Compact Zinc Research Articles

Scaling features of conductivity spectra reveal complexities in ionic, polaronic and mixed ionic-polaronic conduction in phosphate glasses

The scaling behaviour of six series of mixed ion-polaron glasses with the composition xWO3/MoO3-(30–0.5x)Li2O/Na2O/Ag2O-(30–0.5x)ZnO-40P2O5, 0 ≤ x ≤ 60 mol%, has been studied using Summerfield and Sidebottom scaling procedures that are model free. The validity of the Sidebottom scaling procedure for each individual glass confirms that all glasses obey time-temperature superposition principle implying that the conduction mechanism does not change with temperature. On the other hand, Summerfield scaling is not found valid for all glasses. First, this deviation is observed in all glasses containing Li2O up to 20 mol% of MoO3/WO3. We relate this result to a non-typical interaction of Li+ ion with the compact zinc phosphate network resulting either in change of its hopping distance or in available conduction pathways for it as a function of temperature. Second, non-Summerfield scaling was also observed for glasses containing Li2O/Na2O/Ag2O with about 30 to 40 mol% of WO3. Thus, the origin of this deviation lies in the significant amounts of both types of charge carriers - ions and polarons, and their differently thermally activated mobilities.

Scaling Features of Conductivity Spectra Reveal Complexities in Ionic, Polaronic Andmixed Ionic-Polaronic Conduction in Phosphate Glasses

The scaling behaviour of six series of mixed ion-polaron glasses with the composition xWO3/MoO3-(30-0.5x)Li2O/Na2O/Ag2O-(30-0.5x)ZnO-40P2O5, 0≤x≤60 mol%, has been studied using Summerfield and Sidebottom scaling procedures that are model free. The validity of the Sidebottom scaling procedure for each individual glass confirms that all glasses obey time-temperature superposition principle implying that the conduction mechanism does not change with temperature. On the other hand, Summerfield scaling is not found valid for all glasses. First, this deviation is observed in all glasses containing Li2O up to 20 mol% of MoO3/WO3. We relate this result to a non-typical interaction of Li+ ion with the compact zinc phosphate network resulting either in change of its hopping distance or in available conduction pathways for it as a function of temperature. Second, non-Summerfield scaling was also observed for glasses containing Li2O/Na2O/Ag2O with about 30 to 40 mol% of WO3. Thus, the origin of this deviation lies in the significant amounts of both types of charge carriers - ions and polarons, and their differently thermally activated mobilities. Finally, based on a comparison of master-curves of all glasses with varying fractions of Li2O/Na2O/Ag2O and MoO3/WO3 we identify varied effects of the transition metal oxide on the transport of mobile ions as also the presence of mixed ion-polaron conduction.

Screening of effective electrolyte additives for zinc-based redox flow battery systems

The purpose of this work is to assess the suitability of potential electrolyte additives for zinc morphology control and improved electrochemical performance of the zinc electrode for application in zinc based redox flow battery (RFB) systems. Based on existing literature in the field, sixteen candidates are selected, including four metallic additives, two non-ionic surfactants and ten quaternary ammonium compounds. The electrochemical performance of the zinc electrode is assessed using cyclic voltammetry, linear sweep voltammetry and zinc half-cell cycling tests using chronopotentiometry. Zinc electrodepositions are carried out using chronopotentiometry in order to assess the effect of additives on zinc morphology with scanning electron microscopy. Based on zinc reduction and oxidation reaction potentials, the cycling efficiencies, and the effect on zinc morphology, the most promising additives of those tested are tetraethylammonium hydroxide and tetraethylammonium bromide. Both provide smooth and compact zinc deposits and zinc electrode coulombic efficiencies of 95–97% without leading to significant changes in the zinc reduction/oxidation overpotentials, yielding anodic and cathodic current densities of 77–78 mA cm−2 and 31–32 mA cm−2 at overpotentials of ± 50 mV, respectively. In a zinc-nickel flow cell, these additives provide energy efficiencies of 78–79%, compared with 69% without an additive.

