Pulse Current Plating Research Articles

Investigation on the effect of nickel and nickel-chromium alloy pulse current plating on copper substrate

ABSTRACT In the present study, nanocrystalline nickel (Ni) and nickel-chromium (Ni-Cr) alloy coatings were developed on copper (Cu) substrate using pulse current. The pulse current parameters include a cycle time of 240 milliseconds at a duty cycle of 0.5 and 4.17 Hz frequency. The surface morphology, texture, hardness, scratch resistance and porosity were investigated for different coatings developed by pulse plating. Energy Dispersive Spectroscopy (EDS) analysis revealed good quality Ni and Ni-Cr alloy coatings developed on the copper substrate. The peak current of the pulse has been observed to have an impact on the coating weight and thickness. The micrographs of the coatings explored under Field Emission Scanning Electron Microscopy (FESEM), depict uniform coatings consisting of fine primary and coarse secondary granules of Ni and Cr. The hard primary and secondary Ni granules deposited on the surface of Cu increase its hardness, corrosion and wear resistance. Further, it was observed that the Ni-Cr alloy plated samples are harder and less porous in nature compared to Ni plated samples.

Pulsed Current Constructs 3DM Cu/ZnO Current Collector Composite Anode for Free-Dendritic Lithium Metal Batteries

Although lithium metal is an ideal anode material for achieving high-energy-density lithium-based batteries, the uneven deposition/exfoliation process of lithium during cycling easily triggers the formation of lithium dendrites and dead lithium, which leads to a low Coulombic efficiency and safety issues. In this paper, a lithiophilic 3D copper mesh current collector is designed by using lithiophilic ZnO and pulsed current plating and is applied to a lithium metal battery composite anode. Under the action of the pulsed current field, the novel lithium metal composite anode battery achieved the homogeneous deposition of lithium ions. The lithium-to-copper half cells assembled with the 3DM Cu/ZnO current collector from the pulsed current deposition presented a Coulombic efficiency as high as 97.8% after 1 min of activation at 3 mA cm−2 follow by 10 cycles at a stripping current of 0.5 mA cm−2. Moreover, the symmetric cell could be stable for 1500 h at 1 mA cm−2 with a limited capacity of 1 mAh cm−2, and the assembled full cell (LiFePO4 as the cathode) maintained a Coulombic efficiency of about 90% for the 30th cycle at 1 C. This novel mechanism is an advanced strategy to improve cyclic stability and is crucial for designing stable lithium metal batteries.

The Effect of Pulse Current on Electrolytically Plating Nickel as a Catalyst for Grafting Carbon Nanotubes onto Carbon Fibers via the Chemical Vapor Deposition Method

Carbon nanotubes (CNTs) can be directly grafted onto the surface of carbon fibers using the chemical vapor deposition method, in which nanometer-order nickel (Ni) particles, serving as catalysts, are plated onto the surface of carbon fibers via electrolytic plating. In our previous studies, in which a direct current (DC) was used to electrolytically plate Ni onto carbon fibers as a catalyst, the site densities and diameters of Ni particles increased simultaneously with the plating time, making it difficult to independently control the site densities and diameters of the particles. On the other hand, pulse current (PC) plating is attracting attention as a plating technique that can control the deposition morphology of nuclei. In this study, we clarify the effect of the parameters of the PC on the particle number per unit area (site density) and the particle diameters of Ni particles plated onto the surface of carbon fibers, using the PC to electrolytically plate Ni. Electrolytically plating Ni onto carbon fibers (via PC) after the removal of the sizing agent enable Ni particles with sparser site densities and larger diameters to be plated than those plated via DC. Using Ni particles with sparse site densities, it is shown that CNTs with sparse site densities can be grafted.

