Zinc Deposition

In our continual effort to develop a cost effective rechargeable Zn-air batteries, herewith, we demonstrated Zn anodes comprising of (i) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide (ZBK), (ii) 30 wt.% Zn: 3 wt.% bismuth oxide: 5 wt.% lead (II) oxide (ZBP), and (iii) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide: 5 wt.% lead (II) oxide additives (ZBKP) in 6 M KOH aqueous solutions and 1.88 wt.% polyacrylic acid as the gelling agent. KOH gel constituted the remaining mass of the anode wt.%. Results were confirmed via cycle voltammetry (CV), Tafel, electrochemical impedance spectroscopy (EIS), etc., measurements. Among the various Zn anodes analyzed, ZBKP showed a superior cathodic peak of − 1.805 and 1.950 V vs. Hg/ HgCl at 5th and 40th cycles during electrochemical cycle voltammetry. Tafel fitting on linear polarization test shows that ZBK exhibits the highest corrosion behavior followed by ZBP while ZBKP has the lowest corrosion behavior with an estimated corrosion inhibition efficiency of 36.06%. Furthermore, ZBKP displays the lowest dendrite growth, least corrosion rate, and superior capacity even at 60th cycles compared to ZBK and ZBP. In view of our finding, ZBKP has a higher positive electrode potential compare to ZBK and ZBP electrodes. Thus, ZBKP is the most suitable for aqueous battery due to its low minimal side effect. Field emission-scanning electron microscopy/energy dispersive x-ray spectroscopy (FE-SEM/EDS) images confirm that the various elemental additives were evenly deposited on the Zn anode surface. Ex situ spectroscopy and electrochemical performance studies also verified that the dendrite-free nature of improved Zn anode and the modified interfaces between electrolyte and Zn play vital roles towards advancing the energy storage performance. With all this indices and yard stick, the level of improvement we demonstrated in this current study is attractive for the design of an advanced secondary zinc-air batteries.

With bismuth oxide additive in zinc-air batteries anode, we have demonstrated a controlled dendrite formation at the anode surface by high current densities of 0.1 and 0.2 A/cm 2 during charging process. Cyclic voltammetry (CV) was carried out at a voltage range of −2.0 ∼ 0.5 V and a scan rate of 1 mV/s to examine the electrochemical performance of the electrode. Surprisingly, we have been able to reveal that zinc anode with 3 wt% bismuth oxide showed cathodic peaks after 20 cycles with no noticeable loss in performance. Structural characterization via FE-SEM images revealed that 3-dimensional spherical morphology was formed with bismuth oxide at a current density of 0.05 A/cm 2 under controlled kinetics. We have no doubt that our additive successfully mitigated the formation of dendrite at the surface of the anode. Thus, we gained sufficient insight on the critical role of bismuth oxide additive to achieving a dendrite free zinc anode with a stable cycle. Hence, this anode can be use as an excellent anode material in zinc-air secondary batteries.

In our continual effort to develop a cost effective rechargeable Zn-air batteries, herewith, we demonstrated Zn anodes comprising of (i) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide (ZBK), (ii) 30 wt.% Zn: 3 wt.% bismuth oxide: 5 wt.% lead (II) oxide (ZBP), and (iii) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide: 5 wt.% lead (II) oxide additives (ZBKP) in 6 M KOH aqueous solutions and 1.88 wt.% polyacrylic acid as the gelling agent. KOH gel constituted the remaining mass of the anode wt.%. Results were confirmed via cycle voltammetry (CV), Tafel, electrochemical impedance spectroscopy (EIS), etc., measurements. Among the various Zn anodes analyzed, ZBKP showed a superior cathodic peak of − 1.805 and 1.950 V vs. Hg/ HgCl at 5th and 40th cycles during electrochemical cycle voltammetry. Tafel fitting on linear polarization test shows that ZBK exhibits the highest corrosion behavior followed by ZBP while ZBKP has the lowest corrosion behavior with an estimated corrosion inhibition efficiency of 36.06%. Furthermore, ZBKP displays the lowest dendrite growth, least corrosion rate, and superior capacity even at 60th cycles compared to ZBK and ZBP. In view of our finding, ZBKP has a higher positive electrode potential compare to ZBK and ZBP electrodes. Thus, ZBKP is the most suitable for aqueous battery due to its low minimal side effect. Field emission-scanning electron microscopy/energy dispersive x-ray spectroscopy (FE-SEM/EDS) images confirm that the various elemental additives were evenly deposited on the Zn anode surface. Ex situ spectroscopy and electrochemical performance studies also verified that the dendrite-free nature of improved Zn anode and the modified interfaces between electrolyte and Zn play vital roles towards advancing the energy storage performance. With all this indices and yard stick, the level of improvement we demonstrated in this current study is attractive for the design of an advanced secondary zinc-air batteries.