Surface Modification of Q195 Structure Carbon Steel by Electrolytic Plasma Processing

In this study, we applied an emerging, environmentally friendly surface engineering technology, electrolytic plasma processing (EPP), for the surface modification of Q195 structure carbon steel surface pretreatment and further Zn coating. Treating the surfaces of Q195 structure carbon steel by EPP was a quite dynamic process, which was investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results shown that surface scale can be effectively remove after 40 s EPP treatment, and the EPP-treated Q195 structure carbon steel revealed a slight decrease in elastic modulus and hardness, but a substantial improvement in tensile (especially plastic) mechanical properties. Moreover, the further EPP modification conducted on the pretreated Q195 structure carbon steel sample for production of a layer of compact zinc coating with 15 μm thickness under an optimization EPP process. We also identified the modification mechanism of EPP to Q195 structure carbon steel, which may provide theoretical and practical guidance for future researchers and developers.

The impact of operating conditions on component and electrode development for zinc-air flow batteries

Rechargeable zinc-air flow batteries are investigated as possible technology for fast responding large-scale electrical energy storage due to the use of inexpensive, non-toxic and abundant materials, and compact system design. The operating ranges for several parameters such as flow rate (2–8 cm s−1), concentration of electrolyte (6 or 8 M KOH), charge/discharge current densities (up to 100 mA cm−2 mean), and active or passive air supply as well as their influence on the performance and stability of the electrodes are investigated and compared. Bi-catalyzed bifunctional air electrodes are tested by means of half-cell measurements achieving minimum 200 charge/discharge cycles at 50 mA cm−2 with the longest operation time being 800 h. At this current density, charge/discharge efficiencies are in the range of 50% for all tested air electrodes. End-of-life characterization by means of scanning electron microscopy reveals mechanical degradation of the electrode material. On the negative zinc electrode, zinc deposition morphology on different current collector materials (nickel, brass, and steel) is investigated using Rota-Hull cylinders showing nickel to be the most suitable material. The pulse interrupt current method is thereby successfully applied for compact zinc deposition in a broad current density range without any electrolyte additive. Subsequent scale-up of the rechargeable zinc-air flow battery and unit cell operation is finally performed for proof-of-concept.Graphical

Confined Growth of ZIF‐8 Nanocrystals with Tunable Structural Colors

AbstractZeolitic imidazolate frameworks (ZIF‐8) have promising applications as sensors or catalysts due to their highly porous crystalline structures. While most of the previous studies are based on ZIF‐8 crystals either in isolated particles in aqueous environments or in a compact colloidal form, here a facile method is reported to achieve wafer‐based isolated ZIF‐8 nanocrystals to facilitate their integration in microsystems and as surface coatings for catalysis. The fabrication process includes the growth of compact zinc oxide film by atomic layer deposition that functions as the Zn source for the ZIF‐8 synthesis, and the dispersion of gold nanoparticles as inhibitors for the following crystallization transformation of ZIF‐8 crystals. By choosing the concentration of gold nanoparticles, the density of ZIF‐8 nanocrystals can be controlled and the sizes of individual ZIF‐8 crystals can be scaled down to ≈100 nm. A wide range of structural colors generated by the ZIF‐8 nanocrystals is also observed, which can be attributed to the size‐dependent resonant scattering as verified by finite‐difference time‐domain simulations and classical Mie theory. The scalable fabrication of wafer‐based ZIF‐8 nanocrystals empowered with tunable optical properties paves a new way to explore the promising applications in nanophotonics and bionanotechnology.

Effect of Ag doping on hydrothermally grown ZnO thin-film electronic synapse device

The present paper reports the effect of silver (Ag) doping on hydrothermally grown zinc oxide (ZnO) thin-film memristor-based electronic synapse devices. The morphological, structural and electrical characterizations of the zinc oxide memristor devices were carried out using scanning electron microscopy, X-ray diffraction and a programmable electrochemical workstation, respectively. The crystallographic orientation was detected along the (002) plane with well-aligned and compact zinc oxide nanorods for silver-doped zinc oxide memristor devices. An analog memory with a synaptic weight behavior similar to that of a biological synapse was observed for the developed devices. The morphological, structural, electrical and resistive switching mechanism studies clearly show improved performance of silver-doped zinc oxide devices over that of the bare zinc oxide device. Furthermore, the conduction mechanism of the devices follows the ohmic and space-charge-limited conduction theories. The present report is useful for the development and optimization of zinc oxide-based electronic synaptic devices for neuromorphic applications.

