Initial Stage Of Deposition Research Articles

Effect of Surface Textures of Iron Substrate on the Crystal Orientation Relationship between Electrodeposited Zinc and Iron

To investigate the effect of iron texture on the crystal orientation relationship between iron and zinc, Zn deposition was performed galvanostatically at 1500 A/m2 at a charge density of 1.48 × 104 C/m2 onto high-purity electrolytic iron and cold rolled steel sheets in an agitated sulfate solution at 40°C. Fe with a large grain size showed an orientation relationship of {110}Fe//{0001}Zn. However, when the angle of inclination between the {110}Fe plane and the surface of electrolytic Fe was increased, the deviation in the orientation relationship {110}Fe//{0001}Zn increased. This result suggests that the orientation relationship of {110}Fe//{0001}Zn is difficult to maintain during the deposition when the inclination angle of the {110}Fe plane from the surface of electrolytic Fe increases. As a result, the epitaxial growth of Zn changes to random growth. Zn deposited on cold rolled steel sheets with a small grain size showed an orientation of {0001}, regardless of the orientation of Fe. This indicates that the orientation of the deposited Zn is more affected by the overpotential for deposition than by the orientation of steel sheets at the initial stage of deposition. Although strain was introduced into the high-purity electrolytic Fe with sandblasting, the orientation relationship of {110}Fe//{0001}Zn did not change remarkably, showing that the strain of Fe substrate has little effect on the orientation relationship between Fe and deposited Zn.

The geometry of hexagonal boron nitride clusters in the initial stages of chemical vapor deposition growth on a Cu(111) surface.

To understand the nucleation process in the growth of hexagonal boron nitride (h-BN) on transition metal substrates by chemical vapor deposition (CVD), the energy of formation and stability of h-BN clusters of different geometries on a pristine Cu(111) surface were systematically investigated using density functional theory calculations. We find that unlike carbon clusters, h-BN clusters on Cu supports can undergo two possible transformations of the minimum-energy structure at a critical size of 13. Different from freestanding h-BN clusters, on a Cu(111) surface, h-BN chains are more stable than h-BN rings and thus dominate the minimum-energy structure for cluster sizes lower than the critical size. Thus, depending on the experimental conditions of CVD, one-dimensional Bn-1Nn (N-rich environment) or BnNn-1 (B-rich) chains are first created, and they transform to two-dimensional sp2 networks or h-BN islands, but for a BnNn chain, the transformation to a two-dimensional sp2 network h-BN island does not occur. In contrast to carbon islands where pentagons are readily formed, odd-membered rings are extremely rare in h-BN islands, where the transformation to the most stable structure occurs through a combination of trapeziums and hexagons at the edges, so as to avoid B-B and N-N bonds. Moreover, on a Cu(111) surface, trapeziums are destabilized when the four edges are connected to other hexagons because of additional curvature energy, thus favoring the nucleation of planar nuclei. A deep insight into h-BN cluster formation on a Cu support is vital to understanding the growth mechanism of h-BN on a transition metal surface in CVD experiments to further improve experimental designs in the CVD growth of h-BN.

The Role of Humidity in Tuning the Texture and Electrical Properties of Cu2O Thin Films Deposited via Aerosol‐Assisted CVD

AbstractA study on the effect of carrier gas (CG) humidity on the texture and the resulting electronic properties of Cu2O thin films deposited using aerosol‐assisted chemical vapor deposition (AA‐CVD) at low temperatures (<365 °C) is reported. By increasing the CG humidity, the preferred orientation of the films can be tuned from [110] to [111]. By studying the initial stages of film deposition, a different growth mode is found for dry and humid conditions, which in turn directs the final texture of the films. The analysis of the electric properties of the films by Hall effect shows that carrier concentration remains in the order of 1015 cm−3 when using both dry and humid conditions. Converselly, Cu2O samples deposited with humid CG generally present a higher mobility, up to 17 cm2 V−1 s−1. [111]‐textured Cu2O films with high mobility were used to fabricate a diode by depositing a ZnO layer on top using atmospheric pressure spatial atomic layer deposition (AP‐SALD). The diode shows an excellent rectifying behavior with a high asymmetry close to 104 between −1 and +1 V.