With bismuth oxide additive in zinc-air batteries anode, we have demonstrated a controlled dendrite formation at the anode surface by high current densities of 0.1 and 0.2 A/cm 2 during charging process. Cyclic voltammetry (CV) was carried out at a voltage range of −2.0 ∼ 0.5 V and a scan rate of 1 mV/s to examine the electrochemical performance of the electrode. Surprisingly, we have been able to reveal that zinc anode with 3 wt% bismuth oxide showed cathodic peaks after 20 cycles with no noticeable loss in performance. Structural characterization via FE-SEM images revealed that 3-dimensional spherical morphology was formed with bismuth oxide at a current density of 0.05 A/cm 2 under controlled kinetics. We have no doubt that our additive successfully mitigated the formation of dendrite at the surface of the anode. Thus, we gained sufficient insight on the critical role of bismuth oxide additive to achieving a dendrite free zinc anode with a stable cycle. Hence, this anode can be use as an excellent anode material in zinc-air secondary batteries.

Investigation on a series of ABs-type metal hydride electrodes reveals significant improvement of cycle life in the presence of zincate electrolytes (0.5 M ZnO in 6 M KOH) for alloys without substituents such as Ce. For alloys containing Ce, which are known to impart passive protection against corrosion no additional advantage was derived by using zincate electrolytes. X-ray absorption near-edge structure investigation at the Ni K edge, due to its relative high abundance and catalytic importance in the hydriding process, was used to elicit the corrosion characteristics as a function of cycling. The spectra averaged over the bulk of the sample (transmission mode) and those from the top 200 to 250 A (electron yield mode) indicate significant lowering of corrosion and buildup of Ni(OH) 2 in non-Ce substituted alloys when using zincate electrolytes. In Ce substituted samples this effect was marginal.

Critical current densities for the initiation of dendrite growth and powder formation in potentiostatic and galvanostatic deposition are determined. Induction times for dendritic growth formation in potentiostatic and galvanostatic deposition are discussed.

The chemical conversion of Ag 2 O films on Ag surfaces to AgI in aqueous iodide solutions has been studied electrochemically. Ag 2 O films were grown potentiostatically and then exposed to I − solutions. The chemical conversion process was followed at open-circuit potential ͑E OC ͒ using cathodic stripping voltammetry performed after various exposure periods. The E OC showed a sudden drop at the completion of the conversion of Ag 2 O to AgI, reaching a steady-state value close to the equilibrium potential for AgI/Ag and the iodide solution. This sudden drop in E OC allowed easy determination of the total reaction time required for complete conversion of Ag 2 O to AgI. Distinctly separated current peaks were observed for the cathodic reduction of Ag 2 O and AgI to Ag, and the charges associated with these peaks provided a measure of the amount of Ag 2 O converted. The conversion reaction was 100% efficient. The total reaction times from the E OC measurements and the cathodic stripping results were used to determine the reaction order and rate constant required for the development of nuclear reactor safety assessment codes.

Hydrogen evolution reaction has a complex role during zinc electrodeposition. • Current efficiency of zinc deposition is lowered by hydrogen evolution. • Rising hydrogen bubbles increase zinc limiting current density. • Current density ratio is not suitable as zinc morphology indicator.