Development of Stable Bifunctional Air Electrodes for Zinc-Air Flow Batteries

The increasing installation capacities of renewable but fluctuating electricity generators such as wind and solar power systems have raised the need for energy storage with short response times. Out of the many different types of electrochemical energy storage systems, the stationary zinc-air flow battery is promising due to its use of the safe, abundant and inexpensive active storing metal zinc [1]. In this system the zinc is dissolved into the flowing alkaline electrolyte during discharge and can be stored as zincate ion outside the electrochemical cell (see schematic in left figure). It is redeposited during charging, whereby compact zinc morphologies are preferred in order to avoid internal short-circuiting and loss of active material [2]. As in other metal-air batteries, the reactions of the second electrode are the oxygen reduction reaction (ORR) during discharging using oxygen from the air and the oxygen evolution reaction (OER) during charging [1,3]. In practical applications, the recharge capability of the zinc-air cell is dependent on the compact zinc deposition and the mechanical and chemical long-term stability of the air electrode. Furthermore, the low cycling efficiencies of around 50% resulting from the slow ORR/OER reaction kinetics are challenging to overcome and rely on the activity of the chosen catalysts. In air electrodes non-precious metal oxides such as perovskites (e.g. La0.6Sr0.4Co0.2Fe0.8O3, LaNiO3) and spinels (e.g. NiCo2O4) can be utilized, due to their chemical stability in alkaline electrolyte [3,4]. Although many oxide catalysts exhibit bifunctional catalytic activity toward ORR and OER, they are often not equally active toward both reactions. Hence, a combination of two catalysts in one electrode is beneficial, as was investigated in this work. Furthermore, their implementation into a stable and porous electrode structure with balanced gas diffusivity and electrolyte wettability is important in order to obtain a high number of three-phase zones between gas, electrolyte and catalyst. This was achieved by selecting suitable additives such as carbon nanofibers and nickel powder for electrical conductivity and PTFE as hydrophobic binder material [4]. These materials need to be resistant toward the highly oxidative potentials of around 2 V vs. Zn/Zn2+ and the mechanical stress by the vigorous oxygen bubble formation during charging. In addition, nickel foam was found to be an applicable current collector material, which functions at the same time as mechanical backbone of the air electrode. In-house manufactured electrodes were electrochemically characterized in a half-cell set-up in 8 M KOH electrolyte with the addition of 0.5 M ZnO, whereby one air electrode was operated as working electrode and a second air electrode as counter electrode. They were referenced against zinc foil. Discharging was performed at a constant current density of 50 mA cm-2 for 1 h per cycle. Because of the beneficial effects for the deposition of compact zinc layers, charging was conducted with the pulse charging method by applying tripled current densities during a short pulse of 50 ms followed by a pause of 100 ms (24 000 pulses in 1 h). The long-term cycling experiments, as depicted in the right figure, were performed for several hundred hours until the lower cut-off potential of 0.8 V vs. Zn/Zn2+ was reached. Although a decrease of ORR discharge potential of 0.1 V down to 1.0 V was observed within the first 50 hours of cycling, the OER potentials during charging were stable throughout the measurement. All in all, constant long-term performances over the course of more than 200 cycles with maximum charge/discharge potential gaps (ΔV) of 1.03 V were achieved [4]. [1] J. Fu, Z.P. Cano, M.G. Park, A. Yu, M. Fowler, Z. Chen, Electrically Rechargeable Zinc-Air Batteries: Progress, Challenges, and Perspectives, Adv. Mater. (2016). [2] C. Zelger, J. Laumen, A. Laskos, B. Gollas, Rota-Hull Cell Study on Pulse Current Zinc Electrodeposition from Alkaline Electrolytes, Electrochim. Acta. 213 (2016) 208–216. [3] L. Jörissen, Bifunctional oxygen/air electrodes, J. Power Sources. 155 (2006) 23–32. [4] B. Pichler, S. Weinberger, L. Reščec, I. Grimmer, F. Gebetsroither, B. Bitschnau, V. Hacker, Long-term behavior of bifunctional air electrodes with high stability during pulse charging for zinc-air flow batteries (submitted). Figure 1

