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In this report, we show that oxide battery anodes can be grown on two-dimensional titanium carbide sheets (MXenes) by atomic layer deposition. Using this approach, we have fabricated a composite SnO2/MXene anode for Li-ion battery applications. The SnO2/MXene anode exploits the high Li-ion capacity offered by SnO2, while maintaining the structural and mechanical integrity of the conductive MXene platform. The atomic layer deposition (ALD) conditions used to deposit SnO2 on MXene terminated with oxygen, fluorine, and hydroxyl-groups were found to be critical for preventing MXene degradation during ALD. We demonstrate that SnO2/MXene electrodes exhibit excellent electrochemical performance as Li-ion battery anodes, where conductive MXene sheets act to buffer the volume changes associated with lithiation and delithiation of SnO2. The cyclic performance of the anodes is further improved by depositing a very thin passivation layer of HfO2, in the same ALD reactor, on the SnO2/MXene anode. This is shown by high-resolution transmission electron microscopy to also improve the structural integrity of the SnO2/MXene anode during cycling. The HfO2 coated SnO2/MXene electrodes demonstrate a stable specific capacity of 843 mAh/g when used as Li-ion battery anodes.
Interaction of low pH cement solutions and Friedland Ton for 5 months showed that the hydraulic conductivity of the clay had not increased, which is most important for its use as backfill in a repository where concrete is a construction component. Chemical analyses of the cement solutions and XRD investigations showed that the only change of the mixed layer muscovite–montmorillonite clay minerals was some slight dissolution. A very small change in potassium content of the solutions indicates that illitization was insignificant. With the selected technique, 15 cm3 of cement water, corresponding to about 150 cm3 of fully reacted concrete, interacted with 15 g of solid clay. The conclusion is that complete reaction between a 1-cm layer of Friedland Ton and a 10-cm concrete wall made of low pH cement causes insignificant changes of the clay. Hence, concrete plugs can be used in repositories without significantly altering the isolating properties of such backfill in any time perspective.
LiNi0.5Mn0.5O2, a promising cathode material for lithium-ion batteries, is synthesized by a novel solution-combustion procedure using acenaphthene as a fuel. The powder X-ray diffraction (XRD) pattern of the product shows a hexagonal cell with a =2.8955Å and c =14.1484Å. Electron microscopy investigations indicate that the particles are of sub-micrometer size. The product delivers an initial discharge capacity of 161mAhg−1 between 2.5 and 4.6V at a 0.1C rate and could be subjected to more than 50 cycles. The electrochemical activity is corroborated with cyclic voltammetric (CV) and electrochemical impedance data. The preparative procedure presents advantages such as a low cation mixing, sub-micron particles and phase purity.
LiCoO2 is a widely used cathode material in Li-ion batteries for applications such as portable electronics. Here, the authors report multiple-element doping to enable stable cycling of LiCoO2 at high voltages that are not yet accessible with commercial Li-ion batteries.
Engineerings of facet exposure, nonstoichiometric defects and morphology are the key parameters affecting the SnO2 performance. Development of synthetic procedures enabling to control all these variables in one pot towards enhanced physicochemical performance is a big challenge. Herein we report such a facile microwave hydrothermal preparation of 3D hierarchical architecture assembled from single-crystalline nonstoichiometric SnO2 (denote as SnO2-δ) nanosheets with self-doped Sn2+ and controllably exposed {101} facets. Polyvinylpyrrolidone (PVP) is used as capping agent allowing to stabilize the ultrathin and ultra-large SnO2-δ nanosheets and avoid their dissolution in the highly alkaline environment due to the introduction of highly concentrated NaOH, which together with PVP contribute to the formation of nanosheet morphology with preferential growth plane (121) and dominant reactive {101} surfaces. The detailed structural characteristics are examined by XRD, SEM, TEM, FTIR, XPS and Mössbauer spectroscopy, revealing that SnO2-δ contains 17 at.% of Sn2+ dopant. These nonstoichiometric SnO2-δ hierarchical architectures capped with carbonized PVP manifest superior lithium storage properties compared with the stoichiometric SnO2, owing to the novel open hierarchical structure composed of flexible and ultrathin nanosheets with large surface area (82m2/g) and carbon-coating, which avoid the aggregation and provide porous channels facilitating the diffusion of electrolyte and lithium ions.