In this study, the electrodeposition-redox replacement (EDRR) method was studied for the recovery of minor concentrations of silver from dilute solutions. The parameter optimization was carried out with synthetic solutions similar to silver oxide button battery recycling effluents, consisting of sulfuric acid and concentrated base metal (10 g•L −1 H 2 SO 4 , 60 g/L Zn 2+) with a minor amount of silver (100 ppm) and a varying amount of Fe 3+ ions. Results of these experiments were analyzed both electrochemically and by use of SEM-EDS. The role of dissolved Fe 3+ ions was studied by varying the concentration from 0 to 1000 ppm and the results showed that although the presence of Fe ions decreased silver recovery efficiency, final product purity was found to increase slightly. The EDRR process was also found to be more effective for Ag recovery and has less energy consumption when Fe 3+ concentrations are relatively low (≤ 100 ppm) when compared with conventional direct current electrowinning. In the final stage, silver was successfully recovered via EDRR, using the optimized conditions, from a real pregnant leaching solution (PLS) obtained from the leaching of silver oxide batteries.

The most critical disadvantages of the Zn-air flow battery system are corrosion of the zinc, which appears as a high self-discharge current density and a short cycle life due to the non-uniform, dendritic, zinc electrodeposition that can lead to internal short-circuit. In our efforts to find a dendrite-free Zn electrodeposition which can be utilized in the Zn-air flow battery, the surface morphology of the electrolytic Zn deposits on a polished polymer carbon composite anode in alkaline, additive-free solutions was studied. Experiments were carried out with 0.1 M, 0.2 M and 0.5 M zincate concentrations in 8 M KOH. The effects of different working conditions such as: elevated temperatures, different current densities and different flow velocities, on current efficiency and dendrite formation were investigated. Specially designed test flow-cell with a central transparent window was employed. The highest Coulombic efficiencies of 80%-93% were found for 0.5 M ZnO in 8 M KOH, at increased temperatures (50-70 °C), current densities of up to 100 mA•cm-2 and linear electrolyte flow velocities higher than 6.7 cm•s-1 .

Transient ionic mass-transfer rates during the anodic dissolution of an upward-facing horizontal zinc electrode in a 10 wt % ͑1.95 M͒ KOH aqueous electrolyte were monitored by holographic interferometry. The anode potential during zinc dissolution was also measured against a HgO/Hg reference electrode. A two-dimensional mathematical model, wherein a supporting electrolyte also takes part in the electrochemical reactions, was developed to characterize the electrolyte transport phenomena. Transient masstransfer rates of both Zn͑OH͒ 4 2− and OH − ions were numerically analyzed, and calculated transient refractive index profiles and anode overpotentials were compared to measured values. The electrochemical dissolution and passivation phenomena of the zinc anode in an alkaline electrolyte solution were discussed.

liThe macromorphological features of electrodeposited zinc that result from hydrodynamic flow along a fiat plate electrode (fpe) and on a rotating disk electrode (rde) were investigated using an acidic chloride solution. Characteristics of reattaching flow and the possible presence of streamwise-directed counterrotating Taylor vortices were seen in the macromorphology of three dimensional relief imprints. Relief striations in zinc electrodeposition depend on the average current density, the rotation speed (rde) or linear flow velocity (fpe), the time of deposition, the ionic zinc content and electrolyte composition, the pH value, the hydrodynamic flow pattern, and the presence of surfactant. Macromorphological imprints of electrodeposited zinc within a certain current density range (10-100 mA/cm 2) can be employed for both instantaneous and cumulative electrochemical visualization of flow patterns.

Sustainability, environmental and safety concerns raised by the increasing demand of batteries are driving research towards post-lithium technologies. Rechargeable Zn batteries are strong candidates, but still not practically viable, owing to the extensively studied, but poorly understood unstable behavior of Zn metal upon discharge-charge cycling. This limiting factor warrants more fundamental investigations and the present report provides the lacking molecular-level information on the Zn-based compounds forming at the electrode/electrolyte interface as a result of electrochemical cyclic in weakly acidic aqueous electrolyte. The results are obtained using ex situ X-ray absorption spectromicroscopy maps, modelled mathematically and complemented with cyclic voltammetry, symmetric-cell tests and electron microscopy. We have identified the role of the zincate precipitation resulting from local alkalinization during recharge, combined with additional zincate formation and decomposition to zinc oxide during discharge. The mathematical model allowed a transparent interpretation of morphochemical changes observed. The synergy of these processes leads to electrochemical localization effects, resulting in the formation of a complexly structured and low conductive ZnO-based template, that might play a role in driving shape changes.