Early stages of copper microparticles electrodeposition on polypyrrole film

Abstract In this work, we studied the electrodeposition of copper (Cu) microparticles on polypyrrole (PPy) films using cyclic voltammetry and chronoamperometry techniques. The initial stages of Cu deposition were investigated by performing current transients. Models based on Scharifker and Hills calculations were established to determine the nucleation and growth type. The results suggest that the deposition of Cu proceeds via an instantaneous nucleation followed by three-dimensional (3D) diffusion-limited growth. The values of the number density of active sites N∞ and diffusion coefficient D were also determined.

Electrochemical codeposition of silver-gold nanoparticles on CNT-based electrode and their performance in electrocatalysis of dopamine

The formation of silver-gold (Ag-Au) bimetallic nanoparticles by electrochemical reduction from a single bath solution is investigated when changing the deposition conditions and parameters (pulse time, deposition duration or concentration ratio). Remarkable differences in the formation of Ag-Au nanoparticles on the carbon substrate are reflected in their morphological and redox features as well as in their composition. The initial stages of deposition were investigated by cyclic voltammetry, followed by optimization of deposition through double-pulse chronoamperometry combined with SEM and EDX studies. The Ag-Au modified electrode is fairly sensitive and responds to dopamine with an oxidation peak at −0.12 V. The electrochemical experiments showed that for 2:1 precursors ratio of AgNO3/HAuCl4 used in deposition, the obtained Ag-Au bimetallic nanoparticles possess the highest electrocatalytic response toward dopamine, within 1–173 μM range under the optimized conditions (limit of detection 52 nM).

Effect of applied magnetic field on microstructure of electrodeposited copper

There have been many fundamental studies on magnetic field-assisted electrodeposition that focus on the initial stages of thin film deposition but not on the resulting microstructural features (texture, grain size, grain boundary character, phase distribution) of the plating. In this communication we present results on the influence of a gradient magnetic field on the microstructural features of thick (>100μm) electrodeposited copper films. It is shown by electron backscatter diffraction characterization that the application of a gradient magnetic field influenced the grain size and twin boundary fraction. Depletion of Cu2+ ions at the substrate caused by the magnetic gradient force resulted in lower plating thicknesses and larger grain sizes when the direction of applied magnetic field and current was parallel. On the other hand, the magnetic field has little effect on the thickness and grain size for the anti-parallel case. In all cases increased convective flow offered by local magnetohydrodynamic effect resulted in substantially higher twin boundary fraction.

(Invited) Process Development and Analysis of Si Electrodeposition in Ionic Liquid

