Al Surface via Acidic Treatment and its Impact on Plating and Stripping.

Amorphous Al2 O3 film that naturally exists on any Al substrate is a critical bottleneck for the cyclic performance of metallic Al in rechargeable Al batteries. The so-called electron/ion insulator Al oxide slows down the anode's activation and hinders Al plating/stripping. The Al2 O3 film induces different surface properties (roughness and microstructure) on the metal. Al foils present two optically different sides (shiny and non-shiny), but their surface properties and influence on plating and stripping have not been studied so far. Compared to the shiny side, the non-shiny one has a higher (~28 %) surface roughness, and its greater concentration of active sites (for Al plating and stripping) yields higher current densities. Immersion pretreatments in Ionic-Liquid/AlCl3 -based electrolyte with various durations modify the surface properties of each side, forming an electrode-electrolyte interphase layer rich in Al, Cl, and N. The created interphase layer provides more tunneling paths for better Al diffusion upon plating and stripping. After 500 cycles, dendritic Al deposition, generated active sites, and the continuous removal of the Al metal and oxide cause accelerated local corrosion and electrode pulverization. We highlight the mechanical surface properties of cycled Al foil, considering the role of immersion pretreatment and the differences between the two sides.

Untapped options to reduce waste from blister packaging for tablets and capsules

PurposeIn Europe, most medicines are taken orally and primarily packaged as single solid oral dosage forms (SODF) in blister chambers (alveoli) arranged on blister cards. Blister cards are constructed as multilayer laminates of aluminum (Al) foils and/or various plastic polymers bonded together, forming the alveoli, which are separated by more or less large gaps. We calculated the amount of packaging material (and thus waste) generated annually for the packaging of the most commonly prescribed SODF in Germany and estimated how much waste could be saved by rearranging the alveoli.MethodsFor this purpose, we analysed the SODF of the 50 most frequently prescribed medicines that were packaged in alveoli (N = 45; 13 of aluminum-aluminum blisters, 32 of mixed materials), measured and weighed their packaging material and content, calculated the annual amount of waste produced from them, and estimated how much waste could be saved if the alveoli were optimally positioned on the blister cards. In addition, we examined the variability of the blister packaging of eight groups of commonly prescribed generics of the same strength.ResultsDetailed analysis of the blister cards revealed that most of the material (69%) was used for the space between blisters and that aluminum-aluminum alveoli were more than four times larger than the packaged SODF. The (conservatively) estimated annual amount of composite waste generated for the primary packaging of these SODF was 3868 t (and extrapolated to the entire German pharmaceutical market 8533 t), of which an optimized arrangement of the blister chambers, i.e., a 2-mm sealing area around each alveolus and the arrangement of the SODF in 2 rows, would save approximately 37%.ConclusionConsidering that other ecological strategies are not yet mature, the optimal arrangement of blister chambers would be a captivatingly simple and, above all, immediately implementable strategy to avoid large amounts of avoidable waste.

Study of the coating effect of mildly oxidized graphene on aluminium current collectors by electrophoretic deposition and drop-casting methods for Li-ion battery application

Preventing current collector corrosion is critical in Li-ion batteries. This study investigates mildly oxidized graphene (MGO) coating on aluminium (Al) foil for corrosion resistance and battery performance for the first time. Electrophoretic deposition (EPD) and drop-casting are used to apply this coating. Polarization tests and SEM analysis are performed on coatings to determine the optimal EPD conditions. Optimal conditions for EPD of MGO on aluminium are 5 V and 40 s. Using LiNi0.8Co0.15Al0.05O2 (NCA) cathodes, the performance of cells on MGO-coated and uncoated aluminium (Bare-Al) is evaluated. EPD sample shows a capacity of 175 mAh/g at C/2, 35 mAh/g more than the Bare-Al sample despite a 67.3 Ω increase in charge transfer resistance (Rct). Due to inadequate adhesion, the drop-casted sample displays a 136 mAh/g capacity at C/2, poor rate capability, and higher Rct (335.48 Ω). MGO-coated aluminium batteries perform better under the EPD method because of improved corrosion resistance of current collectors, as demonstrated by reduced corrosion currents in the polarization curves and reduced conductivity losses in incremental capacity (ICA) results.

Efficient separation and selective Li recycling of spent LiFePO4 cathode

Given the fast-growing demand for lithium-ion batteries (LIBs) and the upcoming climax of LIB retirement, efficient recycling of spent LIBs has shown increasing importance in both economic benefit and environmental conservation. The LIBs with LiFePO4 (LFP) cathodes account for half of the LIB market, so developing an appropriate recycling way for spent LFP (SLFP) batteries is imperative. In this work, a closed-loop regeneration of SLFP cathodes is proposed, in which a facile cold stimulation route is invented to peel the SLFP layer from Al foil, and then Li and Fe elements are selectively and efficiently extracted from the peeling SLFP layer under mild conditions based on an oxidant of NaClO. The leaching rate of elemental Li could reach 98.3%, and the regenerated LFP synthesized by recovered Li2CO3 and FePO4 shows exceptional performance with a discharge capacity of 162.6 mAh g-1 at 0.5 C. This regeneration route has greatly reduced the use of chemical reagents, shortened the process of impurity removal, and, therefore, realized the closed-loop regeneration of SLFP batteries.

