batterydata/paper-abstracts huggingface dataset:
Electrodeposition at high current densities provides excellent means for the production of deposits with a high surface area. Porous deposits attract great interest due to their wide range of possible applications in electrocatalysis. In addition, an advanced porous electrode should have both, micro and nanoscaled features. We report the synthesis of a multiscale open porous foam of NiCoFe and its excellent electrocatalytic performance. At a current density of 1Acm−2 a 3D dendritic structure with open pores is obtained with pore walls having a morphology that consists of ‘cauliflower-like’ particles containing open multiscaled dendritic structures. Cyclic voltammograms of a smooth NiCoFe electrode are compared with those of the achieved nanodendritic NiCoFe foam electrode. The catalytic activity of the NiCoFe foam is strongly enhanced for both, the cathodic reduction of oxygen and the anodic evolution of oxygen and shows a good reversibility. Therefore the presented new material is promising as bifunctional catalyst in electrochemical energy conversion and storage devices.
Hydrogen as a clean fuel is becoming vital in view of depleting fossil fuels and ever increasing energy demand. Hence hydrogen generation and storage gains immense importance. In this review article, different methods of hydrogen storage viz., physical, chemical and electrochemical in various forms like gas, liquid and solid have been discussed and compared in terms of their efficacy, capacity, operating conditions and other safety aspects. Modeling and simulation studies reported on various aspects of hydrogen storage have been presented and compared vis a vis governing equations, applications, assumptions, merits and demerits. These modeling studies would enable to understand the phenomenon better and to explore new avenues. Kinetic and thermodynamic aspects of hydrogen storage especially employing metal hydrides have been discussed too to understand the mechanism, rate controlling actors and energy aspects. Future challenges and prospects of all the aspects of the review were provided.
Magnesium (Mg) samples prepared with 25ppm, 220ppm and 13000ppm (by weight) of iron (Fe) were subject to specific forms of electrochemical testing with the ability to directly probe the extent of dissolved Mg2+ ion concentration and cathodic reduction during dissolution. To this end, atomic emission spectroelectrochemistry (AESEC) was employed for a direct measurement of Mg2+ dissolved during (and following) anodic polarisation, whilst scanning electrochemical microscopy (SECM) was used as a complimentary tool to observe enhanced catalytic activity for hydrogen evolution during (and following) anodic polarisation. The combination of these methods was able to reveal that prior anodic polarisation was not only responsible for an enhanced catalytic activity, but also for an increase in the rate of Mg2+ dissolution. Additionally, the extent of cathodic activation, and enhanced Mg2+ dissolution, were investigated as a function of the ppmw Fe content, and it is shown that noble elements such as Fe play a role in determining the extent of both anodic and cathodic activation, which is of direct relevance to corrosion of Mg, Mg-anodes and performance of primary Mg-batteries.
Hochstenbach JB, den Otter R, Mulder TW. Cognitive recovery after stroke: a 2-year follow-up. Arch Phys Med Rehabil 2003;84:1499–504. Objectives To determine (1) whether long-term improvement of cognitive function takes place after stroke and (2) which clinical factors influence cognitive recovery. Design Cohort study with patients who were assessed at 2.3 and 27.7 months after stroke. Setting Home-based stroke patients. Participants From a group of 229 stroke patients, 92 were approached to participate. Sixty-five (43 men, 22 women; mean age, 56.4y) agreed, and they were neuropsychologically assessed at 72.2 days after stroke. A group of 33 controls (12 men, 21 women; mean age, 52.4y) was used as a reference sample. Interventions Not applicable. Main outcome measures Orientation, memory, attention, visuospatial, visuoconstructive, language, and arithmetic abilities were assessed with an extensive neuropsychologic test battery. Results Significant improvements across time were noted for all cognitive domains. The biggest improvement was found in the attentional domain; the least, in the memory domain. In addition, a small subset of patients accounted for the significant improvement in all cognitive domains; most patients showed no improvement or declined. Factors influencing recovery were side of the stroke and incidence of lowered consciousness on admission. Patients with right-side brain damage performed better than those with left-side brain damage and showed more improvement over time. Patients with lowered consciousness on admission performed worse than patients without lowered consciousness. No significant effect was found for gender, type of stroke, cortical versus subcortical lesions, having 1 stroke or multiple strokes, or the interval between the stroke and the neuropsychologic assessment. Conclusion There was room for improvement in all cognitive domains, although this improvement was gained by only a small number of patients. Hence, most patients must cope with serious permanent cognitive decline after stroke.