Unique hollow Fe3O4/C spheres are prepared by a simple one-pot solvothermal method, with spinel structure and 750nm in diameter identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The hollow Fe3O4/C spheres exhibit excellent cycling and rate performance as anode material for lithium ion batteries, delivering reversible specific capacities of 984mAhg−1 even after 70 cycles at 0.2C, 620mAhg−1 at 2C, and 460mAhg−1 at 5C, respectively. Lithium insertion mechanisms are also proposed in terms of the ex situ XRD analysis of the electrodes after discharged and charged to certain voltages together with cyclic voltammetry (CV) and voltage profile.
The sodium–metal halide (ZEBRA) batteries have been considered as one of the most attractive energy storage systems for stationary and transportation applications. Even though the battery technologies have been widely investigated for a few decades, there is still a need to further improve the battery performance, cost and safety for practical applications. In the present work, a novel low-cost Na–ZnCl2 battery with a planar β′′-Al2O3 solid electrolyte (BASE) was proposed, and its electrochemical reactions and battery performance were investigated. Compared to Na–NiCl2 chemistry, the ZnCl2-based chemistry was more complicated, in which multiple electrochemical reactions including liquid-phase formation occurred at temperatures above 253 °C. During the first stage of charge, NaCl reacted with Zn to form Na in the anode and Na2ZnCl4 in the cathode. Once all the NaCl was consumed, further charge with the reaction between Na2ZnCl4 and Zn led to the formation of a NaCl–ZnCl2 liquid phase. During the end of charge, the liquid phase reacted with Zn to produce solid ZnCl2. To identify the effect of liquid-phase formation on electrochemical performance, button cells were assembled and tested at 280 and 240 °C. At 280 °C, with the liquid phase formed during cycling, cells revealed quite stable cyclability. On the other hand, more rapid increase in polarization was observed at 240 °C where only solid-state electrochemical reactions occurred. SEM analysis indicated that the stable performance at 280 °C was due to the suppressed growth of Zn and NaCl particles, which were generated from the liquid phase during the discharge of each cycle.
Avian flight heights are currently a focus of interest in terms of assessing possible impacts of offshore and inland wind farms on birds. We therefore analyzed the flight-height distribution in a tracking study of foraging Lesser Black-backed Gulls (Larus fuscus) on the southern North Sea coast during the incubation period. We distinguished between marine and terrestrial, nocturnal and diurnal, straight and tortuous, and outbound and inbound flights. Individuals were equipped with specifically programmed GPS data loggers to ensure accurate flight-height measurements. A total of 89 % of recorded fixes were below 20 m above sea level, indicating an overlap between foraging flights and the rotor area of most operating wind turbines. The gulls flew lower over the sea than over land, and lower at night than during the day. Straight commuting flights were higher than tortuous flights, when the gulls were supposed to be foraging. Outbound and inbound flights occurred at similar heights, and flight height was unaffected by wind. This study provides insights into the individual flight-height distribution in a common seabird species throughout a range of foraging behaviors. These results might prove important for developing a comprehensive understanding of bird movements within and around wind farms, and the potential impacts of such wind farms on foraging patterns.
Abstract Lithium iron phosphate is a promising cathode material for the use in hybrid electrical vehicles (HEV) meeting the demands of good stability during cycling and safe operation due to reduced risk of thermal runaway. However, slow solid state diffusion and poor electrical conductivity reduce power capability. For further improvement, the identification of the rate determining processes is necessary. Electrochemical impedance spectroscopy (EIS) has proven to be a powerful tool for the characterization of electrochemical systems. In this contribution a deconvolution of the impedance with the distribution of relaxation times (DRTs) is used to obtain a better resolution in frequency domain. Therewith, the relevant loss processes are identified and an impedance model is developed. Using DRT and CNLS-fit allows the determination of time constants and polarization resistances of all relevant loss processes. Furthermore, their temperature behavior is studied and a physical interpretation is provided.