Pulsed Current Plating Does Not Improve Microscale Current Distribution Uniformity Compared to Direct Current Plating at Equivalent Time-Averaged Plating Rates

Suppression of surface roughness and dendrite growth under pulsed current (p.c.) plating is a widely reported effect for a variety of electrodeposited metals. Often, this effect is attributed to the modulation of mass transport during pulsing. In the present contribution, we use numerical simulations and scaling analysis to shed light on the transient mass transport effects near a 2D microscale pattern subjected to p.c. plating. Specifically, we compare the microscale current distribution during p.c. to that during direct current (d.c.) plating at an equivalent time-averaged plating rate. Modeling shows that the more uniform current distribution for a given time-averaged plating rate is that obtained during d.c. plating. The current distribution during p.c. plating is found to be less uniform in comparison to d.c., and the mechanistic rationale underlying this effect is explained using scaling analysis. Results reported herein have implications to the understanding of pulsed currents in applications ranging from thin-film electroplating to battery charging.

The Properties of Pulse-Plated Copper Derived from Additive-Bearing, Low-Metal Ion Concentration Electrolytes

In semiconductor devices, copper metallization patterns are created using a combination of photolithography and electroplating. Photolithography, which uses light to transfer geometric patterns from a mask onto a substrate, is a multi-step process that is costly, time-consuming, and entails the use of harmful chemicals. A recent electrodeposition process called Electrochemical nano and micro Fabrication by flow and Chemistry (EnFACE) was developed to enable single-step, direct, mask-less pattern transfers onto metallic substrates. EnFACE offers the possibility of replacing photolithography and avoid the difficulties associated with the process. For typical copper electrolytes, the use of pulsed current and plating additives are known to improve deposit properties such as grain structure, mechanical strength, and throwing power. However, EnFACE uses an acid-free, additive-free, low-conductivity plating electrolyte containing low concentrations of metal salts (0.1 M CuSO4), a composition which significantly differs from the conventional copper plating electrolytes. Since the chemistry of this electrolyte is relatively new, a majority of its properties still needs to be discovered and understood. In this work, we report on the influence of current modulation (i.e., pulsed-current) on the properties of Cu electrodeposits obtained from additive-bearing, low metal salt concentration electrolyte. Copper films were plated from 0.1 M CuSO4 electrolyte containing different concentrations of plating additives (i.e., 0%, 17%, 33%, 50%, 100%, and 200% of the industry recommended concentration) using direct (DC) and pulsed current (PC) modulations. The operating pulse parameters used were θ = 0.25 at a t p of 100ms and the actual plating time was set for a deposit thickness of 25 um. The mechanical properties of deposits were characterised using the tensile test (UTM), while electrical properties were assessed using the four-point probe. Grain characteristics and morphology was investigated using scanning electron microscope (SEM), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD). Results of mechanical tests indicate that the PC-plated films possessed higher yield strength, tensile strength and ductility than its DC-plated counterparts (see Fig.1). Similarly, electrical measurements confirmed that pulse plated films have better conductivity than the DC plated ones. These changes in properties were traced to the changes in microstructure induced by the application of pulsed current modulation during plating. Finally, the use of pulsed current offers the added benefit of reducing the required amount of additives to obtain the desired deposit properties. The optimum additive concentration was 50% of the recommended value when using DC plating; while it was only 33% in PC plating. Figure 1

Thick tungsten coating obtained by pulse reverse electroplating from molten salt in atmosphere

Tungsten (W) coatings were pulse reverse electroplated on low activation steel from Na2WO4-WO3 system in air atmosphere. The introduction of pulse reverse current could result in higher current efficiency and better surface quality of tungsten coatings than those obtained by pulse current plating from molten salt, while the preferential orientation changed from (200) plane to (211) plane. In addition, the ion composition of the Na2WO4-WO3 molten salt kept stable during the process of pulse reverse electrodeposition and a thick W coating could be pulse reverse electroplated from this system with long duration. The tungsten coating with columnar structure and good compactness exhibited a high thermal conductivity of 150.30 W · m−1 · K−1.

The effect of sliding speed on the wear behavior of pulse electro Co-deposited Ni/MWCNT nanocomposite coatings

In this study, Ni/MWCNT nanocomposite coatings were prepared from a modified Watt׳s type electrolyte by using pulse current (PC) plating technique. The influence of multi walled carbon nanotube (MWCNT) content in the electrolyte on the tribological properties of nanocomposites were tested by using a reciprocating ball-on disk apparatus, sliding against to M50 steel ball (Ø 10mm). Coatings were characterized using Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis before and after wear testing. Nanocomposite coatings showed wear rate decrease between 1.31 and 1.40 times compared with pure Ni coatings. Friction coefficient decreased from 0.883 for pure Ni coating to 0.419 for the Ni/MWCNT nanocomposite because of graphitization and self lubrication effect of the MWCNTs.

