batterydata/paper-abstracts huggingface dataset:
γ-Butyrolactone (GBL) has a high boiling point, a low freezing point, a high flashing point, a high dielectric constant and a low viscosity. GBL is a very preferable solvent for lithium ion batteries. However, GBL readily undergoes reductive decomposition on the surface of the negative electrodes, and it forms a solid electrolyte interphase (SEI) with a large resistance. It is causing deterioration of battery performances. In this work, effects of cyclic carbonates as additives to GBL electrolytes were investigated. As these carbonates, ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), vinylethylene carbonate (VEC), and phenylethylene carbonate (PhEC) were investigated using LiCoO2/graphite cells. The effects of these additives were evaluated from the viewpoints of improvement of the battery performance and suppression of the reductive decomposition of GBL. VC, VEC and PhEC were effective to suppress the excess reductive decomposition of GBL. Battery performances were improved and the following results were obtained from the electrochemical measurements of LiCoO2/graphite cells with GBL-based electrolytes. Residual capacity was high in the order of VEC>VC>PhEC. Rate capability was high in the order of PhEC>VC>VEC. These additives have advantages and disadvantages. By optimizing electrolyte formulation, the performances of Li-ion batteries using GBL-based electrolytes will be improved further.
Rechargeable lithium-sulfur battery with a high theoretical energy density attracts intense attention, but it still often suffers from poor cyclability. Herein, a hierarchical porous carbon/graphene hybrid is designed to host sulfur for Li–S battery. The batteries exhibit good performances including a specific capacity of 1178 mA h g−1 after 70 cycles at 0.2C, a stable reversible capacity of 400 mA h g−1 after 600 cycles at 1.0C (80% retention). Extensive characterizations including adsorption-desorption isotherms, XRD, Raman spectroscopy, HAADF-STEM combining with soft XAS study the relationship between the structure and the performance of as-synthesized cathode material. The synergistic effect of graphene and hierarchical porous carbon provides the pathway of the electron and Li+ ingress/egress to react with the confined sulfur clusters, retard the loss of the polysulfide anions from the cathode and suppress the shuttle effect during long-term cycling process.
Objective Our prospective study aimed at the validation of EpiTrack Junior, a neuropsychological screening tool for attention and executive functions in children with epilepsy. Methods Twenty-two children with absence epilepsy aged 8–17years underwent comprehensive neuropsychological evaluation including EpiTrack Junior and measures of intelligence, verbal and nonverbal memory, word fluency and visuoconstructive organization. Concurrent and discriminant validity of EpiTrack Junior subtests and total score as well as sensitivity and specificity of the total score were analyzed. Results EpiTrack Junior total score was impaired in 59% of participants. Concurrent validity was demonstrated in 4/6 subtests and for the total score. Discriminant validity was shown with respect to verbal and nonverbal long-term memory. Sensitivity was higher than specificity and highest for the “working memory index”. Conclusion EpiTrack Junior is recommended as a sensitive and time-efficient screening tool for attention and executive functions in children with epilepsy. Impaired results should be followed up with detailed evaluation including information from the parents and school as well as counseling where indicated.
Ordered arrays of α-PbO2 nanostructures were grown by galvanostatic anodic deposition into the channels of alumina templates. Electrodepositions were performed in an aqueous solution containing lead acetate and sodium acetate at pH 5.4. Bath temperature and electrodeposition time were varied to check their effect on the growth of nanostructures. It has been found that filling of alumina pores is independent of the time and electrodeposition temperature, whilst height and growth kinetics of nanostructures vary with both parameters. Temperature greatly influences morphology: wires grown at room temperature consisted of clusters of particles, leading to poorly compact structures, whilst at 40°C the formation of compact wires was observed, some of them being partially hollow. Finally, nanowires with a very regular and dense structure were obtained at 60°C. Also crystalline structure changes with temperature: polycrystalline nanostructures, with a preferential orientation and an average grain size of 21nm, were obtained at room temperature, whilst at higher temperatures, wires grew almost exclusively along the plane (200) with an average grain size of approximately 28nm. Real surface area of nanowires was evaluated from the FEG-SEM images, and it was found two orders of magnitude greater than the geometrical one.