A 3D spray-dried micro/mesoporous LiFePO4/porous graphene oxide/C (denoted as SP-LFP/PGO/C) composite material is synthesized via a three-step process, i.e., hydrothermal process, carbon coating, and spray dry method in sequence. The 2D porous graphene oxide (denoted as PGO) material is first prepared through an activation method. The galvanostatic charge-discharge measurements of LFP composites without graphene oxide, with 1 wt% graphene oxide, and 1 wt% PGO are conducted in the potential range of 2–3.8 V at various rates (0.1–10C). It is revealed that the SP-LFP/PGO/C material shows the best performance among three samples. The discharge capacities of the SP-LFP/PGO/C composites are observed to 160, 152, 151, 149, 144, 139, 127 mAh g−1 at 0.1C, 0.2C, 0.5C, 1C, 3C, 5C and 10C rate. In particular, the discharge capacity of the SP-LFP/PGO/C composite with 1 wt% PGO is 107 mAh g−1 after 1000 cycles at a 10C rate, and its capacity retention is ca. 97%. It is due to the unique structural and geometrical feature of SP-LFP/PGO/C composite, there the diamond-like (rhombus) LFP nanoparticles are embedded in porous GO matrix which forming a porous three-dimensional network for fast electronic and ionic transport channels.
A “market map” comparison methodology for cigarette smoke chemistry yields is presented. Federal Trade Commission machine-method smoke chemistry was determined for a range of filtered cigarettes from the US marketplace. These data were used to develop illustrative market maps for each smoke constituent as analytical tools for comparing new or non-conventional cigarettes to a sampling of the broader range of marketplace cigarettes. Each market map contained best-estimate “market-means,” showing the relationship between commercial cigarette constituent and tar yields, and yield “market ranges” defined by prediction intervals. These market map means and ranges are the basis for comparing new cigarette smoke yields to those of conventional cigarettes. The potential utility of market maps for evaluating differences in smoke chemistry was demonstrated with 1R4F and 2R4F Kentucky reference cigarettes, an Accord™ cigarette, and an Advance™ cigarette. Conventional cigarette tobacco nicotine, nitrate, soluble ammonia, and tobacco specific nitrosamine levels are reported. Differences among conventional cigarette constituent yields at similar tar levels were explained in part by the chemical composition range of those cigarette tobaccos. The study also included a comparison of smoke constituent yields and in vitro smoke cytotoxicity and mutagenicity assay results for the 1R4F Kentucky reference cigarette and its replacement 2R4F. Significant smoke yield differences were noted for lead, NNK, and NNN. The majority of their smoke constituent yields were within the market range developed from the sampled conventional cigarettes. Within the sensitivity and specificity of the in vitro bioassays used, smoke toxic activity differences for the two reference cigarettes were not statistically significant. These results add to the limited information available for the 2R4F reference cigarette.
The overcharge performances of lithium-ion polymer batteries (LIPB) have been studied by monitoring their temperature variation and analyzing the generated heat during overcharge. The critical concentration of lithium in the cathode material is determined for the thermal runaway of the battery. Solutions against the thermal runaway are proposed based on these results.
The aim of this study was to investigate the influence of the postoperative hippocampal remnant on postoperative seizure and neuropsychological outcome in temporal lobe epilepsy (TLE). Postoperative volumetric MRI measurements of 53 patients surgically treated for TLE revealed a postoperative volume loss of the hippocampal remnant compared with the respective preoperative segment in all patients. Extent of preoperative hippocampal pathology, remnant shrinkage, resection volume, and postoperative volume of the hippocampal remnant did not correlate with seizure outcome 1 year after surgery. With respect to neuropsychological outcome, performance on tasks assessing verbal memory and language-related functions was impaired in patients with left-sided pathology after surgery. Performance of patients with right-sided pathology (n =26) demonstrated no significant correlation with hippocampal measures or with neuropsychological data. Degree of hippocampal remnant shrinkage seems to be associated with decreased verbal memory performance in patients with left-sided TLE.