The electrochemical behavior of the SiO (silicon monoxide) anode during its reaction with Li has been investigated using solid-state nuclear magnetic resonance (NMR) and high resolution transmission electron microscopy (HRTEM). It was mainly focused on identifying the intermediate and final phases formed with their microstructures of the electrochemically lithiated SiO at various voltage steps during the first cycle. A model for the reaction of SiO with lithium was suggested, which was consistent with the discharge capacity of about 2400mAhg−1.
The objective of this systematic review is to create an overview of the literature on the comparison of navigated transcranial magnetic stimulation (nTMS) as a mapping tool to the current gold standard, which is (intraoperative) direct cortical stimulation (DCS) mapping. A search in the databases of PubMed, EMBASE, and Web of Science was performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and recommendations were used. Thirty-five publications were included in the review, describing a total of 552 patients. All studies concerned either mapping of motor or language function. No comparative data for nTMS and DCS for other neurological functions were found. For motor mapping, the distances between the cortical representation of the different muscle groups identified by nTMS and DCS varied between 2 and 16 mm. Regarding mapping of language function, solely an object naming task was performed in the comparative studies on nTMS and DCS. Sensitivity and specificity ranged from 10 to 100% and 13.3–98%, respectively, when nTMS language mapping was compared with DCS mapping. The positive predictive value (PPV) and negative predictive value (NPV) ranged from 17 to 75% and 57–100% respectively. The available evidence for nTMS as a mapping modality for motor and language function is discussed.
The Li–O2 cell performance is largely limited by the insulating and insoluble nature of Li2O2. Here the authors report that dual mediators decouple the electrochemical reactions at the cathode from the formation and decomposition of Li2O2 from solutions, helping stabilize the carbon cathode.
A series of ordered macroporous Li3V2(PO4)3 (LVP) cathode materials with three different pore sizes (65nm, 120nm and 210nm) are prepared via a templating method using poly(methyl methacrylate) (PMMA) colloidal crystals as templates. The structure, morphology and electrochemical properties of the as-prepared LVP samples are characterized by SEM, TEM, XRD, BET, galvanostatic charge–discharge tests, cyclic voltammograms and electrochemical impedance spectroscopy measurements. The three LVP samples all show pure monoclinic structure and ordered macroporous morphology. The LVP sample with pore size of 210nm shows the best electrochemical performance. In the potential range of 3.0–4.8V, it delivers a high initial discharge capacity of 189.4mAhg−1 at 0.1C, which is close to the theoretical capacity (197mAhg−1). Moreover, at 0.5C, 1C and 5C, it exhibits initial discharge capacities of 170.5, 166.0 and 145.9mAhg−1, and can still retain 77.3%, 71.2% and 77.1% of the initial discharge capacity after 100 cycles, respectively.
A free-standing transparent film for sodium-ion conduction in PEO-based solid polymer electrolyte (additionally comprising NaClO4 and nano-sized TiO2) has been fabricated for use in Na-ion batteries by using a solution casting technique. The crystallinity of the solid polymer electrolyte and the interactions between PEO and the Na-ions is characterized by X-ray diffraction (XRD) and Fourier transformed infra-red (FTIR) spectra, which reveals the degree of Na+ ion solvation by PEO oxygen atoms (EO:Na). The ionic conductivities of the films are investigated by impedance analysis from 1 MHz to 1 Hz within the temperature range 303–363 K. A solid polymer electrolyte with anatomic ratio EO:Na = 20 exhibits a maximum ionic conductivity of 1.35 × 10−4 S cm−1, which increases to 2.62 × 10−4 S cm−1 by the addition of TiO2 (3.4 nm, 5 wt%) at temperature 60 °C. The performance of a Na2/3Co2/3Mn1/3O2 half cell with a polymer electrolyte is compared to a similar cell with a liquid electrolyte.