Strategies towards inhibition of aluminum current collector corrosion in lithium batteries

Aluminum (Al) foil, serving as the predominant current collector for cathode materials in lithium batteries, is still unsatisfactory in meeting the increasing energy density demand of rechargeable energy storage systems due to its severe corrosion under high voltages. Such Al corrosion may cause delamination of cathodes, increasement of internal resistance, and catalysis of electrolyte decomposition, thus leading to premature failure of batteries. Hence, a systematic understanding of the corrosion mechanisms and effective anticorrosion strategies are necessary to enhance overall performance of lithium batteries. In this review, the corrosive mechanisms related to Al current collectors are systematically summarized and clarified. In addition, an overview on recent progress and advancement of strategies toward inhibiting Al corrosion is presented. In the end, we also provide a perspective with motivation to stimulate new ideas and research directions to further inhibit Al corrosion to achieve high energy density, long cycle life, and high safety of lithium batteries.

Self-healing liquid metal layer as high-capacity and long cycle life anode for Al-ion batteries

Rechargeable Al-ion batteries (AIBs) with high capacity and Earth-abundant metal resources are gaining attention. However, the anode side of AIBs has been overlooked, with most using pure Al foil as the anode. In this study, a simple brush painting technique using eutectic Ga-In (EGaIn) liquid metal (LM) creates a high-performance AIBs anode. The EGaIn@Mo anode allows uniform and reversible plating/stripping of Al for over 10,000 h at 10 mAh cm−2 with 99.6 % average Coulombic efficiency. It enables half-cell operation at an ultrahigh areal capacity of 50 mAh cm−2 for over 1200 h. A full cell with EGaIn@Mo anode and graphite cathode maintains a reversible capacity of 82.8 mAh g−1 after approximately 6000 cycles at a high rate of 2 A g−2, exhibiting an ultralow capacity fading rate of 0.00064 % per cycle. Moreover, an anode-free cell lasts over 800 cycles with a specific capacity of 75.9 mAh g−1. This work demonstrates the potential of EGaIn LM coating for high-capacity AIBs and LM anode application.

Efficient separation and coprecipitation for simplified cathode recycling

Hydrometallurgical recycling of spent lithium-ion batteries is among the most promising recovery approaches. The current hydrometallurgical method for battery recycling faces challenges such as complex separation and precipitation processes, and environmental concerns from the use of caustic inorganic acid and hazardous hydrogen peroxide. Our proposed modified method, namely polyol-metallurgy, uses citric acid in ethylene glycol as dual-function green solution to overcome these obstacles. This bifunctional solution leaches valuable metal ions from cathode materials (e.g., LiCoO2), and then acts as chelating agents to selectivxely precipitate cobalt through an esterification reaction, without the need for additional precipitation agents. The leaching efficiency of cobalt and lithium reaches 99.55 % and 97.65 %, respectively, and more than 96 % of cobalt could be directly self-precipitated and recovered. The unique characteristics of the dual-function solution also avoids impurities from Al foils and PVDF/carbon black films, enabling the simple separation process. Therefore, the process can be completed in one-pot system with efficient leaching, separation and coprecipitation, making it more efficient and feasible for operation than existing alternatives.

Efficient Fluoride Wastewater Treatment Using Eco-Friendly Synthesized AlOOH

Fluoride ion is essential for health in small amounts, but excessive intake can be toxic. Meeting safety regulations for managing fluoride ion emissions from industrial facilities with both cost-effective and eco-friendly approaches is challenging. This study presents a solution through a chemical-free process, producing a boehmite (AlOOH) adsorbent on aluminum sheets. Utilizing cost-effective Al foil and DI water, rather than typical precursors, yields a substantial cost advantage. The optimized AlOOH adsorbent demonstrated a high fluoride ion removal rate of 91.0% in simulated wastewater with fluoride ion concentrations below 20 ppm and displayed a similar performance in industrial wastewater. Furthermore, the AlOOH adsorbent exhibited excellent reusability through a simple regeneration process and maintained stable performance across a wide pH range of 4 to 11, demonstrating its capability to adsorb fluoride ions under diverse conditions. The efficiency of the AlOOH adsorbent was validated by a high fluoride ion removal efficiency of 90.9% in a semi-batch mode flow cell, highlighting its potential applicability in engineered water treatment systems. Overall, the AlOOH adsorbent developed in this study offers a cost-effective, eco-friendly, and sustainable solution for effectively removing fluoride ion from surface waters and industrial wastewaters.