Spermatogonial stem cell transplantation (SSCT) is a promising therapy in restoring the fertility of childhood cancer survivors. However, the low efficiency of SSCT is a significant concern. SSCT could be improved by co-transplanting transforming growth factor beta 1 (TGFβ1)-induced mesenchymal stem cells (MSCs). In this study, we investigated the reproductive efficiency and safety of co-transplanting spermatogonial stem cells (SSCs) and TGFβ1-induced MSCs.
The influence of the flow cell configuration on the mass spectra obtained when coupling an electrochemical thin-layer flow cell to electrospray mass spectrometry (ESI-MS) has been investigated. It is shown that interferences due to the electrochemical reaction on the counter electrode and/or the absence of 100% conversion efficiency can alter the mass spectra when conventional thin-layer flow cells are used in conjunction with ESI-MS. The effects, which affect the intensities and distribution of the peaks in the mass spectra, can result in the inability to detect products formed at the working electrode. Comparisons of mass spectra, generated after the electrochemical oxidation of a dinuclear Mn complex [ Mn 2 II , II ( bpmp ) ( μ - OAc ) 2 ] + (where bpmp=2,6-bis[bis(2-pyridylmethyl) amino]methyl-4-methylphenol) using two different thin-layer flow cells clearly show that the potential dependence and appearance of the mass spectra depend on the flow cell configuration used. The use of a modified thin-layer flow cell, in which the counter electrode had been separated from the working electrode, gave rise to significantly increased intensities for the oxidised MnIII,IV state of the complex. With the conventional unmodified cell, the corresponding complex was only seen for considerably higher oxidation potentials. The different results can be explained by the reduced risk of redox cycling and interferences due to species generated at the counter electrode with the modified cell. As interferences due to the counter electrode reactions likewise may be expected with many coulometric flow cells, the electrochemical cell design clearly needs to be considered when using electrochemistry coupled to ESI-MS to study electrochemical reactions.
Salinity caused by land clearing is an important cause of land degradation in the Western Australian wheatbelt. Returning a proportion of the cleared land to higher water use perennial vegetation is one option for reducing or slowing the salinisation of land. Over the course of a year patterns of water use by Eucalyptus kochii subsp borealis (C. Gardner) D. Nicolle, a mallee eucalypt species, were monitored in three landscape positions with different water availability. One treatment had groundwater at 2 m, a second at 4.5 m and a third had groundwater below a silcrete hardpan thought to be impenetrable to roots. Hydraulic redistribution was observed in all landscape positions, and rates were positively correlated with the magnitude of soil water potential gradients within the soil. High rates of hydraulic redistribution, facilitated by abundant deep water may increase tree water use by wetting surface soils and reducing stomatal closure. This effect may be countered by increased soil evaporation of water moved from root to soil following hydraulic redistribution; the net volumes of redistributed water though lateral roots was calculated to be the equivalent of up to 27% of transpiration.
The practical application of metal oxides (e.g., Fe3O4) as anode materials for lithium-ion batteries is hindered by their poor electrical conductivity and severe volume change in spite of their high theoretical capacities and abundance nature. In this work, uniform yolk-shell Fe3O4@nitrogen-doped carbon composites are synthesized by combining polymerization of o-phenylenediamine (oPD) with core-shell Fe3O4@SiO2 nanospheres, followed by pyrolysis of poly (o-phenylenediamine) (PoPD) and removal of silica. This novel composites exhibit superior lithium storage capacity and cycling stability due to their unique yolk-shell structure and nitrogen-doped carbon shell, which provide ample space to accommodate the volume expansion of Fe3O4 nanoparticles, prevent the aggregation of Fe3O4 nanoparticles, and enhance the electron conductivity during cycling. This newly developed method can be employed in other yolk-shell structural design of hybrids with high-performance for lithium-ion or lithium-sulfur batteries.