Bifunctional electrode performance for zinc-air flow cells with pulse charging

Bifunctional air electrodes with tuned composition consisting of two precious metal-free oxide catalysts are manufactured for application in rechargeable zinc-air flow batteries and electrochemically tested via long-term pulse charge and discharge cycling experiments at 50mAcm−2 (mean). NiCo2O4 spinel, synthesized via direct impregnation on carbon nanofibers or nickel powder and characterized by energy dispersive X-ray spectroscopy and X-ray diffraction experiments, shows high activity toward oxygen evolution reaction with low charge potentials of < 2.0 V vs. Zn/Zn2+. La0.6Sr0.4Co0.2Fe0.8O3 perovskite exhibits bifunctional activity and outperforms the NiCo2O4 spinel in long-term stability tenfold. By combining the catalysts in one bi-catalyzed bifunctional air electrode, stable performances of more than 1000h and 450 cycles are achieved when supplied with oxygen and over 650h and 300 cycles when supplied with synthetic air. In addition, the pulse charging method, which is beneficial for compact zinc deposition, is successfully tested on air electrodes during long-term operation. The oxygen evolution potentials during pulse, i.e. at tripled charge current density of 150mAcm−2, are only 0.06–0.08V higher compared to constant charging current densities. Scanning electron microscopy confirms that mechanical degradation caused by bubble formation during oxygen evolution results in slowly decreasing discharge potentials.

Electrodeposition of compact zinc from the hydrophobic Brønsted acidic ionic liquid-based electrolytes and the study of zinc stability along with the acidity manipulation

Compact crystalline zinc was electrodeposited on stainless-steel electrode (SS) via potentiostatic/galvanostatic electrolysis from the hydrophobic Brønsted acidic ionic liquid, protonated betaine bis((trifluoromethyl)sulfonyl)imide (IL [Hbet][TFSI]), −based electrolytes containing ZnCl2 or ZnO under argon or ambient air atmosphere. Approximate 10wt% of propylene carbonate and water, respectively, were used as the co-solvents for [Hbet][TFSI] to form the IL-based electrolytes. The efficiency of zinc deposition/stripping, which is significantly affected by the Brønsted acidity of the IL-based electrolytes, was studied at glassy carbon electrode (GC) to evaluate the stability of the zinc electrodeposits along with the electrolyte acidity. The stability is very poor for the zinc electrodeposits obtained from ZnCl2 solution. However, it increases with increasing the quantity of ZnO or urea in the electrolytes; the former neutralize the dissociable protons in [Hbet] cations to form water, and the latter may form H-bonding with [Hbet] or be protonated to form the weakly acidic cations [HUrea]. Both suppress the reaction between the Zn electrodeposits and protons. The stability of the Zn electrodeposits, therefore, can be improved via the manipulation of the IL acidity.

Rota-Hull Cell Study on Pulse Current Zinc Electrodeposition from Alkaline Electrolytes

The electrodeposition of zinc has been studied in the rotating cylinder Hull (RCH) cell with continuous and pulse interrupt current as one of the half-cell reactions for a zinc/air redox flow battery. The morphology of all pulse current deposits was discussed on the basis of the practical current density distribution. The experiments were performed in additive-free 8M potassium hydroxide electrolytes at 60°C, electrolyte flow velocities of 3, 6 and 16cms−1, and zincate concentrations of 0.2 and 0.5 M. In contrast to continuous current deposition, compact zinc deposits have been obtained in Rota-Hull experiments with pulse interrupt current at all electrolyte flow velocities and zincate concentrations. The non-compact filamentous mossy morphology, predominant in continuous current deposition, was not observed. For the highest practical current densities, current efficiencies between 96 and 100% have been found in pulse current experiments. The local practical current densities of all pulse and one continuous current depositions could be determined from the thickness of the zinc deposits measured by X-ray fluorescence. Under the most critical conditions for the deposition of compact zinc, i.e. low zincate concentrations of 0.2M and low electrolyte flow velocities of 3cms−1, pulse interrupt current produced compact zinc deposits up to the limiting current. The results of the pulse current electrodepositions are explained on the basis of the ratio of applied pulse current density to limiting pulse current density. The limiting currents in the Rota-Hull cell were calculated with zincate diffusion coefficients of 6.09×10−6cm2s−1 (0.2M zincate) and 6.38×10−6cm2s−1 (0.5M zincate) determined by rotating disc electrode experiments at 60°C. The absence of the filamentous mossy zinc morphology in pulse interrupt current experiments is ascribed to an effect of the off-time.

