Etched Al Foil Research Articles

Preparation and antibacterial activity of Ag-doped TiO2 coating on the porous surface of aluminum

Aluminum (Al) and its alloys have been widely used in daily life, but the absence of antibacterial properties makes them potential vectors for bacterial transmission. In this study, an Ag-doped TiO2 coating was successfully prepared on the porous surface of etched Al foil using the sol-gel method. The results indicated that the porous layer allowed the gel to permeate through the holes, thereby forming an interface carrying these antibacterial agents with a thickness of about 10 μm. The Ag dopant promoted the transformation of titania from rutile to anatase during the calcination process, with the rutile being absent when the atomic ratio of Ag to Ti reached 0.10. Meanwhile, the doped Ag+ was thermally decomposed into metallic Ag0. As a result, doping Ag enhanced the photocatalytic efficacy of TiO2 coating. Moreover, the antibacterial rate of this coating against Escherichia coli and Staphylococcus aureus under dark conditions could reach more than 99%, and the corrosion resistance of the Al foil was also slightly improved by it.

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.

Ultrahigh loading dry-process for solvent-free lithium-ion battery electrode fabrication

The current lithium-ion battery (LIB) electrode fabrication process relies heavily on the wet coating process, which uses the environmentally harmful and toxic N-methyl-2-pyrrolidone (NMP) solvent. In addition to being unsustainable, the use of this expensive organic solvent substantially increases the cost of battery production, as it needs to be dried and recycled throughout the manufacturing process. Herein, we report an industrially viable and sustainable dry press-coating process that uses the combination of multiwalled carbon nanotubes (MWNTs) and polyvinylidene fluoride (PVDF) as a dry powder composite and etched Al foil as a current collector. Notably, the mechanical strength and performance of the fabricated LiNi0.7Co0.1Mn0.2O2 (NCM712) dry press-coated electrodes (DPCEs) far exceed those of conventional slurry-coated electrodes (SCEs) and give rise to high loading (100 mg cm−2, 17.6 mAh cm−2) with impressive specific energy and volumetric energy density of 360 Wh kg−1 and 701 Wh L−1, respectively.

The preparation of three-dimensional binder-free polyaniline/aligned carbon nanotube on flexible etched Al foil substrate as high-performance pseudocapacitive cathode for nonaqueous lithium-ion capacitor

In this work, 3D binder-free polyaniline (PANI)/aligned carbon nanotube (ACNT) nanocomposite arrays on flexible etched Al foil with strong bonding strength is developed as a high-capacity pseudocapacitive cathode material in a non-aqueous electrolyte for lithium ion capacitors (LICs). The optimized PANI/ACNT nanocomposite with a rational 3D pore structure facilitates the ion transportation and fully utilizes the synergistic effect between PANI and ACNTs to improve capacitive performance substantially. The as-prepared nanoscale PANI demonstrates a specific capacity of 325.2 F•g−1 (180.7 mAh•g−1) at 0.5 A•g−1 in the non-aqueous lithium-ion electrolyte and achieves excellent rate performance and cycling stability (retains 95.6% after for 5,000 cycles charge-discharge at 1 A•g−1 in Li-half cell). Furthermore, when matched with a lithium titanate (Li4Ti5O12) anode, the nanoscale PANI delivers a superior specific energy of 295.3 Wh•kg−1 at the specific power of 125.1 W•kg−1. The as-fabricated LIC delivers a specific energy of 49.6 Wh•kg−1 at the specific power of 21.0 W•kg−1 and successfully retains 39.1 Wh•kg−1 at 480.5 W•kg−1. Moreover, the as-fabricated LIC exhibits an excellent capacity retention of 86.8% after 1,000 cycles at 2 A•g−1. The results verify that the as-prepared PANI/ACNTs/etched Al foil is a promising pseudocapacitive cathode material for high-performance LIC application.