Thin film positive electrodes of lithium-rich manganese oxide spinels were prepared by radiofrequency magnetron sputtering from a LiMn2O4 ceramic target at a total pressure close to 2Pa. Post-annealing treatments were necessary to get well-crystallized thin films displaying interesting electrochemical performances. Raman spectrum exhibiting several well-defined bands between 296 and 635cm−1 is typical for the lithium-rich spinel. Based on ICP, RBS and XRD analyses, the thin films composition is close to Li1.2Mn1.8O4. The latter is also in accordance with a Mn3+/Mn4+ ratio close to 0.1 deduced from XPS measurements. Best electrochemical performance (capacity value, cycling life) between 2V and 3.5V vs Li+/Li was obtained for thin films annealed at 600°C. A volumetric capacity of 52μAhcm−2 μm−1 (close to about 90% of the theoretical value) was obtained at the first cycle at a C/100 regime. Contrary to most studies carried out on spinel thin films cycled in the 3V range, no appreciable degradation of the discharge capacity was observed after few tens of cycles at room temperature, highlighting the beneficial effect of substituting 20% of Mn ions by Li ions and the presence of microvoids in thin films that limits the effect of strain generated from volume variation during the Li insertion/deinsertion process.
In this study, carbon-coated Na2Ti3O7 (Na2Ti3O7/C) is synthesized by a solid-state reaction method, and its charge-discharge characteristics as a negative electrode material in an ionic liquid electrolyte, Na[FSA]-[C3C1pyrr][FSA] (FSA = bis(fluorosulfonyl)amide; C3C1pyrr = N -methyl- N -propylpyrrolidinium), are investigated at 363 K. The Na2Ti3O7/C negative electrode shows an initial discharge capacity of 215 mAh (g-Na2Ti3O7/C)−1 at a current rate of 20 mA (g-Na2Ti3O7/C)−1 in the voltage range 0.01–2.5 V. The high discharge capacity of the Na2Ti3O7/C negative electrode is attributed to the high operation temperature in the Na[FSA]-[C3C1pyrr][FSA] ionic liquid electrolyte. Although high discharge capacity is achieved, the Na2Ti3O7/C negative electrode shows relatively poor cycle performance because of the irreversible insertion of some Na ions and the formation of cracks.
Context Science is not static! In light of this basic approach, it can be expressed clearly that bibliometric methods or analysis has become an indispensable guide to be draw scientific and technological roadmaps in their research areas for researchers especially in recent years. The present study is planned as the first step of the study which will be conducted by authors on nano-encapsulation of phase change materials. Objective This study combines a traditional literature review with data mining procedures by using bibliometric approach to identify the evolution of the knowledge structure related to encapsulation of phase change materials. Papers published from 1990 to 2015 in all journals indexed by the Scopus database were considered. Method Bibliometric methods and knowledge visualization technologies were employed to investigate publication activities based on the following indicators: year of publication, document type, language, country, institution, author, journal, keyword, number of citations. Results As a result of bibliometric analysis; 34,626 papers were determined with the keyword “phase change material” and 1034 papers with the keyword “encapsulation”. The number of publications on encapsulation of phase change materials have increased significantly after 2000. China, the United States and India are the most productive countries, while Tsinghua University and South China University of Technology from China are the most important institutions related to encapsulation. Applied Energy (39) is the most productive journal followed by Energy Conversation and Management (31). Conclusion This is the first bibliometric analysis study on encapsulation of phase change materials. The results of this research support the idea thatthis type of bibliometric analysis would be a fruitful area as a first step for further works, not only associated with phase change materials. Further investigations into research fields are strongly recommended.
