Constant Current Deposition Research Articles

Ru and MWCNTs-OH co-modified copper foam as high-performance electrode materials for electrocatalytic degradation of doxycycline

In this study, an efficient composite electrode for the degradation of doxycycline (DC), i.e., the ruthenium/hydroxylated multi-walled carbon nanotube/copper foam composite electrode (Ru/MWCNTs-OH/CF), was prepared by the constant current deposition method. The composite electrode was characterized by SEM, XRD and XPS. Impedance testing, polarization curve analysis, and linear voltammetry analysis were conducted on the composite electrode, confirming that the combination of MWCNTs-OH and Ru can reduce the charge transfer resistance of the electrode and significantly improve catalytic activity. Under optimal conditions, the degradation efficiency of the Ru/MWCNTs-OH/CF composite electrode for 10 mg/L DC reached 77.20 % at 60 min. The degradation reaction followed the proposed primary reaction kinetics. The degradation efficiency only decreased by 2.23 % after ten cycles of the experiment, indicating the excellent stability of the electrode. The reaction mechanism was investigated by LSV and quenching experiments. The results showed that DC was degraded under the synergistic action of ·OH, H* and active chlorine species. The degradation path of DC was deduced by LC-MS. The E. coli inhibition experiment and toxicological assessment based on ecological conformational relationships confirmed that the toxicity of the product organisms generated by DC degradation at the Ru/MWCNTs-OH/CF electrode was significantly reduced. The results indicate that the Ru/MWCNTs-OH/CF electrode has high activity and stability and is a promising material for practical applications in the removal of antibiotics from water.

Controlling the Morphology of Electrodeposited Lithium Metal Via Seeded Growth: Stepwise Spherial to Fibrous Lithium Growth

Lithium metal has been gained intense research interest because of its high specific capacity and lowest electrochemical potential for next generation battery systems with high energy density. However, the utilization of Li metal as an anode material has been limited due to the uncontrolled Li deposition and side reactions on Li metal surface that induce low coulombic efficiency, poor cycle performance and safety issues. Controlling morphology of electrodeposited Li metal is one major direction to resolve these issues. Identification of Li deposition mechanism governing the morphology evolution is prerequisite for establishing strategy for controlling morphology. Herein, we explore governing deposition mechanism from the morphology evolution at varied current (0.2- 1.8 mA cm-2) and suggest a strategy for growing low surface area Li fibers.We found that fibrous Li growth follows the initial spherical Li particle formation when the Li sphere size reaches the critical value. The diameter of the initially formed Li particles decreases with the current density. Initially formed spherical Li particles at a low current density (0.2 mA cm-2) are sufficiently large to grow with a fibrous morphology. Thus, the spherical particles evolve to fibrous Li during subsequent growth. On the other hand, at a higher current density, the Li particles are initially smaller than the critical size and thus cannot immediately grow into a fibrous morphology. Spherical growth of the existing Li particles and additional nucleation on the current collector surface continue, resulting in multilayer Li particles. After Li particles reach the critical size, Li can grow with a fibrous form. Due to the preferential deposition on the existing fibrous Li, the morphology of spherical Li particles smaller than the critical size does not change. Therefore, only fibrous Li deposits were formed at low current density (0.2 mA cm-2), but both spherical and fibrous Li deposits were formed at higher current densities.Based on the morphology evolution mechanism, seeded Li deposition strategy was proposed to minimize the surface area of Li deposits and improve cycling stability of Li metal electrode. The stepwise spherical to fibrous Li growth was achieved by changing the current from low to high (0.2 to 1.8 mA cm-2). Li deposits morphology was well controlled by this strategy resulting in all fibrous morphology with smooth surface. The Li deposits of seeded growth strategy achieved smaller surface area, suppressed side reactions and improved cycle life more than four times compared to that of constant current deposition with same average current density (1 mA cm-2). Figure 1

Promising corrosion-resistant and pre-osteoblast growth promotion performance in vitro of hydroxyapatite/TiO2 nano-porous composite coatings