Modelling and simulation of stand-alone photovoltaic (SAPV) systems (PV module, battery, regulator, etc.) in real time is crucial for the control, the supervision, the diagnosis and for studying their performances. In this paper, an intelligent simulator for stand-alone PV system was developed. Firstly, a multilayer perceptron (MLP) has been used for modelling and simulating each component of the system, after that the optimal architecture for each component has been implemented and simulated by using the very high-speed description language (VHDL) and the ModelSim. Subsequently, the developed architectures for each component have been implemented under the Xilinx® Virtex-II Pro FPGA (XC2V1000) (field programmable gate array). The obtained results showed that good accuracy is found between predicted and experimental data (signal) in a specific location (south of Algeria). The designed intelligent components (PV-MLP generator, MLP-battery and MLP-regulator) of the SAPV system can be used with success for simulating the system in real time (under a specific climatic condition) by predicting the different output signals for each component constituting the system.
Previous work has verified the possibility to obtain mechanically, chemically and electrically stable electrodes based on manganese oxide (MnOx) thin films for anodic oxidation of solutions containing the Reactive Violet 5 (RV5) azo dye. To improve the morphological and electrochemical properties of these materials, in this study, a surface modification of the titanium support has been presented. Chemically modified surfaces were obtained by etching titanium substrates in hydrocloridric acid at high temperature. Untreated and modified electrodes were coated sequentially with a RuOx film, as interlayer and a MnOx film obtained by adopting three different techniques including anodic electrodeposition, cathodic electrodeposition and thermal decomposition. Surface morphology, topography and composition of all the electrodes were investigated by profilometric and TOF–SIMS analysis. The electrochemical activity of anodes were first determined by cyclic voltammetry, and then in the treatment of solutions containing the RV5 azo dye, as model pollutant, in undivided cell under galvanostatic conditions. The results show that the surface microstructure modifies substantially the electrochemical response of selected electrodes.
One-dimensional (1D) nanostructures of vanadium pentoxide (V2O5) have been successfully synthesized via a precipitation process followed by heating in vacuum at 300°C. The samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical testing by techniques such as cyclic voltammetry (CV) and discharge–charge cycling in lithium cells. Average crystal size of these oxides increased from 36 to 83nm as annealing time was increased from 45min to 1h, which also led to a decrease in Brunauer–Emmett–Teller (BET) specific surface area from 41 to 17m2 g−1. Good cyclability and high capacity (>200mAhg−1) were achieved in the voltage range of 2.0–4.0V (versus Li metal) at a current rate of 50mAg−1 by annealing the oxides for 1h. The increase in crystallinity and higher yield of one-dimensional nanostructure oxides contributed significantly to the improved capacity and enhanced cycle life.
A series of polyaniline (PANI)/Na+-montmorillonite (MMT) clay and PANI/organo-MMT nanocomposite materials have been successfully prepared by in situ emulsion polymerization in the presence of inorganic nanolayers of hydrophilic Na+-MMT clay or organophilic organo-MMT clay with DBSA and KPS as surfactant and initiator, respectively. The as-synthesized Na+-PCN and organo-PCN materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Na+-PCN materials in the form of coatings with low loading of Na+-MMT clay (e.g., 3wt.%, CLAN3) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of organo-PCN materials with same clay loading based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5wt.% aqueous NaCl electrolyte. The molecular weights of PANI extracted from PCN materials and neat PANI were determined by gel permeation chromatography (GPC) with NMP as eluant. Effects of material composition on the gas permeability, optical properties and electrical conductivity of neat PANI and a series of PCN materials, in the form of free-standing film, solution and powder-pressed pellet, were also studied by gas permeability analyzer (GPA), ultraviolet–vis spectra and four-point probe technique, respectively.