High Peel Strength and Flexible Aligned Carbon Nanotubes/Etched Al Foil Composites with Boosted Supercapacitor and Thermal Dissipation Performances

In this work, aligned carbon nanotubes (ACNTs) were grown on etched Al foil with improved bonding strength by direct thermal chemical vapor deposition. In the interface of the ACNTs adjacent to the etched Al substrate, the ACNTs, tangled together as irregularly shaped “tiny twine balls,” were embedded in the cavities of the etched Al foil. Such a unique structure generated strong bonding strength between the as-grown ACNTs and etched Al substrate. The minimal changes for the equivalent series resistance and deformation of the ACNT/etched Al foil after bending test demonstrated the good flexibility and structural stability of the as-prepared composite material. This flexible, binder-free ACNTs/etched Al foil composite material exhibited excellent electrochemical and thermal dissipation performances. This work provided a versatile and adaptable method by forming micro-sized and irregularly shaped cavities on different kinds of substrates to grow CNTs with strong peel strength for various practical applications.

Stacked High Voltage Al Electrolytic Capacitors Using Zr-Al-O Composite Oxide

A stacked high-voltage (900 V) Al electrolytic capacitor made with ZrO2 coated anode foils, which has not been studied so far, is realized and the effects of Zr-Al-O composite layer on the electric properties are discussed. Etched Al foils coated with ZrO2 sol are anodized in 2-methyl-1,3-propanediol (MPD)-boric acid electrolyte. The anodized Al foils are assembled with stacked structure to prepare the capacitor. The capacitance and dissipation factor of the capacitor with ZrO2 coated anode foils increase by 41 % and decrease by 50 %, respectively, in comparison with those of Al anode foils. Zr-Al-O composite dielectric layer is formed between separate crystalline ZrO2 with high dielectric constant and amorphous Al2O3 with high ionic resistivity. This work suggests that the formation of a composite layer by coating valve metal oxide on etched Al foil surface and anodizing it in MPD-boric acid electrolyte is a promising approach for high voltage and volume efficiency of capacitors.

Etching Anode Foil with Branch Tunnels for Aluminum Electrolytic Capacitors.

Al foil for high-voltage aluminum electrolytic capacitor was first D.C. etched in HCl-H₂SO₄ mixed acidic solution to form main tunnels and then D.C. etched in natural NaCl solution containing 0.1% H2C2O4 and different trace amounts of Zn(NO₃)₂. Between the two etching processes, Zn nuclei were deposited on the interior surface of the main tunnels by the natural occluded corrosion cell effect to form micro Zn-Al galvanic local cells. The effects of Zn nuclei on the cross-section etching and electrochemical behavior of Al foil were investigated using scanning electron microscopy, polarization curve measurement, and electrochemical impedance spectroscopy. The sub-branch tunnels can form along the main tunnels owing to the formation of Zn-Al micro-batteries, in which Zn is the cathode and Al is the anode. Increasing Zn(NO₃)₂ concentration increases the number of Zn nuclei that can serve as sites for branch tunnel initiation along the main tunnels, thereby enhancing the specific capacitance of etched Al foil.

Effects of ZrO2 sol concentration on microstructure and electrical properties of ZrO2-Al2O3 dielectrics formed on Al foils

The effects of ZrO2 sol concentration on the microstructure and electrical properties of ZrO2-Al2O3 dielectrics on etched Al foils are studied. The experiment is carried out by coating the surface of etched Al foils with ZrO2 sol with a series of concentrations and anodizing in the 2-methyl-1,3-propanediol (MPD)-boric acid electrolyte at 700, 800, and 900 V. The increase in the thickness of the ZrO2-coated layer with increasing ZrO2 sol concentration causes a reduction in the total thickness of dielectrics. The tetragonal-to-monoclinic ZrO2 phase change can be induced by anodization and the increase in the crystalline size of tetragonal ZrO2. The Zr-Al-O composite layer after anodization exhibits a microstructure that is a combination of the microstructures of separated high-permittivity crystalline ZrO2 and amorphous high-resistivity Al2O3. The optimal ZrO2 sol concentration is 1.3 M, and the specific capacitances increased by 38% for 700 V, 40% for 800 V, and 66% for 900 V compared with those of non-coated samples.