The inertness of titanium alloys restricts the high intensity of the biological bonding between artificial implants and human skeletons, and there is residual stress in hydroxyapatite (HA) coatings fabricated by the frequently applied plasma spraying method. With the intention to address the aforementioned two issues, combined utilization of constant current anodization and pulsed laser deposition (PLD) was conducted to fabricate HA/TiO2 nano-porous composite coatings, and the as-fabricated samples were heat-treated under the selected appropriate conditions. The oxygen bubble mold theory has made a persuasive explanation for the growth mechanism of TiO2 nano-porous arrays. The morphologies and composition of the composite coatings including the heat-treated ones were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), grazing incidence X-ray diffraction (GI XRD) and X-ray photoelectron spectrometer (XPS). Through comprehensive analysis of the corrosion resistance in modified simulated body fluid (m-SBF) and growth efficiency of cocultured MC3T3-E1 cells in vitro, together with the characterization results, it is concluded that the sample heat-treated at 450 °C shows the most satisfactory performance in general. Therefore, the HA/ TiO2 nano-porous composite coatings have broad application prospect in the osseointegration and bone repairing abilities of artificial implants.

Anode Electrolysis of Manganese Dioxide in Photoelectrochemical Cells

Photoelectrochemical deposition technology has been applied to the process of electrolytic manganese dioxide production. The effect of light on the electrochemical behavior of the electrodeposited manganese dioxide was studied by the cyclic scanning method, electrochemical impedance method, and chronoamperometry method. Illumination increased the peak current of electrolytic manganese dioxide anodization, reduced the charge transfer resistance, and provided a greater driving force for nucleation and growth of manganese dioxide. In addition, photoelectrochemical constant-current deposition of manganese dioxide was used. Photoelectrochemical deposition reduced the ~ 50 mV cell voltage, improved the current efficiency by approximately 11%, and reduced the power consumption by approximately 13%. Photoelectrochemical deposition is beneficial to energy saving and consumption reduction in the production process of electrolytic manganese dioxide.

Enhanced hydrogen evolution efficiency achieved by atomically controlled platinum deposited on gold nanodendrites with high-index surfaces

Minimum Pt atom deposition on the Au NDs surface (O-Pt on Au NDs) by the constant-current deposition method in acidic conditions played a substantial role in accomplishing the Tafel reaction in the hydrogen evolution reaction.

Photoelectrochemical cathodic protection of Cu2O/TiO2 p-n heterojunction under visible light

The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu2O nanoparticles on the surface of TiO2 nanotubes via anodic oxidation and constant current deposition. Field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that Cu2O nanoparticles not only deposited on the surface of TiO2 nanotube array, but also on the wall of TiO2 nanotubes. The Cu2O deposition amount could be adjusted by changing the deposition time. The photoelectrochemical cathodic protection (PECCP) performance of the prepared photoelectrodes for 316L stainless steel (SS) was tested under visible light. The constant current deposition time had a significant effect on the PECCP performance of Cu2O/TiO2-X photoelectrodes and Cu2O/TiO2-20 had the best PECCP performance for the coupled 316L SS. This was attributed to the appropriate amount and thickness of Cu2O to form p-n heterojunctions with TiO2, in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.

Electrodeposition of nickel from alkaline NH4OH/NH4Cl buffer solutions

Abstract The electrodeposition of nickel on steel and copper from alkaline NH4OH/NH4Cl buffer solutions was investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA) as well as an opto-digital microscope, glow-discharge optical emission spectroscopy (GD-OES), XRF, and SEM-EDS techniques. The aim was to obtain Ni coatings from weak alkaline solutions and to optimize the process. The electrolyte composition, pH, temperature as well as current and potential parameters of the process were optimized using the quality of Ni deposit as a criterion. The role of hydrogen evolution in the process was discussed. An influence of Co as an additive was also investigated. It was found that a small amount of Co catalyzes Ni deposition process and improves the quality and color of the deposit. Therefore, in the possible application, the Ni/Co codeposition should be seriously considered. It was also shown that for constant current deposition mode, the width of self-established potential range, revealed at the very beginning of the process by the chronopotentiometric E=f(t) curves, is related to the quality of the coating.