Si thin films and micro/nano structures have been widely used for various applications such as semiconductor and MEMS devices, solar cells, battery electrodes, etc. While dry processes such as chemical vapor deposition have been conventionally applied for their fabrication, electrochemical approaches attract attention for their capability to form uniform and precise structures to wide and non-flat surfaces, with high productivity. In this paper we describe the results of our investigation on Si electrodeposition, mainly focusing upon the process development as well as mechanistic understanding of the deposition process through experimental and theoretical approaches. Since the redox potential of Si species is very negative, nonaqueous systems such as organic solvents, molten salts or ionic liquids have been applied for the electrodeposition of Si [1-3]. We have mainly used low temperature (up to 40°C) ionic liquid (IL), trimethylhexyl ammonium (TMHA+) bis-trifluorosulfonyl imide (TFSI-), as electrolyte [4]. The TMHA-TFSI is hydrophobic IL in which SiCl4, the precursor of Si, could be sufficiently dissolved. The electrodeposition was carried out potentiostatically using a three electrode sell. Au/n-Si or FTO substrate, Pt wire, and Ag/Ag+ were used as working, counter, and reference electrodes, respectively. By optimizing the deposition parameters, uniform Si films were obtained. The results of structural and compositional analyses indicated that the as-deposited films were amorphous and contained impurities such as C, while their amount could be reduced by annealing. It was also confirmed that the electric properties of the deposited films could be controlled by adding dopant species such as AlCl3 in the bath for the electrodeposition [5]. In order to investigate the mechanism of the deposition process, we applied electrochemical quartz crystal microbalance (EQCM) and the results indicated that the reduction of SiCl4 to Si proceeded via intermediate species such as Si (III) and Si (II) [4, 6]. In situ X-ray reflection measurements were also employed using synchrotron radiation lightsource in combination with density functional theory (DFT) calculation for nanoscopic analysis of the structure of IL-electrode interface during the deposition [7]. It was indicated that layered structure consisting of Si multimer such as Si2Cl6 dimer was formed at the surface of electrode prior to the deposition of elemental Si, suggesting formation of the intermediate states during the initial deposition stage of Si. The authors would like to thank Dr. J. Komadina, Dr. A. Mehta, Mr. M. Nishida, and Mr. H. Takai for their experimental help and valuable discussion. This study was financially supported in part by the Japan Science and Technology Agency (JST) CREST program. [1] T. Munisamy, A. J. Bard, Electrochim. Acta, 55, 3797 (2010). [2] M. Bechelany, J. Elias, P. Brodard, J. Michler, L. Philippe, Thin Solid Films, 520, 1895 (2012). [3] F. Endres, A.P. Abbott, D.R. MacFarlane, Electrodeposition from Ionic Liquids, Wiley-VCH, 2008. [4] J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, T. Homma, Electrochim. Acta, 100, 236 (2013). [5] Y. Tsuyuki, H. Takai, Y. Fukunaka, T. Homma, Jpn. J. Appl. Phys., in press. [6] Y. Tsuyuki, A. Pham, J. Komadina, Y. Fukunaka, T. Homma, Electrochim. Acta, 183, 49 (2015). [7] Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma, J. Electrochem. Soc., 164, D994 (2017).

From the Very First Stages of Mn Deposition on Ge(001) to Phase Segregation

In this work, we have combined scanning tunneling microscopy with high-resolution transmission electron microscopy (HR-TEM) to investigate the initial stages of Mn deposition on Ge(001) surfaces. The growth temperature was chosen to be (353 ± 5) K, which is typical for the synthesis of Ge1–xMnx thin films. At the early stage of the Mn deposition, two distinct kinds of islands are observed even for Mn coverage much smaller than a monolayer with an average size of 1–2 nm and 4–5 nm, respectively. Small islands were found to nucleate in the hollow between the Ge dimer rows, and they were formed by consuming Ge from two adjacent rows. This indicates that Mn–Ge alloying has been taken place even at the early stage of the Mn deposition. When the Mn coverage increases, coarsening between small islands with newly deposited ad-atoms occurs, giving rise to the formation of monosized islands. Interestingly, these nanostructures have an average size of 4–5 nm and separated by a spacing of 7–8 nm that are similar to the spatial ordering of nanocolumns resulting from spinodal decomposition in (Ge,Mn) thin films. HR-TEM analyses indicate that those nanoislands are epitaxial, defect-free, and perfectly coherent with the Ge substrate. A subsequent anneal will result in the formation of Mn5Ge3 islands.