Preparation of Surfaces of Germanium and Kovar Substrates By Electroplating for Soldering

Germanium is used as a window material in packaging infrared detector structures, due to its high refractive index and transmittance to infrared radiation. It must be joined to the dewar body made of Kovar® (registered trademark of Carpenter Technology Corporation) material by soldering during packaging. A surface coating (metallization) well adhered to both substrates was developed as a surface preparation step prior to soldering to overcome the poor wetting characteristics of germanium. Successive electroplating of 3 mm wide nickel and gold frames to the outer edge of a circular germanium window and kovar body was applied to attain successful joining of germanium to kovar. Surface cleaning of parts to be joined or plated is very essential to remove contaminants from the surface and reduce oxides to the highest possible extent. Onsia and Conard [1], reported that wet chemical processes need to be developed to prepare germanium surface for subsequent growth processes. The wet chemical treatment for germanium surface preparation used in this study followed the reciepe originally proposed by Shiyu Sun et. Al. [2]. The samples were first dipped into deionized water having a resistivity of 18.6 MΩ cm, for 30 seconds to dissolve the native oxide. Then, they were placed into 10% H2O2 solution for 30 seconds to eliminate the carbon contaminations on the surface. Finally, the samples were immersed into a hydrofluoric acid solution for 10 minutes to remove the oxides. X-Ray Photoelectron Spectroscopy (XPS) results showed that more than 70% of oxides on the surface could be eliminated by the surface preparation treatment proposed above. A chemical polishing method was applied for kovar surface cleaning. Solution bath was composed of 750 mL CH3COOH (Sigma Aldrich, 1005706), 250 mL HNO3 (Sigma Aldrich, 438073) and 3 mL HCl (Sigma Aldrich, 438073). The temperature was kept constant at 60°C and the solution was not stirred during cleaning. The nickel was deposited at 55oC from the Watts solution, containing 240 g/L NiSO4.6H2O, 45 g/L NiCl2.6H2O and 30 g/L boric acid (Merck, 100165), because it is easy to control the bath and deposits have lower internal stresses. The wave characteristic of pulse current and saccharin addition have important effects in nickel plating [3] in terms of porosity, grain size and densty of coatings Addition of saccharin to the bath and the use of pulse plating decreased the grain size of the nickel and changed the morphology of the grains from pyramidal structure to colony like in coating. A thin layer of gold, as pore free as possible, was required to protect the nickel surface from oxidation. Gold was electrodeposited on the nickel coated kovar substrate from the acid cyanide bath at 50oC by pulse and direct current plating in this study. The bath was composed of 10 g/L potassium gold cyanide and 180 g/L potassium citrate. The gold films obtained by pulse plating exhibited stronger adhesion to nickel surface and contained less porosity compared to DC plating. The porosity of gold coating was determined by the IPC-TM-650 test method. The solution used in porosity test was composed of 980 mL ethanol, 7 g dimethylglyoxim (Sigma Aldrich, 162574), 20 mL de-ionized water and 1 g ammonium chloride (Merck, 168320). The increase in gold deposit thickness in 0.1 to 0.4 µm range decreased porosity.

CHARACTERIZATION AND MICROHARDNESS OF ELECTRODEPOSITED Ni–W COATINGS OBTAINED FROM GLUCONATE BATH

Ni – W alloy coatings are electrodeposited with direct and pulse current using gluconate bath at pH5. Effects of direct current (DC) and pulse current (PC) on structural characteristics of the coatings have been investigated by energy dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). EDXS shows that W contents are 13.3 and 12.6 at.% in DC and PC (10:40) Ni – W coatings, respectively. FESEM analysis exhibits the homogeneous coarse nodular morphology in DC plated deposits. DSC studies reveal that Ni – W coatings are thermally stable up to 400°C. XPS studies demonstrate that DC plated coating has significant amount of Ni and W in elemental form along with their respective oxidized species. In contrast, mainly oxidized metals are present in the as-deposited coatings prepared with PC plating. The microhardness of pulse current (100:400) deposited Ni – W coating is about 750 HK that is much higher than DC plated coating (635 HK). Heat treatment of the deposits carried out at different temperatures show a significant increase in microhardness which can be comparable with hard chromium coatings.