A short-term exposure of zinc (Zn) electrodes in polyethylene glycol (PEG) containing alkaline electrolytes at a temperature range of 45-65°C significantly reduces the corrosion rate of the Zn in the strong alkaline solutions. The enhanced characteristics of the protective film formed during this pretreatment process is attributed to a substantial reduction in the cross-sectional Bdiameter^of the hydrated inhibitor molecules, due to a decrease in the hydration number at warmer temperatures. One can expect that Bslimmer^organic molecules with a lower cross-sectional dimension, having a lower hydration number, will constitute a denser surface layer, providing enhanced isolation of the neighborhood active sites at the Zn anode. Implementing this approach in alkaline batteries utilizing Zn anodes may result in battery performance enhancement.

Flow-assisted zinc-nickel batteries offer an inexpensive and safe solution to grid-scale energy storage [1]. However, they remain prone to dendrite formation on charging, limiting battery cycling. Dendritic zinc deposition occurs under a mass-transfer limitation and convection improves cycle life but the phenomenon is not well understood. Naybour [2] qualitatively studied the effect of convection on dendritic growth of zinc. However, the flow modeled was not laminar and significantly higher than required for feasible operation of a flow-assisted battery. Gallaway et al [3] reported a strong dependence of zinc deposition on electrolyte flow and current density, which highlights the need for theoretical model to predict the growth and form of zinc dendrites.

The conditions under which ohmic controlled metal electrodeposition occurs are discussed using a simple mathematical model. It is shown that ohmic controlled electrodeposition can be operative if the value of the exchange current density for the electrodeposition process is more than 10 times larger than the corresponding value of the limiting diffusion current density. In this case, a linear dependence of the current density on overpotential up to the value of the limiting diffusion current density can be observed. On the other hand, the initiation of dendrite growth under these circumstances is possible, even at very low values of overpotential, at the moment when the limiting diffusion current density is attained in potentiostatic electrodeposition. In this way, instead of a limiting diffusion current density plateau, an inflection point on the polarization curve can be observed, since dendritic growth is followed by an increase in the deposition current density. At the same time, it is shown that the ensemble of tips of dendrites can behave as an ensemble of microelectrodes working independently under mixed or activation control due to the absence of a common diffusion layer. This was confirmed by deposition of copper on a copper dendritic electrode and by silver electrodeposition from a silver nitrate solution onto a graphite substrate.

The overall goal of this work is the use of COMSOL Multiphysics in the modelling of the current density distributions for the electrodeposition of Aluminium coatings from Ionic Liquids. The local current distribution is strongly dependant on the conductivity and on the geometry of the galvanic cell and can only be performed by the numerical solution of the PDE's governing the system. The ability to predict the local current density on an electrode is crucial to eventually evidence portions where the deposition may be invalidate.

Investigation on a series of ABs-type metal hydride electrodes reveals significant improvement of cycle life in the presence of zincate electrolytes (0.5 M ZnO in 6 M KOH) for alloys without substituents such as Ce. For alloys containing Ce, which are known to impart passive protection against corrosion no additional advantage was derived by using zincate electrolytes. X-ray absorption near-edge structure investigation at the Ni K edge, due to its relative high abundance and catalytic importance in the hydriding process, was used to elicit the corrosion characteristics as a function of cycling. The spectra averaged over the bulk of the sample (transmission mode) and those from the top 200 to 250 A (electron yield mode) indicate significant lowering of corrosion and buildup of Ni(OH) 2 in non-Ce substituted alloys when using zincate electrolytes. In Ce substituted samples this effect was marginal.

Zinc-air batteries offer large specific energy densities, while relying on abundant and non-toxic materials. In this paper, we present the first multi-dimensional simulations of zinc-air batteries. We refine our existing theory-based model of secondary zinc-air systems. The model comprises thermodynamically consistent multi-species transport in alkaline electrolytes, formation and dissolution of metallic zinc and passivating zinc oxide, as well as multi-phase coexistence in gas diffusion electrodes. For the first time, we simulate zinc shape-change during battery cycling by modeling convection of zinc solids. We validate our model with in-situ tomography of commercial button cells. Two-dimensional volume-averaged simulations of cell voltage and zinc electrode morphology during discharge agree with these measurements. Thus, we can study how electrolyte carbonation limits shelf-life and how zinc shape-change limits cycle-life. The charging current is found to be the major contributor to cycle-life limitations. Finally, we optimize initial anode structure and charge-discharge protocols for improved performance and cycle-ability.