Experimental and density functional theory study of the effect of polar groups on interaction at the polyolefin-aluminum laminated film interface

Good adhesive strength and joint durability are necessary for aluminum (Al)/polymer laminated film for lithium-ion battery packages. A modified propylene-based elastomer (mPBE) was prepared as the inner adhesive in this study. The polar group was grafted onto the PBE molecular chain via melt grafting with the assistance of styrene. The adhesive performance of PBE modified with glycidyl methacrylate is significantly higher than that of commercially available inner adhesives, Mitsui A and Dupont 739. Moreover, environmentally friendly trivalent chromium [Cr(III)] chemical conversion was used to treat Al foil and improve the adhesive joint. The wettability behavior of adhesive melt on the surface of Al foil was studied using high-temperature contact angle testing. The results indicate that wettability is not the sole factor impacting interfacial strength, surface energy of the adhesive melt also plays a role. To further study the effect of polar groups on the mPBE adhesion, a solvent casting-evaporation method was developed to prepare an ultra-thin mPBE coating on the Al foil surface. The morphology of mPBE-coated Al foils and the thickness of the coating were studied by atomic force microscope. The bonding mechanism at the interface was studied through time-of-flight secondary ion mass spectroscopy, and it was shown that the Cr(III) conversion coating could react with polar groups via acid-base interaction. Moreover, quantum chemical calculations based on density functional theory were used to reveal the bonding mechanism at the molecular level, and it is found that the adhesive strength is related to the electron-donor abilities and reactivity of the adhesive molecules.

Effect of pretreatment on the interfacial bonding strength between modified polyolefin and aluminum foil treated with trivalent chromium chemical conversion: Experimental, quantum chemical calculations and molecular dynamics simulation

Good adhesive strength and joint durability are necessary for aluminum (Al)/polymer laminated film for lithium-ion battery packages. A pretreatment method involving alkaline degreasing followed by acid pickling was employed to treat the Al foil surface to facilitate the deposition of trivalent chromium [Cr(III)] conversion coating on the surface. The adhesive strength between propylene-based elastomer grafted glycidyl methacrylate (GMA-g-PBE) and Cr(III)-converted Al foil pretreated with 0.5 M HF pickling was 51% higher than Cr(III)-converted Al foil without pretreatment. Moreover, the effect of different pretreatments on the interfacial bond strength of GMA-g-PBE/Cr(III)-converted Al foil was studied from macroscopic to microscopic perspectives. The results indicate that the pretreatment of 0.5 M HF pickling results in complete coverage of the Cr(III) compounds and the formation of a thicker Cr(III) conversion coating on the Al foil compared to other pretreatments. A higher content of Cr(III) compounds results in an increased surface free energy of Cr(III)-converted Al foil, improving the wettability of adhesive melt on the substrate and enhancing the adhesion strength. Moreover, quantum chemical calculations and molecular dynamics simulations were used to investigate the interface bonding mechanism, and the results indicate that GMA in the adhesive exhibits a higher binding energy with Cr(III) oxides and hydroxides compared to Al oxides and hydroxides.

Protective behavior of phosphonate-functionalized imidazolium ionic liquid and its impact on the Li-ion battery performance

The commercial lithium-ion batteries (LIBs) rely on lithium hexafluorophosphate (LiPF6), which is extremely sensitive to moisture and liable to thermal decomposition. Lithium bis (trifluoro methane sulfonyl) imide (LiTFSI), as a promising electrolyte salt, possesses high thermal stability and excellent moisture tolerance. However, LiTFSI is closely related to severe corrosion of the aluminum (Al) current collector at high voltage. Herein, phosphonate-functionalized imidazolium ionic liquid (PFIL) is developed and utilized as an electrolyte co-solvent to inhibit the oxidative dissolution of the Al current collector. PFIL can suppress Al corrosion by participating in the interface reaction and forming a stable and reliable protective film on the surface of Al foils, as confirmed by X-ray photoelectron spectroscopy. Thanks to the corrosion suppression of the Al current collector, the Li||LiNi0.8Mn0.1Co0.1O2 (NCM811) cells with PFIL-containing electrolytes exhibit better cycling performance and improved capacity retention. This work proposes an effective strategy for the advancement of high-voltage LIBs and contributes to promoting the widespread use of the sulfone imide-based lithium salts.