Initial nucleation stage in photo-CVD of GeH4 on SiO2 substrate monitored by real-time spectroscopic ellipsometry and photo reflectance: Accurate determination of incubation time

The initial stage of photoexcited chemical vapor deposition (CVD) of Ge layers on SiO2 substrate was studied through a combined analysis of real-time spectroscopic ellipsometry and photoreflectance (PR). Just after GeH4 gas was admitted into the growth chamber, there was a certain period during which both the ellipsometric (Ψ, Δ) angles and PR intensity remained unchanged from their initial values. This phenomenon prior to steady-state growth is known as incubation, and it is due to the very slow reactive sticking of GeHx species on the dangling-bond free SiO2 surfaces. The incubation time was accurately determined from the time derivatives of (Ψ, Δ) and the PR intensity. In most cases, the incubation times independently derived from (Ψ, Δ) and the PR intensity coincided, but for other cases, those derived from the PR intensity were slightly longer than those derived from (Ψ, Δ). The incubation time decreased as thermally activated decomposition of GeHx species became prevalent above 300 °C. An activation energy of 18 kJ/mol was obtained by assuming that the rate of creating nucleation seeds on SiO2 is proportional to the inverse of the incubation time. Such a low activation energy, much lower than that of thermal CVD, is due to partial decomposition of GeH4 by photoexcitation to create reactive GeHx fragments. At the end of incubation, the Ge layer wetting the SiO2 surface changed into self-assembled Ge dots when more Ge atoms were deposited. The dot density was maximum at the beginning of dot formation and gradually decreased as the dot size became larger. The activation energy of continuous Ge growth on Ge-covered SiO2 surface was derived from the time evolution of Δ to be 13 kJ/mol. The minimum PR intensity for three-dimensional (3D) dot formation was lower than that of two-dimensional (2D) layer growth, reflecting greater surface roughness. Contrasting behaviors between 2D and 3D growth were also observed in terms of the recovery level of the PR intensity after prolonged growth; continued 2D growth recovered up to 90% of the initial level, while 3D dot formation recovered only 50 −60%.

Effects of deposition time and current density on PbO2 electrosynthesis from methanesulfonate electrolyte

This work investigated the effects of current density and deposition time on the properties of electrodeposited PbO2. The PbO2 preparation was conducted on Ti/SnO2–Sb substrates by galvanostatic anodic deposition in a newly proposed methanesulfonate electrolytic solution. Phase constituents and microstructures of the deposited PbO2 coatings were characterized. Increasing current density in the range ≤ 100 mA cm− 2 leads to the formation of highly textured coatings with an increased content of α-PbO2 phase. Concurrently, a high current density favors a compact and flat surface morphology. The study of deposition time indicates a change of crystallite growth manner from an initially random growth to a later-stage preferred growth along distinct orientations. The change of crystallite growth is corroborated by the cross-sectional microstructures of the PbO2 deposits. The microstructural transition occurs only in the initial deposition stage. After a brief period, prolonged electrodeposition barely changes the surface morphology of PbO2 coatings.

Mechanism of Initial Film Formation during Cathodic Electrodeposition of Coatings

Electrodeposition of coatings is an effective way to form a protective layer on metal surfaces of complex shape. The uniformity of the deposit is a function of the current distribution, and depends on the induction time (time prior to “initiation” of deposition), the local deposition rate and the resistivity of the film that is formed. In cathodic electrodeposition, hydrogen gas evolves on the deposition surface, leading to an increase in the local pH. The change in pH reduces the solubility of the positively charged resin-containing micelles and causes a coating to form on the surface. The induction time, which is a key factor in the prediction of film thickness, has been attributed to the time that is required to increase the local pH to about 12 [1, 2]. The deposition rate, which is initially low, changes significantly during the induction period and eventually increases to a steady value that is proportional to the charge passed. An increased fundamental understanding is needed to improve our ability to accurately model E-coat systems in order to optimize performance. The purpose of this study is to develop a detailed understanding of the initial stages of deposit growth. Of particular interest are the changes that take place during the induction time. Experiments designed to elucidate the role of pH change clearly show that the local change in pH alone is not responsible for the induction time. This observation was further supported by additional experiments where the induction time at a specified current was observed to vary with the type of substrate used for deposition. Consequently, scanning electron microscopy was used to study the morphology of the initial deposit on different substrate surfaces including bare steel, galvanized steel, and phosphated steel. It was found that the initial film tends to form preferentially on defects and scratches in the metals. This observation was validated by experiments with intentionally scratched surfaces. The initial film also appeared to form around gas bubbles that were present on the substrate surface. The mechanism for preferred deposition at defects and bubbles is currently under investigation. As part of this effort, deposition on “defect free” surfaces has been performed. Microscopic images are used to track deposit formation as a function of time during the initial stages of deposition before formation of a highly resistive film. The rate of deposition increases with time, which may be connected to an increase in the local current density in the deposit free areas. The additional insight provided by this study will provide the basis for an improved model of the early stages of E-coat deposition. This model will then be incorporated into a large-scale simulation tool to enable improved process prediction and optimization. Acknowledgment The authors gratefully acknowledge funding from the Ford Motor Company under their University Research Program (URP). References Miskovic-Stankovic, V.B. and M.D. Maksimovic, The effect of concentration on the cathodic electrodeposition process. Process in Organic Coating, 1988. 16: p. 255-263.Pierce, P.E., The physical chemistry of the cathodic electrodeposition process. Journal of Coatings Technology and Research, 1981. 53: p. 52.