Electrodeposition of Gold to Conformally Fill High Aspect Ratio Nanometric Silicon Grating Trenches: A Comparison of Pulsed and Direct Current Protocols.

Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of x-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.

Effect of PC electrodeposition on the structure and tribological behavior of Ni–Al2O3 nanocomposite coatings

In this study, Ni–Al2O3 metal matrix composite (MMC) coatings were prepared from a modified Watt's type electrolyte by pulse current (PC) plating under current densities varying between 1 and 9A/dm2. The tribological tests were performed with a reciprocating ball-on-disk apparatus sliding against a M50 steel ball (Ø 10mm). The wear tests were carried out at sliding velocities of 50, 100 and 150mm/s under a constant load. The results compared with our previously published work of DC electrodeposited coatings. The results showed that the electrodeposition method can significantly affect the microstructure and tribological behavior of Ni–Al2O3 nanocomposite coatings. For the same current density, PC electrodeposition creates coatings with higher co-deposited particle content, more homogenous particle distribution, higher wear resistance at high sliding distance and improved friction coefficients. The superior dispersion of Al2O3 nanoparticles in PC-coated materials contributed to its increased load bearing capacity. Detailed tribological tests and characterization showed that DC- and PC-coated nanocomposite layers yielded different wear mechanisms depending on the sliding velocity.

Pulse plated Zn transition layer in electroplating Sn–Ni alloy coatings on magnesium alloys

An environmentally friendly Zn transition layer was electrodeposited on the AZ31 magnesium alloy substrate aimed to improve its corrosion resistance during the process of electroplating Sn–Ni alloy coating. Direct current (DC) and pulse current (PC) electroplated Zn layers with different thicknesses were compared. Scanning electron microscopy and X‐ray diffraction were employed to investigate the surface morphology and microstructure. The corrosion resistance of the Zn transition layers was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in Sn–Ni plating solution. The results showed that the Zn transition layer was essential for subsequent electroplating Sn–Ni alloy coating on magnesium alloy. For the same thickness, the application of the PC plating mode was more favorable to prepare compact, smooth, non‐porous, and fine Zn transition layer. Moreover, the corrosion resistance of PC plated Zn transition layer was enhanced compared to the DC plated layers. Most importantly, a Sn–Ni alloy coating could be successfully electrodeposited on magnesium alloy by using PC plated Zn transition layer.