Impact of anode substrates on electrodeposited zinc over cycling in zinc-anode rechargeable alkaline batteries

Electrochemical behavior of Ag, Bi, Cu, Fe, Ni and Sn substrates on zinc deposition was evaluated over battery cycling by cyclic voltammetry and electrochemical impedance spectroscopy. The effect of Bi, Cu, Ni, and Sn substrates on zinc electrodeposition during battery cycling was investigated using scanning electron microscopy and X-ray diffraction. The corrosion behavior of each metal in 9M KOH and the corrosion rates of zinc plated on each substrate were analyzed by Tafel extrapolation method from the potentiodynamic polarization curves and electrochemical impedance spectroscopy. Although the charge-transfer resistance (Rct) of zinc electrodeposition is lowest on Sn, Sn eventually corrodes on cycling in alkaline media. Use of Ni as a substrate causes zinc to deteriorate on account of rapid hydrogen evolution. Bi and Cu substrates are more suitable for use as current collectors in zinc-anode alkaline rechargeable batteries because of their low corrosion rate and compact zinc deposition over battery cycling.

Study of Electrodeposited Zinc Morphology in Rechargeable Alkaline Batteries

Rechargeable zinc-nickel flow-assisted batteries are attractive in applications like frequency regulations, UPS inverters and hybrid electrical vehicles, etc[1] due to their advantages, such as, being cheap, capable of rapid charging and discharging and high energy density. However, the challenge that rechargeable zinc-anode batteries are facing is short lifespan time due to non-uniform morphology of zinc deposition during charging, hydrogen evolution that compromises energy efficiency and zinc corrosion during battery resting, which leads to further capacity loss[2]. We developed an indicator that monitors the transition of zinc morphology during battery charging[3]. Zincate concentration in the electrolyte, flow velocity and current density were varied over a wide range in the experiments. The results from SEM and 3D X-ray computer tomography (figure 1) show that the ratio between the effective current density and the limiting current density (current density ratio), which is directly related to the zincate concentration at the electrode surface, determines the zinc morphology. Furthermore, we investigated the causes of transition of zinc morphology. Compact zinc deposits are found to have a fine-grained, bright finish and the highest anodic efficiency (figure 2)[4]. Electrochemical impedance spectroscopy (EIS) proves that compact zinc corresponds to the minimum in the half-cell resistance, indicating it is kinetically preferred for compact zinc to form. Preferred crystal orientations of compact zinc depositions make good agreement with the EIS results. Anode substrate is a parameter that also influences the zinc morphology. We studied the effects of various novel metal substrates on zinc morphology over battery cycling. Results from electrochemical techniques, chemical characterization and cell cycling showed that Cu and Bi are promising anode substrates. In order to alleviate the corrosion rate and increase the lifespan of zinc-anode batteries, we investigated the impacts of additives on zinc morphology and cell performance. Lab-scale cells have demonstrated more than 2000 cycles and large-scale cells (113Ah) have demonstrated more than 200 cycles (figure 4 and figure 5). The results indicate that the morphologies of zinc deposition with the presence of additives are finer and the battery performance is improved as well.

Chemical bath deposition of textured and compact zinc oxide thin films on vinyl-terminated polystyrene brushes.

In this study we investigated the influence of an organic polystyrene brush on the deposition of ZnO thin films under moderate conditions. On a non-modified SiOx surface, island growth is observed, whereas the polymer brush induces homogeneous film growth. A chemical modification of the polystyrene brushes during the mineralization process occurs, which enables stronger interaction between the then polar template and polar ZnO crystallites in solution. This may lead to oriented attachment of the crystallites so that the observed (002) texture arises. Characterization of the templates and the resulting ZnO films were performed with ζ-potential and contact angle measurements as well as scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Infrared spectroscopy (IR) measurements were used to investigate the polystyrene brushes before and after modification.