Effects of current density on anodizing behavior, micro-structure, and electrical properties of ZrO2-coated Al foils

The effect of current density on the anodizing behaviors, micro-structure, and electric properties of ZrO2-coated Al samples is reported. The experiment is performed by coating ZrO2 on the surface of etched Al foils and anodizing in 2-methyl-1,3-propanediol (MPD)-boric acid electrolyte at current densities of 0.01, 0.05, and 0.10 A/cm2 at 700 V. The samples are characterized using X-ray diffraction, field emission transmission electron microscopy, and electrochemical impedance spectroscopy. Marked enhancements in anodization rate, and specific capacitance are achieved by the increase in current density during anodization. A maximum enhancement of 14.8% in specific capacitance and increase of 25.7% in charging ability are realized by anodizing at 0.10 A/cm2. The specific capacitance is finally increased by 54.3% after ZrO2 coating and current density modification. This work provides a valuable forerunner for research into the effect of current density on the anodizing behavior, micro-structure, and electric properties of valve metal oxide-coated Al foils.

Carbon Nanosponge Cathode Materials and Graphite-Protected Etched Al Foil Anode for Dual-Ion Hybrid Supercapacitor

Al-based anode can potentially reduce the dual-ion energy storage device's quality and volume, however, the cycling performance is always insufficient. Herein, we fabricated Al-CNSs hybrid supercapacitors (SCs) using carbon nanosponge materials (CNSs) as cathode materials and graphite-protected etched Al foils as the anodes. The macro-/mesoporous structure in CNSs facilitates the ions (solvated PF6−) transport, resulting in much better SC rate capability compared to the commercial activated carbon. The etched pores in Al foil offer numerous alloying reaction sites to accommodate the volume expansion. In addition, the graphite layer on the Al surface blocks the Li dendrite growth, leading to homogeneous alloying-dealloying reaction. Such Al-CNSs hybrid SC delivered a high maximum specific capacitance of 181 F g−1 at 0.05 A g−1, remained 62 F g−1 at 1 A g−1, and offered a retention value of 83% after 1000 cycles, which was largely improved compared to the pure Al and etched Al without coating. The whole device can offer 75 Wh L−1 due to the thin anode design, which is comparable to the lead acid batteries.

Effects of borate polyester mixed with water on anodizing behavior and electrical properties of ZrO2-coated Al foil

ZrO2-Al2O3 composite oxide film is a promising dielectric material for future application in aluminum electrolytic capacitors. Herein, ZrO2-Al2O3 composite oxide films are prepared on etched Al foils via ZrO2 sol-gel coating and anodization. Generally, Al foil anodization is performed in an aqueous boric acid electrolyte. However, if the Al foils are anodized above approximately 700V, a boric acid solution is unsuitable for use as an electrolyte, because it facilitates O2 evolution. Therefore, in this study, we use a borate polyester solution as an electrolyte for anodization at a relatively high voltage, and discuss the effects of the borate polyester concentration on the anodization behavior and electrical properties of the ZrO2-coated Al foils. The results suggest that a borate polyester electrolyte with high resistivity is suitable for use in high-voltage anodization, as it effectively increases the sample withstanding voltage. Further, the specific capacitances of the samples decrease as the borate polyester to water ratio increases; the most suitable ratio is found to be 0.4. Relative to those of samples anodized in boric acid solution, the specific capacitances of the samples anodized in the borate polyester electrolyte with a 0.4 mixing ratio are increased by 12.7%, 8.9%, and 43.3% for 700, 800, and 900V, respectively.