Metallization of Germanium by Electroplating Prior to Soldering

Elemental semiconductors; mainly silicon and germanium, are widely used in various technological fields such as optics, electronics and solar cells. For devices that work with IR (Infrared) radiation such as IR detectors, thermal and night vision cameras, germanium is the most widely used window material because of its high IR radiation transmittance. One of the problems regarding the use of semiconductors as part of an electronic device is their integration into the device and joining of the parts. The aim of this study is to provide a solution to germanium-metal joining problem by successively electroplating 3 mm wide nickel and gold frame on the outer edge of a circular germanium window.Surface cleaning of parts to be joined or plated is very essential in order to remove contaminants from the surface and reduce oxides to the highest possible extent. Onsia and Conard [1], reported that wet chemical processes need to be developed to prepare germanium surface for subsequent growth processes. The wet chemical treatment for germanium surface preparation used in this study followed the reciepe originally proposed by Shiyu Sun et al [2]. Samples were first dipped into deionized water having a resistivity value of 18.6 MΩ cm, for 30 seconds to dissolve the native oxide. Then, they were placed into 10% H2O2 solution for 30 seconds to eliminate the carbon contaminations on the surface. Finally, the samples were immersed into a hydrofluoric acid solution for 10 minutes to remove the oxides. X-Ray Photoelectron Spectroscopy (XPS) results showed that more than 70% of oxides on the surface could be eliminated by the surface preparation treatment proposed above.In this study, nickel was deposited at 55oC from the Watts solution, whose chemical composition is given in Table 1, because it is easy to control the bath and deposits have lower internal stresses. An important parameter in nickel plating is the applied current waveform: pulse or direct current. Chandrasaker and Pushpavanam [3] indicated that pulse plating methods produced less porous, finer grained and denser coatings when compared to direct current deposition of nickel. Another factor affecting the grain size and microstructure of Ni deposits is using additives like saccharin. SEM images of two different nickel deposits are shown in Figure 1. It can clearly be seen that addition of saccharin to the bath and using pulse plating technique decreased the grain size of the nickel plating and changed the morphology of the grains from pyramidal structure to colony like structure.A thin layer of gold is required to protect the nickel surface from oxidation, which must be as pore free as possible to prevent the diffusion of oxygen to nickel or nickel to the surface. Gold was electrodeposited on the nickel coated germanium substrate from the acid cyanide bath (see Table 1) at 50oC by pulse and direct current plating in this study. Gold films obtained by pulse plating exhibited stronger adhesion to nickel surface and contained less porosity compared to DC plating. Homogeneous and bright yellow deposits were obtained at higher duty cycles.Table 1: Watts nickel and acid cyanide gold plating bathsWatts Nickel Plating BathAcid Cyanide Gold Plating BathNickelSulfate240 g/lPotassiumGoldCyanide10 g/lNickelChloride45 g/lBoric Acid30 g/lPotassiumCitrate180 g/l Figure CaptionFigure 1: SEM images of nickel plated surfaces by (a) DC plating and (b) pulse plating with saccharin addition.

Characterisation of tungsten coatings by pulsed current plating from molten salt in air atmosphere

Pure and compact tungsten coatings with high (200)-orientation were successfully electrodeposited from Na2WO4–WO3 binary oxide molten salt by direct and pulse current techniques on copper based alloy substrate in air atmosphere at 1173 K. The tungsten coatings and copper alloy substrates combined well with no obvious voids and cracks. In addition, the influence of pulse plating on the microstructure, crystal structure and Vickers microhardness of coatings, adhesive strength between coatings and substrates as well as the current efficiency was investigated. It was also observed that applied pulse current led to tungsten coatings with better mechanical properties than those obtained by direct current plating. In addition, a tungsten coating of 500 μm which had lower oxygen content and higher adhesive strength than the coating obtained by the plasma spray method was obtained.

Effects of plating parameters on the Ni–P–Al2O3 composite coatings prepared by pulse and direct current plating

In this study, Al2O3 nanoparticles were incorporated into Ni–P alloy matrix by pulse current (PC) and direct current (DC) plating. The effects of bath composition and operating conditions of electrodeposited Ni–P–Al2O3 composite coatings were studied, and the micro-hardness of the deposits was determined. The results showed that with increasing current density as well as Al2O3 content in the bath for DC plating, the embedding volume percentage of Al2O3 of coating increased and the phosphorus content decreased. The incorporation percentage of Al2O3 particles in the composite coatings prepared by PC plating was significantly affected by pulse plating parameters such as average current density, duty cycle and frequency as well as the bath composition. It is also found that PC plating leads to higher embedding percentages and more homogeneous distribution of Al2O3 particles in the Ni–P matrices compared with deposits prepared under DC conditions. The incorporation percentage of Al2O3 particles in PC plated composite coatings increased when high duty cycles and high frequencies were used. The hardness of the composite coatings deposited with a pulse current increased as the duty cycle increases from 0.2 to 0.7.

Plating pulse switching power based on a CPLD

This paper presents a method of using a CPLD to generate a PWM trigger pulse to a full bridge inverter and a chopper circuit. This method results in a very good high power and low voltage large current pulse plating power supply. A single-chip microcomputer is the core of the feedback control system. A fuzzy PID algorithm with SCM and CPLD complexes precisely controls the output voltage, allowing it to maintain a constant value. The system contains a protection circuit that detects output current and output voltage and can correct the system if it enters an over-current abnormal state, ensuring that the driving circuit can effectively drive the IGBT. The circuit is also protected by setting the inverter frequency and dead time of a digital PWM chip. This method for bidirectional pulse plating power supply digital control was verified to be correct and practicable by a Matlab software simulation.