Molecular dynamics simulation of temperature effects on deposition of Cu film on Si by magnetron sputtering

The temperature effects on the growth of Cu thin film on Si (0 0 1) in the context of magnetron sputtering deposition were systematically studied using molecular dynamics (MD) method. To improve the comparability of simulation results at varying temperatures, the initial status data of incident Cu atoms used in all simulations were read from an identical file via LAMMPS-Python interface. In particular, crystalline microstructure, interface mixing and internal stress of Cu thin film deposited at different temperatures were investigated in detail. With raising the substrate temperature, the interspecies mixed volume and the proportion of face-centered cubic (fcc) structure in the deposited film both increased, while the internal compressive stress decreased. It was found that the fcc structure in the deposited Cu thin films was 〈1 1 1〉 oriented, which was reasonably explained by surface energy minimization and the selectivity of bombardment energy to the crystalline planes. The quantified analysis of interface mixing revealed that the diffusion of Cu atoms dominated the interface mixing, and the injection of incident Cu atoms resulted in the densification of phase near the film-substrate interface. More important, the distribution of atomic stress indicated that the compressive stress was mainly originated from the film-substrate interface, which might be attributed to the densification of interfacial phase at the initial stage of film deposition.

Dietary manganese supplementation affects mammillary knobs of eggshell ultrastructure in laying hens

This study evaluated the mechanism by which dietary manganese (Mn) supplementation-in either an organic or inorganic form-affects mammillary knobs of the eggshell ultrastructure in laying hens. A total of 225 54-week-old Hy-Line Brown laying hens were fed a basal diet containing 27.5mg Mn/kg feed for 2 wk, after which they were randomly allocated into 3 groups and fed a basal diet (control) or a basal diet supplemented with 120mg Mn/kg feed from monohydrate Mn sulfate (an inorganic source of Mn) or with 80mg Mn/kg feed from an amino acid-Mn complex (an organic source of Mn) for 10 wk. For each group, 5 replicates of 15 hens each were used with 1 hen per cage. Compared with the control, dietary Mn supplementation increased the mammillary-knob density of eggs at 9.5h post-oviposition (P <0.05). The Mn content in both blood and eggshell gland was increased with the supplementation of Mn in inorganic and organic forms (P <0.05), but the blood Mn content was higher after inorganic-Mn supplementation as compared with organic-Mn supplementation (P <0.05). RNA sequencing and quantitative real-time PCR analysis of the eggshell gland showed that dietary Mn supplementation increased the expression of genes encoding some proteoglycans, glycoproteins, and calcium-binding proteins in the eggshell gland (P <0.05), and involved in the process of the protein glycosylation and glycan metabolism in the eggshell gland (P <0.05). Overall, dietary Mn supplementation can involve in the process of protein glycosylation and glycan metabolism and improve the expression of genes encoding proteoglycans and glycoproteins in the eggshell gland, thus increasing the mammillary-knob density during the initial deposition stage of shell formation.