Great strides have been made over the past century in our ability to harness energy sources, leading to profound transformations — both good and bad — in society. Looking at the energy system of today, it is clear that meeting the energy needs of the world now and in the years to come requires the concerted efforts of many different actors across a range of technologies and approaches. In this Feature, ten leading experts in energy research share their vision of what challenges their respective fields need to address in the coming decades. The issues being faced are diverse and multifaceted, from the search for better materials for fuels, to the design of energy policy and markets for the developing world. However, a common theme emerges: changes to adapt and improve our energy system are greatly needed. By improving our mutual understanding of the issues faced by each area of energy research, these changes can happen more smoothly, efficiently and rapidly.
The LiFePO4/C composites with different morphology are synthesized by an ammonia assisted hydrothermal method at various ammonia concentrations (from 0 to 1.6molL−1) using inexpensive Fe(NO3)3 and LiOH as raw materials. The influences of the ammonia concentration on the structure, morphology and electrochemical properties of the LiFePO4/C composite are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results demonstrate that the ammonia concentrations markedly impact the morphology and electrochemical properties of the LiFePO4/C. With the change of ammonia concentrations, the LiFePO4/C synthesized with 0.4molL−1 ammonia shows the smallest average particle size, the most uniform microsphere particle distribution and relatively high tap density (1.27gcm−3). In addition, the sample appears a high discharge capacity of 153.9mAhg−1 at the first cycle as well as stable cycling performance (the capacity was not almost changed till 100 cycles) at a rate of 1C (170mAg−1). Moreover, it exhibits a good rate capability and still shows a high discharge capacity of over 125mAhg−1 even at a rate of 5C.
The thermal behavior of the fully lithiated nano-silicon electrode in contact with an 1 M LiPF6 in EC/DEC electrolyte is investigated by differential scanning calorimetry (DSC) in the absence and presence of fluoroethylene carbonate (FEC) and vinylene carbonate (VC) electrolyte additives. In the additive-free electrolyte, intense exothermic reactions commence at approximately 153 °C when in contact with Li x Si. At contrast, the onset temperature of the thermal runaway is shifted to 200 °C and 214 °C when the charged Li x Si is heated in the presence of FEC and VC in the electrolytes, respectively. The mechanism of this thermal stability improvement by FEC and VC is studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and by specific measures to design the SEI on the surface of the nano-Si particles. The additives form a robust “primary SEI” on the surface of the Li x Si particles during the first charge that is rich in polycarbonate species and stable at elevated temperatures. In addition, the thermal degradation of FEC and VC in the electrolyte solution yields a highly resistive “secondary SEI” on the electrode surface that covers the lithiated silicon electrode (together with the “primary SEI”) and protects it from thermal runaway up to 200 °C.
Polysulfone acidic ionomers have been extensively used as Fuel Cell membranes, mainly because of their mechanical, thermal, chemical and electrochemical stability as well as their excellent film-forming capability. This contribution deals with the development of blends based on polysulfone-sodium sulfonate and macromolecular/molecular solvents, consisting of poly(oxyethylene), POE, and propylene carbonate, PC, respectively. The objectives were to take advantage of both the thermomechanical performances and the macromolecular polyanions provided by the polysulfone ionomer. Combining POE/PC solvents, didn’t allow obtaining sufficient blend’s conductivities. Nevertheless, the addition of very low amounts of sodium perchlorate led to appreciable conductivities.