The instability of the Solid Electrolyte Interphase (SEI) at the surface of nano-silicon electrodes has been recognized as one of the key issues to explain the rapid capacity fading of theses electrodes. In this paper, two distinct Si-based systems are studied by using Electrochemical Impedance Spectroscopy (EIS). First, several EIS spectra are recorded along the second electrochemical cycle. Although the active material, the electrode formulation, and the experimental conditions are different for the two systems, the same phenomena are observed in both cases: (i) the SEI deposit around 50kHz, (ii) the charge transfer (CT) with a characteristic frequency varying from 300 to 1 500Hz, and (iii) an inductive loop at ∼1Hz which appears only when the potential of the electrode is below 0.35V vs Li. As the latter has never been reported for Si-based electrodes, the second step of the work consists in understanding this phenomenon. Thanks to the results obtained in a set of several complementary experiments, we finally attribute the inductive loop to the constant formation/deposition of SEI products, in competition with the CT process. In addition, we propose a mechanism for this specific phenomenon and the equivalent circuit to fit the recorded EIS spectra.
Objective In this study the theta/gamma ratio was investigated as early marker of cognitive decline. Methods Forty-nine subjects with mild cognitive impairment (MCI) underwent EEG recording and MRI scan. The theta/gamma ratio of the relative power at the peak frequency was computed. Based on the tertiles values of the ratio, three groups with increasing values of theta/gamma ratio were obtained. The groups were characterized by the performance on cognitive tests. Changes in functional brain connectivity, as expressed by interhemisperic and intrahemispheric EEG linear coherence in the groups were also evaluated. Results Increase in theta/gamma ratio was associated with impairment in memory tests. This relationship was confirmed by correlation and multiple regression analysis. An independent association was found between theta/gamma ratio and alpha3/alpha2 power ratio. Coherence analysis showed modifications of interhemispheric functional coupling on temporal regions on slow frequencies. Conclusions Theta/gamma ratio of relative power at peak frequency is significantly associated to memory decline. It could be a useful tool in detecting MCI subjects which are at major risk to develop Alzheimer’s disease (AD) or other dementias. Significance A global modulation of brain rhythms could be driven by the pathological alterations of theta/gamma ratio.
Three-dimensional SnS2 hierarchitectures have been fabricated via a facile solvothermal method. A possible growth mechanism has been propounded based on the time-dependent experiments. As anode material for lithium-ion batteries, the SnS2 hierarchitectures display long-term cycle stability and excellent high-rate performance. A high specific capacity of 549.5 mA h g−1 is achieved at a current density of 100 mA g−1 after 100 discharge/charge cycles. The superior electrochemical performances of SnS2 as lithium-ion batteries anode material can be attributed to the synergistic effect of the specific porous structure and the thin nanosheets.
In this paper, we describe a novel and high-yield strategy to fabricate high-purity carbon nanocoils (CNCs) with Cu nanoparticles as catalysts produced by atomic layer deposition (ALD). The pristine CNCs display uniform structure and are rich of abundant functional groups, which is more beneficial to achieve high content of nitrogen doping. The high-content nitrogen-doped CNC exhibits improved electrical double-layer capacitive properties (143 F g−1 at 0.5 A g−1) over previously reported CNC-based electrode materials. Moreover, the carbonized CNC can act as conductive matrix to promote the electrochemical performance of metal oxides. The prepared NiO/CNC composites show high specific capacity (430 C g−1 at 1 A g−1), super rate capability and outstanding cycling stability. Ultimately, A hybrid supercapacitor assembled by using N-doping CNC as negative electrode and NiO/CNC as positive electrode, delivers a high energy density of 17.54 W h kg−1 at a power density of 849.56 W kg−1 and a high power density of 12.74 kW kg−1 at an energy density of 7.47 W h kg−1, along with desirable cycling lifetime. This work suggests that CNCs have great potential for the electrochemical energy storage devices.
A new microelectrode technique was developed for studying hydrogen diffusion in Mg2Ni alloy electrodes during charging and discharging in 6 M KOH solution based on a spherical core shrink model. The diffusion coefficients of hydrogen in α- and β-phase hydrides were measured on a single particle electrode using the potential-step method. It was found that the diffusion of hydrogen in the β-phase of the hydride occurs more slowly than in the α-phase. This effect is attributed to formation of a β-phase hydride layer beneath the particle surface during charging which retards hydrogen transport and results in incomplete charging. This leads to an extremely low electrochemical capacity. The diffusivity of hydrogen in magnesium alloy powders measured by the microelectrode technique was also compared with those evaluated by a porous plate electrode.