Effects of Br− and I− concentrations on Zn electrodeposition from ammoniacal electrolytes

The effects of Br− and I− concentrations on the cell voltage, anodic polarization, current efficiency (CE), and energy consumption (EC) of zinc electrodeposition from ammoniacal ammonium chloride solutions were investigated. The surface morphology of zinc deposits was also examined. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology of zinc deposits and the phase of anodic sediments produced during electrolysis. The results clearly showed that the CE slightly increased from approximately 95.12% in the absence of I− and Br− to 97.08% in the presence of 10 g·L−1 Br−; in contrast, the CE significantly decreased to less than 83% in the presence of 10 g·L−1 I−. The addition of Br− and I− positively affected the EC, which decreased from 2514 kW·h·t−1 to approximately 2300 kW·h·t−1. The results of anodic polarization measurements showed that the voltage drops were 130 and 510 mV when the concentrations of Br− and I− were 10 g·L−1 at a current density of 400 A·m−2, respectively. SEM images showed that the addition of Br− and I− caused different crystal growth mechanisms, which resulted in the production of compact and smooth zinc deposits. The anodic reactions of I− were also studied.

Simulating study of atmospheric corrosion of Zn–Ni alloy coating on steels in marine zone: Structure and properties of artificially synthesized Ni(II)-doped zinc hydroxychloride rust particles

To simulate the atmospheric corrosion of Zn–Ni alloy coating on the steel in marine zone, artificial Ni(II)-doped zinc hydroxychloride (Zn5(OH)8Cl2⋅H2O:ZHC) rust particles were prepared by hydrolysis of ZnO particles in a mixture of aqueous ZnCl2 and NiCl2 solutions at 85°C and were characterized by various means. Then, the Ni(II)/(Zn(II)+Ni(II)) atomic ratio in starting solution (XNi) was 0–0.10. XRD results indicated that crystallization of the layered structure of ZHC was strongly inhibited with an increase of XNi and no new particles were generated. The Ni(II) was incorporated into ZHC crystal by substitution with Zn(II) and the Ni/(Zn+Ni) molar ratio in the particles was almost consistent with XNi. The ZHC particles formed at XNi=0 were hexagonal plate with a size of ca. 3.2μm and a thickness of ca. 0.3μm. Increasing XNi reduced the size and thickness of ZHC particles. Besides, addition of Ni(II) suppressed the adsorption of CO2 and SO2 gasses on ZHC, because of layered structure of this material to be disintegrated. The foregoing results suggest that atmospheric corrosion of Zn–Ni alloy coating in marine zone forms dense and compact zinc rust layer composed of fine Ni(II)-doped ZHC particles with a low affinity to corrosive gasses on the steels, leading to the suppression of further corrosion of steel. Also, role of Ni on the atmospheric corrosion of Zn–Ni alloy coating in marine zone can be suggested by studying the structure and properties of artificial Ni(II)-doped ZHC rust particles.

Ubiquitin recognition by FAAP20 expands the complex interface beyond the canonical UBZ domain.

FAAP20 is an integral component of the Fanconi anemia core complex that mediates the repair of DNA interstrand crosslinks. The ubiquitin-binding capacity of the FAAP20 UBZ is required for recruitment of the Fanconi anemia complex to interstrand DNA crosslink sites and for interaction with the translesion synthesis machinery. Although the UBZ–ubiquitin interaction is thought to be exclusively encapsulated within the ββα module of UBZ, we show that the FAAP20–ubiquitin interaction extends beyond such a canonical zinc-finger motif. Instead, ubiquitin binding by FAAP20 is accompanied by transforming a disordered tail C-terminal to the UBZ of FAAP20 into a rigid, extended β-loop that latches onto the complex interface of the FAAP20 UBZ and ubiquitin, with the invariant C-terminal tryptophan emanating toward I44Ub for enhanced binding specificity and affinity. Substitution of the C-terminal tryptophan with alanine in FAAP20 not only abolishes FAAP20–ubiquitin binding in vitro, but also causes profound cellular hypersensitivity to DNA interstrand crosslink lesions in vivo, highlighting the indispensable role of the C-terminal tail of FAAP20, beyond the compact zinc finger module, toward ubiquitin recognition and Fanconi anemia complex-mediated DNA interstrand crosslink repair.