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

In this study, the effect of the incorporation of composite and ecofriendly particles to develop new engineering materials on the developed zinc electrolyte containing TiO 2 /TiB and Solanum tuberosum is presented. The electro-depositions were completed at 20 min at a stirring rate of 150 rpm at temperature of 50°C and pH of 4.The effect of S. tuberosum (ST) as bath additive at varied interval of 5-25 ml to the coating properties was noted. Electrodeposition parameters were constant at a voltage of 3.5 V for Znbased coatings. The outline of bath condition as it influences the microhardness and wear rate were set into consideration. Hence, the coating microhardness and wear rate at constant electrodeposition parameters and varied ST were acquired. Hence, liquid fluid additives can be used for performance of fabricated coatings in advanced surface engineering application.

Controlling the wetting properties at the three-phase interface is important for improving the performance of alkaline fuel cells. The meniscus of a potassium hydroxide droplet was formed on a nickel electrode, and the interference fringe during the oxygen reduction reaction was observed by confocal laser microscopy. The high spatial resolution of the microscope revealed thin film formation at the meniscus front interface. The thickness decreased with increasing cathodic potential. The generation of microscopic convection by interfacial surface tension may affect mass transfer in the thin film.

The present simplified electrochemical model of a horizontal upward-facing Zn anode combined with a Ni(OH)2/NiOOH cathode thus reasonably simulates the time-dependent coupling phenomena between the electrode surface morphological variations and the ionic mass transfer rate inside the model-pore mesoporous microstructure that extends across the width of a Zn battery cell.

Copper is commonly regarded to be immune to corrosion in deaerated deionized electrolytes. The present work shows that, in the absence of hydrogen, copper will corrode on the order of 1 nm/day in deionized water with an O 2 concentration on the order of, or less than, 1 ppb. While a corrosion rate of this magnitude can normally be neglected, it may be catastrophic for nanoscale copper structures utilized in emerging applications to enhance energy transport at the solid-electrolyte interface, such as in cooling advance electronics. This conclusion is supported by a set of experimental and analytical studies that encompass impedance spectroscopy, slow-scan linear sweep voltammetry, thermodynamic calculations for the environment under study, and kinetic simulations. The studies provide a comprehensive insight on details of the corrosion mechanism for copper in deaerated water.

The plating parameter effect of zinc deposition on mild steel substrates was investigated. The results showed an improved surface finished and homogeneous layer. The distance between the anode and the cathode on voltage, plating time and coating thickness were considered. The mild steel was deposited into solution of zinc bath for varying voltage between 0.5 v and 1.0 v. It was discovered that the sample plated at 0.8 v for 15 minutes gives the best plating deposition and appearance. The surface morphology of ...

This paper is devoted to the description of magnetic field effects on zinc electrodeposition from basic media. The major effect of the magnetic field stems from a slight magnetohydrodynamic forced convection located close to the cathodic interface. Classical impedance analysis reveals that the reaction mechanism is governed by two diffusing species, Zn(II) and OH -, the contributions of which have been discerned. This leads to a good agreement between experimental and theoretical impedance diagrams and shows, once again, that the magnetic field exerts no effect upon the transfer kinetics.

Both AFM imaging and stress measurements were carried out in-situ during potentiostatic electrodeposition of copper on gold in 0.05 mol dm-3 CuSO4 in 0.1 mol dm-3 H2SO4. In the absence of additives, compressive stress generally developed initially and films subsequently underwent a compressive-to-tensile (C-T) transition. The nucleation density measured by AFM increased from 2.7x107 cm-2 at -75 mV to 2.5x109 cm-2 at -300 mV. Very little coalescence of nuclei was observed at -75 mV but the rate of coalescence increased rapidly with increasing negative potential. The time for the C-T transition correspondingly decreased rapidly until, at -75 mV, none was observed. This is consistent with models that attribute the C-T transition to increasing tensile stress due to coalescence of nuclei. With a combination of Cl-, PEG and MPSA, compressive stress generally developed initially and was greater than in additive-free electrolyte. At less negative potentials, the stress continued to evolve i...