Highly conductive NMP-free carbon-coated nano-lithium titanate/carbon composite electrodes via SBR-assisted electrophoretic deposition

Li-ion storage electrodes are manufactured through the conventional cast process involving the use of a toxic solvent (n-methyl-2- pyrrolidone, NMP) and the binder polyvinylidene fluoride (PVDF). This process can be problematic for nanosized materials as they form viscous suspensions that prevent the formation of uniformly dense coatings. Additionally, the NMP solvent is very hazardous. Herein lies the viability of using electrophoretic deposition (EPD) as an alternative manufacturing process that would both eliminate the need for a toxic solvent and improve electrode properties is presented. In particular, it is shown that styrene- butadiene rubber (SBR) enables the assembly of carbon-coated LTO and carbon nanoparticles into bridged hetero-aggregates that render themselves to fast growth of adherent highly performing LIB electrodes. The electrodes are built by suspending C-coated LTO, carbon, and SBR at 80/10/10 wt% ratio in a medium consisting of 90/10 vol% acetonitrile and water, performing 3–5 stages of 15-s constant current deposition cycles followed by pressing at 4 MPa and drying in a vacuum oven. Raman spectroscopy, thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS) with SEM were performed to examine carbon/LTO composite film homogeneity and compared to conventional PVDF-based electrodes. More importantly, photoemission electron microscopy (PEEM) and X-ray absorption near edge structure (XANES) were used to probe the presence/distribution of the SBR binder in the coating. The EPD-based electrode exhibits superior rate capability when compared to the PVDF-based electrodes. The conductivity, as shown by EIS, of the pressed EPD electrodes was 15 times higher than that of the pressed PVDF electrodes demonstrating the superiority of EPD in fabricating highly conductive electrodes for high-power LIB application.

Electrochemical CO2 Reduction on Oxide-Derived Cu Surface with Various Oxide Thicknesses

Cuprous oxide on copper foil electrodes prepared via electrochemical deposition and thermal annealing are investigated towards CO2 electrochemical reduction at low overpotential. The thickness of the electrochemical deposited Cu2O was controlled by varying the constant-current deposition time. The surface morphology and roughness were examined with SEM and CV respectively. The electrode fabricated by cuprous oxide deposited for 20 min demonstrated the best faradic efficiency (7.02%) and specific activity (0.123 mA/cm2) towards format/formic acid formation at -0.5 V vs. RHE in CO2 saturated 0.5 M K2CO3 among studied samples.

Mössbauer and XRD study of novel quaternary Sn-Fe-Co-Ni electroplated alloy

Constant current electrochemical deposition technique was used to obtain quaternary alloys of Sn-Fe-Co-Ni from a gluconate electrolyte, which to date have not been reported in the literature. For the characterization of electroplated alloys, 57Fe and 119Sn Conversion Electron Mossbauer Spectroscopy (CEMS), XRD and SEM/EDAX were used. XRD revealed the amorphous character of the novel Sn-Fe-Co-Ni electrodeposited alloys. 57Fe Mossbauer spectrum of quaternary deposit with composition of 37.0 at% Sn, 38.8 at% Fe, 16.8 at% Co and 7.4 at% Ni displayed a magnetically split sextet (B = 28.9T) with broad lines typical of iron bearing ferromagnetic amorphous alloys. Magnetically split 119Sn spectra reflecting a transferred hyperfine field (B = 2.3T) were also observed. New quaternary Sn-Fe-Co-Ni alloys were successfully prepared.

Evaluation of Key Factors for Preparing High Brightness Surfaces of Aluminum Films Electrodeposited from AlCl3-1-Ethyl-3-Methylimidazolium Chloride-Organic Additive Baths

The effects of additives, such as 4-pyridinecarboxylic acid hydrazide (4-PCAH) and its analogs, and organic solvents, such as toluene, benzene and xylene, on the brightness of aluminum (Al) prepared using constant-current deposition from an ionic liquid of ethyl-3-methylimidazolium chloride (EMIC)-aluminum chloride (AlCl3) were investigated by light spectroscopy, scanning electron microscopy (SEM), reflectivity tests, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy. In order for the deposited Al films to exhibit high brightness, a combined use of 4-PCAH and toluene is effective. Moreover, the relationship between the brightness (i.e., reflectance) of the prepared Al films and the molecular structure of a variety of additives was clarified. Both a pyridine ring and an acetyl hydrazine group are necessary for constituting an effective additive. The structural isomers of a given additive bring about different surface brightness, e.g., for PCAHs the reflectance at 450 nm is in the order of para-isomer > meta-isomer > ortho-isomer. It was considered that in 4-PCAH electron-withdrawing acetyl hydrazine group is bounded to the pyridine ring, and consequently the electron density around the nitrogen atom in the pyridine ring is decreased, which is conducive to the adsorption of 4-PCAH on the cathode of deposited Al films. In addition, the reflectance was found to increase with decreasing the crystalline domain size of Al deposits and with increasing the reaction resistance for Al electrodeposition. The reaction mechanism of Al electrodeposition from the present ionic liquid media containing various additives is also discussed briefly.