Olivine-structured LiFePO4 cathode materials were prepared via a combination of carbothermal reduction (CR) and molten salt (MS) methods. To enhance the powder's tap density, the LiFePO4/C composite was pressed into pellets and then sintered for at least 1h at 1028K in the reaction environment of KCl molten salts. The use of molten salt can effectively influence unit cell volume, morphology and tap density of particles, and consequently change the electrochemical performance of LiFePO4/C. The composites were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy and tap density testing. The final product with high tap density of 1.50gcm−3 contains 4.58wt% carbon and exhibits good discharge capacity of 141mAhg−1 at a 0.2C-rate in the potential range of 2.8–4.0V.
Zinc accumulation is recognized as one of the most critical issues that affect the cycle life of zinc-nickel single flow batteries (ZNBs). In this paper, a novel and very specific method has been proposed to solve the above problem. The side reactions, which are always regarded as negative factors, are promoted at negative side to balance the side reactions at positive side. A novel electrode with high reaction area and well mass transport structure has been designed to facilitate parasitic reactions at negative side. The result shows that zinc accumulation has been successfully solved by balancing positive reactions and negative reactions with this novel electrode, and no zinc accumulates on the negative electrode over 400 cycles. This paper provides an effective way to improve the cycling stability of ZNBs, which is the most troublesome for the commercialization of ZNBs.
For several applications, batteries with a high power/energy ratio are required. In order to meet these requirements, alkaline batteries based on fibre structures and hydrogen storage negative electrodes that are arranged in bipolar stacks, can be used. The bipolar stacks are designed to provide comparatively high voltages, e.g. 12, 36 and even 110V. These stacks display electrochemical characteristics of a typical battery but are able to provide high power densities. This paper compiles data obtained from such storage units.
The enhancing sodium ion insertion and deinsertion characteristics of Li in layered structure compound were studied. Layered structure materials Na2/3Ni1/3Mn2/3O2 and Na0.7Li0.3Mn0.75O2 were synthesized. They can be used as cathode materials for sodium ion batteries. Although they displayed same crystal structures, the Na0.7Li0.3Mn0.75O2 exhibited better electrochemical properties than Na2/3Ni1/3Mn2/3O2. For Na0.7Li0.3Mn0.75O2, when cycled between 2.0 and 4.4 V at a current rate of 17 mA g−1, its charge capacity of reached 175 mAh g−1, and its discharge capacity was 149 mAh g−1. In the first several charge-discharge cycles, the capacity decreased with cycles performing. Then capacity tended to be stable and began to increase. After 40 cycles, its discharge capacity was 143 mAh g−1. It discharge capacity could reach 121 mAh g−1 at current rates of 0.34 mA g−1-charge/0.85 mA g−1-discharge. Li element enhanced the electrochemical properties such as cycle performance and rate capability.
A series of nitrogen doped porous carbons are prepared using a simple and economic template carbonization method, in which nano-CaCO3 and ethylenediamine (EDA) and carbon tetrachloride (CTC) serve as a template and nitrogen-containing carbon precursors, respectively. The textural parameters of all the obtained carbon materials are tunable. The porosity and nitrogen content of the nitrogen doped porous carbons strongly depend on the dosage of nano-CaCO3. When the ratio of CaCO3 to the sum weight of EDA and CTC increases from 0.2 to 0.4, the specific surface area increases from 783.72 to 2535.09m2 g−1, meanwhile the nitrogen content decreases from 16.13 to 9.47wt%. While when the ratio of CaCO3 to the sum weight of EDA and CTC is moderate, the as-prepared nitrogen doped porous carbons (NPC-0.3) contains as high as 13.45wt% of nitrogen has a balanced specific surface areas of 1276.14m2 g−1, exhibits the largest specific capacitance of 226Fg−1 at a current density of 0.1Ag−1 in 1M H2SO4 aqueous electrolyte, due to the co-contribution of double layer capacitance and pseudo-capacitance. Additionally, it shows excellent rate capability (capacitance retention ratio of 58.4% at a current density of 30Ag−1) and good cycling stability (no capacitance decay over 10 000 charge-discharge cycles), making it a promising electrode material for supercapacitors.