Structures and interfaces of CNT: pyrolytic C coated Al foil and its performance as current collector of electrochemical double layer capacitor

Al foil with CNT—pyrolytic C composite layer of 300 nm (CNT-C/Al) has been prepared by coating Al foil with CNT and polymeric precursors and heating it in rolls at 585 °C in argon flow. By Raman analysis, both sp3 and sp2 mode carbon are formed in pyrolytic C produced in-situ in the coating, and has interacted with walls of CNTs. Well—combined interfaces of CNT with pyrolytic C and carbon coating with Al matrix are seen in CNT-C/Al by scanning electron microscope and high resolution transmission electron microscopy. Metallurgical bonding of carbon layer and Al matrix is confirmed by X-ray Diffraction for generation of Al4C3 in CNT-C/Al. Interfacial resistances of Al foil with carbon coating are evaluated by resistances of “sample piece/PEDOT layer/sample piece” stacks, which is 12 ± 2 mΩ for CNT-C/Al and 44 ± 2 mΩ for CNT-C/Al-control with generation of Al4C3 restrained. Researches on electrochemical double layer capacitor (EDLC) electrodes reveal that samples using etched Al foil (E-Al) as current collector present higher sheet resistances than CNT-C/Al. EDLCs using CNT-C/Al as current collector show higher capacitances and lower resistances than those using E-Al, and the differences become bigger when current flow increases. Notably, EDLCs using CNT-C/Al prove outstanding stability in resistance during galvanostatic charge—discharge cycles at current of 4.0 A for 10,000 times and accelerate lifetime test at 85 °C/2.85 V for 64 h, while the corresponding increase rates for EDLC using E-Al are 19.6% and 30% respectively.

Effect of electrodepositing Ag on DC etching aluminum foils for electrolytic capacitor

Ag nuclei were electrodeposited on the surface of aluminum foil to induce tunnel etching. The effects of Ag nuclei on the surface and cross-section etching morphologies and electrochemical behavior of Al foil was investigated with SEM, polarization curve (PC) and electrochemical impedance spectroscopy (EIS). It is proved that the tunnels etched in this way are distributed more uniformly and the density of tunnels and pits are enhanced, leading to increase in specific capacitance of etched Al foil. These effects can be attributed to the mechanism that the Ag nuclei can serve as the favorable sites for tunnel initiation on aluminum foil surface owing to the formation of Ag–Al micro-batteries, in which Ag is cathode and Al is anode. This mechanism is supported by the SEM, PC and EIS.

Improving the Electrochemical Properties of High-Voltage LiNi0.5Mn1.5O4 for Li-Ion Battery by Modified Current Collectors

The stability of current collector in high voltage LiNi0.5Mn1.5O4 batteries and the rate performance and cyclic stability of LiNi0.5Mn1.5O4 electrodes using three current collectors were investigated, including an Al foil, an etched Al foil (E-Al), and a carbon-coated Al foil (C-Al). The oxidation stability of current collector at high voltage is significantly improved by carbon coating on the Al foil, which can make a good contact between the current collector and active layer. The surface structure and composition of the current collectors strongly affect the rate capability and cyclic performance of LiNi0.5Mn1.5O4 electrodes. Interestedly, using the C-Al current collector not only remarkably increases the rate capability with the capacity of 78 mAh g−1 and the average discharge voltage of 4.1 V at 40 C-rate, but also greatly enhances its cyclic stability at 55°C. Furthermore, the formation of a thin and uniform surface film is observed on the cycled LiNi0.5Mn1.5O4 electrode using the C-Al current collector, which can be attributed to reducing the electrode polarization and suppressing the electrolyte decomposition, leading to good capacity retention. In brief, the carbon-coated Al foil can be applicable to the high voltage LiNi0.5Mn1.5O4 material of Li-ion battery.

Effects of 2-methyl-1, 3-propanediol in boric acid solution on the anodizing behavior and electrical properties of ZrO2-coated Al foil

Zr-Al2O3 composite oxide films are promising dielectric materials for future use in aluminum (Al) electrolytic capacitors. The films were prepared on etched Al foil samples by ZrO2 sol-gel coating and anodizing. To inhibit O2 evolution during anodization, 2-methyl-1, 3-propanediol (MPD) was used with boric acid solution as an electrolyte. In this study, we investigated the effects of the ratio of MPD in boric acid solution on the anodizing behaviors and electrical properties of ZrO2-coated Al foil. The thickness of the Al2O3 layer decreased as the MPD ratio increased. The MPD-boric acid solution effectively inhibited O2 evolution. The samples anodized in MPD-boric acid electrolyte with a ratio of 3:10 (volume %) exhibited the highest specific capacitance. Relative to those of samples anodized in boric acid solution, the specific capacitances of samples analyzed in the MPD-boric acid electrolyte increased by 45.5% at 700V, 40.0% at 800V, and 66.7% at 900V.