Electrodeposition of Aluminum onto Copper-Coated Printed Circuit Boards

The electrodeposition of aluminum thin films onto copper-coated printed circuit boards from aluminum chloride-trimethylphenylammonium chloride ionic liquids is studied. Various electrodeposition methods with different surface pretreatment procedures were investigated and compared to optimize the deposited aluminum morphology and properties. For the same amount of charge, a pulse current deposition approach applied at a low duty cycle of 10% allowed the use of higher deposition current densities, leading to finer and more compact aluminum deposits compared with those produced by constant potential and constant current deposition techniques. Pulse current deposition with various peak current densities of −25 mA/cm2 to −65 mA/cm2 was conducted over a temperature range of 20°C to 60°C. At a moderate temperature of 40°C, the electrodeposited aluminum layer was the most adherent. An increase of peak current density did not have an obvious effect on the deposit morphology, but it led to an increased amount of both deposited aluminum and incorporated impurities (oxygen and chloride). At room temperature, the electrical resistivity of the copper-coated printed circuit boards with deposited aluminum decreased as the peak current density for aluminum deposition increased.

Design and synthesis of graphene/activated carbon/polypyrrole flexible supercapacitor electrodes

A ternary composite of graphene/activated carbon/polypyrrole (GN/AC/PPy) used as an electrode active material for supercapacitors has been synthesized via vacuum filtration and anodic constant current deposition methods.

Evaluation of Key Factors for Preparing High Brightness Surfaces of Aluminum Films Electrodeposited from AlCl3-1-Ethyl-3-Methylimidazolium Chloride-Organic Additive Baths

The effects of additives, such as 4-pyridinecarboxylic acid hydrazide (4-PCAH) and its analogs, and organic solvents, such as toluene, benzene and xylene, on the brightness of aluminum (Al) prepared using constant-current deposition from an ionic liquid of ethyl-3-methylimidazolium chloride (EMIC)-aluminum chloride (AlCl3) were investigated by light spectroscopy, scanning electron microscopy (SEM), reflectivity tests, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy. In order for the deposited Al films to exhibit high brightness, a combined use of 4-PCAH and toluene is effective. Moreover, the relationship between the brightness (i.e., reflectance) of the prepared Al films and the molecular structure of a variety of additives was clarified. Both a pyridine ring and an acetyl hydrazine group are necessary for constituting an effective additive. The structural isomers of a given additive bring about different surface brightness, e.g., for PCAHs the reflectance at 450nm is in the order of para-isomer>meta-isomer>ortho-isomer. It was considered that in 4-PCAH electron-withdrawing acetyl hydrazine group is bounded to the pyridine ring, and consequently the electron density around the nitrogen atom in the pyridine ring is decreased, which is conducive to the adsorption of 4-PCAH on the cathode of deposited Al films. In addition, the reflectance was found to increase with decreasing the crystalline domain size of Al deposits and with increasing the reaction resistance for Al electrodeposition. The reaction mechanism of Al electrodeposition from the present ionic liquid media containing various additives is also discussed briefly.

The effect of peptone on the structure of electrodeposited Sn-Fe binary alloys

Sn-Fe thin films were electrodeposited by constant current deposition on copper substrates using an aqueous gluconate based electrolyte with varying concentrations of the organic additive peptone. Good quality metallic deposits were obtained with surface morphologies which varied with the concentration of peptone present in the electrolyte. The effect of peptone concentration on the deposition process was studied using electrochemical polarization curves and EDX analysis. The effect of peptone concentration on deposit structure and surface morphology was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and 57Fe and 119Sn conversion electron Mossbauer spectroscopy (CEMS). It was concluded that the addition of small amounts of peptone to the electrolyte slightly increased the bath stability and led to changes in the alloy composition of the electrodeposits. It was found that increases in the peptone content increased the amount of the crystalline structure in the deposits with corresponding reductions in the amounts of amorphous structure present in the deposits.

Efficiently Visible-Light Driven Photoelectrocatalytic Oxidation of As(III) at Low Positive Biasing Using Pt/TiO2 Nanotube Electrode.