Oxygen Transfer at Metal-Reducible Oxide Nanocatalyst Interfaces: Contrasting Carbon Growth from Ethane and Ethylene

Carbon deposition from hydrocarbon gases onto metal nanoparticles is an important process impacting materials synthesis and catalysis. Typically, light hydrocarbons may decompose on metal nanoparticles resulting in the formation of graphene layers and hydrogen gas. During hydrocarbon reforming, hydrocarbons are converted to syngas (CO and H2), and carbon deposition is an undesirable side reaction, which can deactivate the catalyst and cause mechanical degradation. Here, aberration-corrected in situ environmental transmission electron microscopy (ETEM) was employed to investigate the atomic-level three-phase interactions occurring at the metal–support interface during the initial stages of carbon deposition from light hydrocarbons over model Ni/CeO2 and Ni/SiO2 catalysts. During exposure to C2H6, no carbon deposition took place, and localized reduction zones at the metal–CeO2 interface demonstrated a carbon oxidation mechanism. In contrast, during exposure to C2H4, carbon deposition occurred and was associ...

Molecular orientation in electrodeposited polypyrrole films

The molecular arrangement in electrodeposited polypyrrole films was studied by means of linear dichroism in the near-edge X-ray absorption fine structure (NEXAFS) spectra measured at the K absorption edges of carbon and nitrogen. It has been found that the change of the exciting radiation incidence from normal to grazing leads to an increase in the intensity of π*-related resonances with simultaneous decrease in the intensity of σ*-related resonances in the spectra. Similar changes in the spectra measured for both absorption edges indicate a pronounced conjugation of π-bonds in the polypyrrole chains in the grown films. Preferential in-plane orientation of pyrrole rings relative to the substrate surface is observed for all the deposited films. The linear dichroism is more pronounced at the initial stages of deposition (2D growth) than at later stages characterized by “cauliflower”-like morphology of the grown film.

Absorption and translocation of cesium through Konara oak (Quercus serrata) bark

ABSTRACT Bark–wood translocation has been suggested as an important route for the contamination of trees via radiocesium in the initial stage of deposition. In this study, we investigated the cesium absorption through bark of mature Konara oak (Quercus serrata). Stable Cs (133Cs) was applied onto the bark at 1.2 m, and then after 8 weeks, the 133Cs concentration was determined in the outer bark, inner bark, sapwood, and heartwood of stem disks at several heights, as well as in the current-year leaves and branches from the tree tops. At the height of 1.2 m, the 133Cs concentration was significant higher in the sapwood of the treated trees than in those of the control trees. However, no difference was found in the 133Cs concentration in the heartwood of the treated and control trees not only in the wood above and below 1.2 m but also at 1.2 m. There was no significant difference in the 133Cs concentration of the current-year leaves and branches of the treated and control trees. Our results suggest that Cs absorption through bark may occur even in the dormant period of tree and the absorption is probably independent of cambial activities.

Initial stage of atomic layer deposition of 2D-MoS2 on a SiO2 surface: a DFT study.

In this study, we investigate the reactions involving Atomic Layer Deposition (ALD) of 2D-MoS2 from the heteroleptic precursor Mo(NMe2)2(NtBu)2 and H2S as the co-reagent on a SiO2(0001) surface by means of density functional theory (DFT). All dominant reaction pathways from the early stage of adsorption of each ALD reagent to the formation of bulk-like Mo and S at the surface are identified. In the metal pulse, proton transfer from terminal OH groups on the SiO2 to the physisorbed metal precursor increases the Lewis acidity of Mo and Lewis basicity of O, which gives rise to the chemical adsorption of the metal precursor. Proton transfer from the surface to the dimethylamido ligands leads to the formation and desorption of dimethylamine. In contrast, the formation and desorption of tert-butylamine is not energetically favorable. The tert-butylimido ligand can only be partially protonated in the metal pulse. In the sulphur pulse, co-adsorption and dissociation of H2S molecules give rise to the formation and desorption of tert-butylamine. Through the calculated activation energies, the cooperation between H2S molecules ('cooperative' mechanism) is shown to have a profound influence on the formation and desorption of tert-butylamine, which are crucial steps in the initial ALD deposition of 2D-MoS2 on SiO2. The cyclic ALD reactions give rise to the formation of a buffer layer which might have important consequences for the electrical and optical properties on the 2D layer formed in the subsequent homodeposition.