Ordered nanoporous bismuth oxide layer consisting of metastable β-Bi 2 O 3 phase that showed n-type semiconductivity was synthesized by a simple electrochemical anodization of bismuth substrate. When the anodic nanoporous β-Bi 2 O 3 samples were tested as photoanodes for solar water splitting application in 0.5 M Na 2 SO 4 (pH:5.8), and 1 M KOH (pH:13.7), the photocurrent decayed continuously with time from an initial value of 0.95 mA/cm 2 under 1-sun illumination at a bias potential of 1.5 V RHE. Accumulation of photo generated holes at the photoanode/ electrolyte was attributed to the photocurrent decay. Addition of methanol as sacrificial hole scavenger was not found to be effective for the bismuth oxide photoanodes. When hydrogen peroxide was added to the 0.5 M Na 2 SO 4 electrolyte, the photocurrent density increased to ∼4 mA/cm 2 and was stable for more than 1 h of illumination of AM1.5 global light at 1.5 V RHE. Addition of hydrogen peroxide to the 1 M KOH solution showed a gradual increase in the photocurrent density for the first 300 seconds of light illumination to a maximum value of ∼10 mA/cm 2 at 0.65 V RHE and then it decreased continuously. The high photocurrent density of nanoporous β-Bi 2 O 3 in 1 M KOH + 0.3 M H 2 O 2 was be attributed to the presence of photo-converted Bi 2 O 4-x phase which harvested more light in the visible wavelengths.

Ordered nanoporous bismuth oxide layer consisting of metastable β-Bi 2 O 3 phase that showed n-type semiconductivity was synthesized by a simple electrochemical anodization of bismuth substrate. When the anodic nanoporous β-Bi 2 O 3 samples were tested as photoanodes for solar water splitting application in 0.5 M Na 2 SO 4 (pH:5.8), and 1 M KOH (pH:13.7), the photocurrent decayed continuously with time from an initial value of 0.95 mA/cm 2 under 1-sun illumination at a bias potential of 1.5 V RHE. Accumulation of photo generated holes at the photoanode/ electrolyte was attributed to the photocurrent decay. Addition of methanol as sacrificial hole scavenger was not found to be effective for the bismuth oxide photoanodes. When hydrogen peroxide was added to the 0.5 M Na 2 SO 4 electrolyte, the photocurrent density increased to ∼4 mA/cm 2 and was stable for more than 1 h of illumination of AM1.5 global light at 1.5 V RHE. Addition of hydrogen peroxide to the 1 M KOH solution showed a gradual increase in the photocurrent density for the first 300 seconds of light illumination to a maximum value of ∼10 mA/cm 2 at 0.65 V RHE and then it decreased continuously. The high photocurrent density of nanoporous β-Bi 2 O 3 in 1 M KOH + 0.3 M H 2 O 2 was be attributed to the presence of photo-converted Bi 2 O 4-x phase which harvested more light in the visible wavelengths.

A critical hurdle in realizing rechargeable lithium-metal batteries is the dendritic electrodeposition of lithium during the battery charging process. Here, we investigate the onset of dendritic morphology during galvanostatic lithium electrodeposition using electrochemical techniques combined with optical microscopy. We show that lithium dendrites initiate at the time when the surface overpotential during galvanostatic electrodeposition reaches a maximum value. This observation is explained using an analytical transport model wherein the Li + concentration within the solid electrolyte interphase (SEI) near the lithium metal surface decreases gradually as the SEI thickness and its transport resistance increases with time. At the dendrite onset time (τ onset), the Li + concentration at the lithium-SEI interface approaches zero-a condition under which surface roughness on the lithium electrode amplifies, producing dendrites. Once dendrites form, they rupture the SEI, lowering the surface resistance for plating. Model predictions of how τ onset varies with current density and soak time are shown to be in qualitative agreement with experimental observations. Furthermore, pulsed currents are applied to mitigate Li + concentration depletion within the SEI, thereby delaying or preventing altogether the formation of lithium dendrites.