A constant current deposition method was selected to load highly dispersed Pt nanoparticles on TiO2 nanotubes in this paper, to extend the excited spectrum range of TiO2-based photocatalysts to visible light. The morphology, elemental composition, and light absorption capability of as-obtained Pt/TiO2 nanotubes electrodes were characterized by FE-SEM, energy dispersive spectrometer (EDS), X-ray photoelectron spectrometer (XPS), and UV-vis spectrometer. The photocatalytic and photoelectrocatalytic oxidation of As(III) using a Pt/TiO2 nanotube arrays electrode under visible light (λ > 420 nm) irradiation were investigated in a divided anode/cathode electrolytic tank. Compared with pure TiO2 which had no As(III) oxidation capacity under visible light, Pt/TiO2 nanotubes exhibited excellent visible-light photocatalytic performance toward As(III), even at dark condition. In anodic cell, As(III) could be oxidized with high efficiency by photoelectrochemical process with only 1.2 V positive biasing. Experimental results showed that photoelectrocatalytic oxidation process of As(III) could be well described by pseudo-first-order kinetic model. Rate constants depended on initial concentration of As(III), applied bias potential and solution pH. At the same time, it was interesting to find that in cathode cell, As(III) was also continuously oxidized to As(V). Furthermore, high-arsenic groundwater sample (25 m underground) with 0.32 mg/L As(III) and 0.35 mg/L As(V), which was collected from Daying Village, Datong basin, Northern China, could totally transform to As(V) after 200 min under visible light in this system.

Enhanced electrochemical performance of ZnO nanorod core/polypyrrole shell arrays by graphene oxide

Facile synthesis of ZnO nanorod core and polypyrrole shell arrays by electrochemical constant current deposition mode is reported. The effects of electrosynthesis parameters for polypyrrole (PPy) shell and its hybridization with graphene oxide (GO) on the structure, morphology and electrochemical properties of the core-shell arrays were analyzed. The results indicated a synergetic effect towards improving the electrochemical properties by tailoring the interfacial surface in ZnO/PPy core-shell arrays. High retention ratio (66 %) and an increase in voltammetric charge stored at inner surface (80 %) were exhibited by the ZnO/PPy-GO core/hybrid shell arrays with respect to ZnO/PPy ones.

Bottom-up Filling of TSV-Scaled Trenches by Using Step Current Electrodeposition

Void-free filling of TSV-scaled trenches is achieved by adding a new leveler with an accelerator and polymeric suppressor. Leveler containing two quaternary ammonium salts allows for the galvanostatic bottom-up filling. In addition, the filling time is reduced by applying the step current comprising a first step to establish a growing surface and a second step to reduce the filling time. The deposition height of the growing surface during the first step critically determines the filling performance. By modulating the step condition, the filling time reduced by 47% compared to the constant current deposition. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0061510eel] All rights reserved.

(Invited) Semi-Automated System for Electrodeposition of Pt Monolayer Shell on Refractory Metal Core Fuel Cell Electrocatalysts Directly on Gas Diffusion Layer