Effect of Novel Substrates on Zinc Anode - Secondary Alkaline Battery Performance

Zinc electrodeposition in alkaline battery has important effect on the performance of the battery and the substrate metal has a strong effect on the performance of zinc anodes, especially at the earliest stages. Rotating disk electrodes were fabricated using 99.9%+ pure metal rods to investigate the performance of zinc deposition on silver, bismuth, copper, iron, nickel and tin substrates. The amount of charge passed in all the experiments was 5 C/cm2. Iron and nickel do not have desirable performance, due to hydrogen evolution. The hydrogen evolution on iron is rapid and soon covers the entire surface of the electrode. Bismuth and tin have desirable performance. The coulombic efficiency on each of these substrates is well in excess of 90% when deposited at -20 mA/cm2. Due to their relatively low cost, tin and bismuth are seen as promising choices of substrate metals in zinc anodes.The morphology of zinc deposition and crystal orientation on copper, nickel and tin substrates was investigated. Zinc deposition is more compact on Sn than on Ni and Cu for the same amount of charge passed. Additionally, Ni and Cu have a propensity to evolve mossy zinc much more easily.The extent of preferred orientation decreases with zinc deposition, and mossy zinc is depositied with almost no texture. Compact zinc has preferred orientation, strongest on Sn.Zinc-based rechargeable batteries are attractive electrical energy storage systems due to their low cost, high energy density and low toxicity. However, zinc redistribution on periodic cycling and dendrite formation is known to severely limit battery life. Short cycle life due to internal short circuits have prevented wide spread secondary storage applications.Zinc electrodeposition in alkaline battery has important effect on the performance of the battery and the substrate metal has a strong effect on the performance of zinc anodes, especially at the earliest stages. Rotating disk electrodes were fabricated using 99.9%+ pure metal rods to investigate the performance of zinc deposition on silver, bismuth, copper, iron, nickel and tin substrates. The amount of charge passed in all the experiments was 5 C/cm2. Iron and nickel do not have desirable performance, due to hydrogen evolution. The hydrogen evolution on iron is rapid and soon covers the entire surface of the electrode. Bismuth and tin have desirable performance. The coulombic efficiency on each of these substrates is well in excess of 90% when deposited at -20 mA/cm2. Due to their relatively low cost, tin and bismuth are seen as promising choices of substrate metals in zinc anodes.The morphology of zinc deposition and crystal orientation on copper, nickel and tin substrates was investigated. Zinc deposition is more compact on Sn than on Ni and Cu for the same amount of charge passed. Additionally, Ni and Cu have a propensity to evolve mossy zinc much more easily.The extent of preferred orientation decreases with zinc deposition, and mossy zinc is depositied with almost no texture. Compact zinc has preferred orientation, strongest on Sn.

Electrodeposition of preferentially oriented zinc for flow-assisted alkaline batteries

Preferred orientation of zinc deposits during charging is shown to significantly improve performance and cycle life in flow-assisted alkaline zinc batteries, which has not been demonstrated earlier. The preferred orientation of zinc deposits was investigated using X-ray diffraction (XRD). Compact zinc is found to have (112¯2) preferred orientation on brass, which contributes to ∼60% of the texture. The effect of charging current and zincate concentration on morphology was investigated in a rotating hull cell and correlated with anodic efficiency. Compact zinc deposits are found to have a fine-grained, bright finish and the highest anodic efficiency. Electrochemical impedance spectroscopy (EIS) proves that compact zinc corresponds to the minimum in the half-cell resistance. Morphological control using compact zinc could be accomplished using innovations such as pulse charging or enhanced mass-transfer to improve anode performance without affecting the cathode.

Structure and properties of Ti(IV)-doped zinc hydroxychloride rusts formed at various temperatures

To simulate the atmospheric corrosion of steels galvanized with Ti–Zn alloys under different atmospheric temperatures, Ti(IV)-doped zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O: ZHC) was prepared at various aging temperatures of 6–120 °C. Adding the Ti(IV) inhibited the crystallization and particle growth of ZHC, showing a minimum at 50 °C. Higher aging temperature promoted the formation of TiO 2 nano-particles. Elevating the aging temperature suppressed the adsorption of H 2O and CO 2 on Ti(IV)-doped ZHC. These results suggest that the alloying Ti in galvanized steel forms compact zinc rust layer at various atmospheric temperatures in marine environment, which would lead to the enhancement of corrosion resistance.