The aim of this study was to investigate the effects of n-3 LC-PUFA (omega3 long-chain unsaturated fatty acid) supplementation on hand-eye coordination. This research was a single-blind placebo-controlled trial. Fifty three individuals (10,89±1,57 years old) who had never played tennis before took part in the study. They were randomly allocated to three groups. Omega group received n-3 LC-PUFA (670mg · day-1; n=21); placebo group received olive oil (670mg · day-1; n=18) during 16 weeks; and control group. All of the groups (omega, placebo and control) joined to the tennis trainings which involved 3hours per week for 16 weeks. Individual's hand-eye coordination was evaluated before and after 16 weeks tennis trainings with two hand-eye coordination test battery. The data were evaluated with repeated measures analysis of variance and also with paired simples T-Test. The results show that there were no significant differences between groups (p>0,05), but omega (p=0,004) and placebo (p=0,006) groups has significant improvement on their hand-eye coordination in spite of control group (p=0,086). Consequently, it can be said that n-3 LC-PUFA supplementation might be improve hand-eye coordination of children but tennis training also efficient on hand-eye coordination.
Non-aqueous Mg-ion batteries offer a promising way to overcome safety, costs, and energy density limitations of state-of-the-art Li-ion battery technology. We present a rigorous analysis of the magnesium aluminum chloride complex (MACC) in tetrahydrofuran (THF), one of the few electrolytes that can reversibly plate and strip Mg. We use ab initio calculations and classical molecular dynamics simulations to interrogate the MACC electrolyte composition with the goal of addressing two urgent questions that have puzzled battery researchers: (i) the functional species of the electrolyte, and (ii) the complex equilibria regulating the MACC speciation after prolonged electrochemical cycling, a process termed as conditioning, and after prolonged inactivity, a process called aging. A general computational strategy to untangle the complex structure of electrolytes, ionic liquids and other liquid media is presented. The analysis of formation energies and grand-potential phase diagrams of Mg–Al–Cl–THF suggests that the MACC electrolyte bears a simple chemical structure with few simple constituents, namely the electro-active species MgCl+ and AlCl4− in equilibrium with MgCl2 and AlCl3. Knowledge of the stable species of the MACC electrolyte allows us to determine the most important equilibria occurring during electrochemical cycling. We observe that Al deposition is always preferred to Mg deposition, explaining why freshly synthesized MACC cannot operate and needs to undergo preparatory conditioning. Similarly, we suggest that aluminum displacement and depletion from the solution upon electrolyte resting (along with continuous MgCl2 regeneration) represents one of the causes of electrolyte aging. Finally, we compute the NMR shifts from shielding tensors of selected molecules and ions providing fingerprints to guide future experimental investigations.
Charge transport and chemical reactions during charging and discharging of a battery produce heat that determines temperature behaviors. The elevated temperature causes undesired side reactions that accelerate degradation and potentially result in catastrophic operating conditions like a thermal runaway. The heat generated in an operating battery is generally approximated by the sum of the reversible and irreversible heat. The reversible heat is produced by the change of entropy. The irreversible heat is approximated by either the overpotential heating or Ohmic and reaction heating. Most studies have compared the surface temperature with tuned convection coefficients, but not investigated the heat generation directly. A study conveyed shows that two other heat source terms, enthalpy heating and heat of mixing, should be included to accurately and completely describe the heat generation. The first one is caused by diffusion of lithium ions in the solid phase and the second one by change of the gradient of ion concentrations. An electrochemical thermal model including these additional terms is experimentally validated against calorimetric measurements on a 15.7 Ah LiMn2O4/carbon pouch type power cell using a specially designed calorimeter.
A quantum chemical study of the binding of Li+ cation to polyalkyloxides has been carried out. The lithium cation interaction with three polyalkyloxides (polyethylene oxide (PEO), polytrimethylene oxide (PTMO), and polypropylene oxide (PPO)) has been investigated using ab initio molecular orbital theory at the HF/6-31G∗ level with molecular models for the polymers. Coordination by one to six oxygens was considered. In addition, higher level calculations were carried out using G3(MP2) theory for coordination of Li+ by one oxygen. For coordination of lithium by one oxygen, the binding energy ordering is PTMO>PPO>PEO, with PTMO having the largest lithium cation affinity. The same ordering is found for larger coordination numbers with the exception of coordination by six oxygens, where the ordering changes due to the steric interactions.
Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, thus easily up-scalable, anodic oxidation of a titanium foil followed by rapid thermal annealing. The structural/morphological characterization shows the formation of well defined one-dimensional nanotube carpets, while the X-ray diffraction analysis reveals the pure anatase crystalline structure of the thermal treated samples. The electrochemical response in laboratory-scale lithium cells is highly satisfying: at a very high discharge/charge rate of 12C, the NTs can perform with good stability and capacity retention after long-term cycling along with improved durability (>1100 cycles). High surface area, self-induced doping, short diffusion path and fast kinetics of the unidirectionally aligned TiO2 nanotube arrays are intriguing prospects which can be considered responsible for the noticeable electrochemical performance obtained in the absence of foreign ingredients such as binders and conductive agents, which would affect the overall energy density.
Spenel lithium manganese oxides with a nominal composition of LiMn2O4 are prepared by using a conventional ceramic synthesis method and are coated by a chemical deposition of silver particles. The silver-coated nano-particle LiMn2O4 shows excellent cycleability at 2C galvanostatic conditions. The high surface electronic conductivity caused by the metal coating reduces cell polarization. The results indicate that such surface treatment of cathode powders should be an effective way to improve cycle-life with high current retention.
The effect of the main structural parameters of the current collectors on efficiency of operation of the positive electrode of the lead–acid battery was investigated.
In this study, we show that invisible flicker adaptation reduces the perceived duration of a subsequently viewed stimulus in control subjects, but not in dyslexics. Dyslexics, like controls, show apparent duration compression after 20Hz flicker and show normal shifts in apparent temporal frequency after adaptation. However a subgroup of the test group, scoring low on both a test of phonological skill (spoonerisms) and a test of literacy (NART), show an apparent temporal expansion after 5Hz flicker adaptation, a finding not previously seen in controls. Recent studies have linked genes conferring susceptibility to a cluster of language and sensory deficits to anomalous neural migration, providing a tentative biological basis for dyslexia. However it has proved difficult to establish a clear link between sensory deficits and impaired reading. The results presented here point to an abnormal adaptation response within the early precortical stages of the magnocellular pathway, occurring in tandem with a deficit in word-level cognitive processing, providing psychophysical evidence for anomalous cortico-thalamic circuits in dyslexia.
In this work we investigated the transition metal dissolution of the layered cathode material Li1.04Ni1/3Co1/3Mn1/3O2 in dependence on the cycle number and cut-off cell voltage during charge by using the total reflection X-ray fluorescence technique for the elemental analysis of the specific lithium ion battery degradation products. We could show that with ongoing cycling transition metal dissolution from the cathode increased over time. However, it was less pronounced at 4.3 V compared to elevated charge cut-off voltages of 4.6 V. After a maximum of 100 cycles, we detected an overall transition metal loss of 0.2 wt‰ in relation to the whole cathode active material for cells cycled to 4.3 V. At an increased charge cut-off voltage of 4.6 V, 4.5 wt‰ transition metal loss in relation to the whole cathode active material could be detected. The corresponding transition metal dissolution induced capacity loss at the cathode could thus be attributed to 1.2 mAh g−1. Compared to the overall capacity loss of 80 mAh g−1 of the complete cell after 100 galvanostatic charge/discharge cycles the value is quite low. Hence, the overall full cell capacity fade cannot be assigned exclusively to the transition metal dissolution induced cathode fading.
Co3O4 quantum dots/graphene composites were synthesized by a facile and efficient microwave irradiation method, and they were analyzed using XRD, TEM, HRTEM, and TG. Uniform Co3O4 nanocrystals of about 3-8nm with a high density are homogeneously dispersed on graphene nanosheets. When used as anode materials for Li-ion batteries, the Co3O4 quantum dots/graphene composites show a significantly enhanced cycling performance (1785 mAh g−1 at 0.1C after 90 cycles) as well as high rate capability (485 mAh g−1 at 5C). The reversible capacity is found to be much higher than the theoretical value. The superior performance could be attributed to the interfacial lithium-storage and the quantum and size effects of quantum dots that lead to high activity during the lithiation/delithiation process. In addition, the flexible and conductive graphene nanosheets and well dispersed Co3O4 nanodots as well as the synergetic effect between them also benefit the electrochemical performance by endowing a superior high surface area and shortening the diffusion pathway of lithium ions.