MOVPE growth and transport characterization of Bi2−xSbxTe3−ySey films

We present a first study of films of the quaternary Bi2−xSbxTe3−ySey solid solutions on (0001) sapphire substrates grown by atmospheric pressure MOVPE. Trimethylbismuth, trimethylantimony, diisopropylselenide and diethyltelluride were used as precursors. To passivate the free bonds of the substrate and to improve the epitaxy, a thin (15 nm) ZnTe buffer layer was first grown. EDX analysis of the films grown at a temperature of 445 °C and about 10-fold excess of chalcogen in the vapor phase indicates on their compliance with V2VI3 stoichiometry. AFM and SEM investigations showed that at the initial stage of deposition the Stranski-Krastanov growth mode is dominant. Complete coalescence of nanoislands occurs at a thickness about 60 nm and further film formation is in the 2D layer-by-layer growth mode. A high mole fraction of antimony in the vapor phase leads to bad crystalline quality of the films and even to their discontinuity. Transport properties of the Bi2−xSbxTe3−ySey films were evaluated using Van der Pauw Hall effect measurements in the range of temperatures of 10–300 K. Some films are always n- or p-type; in other samples the change of conductivity from p- to n-type was observed when the temperature decreases.

Improving Li anode performance by a porous 3D carbon paper host with plasma assisted sponge carbon coating

Li metal has been regarded as the most promising anode material for next high-energy batteries. However, the high capacity of Li metal (3860mAhg−1) is severely counteracted by the loss in side reactions at its unstable Li/electrolyte interface. Herein, we prepare a special composite, by growing a high-quality Sponge Carbon layer onto a 3D Carbon Paper (SCCP). During initial stage of Li deposition, Li ions are intercalated in the carbon paper skeletons then followed by Li metal plating, enabling the entire Li metal deposition underneath the sponge carbon layer. Such a conformal surface accommodation with modulated Li metal deposition provides highly stable Li/electrolyte interfaces. The Coulombic efficiencies for Li plating at 3 and 4mAhcm−2 are as high as 98–99% in the SCCP, obtained in corrosive carbonate electrolytes. Paired with high areal capacity LiFePO4 cathodes (~ 1.8mAhcm−2), a SCCP protected Li foil can still keep its metal luster after 650 cycles, in sharp contrast to a side products covered surface observed on naked Li foil after 400 cycles. These results clearly demonstrate the ability of the SCCP to stabilize Li surface, which may be applied in Li metal batteries for long-term operation.

A novel method used to study growth of ash deposition and in situ measurement of effective thermal conductivity of ash deposit

AbstractAsh deposition always brings boilers some trouble due to fouling or slagging. In this paper, a completely controlled system was developed to study the growth of ash deposit. A novel sampling probe was designed to online measure the heat flux through ash deposit. Additionally, the thickness of ash deposit can be obtained by an online figure collecting system. The results of this research showed that as the thickness of ash deposit increased, the heat flux decreased. It was also found that at the initial stage of ash deposition when the thickness of ash deposit is approximately 1 mm, the heat flux through ash deposit had a sharp reduction. An effective method was attempted to situ measure the effective thermal conductivity of the ash deposit in the simulated combustion flue gas. It was found that temperature of the ash deposit layer had no obvious effect on its value. It was concluded that the structure of ash deposit had no obvious change in a short deposition time of 30 min with varied surface temperatures of the probe head between 400 °C and 600 °C.