Effect of Al2O3-ZrO2 Composite Oxide Thickness on Electrical Properties of Etched Al Foil

To increase the capacitance of an Al electrolytic capacitor, the anodic oxide film, Al2O3, was partly replaced by an Al2O3-ZrO2 (Al-Zr) composite film prepared by the vacuum infiltration method and anodization. The microstructure and composition of the prepared samples were investigated by scanning electron microscopy and transmission electron microscopy. The coated and anodized samples showed multi-layer structures, which consisted of an inner Al hydrate layer, a middle Al- Zr composite layer, and an outer Al2O3 layer. The thickness of the coating layer could go up to 220 nm when the etched Al foil was coated 8 times. The electrical properties of the samples, such as specific capacitance, leakage current, and withstanding voltages, were also characterized after anodization at 100 V and 600 V. The capacitances of samples with ZrO2 coating were 36.3% and 27.5% higher than those of samples without ZrO2 coating when anodized at 100 V and 600 V, respectively.

Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

Al2O3–TiO2 (Al–Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol–gel process were annealed at various temperatures (450, 500, and 550°C) for different time durations (10, 30, and 60min) for 4 cycles, and then anodized at 100V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al–Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550°C for 10min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

Formation and properties of Al2O3–ZrO2 composite anodic oxide film on etched aluminum foil by electrodeposition and anodization

Etched-Al foils were cathodic electrodeposited in Zr(NO3)4 solution, following by annealing at 500 °C and anodization to fabricate Zr–Al composite anodic oxide film. The time-variation in anode potential during anodization was recorded on a digital multimeter connected to a PC system. The surface morphology, composition and electrochemical properties of the film were examined with SEM, EDS, RBS, EIS and LCR digital bridge, respectively. The results show that the resulted composite anodic oxide film has triple layer of ZrO2/Al–ZrOx/Al2O3 on aluminum substrate. The specific capacitance and formation efficiency for the deposited and annealed sample are much higher than those without deposition or annealing, due to the higher dielectric constant of ZrO2 and thermal aluminum oxide. But the resistance of composite anodic oxide film is decreased, due to doping-introduced structural defects.

Preparation and Properties of Y2O3-Doped ZrO2 Films on Etched Al Foil by Sol-Gel Process

Preparation and Properties of Y2O3-Doped ZrO2 Films on Etched Al Foil by Sol-Gel Process

Formation Behavior of Multi-Layer Oxide Films on Etched Al Foil by Vacuum Infiltration and Anodization

A vacuum infiltration method was proposed to coat uniform zirconia (ZrO2) films on etched aluminum (Al) foil. The formation behavior of the composite oxide films on aluminum (Al) foils with etch pits was different from that of flat Al foils. The multi-layer structures were formed on the ZrO2-coated Al foil after being anodized. The formation mechanism of the multi-layer films on etched Al foils was discussed. The structure and composition of each layer were investigated by scanning electron microscopy and transmission electron microscopy. The multi-layer films consisted of an inner aluminum hydrate layer, middle Al2O3-ZrO2 (Al-Zr) composite layer, and outer Al2O3 layer. Many Al3+ ions passed through the coating layer and transferred into the inner layer. A particle-like and layered structure was observed in the inner layer. The formation of multi-layer films was mainly affected by the volume expansion of the outer Al2O3 layer and the dense middle Al-Zr composite oxide film. The ZrO2 coated foils exhibited 26% higher specific capacitance than foils with only Al2O3 layer when being anodized at 600 V.