STUDIES ON SURFACE STRUCTURE, MORPHOLOGY AND COMPOSITION OF Co–W COATINGS ELECTRODEPOSITED WITH DIRECT AND PULSE CURRENT USING GLUCONATE BATH

Co–W alloy coatings were deposited with direct current (DC) and pulse current (PC) electrodeposition methods using gluconate bath at pH5 and characterized by X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). DSC studies hint at the possibility of formation of metallic glasses. Detailed XPS studies of these alloy coatings have been carried out to compare elemental states and composition of Co and W in DC and PC electrodeposited alloys. DC-plated alloy has significant amount of Co and W metal along with their respective oxidized species. In contrast, mainly oxidized metals are present in the following layers of as-deposited coatings prepared with PC plating. Concentration of Co metal is observed to increase during sputtering, whereas there is no change in W6+ concentration. Microhardness measurement of all the Co–W coatings shows higher hardness compared to Co metal and 1:1 and 1:4 PC electrodeposited coatings show little higher hardness compared to 1:2 PC electrodeposited coating.

Structural and corrosion characterisation of pulse plated Zn and Zn–Ni alloy coatings

The effects of pulse plating on the phase and chemical composition, preferred orientation and surface morphology of Zn and Zn–Ni (12 wt-%) electrodeposited coatings have been investigated using atomic force microscopy, scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy and electrochemical techniques. It has been established that pulse current plating with respect to direct current (dc) conditions resulted in ∼50% reduction in the grain size dimensions and in fourfold and twofold reduction in the corrosion current densities of Zn and Zn–Ni coatings respectively. Under all the pulse plating conditions applied the deposited alloy consisted of the single γ-Zn21Ni5 phase, while, according to the XRD measurements both coatings possessed inclusions of the oxide phase. The analysis of the protective properties and the thickness of the oxide films formed on the surface of investigated coatings revealed the fact that the surfaces of pulse plated samples were favourable for the formation of thinner oxide films which at the same time exhibited higher protective properties. Pulse plating increased the amount of non-metallic inclusions in Zn and Zn–Ni coatings, however, these amounts were not high, as the O concentration in the deposits did not exceed 1·5 and 0·2 wt-% for Zn and Zn–Ni respectively.

In-situ analysis of inner crack instability of electro-deposited trivalent chromium layers using small angle neutron scattering

Inner crack behavior of electro-deposited trivalent chromium was analyzed in-situ by small angle neutron scattering to study the abrasive heating effect on neutral salt fog spray life. The trivalent chromium was prepared by different current wave forms, namely, direct and pulse current-plating with a modified chromium chloride bath. The trivalent chromium layer has columnar grains in which small chromium clusters and inner cracks are present. Pulse current plated trivalent chromium has a longer neutral salt fog spray life than direct current plated trivalent chromium. As surface temperature increases to 80 °C, inner cracks of the trivalent chromium layer formed by direct current plating tend to have a fractal shape by opening crack tips, whereas those of the chromium layer formed by pulse current plating are relatively stable. The inner crack with a fractal shape is related to an abrupt reduction of the neutral salt fog spray life of the trivalent chromium.

Development of high energy capacities of nanoscaled Sn–Cu alloy thin film electrode materials for Li-ion batteries

A nanoscaled Sn–Cu alloy film material is intended to improve charge–discharge capacities with respect to the negative electrode in Li-ion batteries. Sn–Cu alloy film electrodes are prepared using sulfate electrolyte by a pulse current plating method. Pulse duty cycles of 10% at a frequency of 10Hz with a peak current density 1Adm−2 are employed. The electrochemical discharge–charge capacities of the lithium insertion process and the reversible charging process are 1058mAhg−1 and 612mAhg−1 in the initial cycling, respectively. Also, Coulombic efficiency was 87.2% at the end of the 30th cycle. Thus, nanoscaled Sn–Cu alloy film electrodes are good candidates for anode material in Li-ion rechargeable batteries.