Investigation on a series of ABs-type metal hydride electrodes reveals significant improvement of cycle life in the presence of zincate electrolytes (0.5 M ZnO in 6 M KOH) for alloys without substituents such as Ce. For alloys containing Ce, which are known to impart passive protection against corrosion no additional advantage was derived by using zincate electrolytes. X-ray absorption near-edge structure investigation at the Ni K edge, due to its relative high abundance and catalytic importance in the hydriding process, was used to elicit the corrosion characteristics as a function of cycling. The spectra averaged over the bulk of the sample (transmission mode) and those from the top 200 to 250 A (electron yield mode) indicate significant lowering of corrosion and buildup of Ni(OH) 2 in non-Ce substituted alloys when using zincate electrolytes. In Ce substituted samples this effect was marginal.

The influence of Saponin, Licorice, Tennafroth 250, and Dowfroth 250 at different concentration levels (0, 5, 10, and 15 ppm) were investigated during zinc electrowinning from industrially supplied spent electrolyte. Acid mist suppression efficiency, polarization behavior, current efficiency and energy consumption were investigated for a current density of 500 A.m-2. Surface tension measurements were used to find a correlation between the concentration of the different additives and the acid mist suppression efficiencies. Morphological and crystallographic orientation studies indicated dense and well defined crystalline grains with homogeneous distribution mostly at the 5 ppm level of suppressant. Electrowinning in the presence of Saponin and Tennafroth was found to have high current efficiencies of 90% each with low energy consumptions of 2641 and 2675 kWh/t, respectively and the deposited crystals were found to be oriented preferably in the [101], [102], [103] and [112] planes for both.

Porous electrode theory was applied to estimate the exchange current density, the polarization resistance, and symmetry factor for LaNi427Sn024 hydride electrode in alkaline solution. The exchange current density, polarization resistance, and symmetry factor were determined from polarization curves which were obtained at low overpotentials,

Polarization experiments and a potentiostatic pulse technique have been used to show that a monolayer coverage of zinc effectively inhibits the absorption of hydrogen into Monel K500. By depositing a monolayer of zinc on Monel K500, the hydrogen evolution reaction and hydrogen ingress flux rate were reduced by 60%.

The Devanathan-Stachurski permeation technique13 was used to investigate the rate of hydrogen permeation through an iron membrane with consecutively electroplated zinc layers. Hydrogen evolution rates and hydrogen permeation rates were followed as functions of time at different applied potentials. Hydrogen evolution and permeation decreased with each successive zinc layer until finally reaching an average decrease of 93 and 96%, respectively, as compared with bare iron. Hydrogen surface coverage, exchange current density, absorption-adsorption reaction constant, and hydrogen recombination constant were estimated on bare iron and on zinc-plated iron. It was found that the decrease in the permeation rate of hydrogen through the iron membrane was due to (i) the decrease of hydrogen discharge rate and (ii) the suppression of hydrogen absorption and adsorption on the deposited zinc layers.

LaNi 5 intermetallic-hydride forming compound and several metal-substituted derivatives have been compared in terms of cycling behavior observed by means of the cavity microelectrode (CME) at high scan rates (50 mV s À1). LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 was found to have a stable behavior over 1000 cycles, whereas, the capacity of LaNi 5 decreases after only 200 cycles. The performances for the mono-substituted compounds are intermediate. The rechargeability decreases according to the following order: LaNi 4:6 Mn 0:4 > LaNi 4:7 Al 0:3 > LaNi 4:25 Co 0:75 > LaNi 5. This study demonstrates the capability of the CME to check numerous battery materials in a very short period of time, which allows to bring out the effect due to the corrosion of the material.

LaNi 5 intermetallic-hydride forming compound and several metal-substituted derivatives have been compared in terms of cycling behavior observed by means of the cavity microelectrode (CME) at high scan rates (50 mV s À1). LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 was found to have a stable behavior over 1000 cycles, whereas, the capacity of LaNi 5 decreases after only 200 cycles. The performances for the mono-substituted compounds are intermediate. The rechargeability decreases according to the following order: LaNi 4:6 Mn 0:4 > LaNi 4:7 Al 0:3 > LaNi 4:25 Co 0:75 > LaNi 5. This study demonstrates the capability of the CME to check numerous battery materials in a very short period of time, which allows to bring out the effect due to the corrosion of the material.