Recycling of Cathode active materials from Spent Lithium-ion Batteries (LIBs): Effective Methodology for Environmental Remediation

In this work, three different solvents such as N, N-Dimethylformamide (DMF), N-Methyl-2-pyrrolidone (NMP) and Dimethyl sulfoxide (DMSO) were used to recycle cathode active materials (CAM) from spent lithium ion batteries (LIBs). Both calcination and solvent dissolution processes were used. The cathode active materials recycled from DMF, NMP and DMSO solvent dissolution process were named as CAM 1, CAM 2 and CAM 3, respectively. Initially, cathode electrode cut into small pieces and then baked at 600 °C for 7 h in tube furnace under argon environment. In the send step baked electrode transferred to solvent and then continue reflux reaction 24 h. In the final step the Al foils were separated from the solution and the cathode active material were collected by vacuum filtration and heat treatment. The structure and morphology of the cathode active materials were characterized by using XRD, Raman, SEM and TEM instruments. The SEM morphology shows that PVDF polymer and acetylene black removed from the cathode active materials by calcination and solvent dissolution process. EDAX and mapping shows that CAM 3 is more pure and uniform morphology than CAM 1 and CAM 2 cathode active materials. The elemental analysis shows that CAM 1, CAM 2 and CAM 3 are NMC 532 cathode powder with a chemical formula Li (Ni5Mn3Co2) O2. XRD results show that R3m layered structure with strong crystalline peaks for all three recycled cathode active materials. Raman analysis confirms the presence of metal oxide.

Recovery of Graphite from Spent Lithium-Ion Batteries

Critical raw materials, such as graphite and lithium metal oxides (LMOs), with a high supply risk and high economic importance are present in spent lithium-ion batteries (LIBs). The recovery and recycling of these critical raw materials from LIBs will contribute to the circular economy model, reduce the environmental footprint associated with the mining of these materials, and lower their high supply risk. The main aim of this paper is to present a separation process to recover graphite from black mass (BM) from spent LIB. Simultaneously, LMO and copper (Cu) and aluminum (Al) foils were also recovered as by-products from the process. The process used a combination of simple and/or low environmental footprint technologies, such as sieving, sink-float, citric acid leaching, and milling through ultrasound and soft attrition, to allow separation of the LIB valuable components. Three graphite-rich products (with purities ranging between 74 and 88 wt.% total carbon and a combined yield of 14 wt.%) with three different sizes (<25 µm, <45 µm, and <75 µm), Cu and Al foil fragments, and an LMO-rich precipitate product are delivered. The developed process is simple, using low temperatures and weak acids, and using affordable and scalable equipment available in the market. Its advantage over other LIB recycling processes is that it can be implemented, so to speak, “in your backyard”.

Microstructure and mechanical properties of Ti/Al laminates fabricated by ultrasonic additive manufacturing assisted by Joule heat and post-welding heat treatment

In this study, a novel electrical-current assisted ultrasonic additive manufacturing (UAM) method was proposed and CP-Ti/Al3003 laminates were prepared by this process. The concept is that the Joule heat generated by the electrical current flowing through the CP-Ti foil is used to improve the material's plasticity, promote the interfacial bonding strength and continuous ultrasonic consolidation ability. Ti/Al laminates with excellent interfacial bonding strength and mechanical properties can be obtained by alternating the use of Ti foil and Al foil and subsequently applying post-welding heat treatment for interfacial strengthening. The current density distribution at the CP-Ti foil and Ti/Al interface was studied by finite element model. The interfacial microstructure of the laminates was characterized and analyzed by optical microscopy, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, and the inhibition effect of current on the resonance cracking of Ti foil during the UAM process was verified. The effect of current on the interfacial bonding strength of the Ti/Al interface and the tensile strength of the laminates was investigated by peel test and tensile test. The growth kinetics of TiAl3 under the assisted current was also studied and CP-Ti/Al laminates with the tensile strength of 242.4 MPa in the rolling direction. The combined effect of Joule heating of current and subsequent post-weld heat treatment strengthened the reaction between Ti/Al and formed TiAl3 IMC layer and obtained CP-Ti/Al laminates without interface defects.

Recycling of NCA cathode material from end-of-life LiBs via Glycerol-triacetate solvent -based separation

Currently, a challenging task for recycling both spent lithium-ion batteries and cathode scrap is the separation of cathode materials from the current collector. A promising and efficient recovery method is to use an organic solvent to dissolve the organic polyvinylidene difluoride (PVDF) binder to recover both cathode materials and aluminum foil. However, the use of toxic solvents hinders its practical application in recycling the large amounts of cathode scrap generated during the manufacturing process. The proposed solvent-based separation process uses glycerol triacetate, a bio-derived green solvent. This study investigates a closed-loop recovery process that recovers cathode materials, including Al foil and PVDF binder, from cathode scrap. Using the glycerol triacetate solvent, a closed-loop recycling process was developed. The glycerol triacetate separation process provides a sustainable platform for the recovery and reuse of electrodes, thereby contributing to battery recycling efforts.