According to the US Department of Energy (DOE), reducing the cost and improving the durability of the polymer electrolyte membrane fuel cells (PEMFCs) are the main challenges that hinder their commercialization [1]. The largest portion of the cost of the fuel cell stacks (49%) is attributed to the large amount of Pt on the cathode side, because of the sluggish kinetics of the oxygen reduction reaction (ORR) [1, 2]. Reduction of the amount of the Pt contained in the PEMFCs stacks is required for large scale automotive applications, both for reasons of cost and Pt supply limitations. In order to challenge the researchers all over the world, and to boost the implementation of the PEMFCs in transportation, DOE has set demanding technical targets for development of fuel cell electrocatalysts for transportation applications [1]. It has recently been demonstrated that the mass and specific activities, and as well as the durability of the Pt monolayer (ML) type electrocatalysts exceed the DOE targets for 2020, which renders them as the most advanced type of fuel cell electrocatalysts [3, 4]. In this class of electrocatalysts, a surface limited redox replacement (SLRR) strategy is used in order to deposit a Pt ML shell on another transition metal (or alloy) nanoparticle core [3]. A pre-deposited Cu ML on respective nanoparticles at underpotentials (UPD) is galvanically displaced by Pt in a consecutive step, upon immersion of the sample in Pt2+ solution. Thus, a full Pt utilization is achieved in the Pt ML core-shell electrocatalysts, and their excellent activity and performance stability has been demonstrated in either rotating disk electrode (RDE) or MEA studies [3-5]. Although, those catalysts showed outstanding performance, their reproducible synthesis in large scale remained unresolved. In this contribution we are reporting on novel fast and facile methodology for fabrication of PEMFC cathodes with ultra-low PGM loading. We have designed and developed a semi-automated system for electrodeposition of Pt ML core-shell fuel cell electrocatalysts, utilizing the SLRR strategy, directly on gas diffusion layer (GDL). The system is software controlled and allows fabrication of highly active and durable FC electrodes with geometric area of up to 500 cm2 in a couple of hours, starting from raw materials (chemical salts, and commercial GDLs). The system is consisting of: (i) electrochemical cell that allows fabrication of large electrodes with industrial relevance; (ii) pneumatic control unit with respective electronic control that governs the exchange of different electrolyte solutions from the de-aerated stock solutions to the cell in a particular order; (iii) electronic data acquisition board from National Instruments that allows the LabView software to control step by step all the processes; and (iv) BioLogic potentiostat-galvanostat that controls the refractory alloy electrodeposition, Pd displacement, and Cu UPD and Pt ML deposition processes. The electrodeposition of PtML/Pd/W(Mo)Ni catalysts directly on the GDL is realized in three sequential steps. In the first step, refractory WNi or MoNi alloy nanoparticles are co-electrodeposited directly on functionalized GDL by applying a constant current or pulse deposition protocol, from solution containing Na2WO4 or Na2MoO4, NiSO4, and sodium citrate. In the consecutive step, the solution in the cell is replaced by PdCl2 solution, and Ni is partially displaced by Pd. As a result, WNi (MoNi) core nanoparticles are covered with thin (2-3 monolayers) Pd shells. In the third step, Pt ML is deposited on Pd/WNi (Pd/MoNi) nanostructures in “one-cell configuration” [6] from solution containing both Pt2+ and Cu2+ ions. At the end of the deposition process, the electrode is rinsed with nanopure water, and after drying is ready for assembly. Thus, highly active, inexpensive and durable PtML/Pd/WNi (PtML/Pd/MoNi) electrocatalysts with ultra-low PGM loading are directly electrodeposited on up to 500 cm2 GDL. The features of the system will be discussed along with the electrodes characterization and MEAs performance at real fuel cell operating conditions. Acknowledgment Work at Brookhaven National Laboratory is supported by US Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences Division, under the Contract No. DE-AC02-98CH10886. References http://energy.gov/eere/fuelcells/downloads/fuel-cell-technologies-office-multi-year-research-development-and-22.H. A. Gasteiger, S. S. Kocha, B. Sompalli and F. T. Wagner, Applied Catalysis B-Environmental, 56, 9 (2005).R. R. Adzic, Electrocatalysis, 3, 163 (2012).K. Sasaki, H. Naohara, Y. Choi, Y. Cai, W.-F. Chen, P. Liu and R. R. Adzic, Nature Communications, 3, 1115 (2012).R. Adzic, S. Bliznakov, and M. Vukmirovic. US Patent: Core-Shell Fuel Cell Electrodes,US2015/0017565 A1, Jan. 15, 2015.M. Fayette, Y. Liu, D. Bertrand, J. Nutariya, N. Vasiljevic and N. Dimitrov, Langmuir, 27, 5650 (2011).

Enhancement of the lithium cycling capability using Li–Zn alloy substrate for lithium metal batteries

The cycling performance of a Li metal electrode in rechargeable Li batteries is studied using a novelly formed Li–Zn alloy as a substrate. A Zn layer electrodeposited on a Cu disk with ultrasonic assistance is used as a substrate precursor. Li electrodeposition followed to form the Li–Zn alloy. The morphologies of the substrate before and after Li deposition and stripping are investigated by scanning electron microscopy (SEM), and the electrochemical properties of the substrate are investigated by galvanostatic charge-discharge and cyclic voltammetry (CV). The growth states of solid electrolyte interface (SEI) films of Li deposits on the Li–Zn alloy and Cu surfaces are compared by electrochemical impedance spectroscopy (EIS); exchange current densities of Li electrodeposition on Cu, Zn, and Li–Zn alloy substrates are also compared based on tests of constant current pulse deposition. The efficiency of Li deposition/stripping on the Li–Zn alloy substrate remains high at 96.7% after 400 cycles at a current density of 0.1mAcm−2 and 250 cycles at the current density of 0.2mAcm−2. These results can be attributed to the formation of a stable SEI film on the Li–Zn substrate and the high exchange current density of Li deposition and stripping on this substrate. The Li–Zn alloy proposed in this work may be a perfect substrate for enhancing the cycling capability of Li metal electrode.