The cycleability of a lithium anode has been investigated in two solutions containing LiClO 4 : (i) a propylene carbonate (PC) solution and (ii) a blended solution consisting of PC, ethylene carbonate (EC) and 1,2-dimethoxyethane (DME) (volume RATIO = 1:1:2). Lithium and ...

Developing a cheap, sustainable, and simple to use low power electrical energy source will substantially improve the life quality of 1.6ϫ 10 9 people, comprising 32% of the developing non-Organization for Economic CoOperation and Development populations currently lacking access to electrical infrastructure ͑World Energy Outlook, 2006, http://www.worldenergyoutlook.org/2006.asp, 10 September 2009͒. Such a source will provide important needs as lighting, telecommunication, and information transfer. Our previous studies on Zn/Cu electrolysis in animal tissues revealed a new fundamental bioelectrical property: the galvanic apparent internal impedance ͑GAII͒ ͓A. Golberg, H. D. Rabinowitch, and B. Rubinsky, Biochem. Biophys. Res. Commun. 389, 168 ͑2009͔͒, with potential use for tissue typing. We now report on new fundamental studies on GAII in vegetative matter and on a simple way for significant performance improvement of Zn/Cu-vegetative battery. We show that boiled or irreversible electroporated potato tissues with disrupted cell membranes generate electric power up to tenfold higher than equal galvanic cell made of untreated potato. The study brought about basic engineering data that make possible a systematic design of a Zn/Cu-potato electrolytic battery. The ability to produce and utilize low power electricity was demonstrated by the construction of a light-emitting diode based system powered by potato cells. Primary cost analyses showed that treated Zn/Cu-potato battery generates portable energy at ϳ9 USD/ kW h, which is 50-fold cheaper than the currently available 1.5 V AA alkaline cell ͑retail͒ or D cells ͑ϳ49-84 USD/ kW h͒. Admittedly very simple, the treated potato or similarly treated other plant tissues could provide an immediate, environmental friendly, and inexpensive solution to many of the low power energy needs in areas of the world lacking access to electrical infrastructure.

Layered double hydroxides (LDH) as active electrode materials have become the focus of research in energy storage applications. The manufacturing of excellent electrochemical performance of the LDH electrode is still a challenge. In this paper, the production of CoAl-LDH@Ni(OH) 2 is carried out in two steps, including hydrothermal and electrodeposition techniques. The prominent features of this electrode material are shown in the structural and morphological aspects, and the electrochemical properties are investigated by improving the conductivity and cycle stability. The core of this experimental study is to investigate the properties of the materials by depositing different amounts of nickel hydroxide and changing the loading of the active materials. The experimental results show that the specific capacity is 1810.5F • g −1 at 2 A/g current density and the cycle stability remained at 76% at 30 A g −1 for 3000 cycles. Moreover, a solid-state asymmetric supercapacitor with CoAl-LDH@Ni(OH) 2 as the positive electrode and multi-walled carbon nanotube coated on the nickel foam as the negative electrode delivers high energy density (16.72 Wh kg −1 at the power density of 350.01 W kg −1). This study indicates the advantages of the design and synthesis of layered double hydroxides, a composite with excellent electrochemical properties that has potential applications in energy storage.

Bipolar rechargeable alkaline manganese dioxide–zinc (RAM) batteries are produced in the laboratory. These are obtained through minimizing the passivation problems associated with the zinc electrode, which is considered to have a limiting effect on the charge–discharge ...

Zinc batteries are a more sustainable alternative to lithium-ion batteries due to its components being highly recyclable. With the improvements in the screen printing technology, high quality devices can be printed with at high throughput and precision at a lower cost compared to those manufactured using lithographic techniques. In this paper we describe the fabrication and characterization of printed zinc batteries. Different binder materials such as polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB), were used to fabricate the electrodes. The electrodes were first evaluated using three-electrode cyclic voltammetry, x-ray diffraction (XRD), and scanning electron microscopy before being fully assembled and tested using charge-discharge test and two-electrode cyclic voltammetry. The results show that the printed ZnO electrode with PVB as binder performed better than PVP-based ZnO. The XRD data prove that the electro-active materials were successfully transferred to the sample. H...