In this work, a sensitive DNAzyme-based electrochemical sensor had been developed for Pb2+ detection with platinum nanoparticles decorated TiO2/α-Fe2O3 composite as signal labels. The morphological and compositional properties of the PtNPs/TiO2/α-Fe2O3 were examined by using transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The result showed that the shape of α-Fe2O3 nanocrystals were the cubic, the average length ranged from 150 to 300 nm, and the PtNPs with about 3–4 nm in diameter were well dispersed on the surface of TiO2/α-Fe2O3. TiO2/α-Fe2O3 were used as a “carrier” to load the PtNPs tracers as well as for Apt3 immobilization. In turn, the DNAzyme structure of Apt1 and Apt2 was immobilized on the gold electrode surface as the capture probes. Subsequently, DNAzyme modified electrodes reacted with target Pb2+ and the Apt3/PtNPs/TiO2/α-Fe2O3 composite were deposited on the electrode surface. The performance of the DNAzyme-based electrochemical sensor was tested by recording the electrocatalytic reduction current toward H2O2. Enhanced sensitivity was achieved by TiO2/α-Fe2O3 nanocomposites as a nanocarrier in order to PtNPs at a high ratio. The DNAzyme-based electrochemical sensor described here exhibited excellent sensitivity and specificity for target ion. This work represented a promising potential for on-site testing Pb2+ in real drinking water and serum sample analysis.
Excessive weight gain during pregnancy increases the risk for negative effects on mother and child during pregnancy, delivery, and also postnatally. Excessive weight gain can be partially compensated by being sufficiently physically active, which can be measured using activity trackers. Modern activity trackers often use accelerometer data as well as heart rate data to estimate energy expenditure. Because pregnancy affects the metabolism and cardiac output, it is not evident that activity trackers that are calibrated to the general population can be reliably used during pregnancy. We evaluated whether an activity monitor designed for the general population is sufficiently accurate for estimating energy expenditure in pregnant women.
An easy, one-step carbonization of alkali-treated wheat flour is proposed for the synthesis of three-dimensionally (3D) interconnected honeycomb-like porous carbon foam (HPC). Due to its interconnected porous structure with narrow pore size distribution, high specific surface area (1313m2 g−1), and heteroatom doping (N: 1.1at%, O:11.2at%), the HPC electrode exhibits a high specific capacitance of 473Fg−1 at 0.5Ag−1 in 6M KOH and outstanding electrochemical stability with capacitance retention up to 94.5% after 10,000 cycles. More interestingly, the assembled HPC//HPC symmetric supercapacitor delivers an ultrahigh energy density of 29.3Whkg−1 (based on the total mass of the active materials of the two electrodes), much higher than most of carbon-based supercapacitors. Additionally, the HPC//MnO2/HPC asymmetric supercapacitor exhibits a high energy density of 63.5Whkg−1 (based on the total mass of the active materials of the two electrodes) and excellent cycle stability (93.4% of initial capacitance retention after 5000 cycles).
Sperm morphometry and motility are important male traits affecting fertility and post-copulatory competitive ability. However, studies examining consistency in sperm traits over time for individual males are rather scarce, particularly in free-living animals. Here, we report our analysis of various measures of sperm morphometry and sperm motility in the Barn Swallow (Hirundo rustica), both within and between breeding seasons. We found high within-season repeatabilities for all measures of sperm morphometry (all r > 0.70) and moderate repeatability of sperm motility (all r > 0.42). Between seasons, repeatabilities were somewhat lower, but total sperm length and flagellum length also showed very high repeatabilities between seasons (r > 0.85). Furthermore, sperm motility showed higher repeatabilities between seasons than within a season (all r > 0.63). Although measures of sperm motility are likely to be more plastic due to, for example, changes in body condition, they still showed moderate repeatabilities within and between seasons. Our study results also imply that a single ejaculate would be sufficient to obtain representative measures of an individual’s sperm quality traits within the same breeding season.