batterydata/paper-abstracts huggingface dataset:
Sodium-ion batteries are attractive for large-scale energy storage due to the abundance of sodium, but the deficient capacity achieved by cathode materials prevents their further applications. Chemical substitution of Na in transition metal layers is a promising solution to utilize both the cationic and anionic redox activities for boosting energy storage. Unfortunately, different from the classic Li-rich Li2MnO3, a pure prototype with anionic redox activity has not been found among the typical Na-rich cathodes. Herein, we originally design a Na-rich layered oxide prototype, namely Na3RuO4 (Ru5+), which delivers a partial reversible capacity solely via the participation of oxygen anions. More importantly, the anionic redox activity is validated by the in situ Raman observation of reversible peroxo-based O–O (de)bonding upon cycling. Our findings not only highlight the multiple electron-transfer strategy for capacity extension, but also broaden the horizon in designing Na-rich electrode materials for high-energy sodium-ion batteries.
Studies have linked perceived racism to psychological distress via certain coping strategies in several different racial and ethnic groups, but few of these studies included indigenous populations. Elucidating modifiable factors for intervention to reduce the adverse effects of racism on psychological well-being is another avenue to addressing health inequities.
We report a new carbonate electrolyte of 1 M LiFSI dissolved in the EMC/FEC (70/30, v/v) solvent for lithium metal based batteries. Favorable LiF-rich SEI layer is formed on Li anode to suppress side reactions under the synergistic effect of LiFSI and FEC. Thus, the dendrite-free Li morphology and high Coulombic efficiency for Li plating/stripping can be obtained with improved cycle stability compared with conventional LiPF6/EC-DMC electrolyte. Li | S@pPAN cell assembled with the new electrolyte shows quite low lithium ion transfer resistance, excellent long cycle stability and rate performance. A high discharge capacity of 1270 mAh g−1 remains after 1000 cycles at 2 C, with an inappreciable capacity decay of 0.0015% per cycle. Due to the low interface impedance and high Li+ diffusion coefficient, a capacity of 1210 mAh g−1 even at 10 C can be maintained. This deliberately designed electrolyte offers new insights into the understanding of interfacial stability between electrolyte and Li anode. Furthermore, our work offers a new approach towards high energy-density and high rate Li-S battery.
In this work, we present a facile approach to synthesize nitrogen-doped porous carbon materials via a two-step fabrication process using the stem bark of broussonetia papyrifera (BP) as the biomass precursor. Firstly, the BP stem bark is hydrothermally treated in a KOH aqueous solution. After filtration and drying, the hydrothermal product is directly subjected to simultaneous pyrolysis and activation, giving nitrogen-doped porous carbon materials. The morphology, structure and textural properties of the carbon materials are investigated by scanning electron microscopy, transmission electron microscopy, N2 sorption isotherms, and X-ray photoelectron spectroscopy. The obtained porous carbon exhibits a high BET surface area of 1212m2 g−1 and an average pore size of 3.8nm. Such porous carbon shows outstanding capacitive performance (320Fg−1 at 0.5Ag−1), good rate capacitive behavior, and excellent cycling stability due to the synergistic effect of N, O-doped species, indicating a great potential for supercapacitors.
Flexible and wearable pressure sensors are of essential importance in developing artificial electronic skin (e-skin) for areas such as healthcare monitoring and clinical diagnosis. Here, we report an ultrasensitive cellular fluorocarbon piezoelectret pressure sensor (FPS) via a three-step hot-pressing method. By constructing micron-sized voids in the inner cell, and combination with outstanding charge storage ability of the fluorocarbon electrets, tremendous piezoelectric activity can be obtained. The flexible FPS showed advantages of remarkable sensitivity (7380pCN−1) in the subtle-pressure regime (<1kPa), fast response time (50ms), very low limit of detection (5Pa) as well as high stability (30,000 cycles). In addition, the flexible and self-powered FPS owns the capability for detecting human motions such as wrist stretching, cheek motion from open-bite-open, eyes blinking and chest respiration, respectively. It can be also used for monitoring human physiological signals such as radial artery pulse wave. By virtue of easy processability in large scale, light weight, and low cost, the FPS is especially suitable for mass production and flexible electronics, indicating their promising applications in artificial intelligence and mobile healthcare monitoring systems.
The oxygen evolution and reduction reactions are two extremely important reactions in terms of energy applications. Currently, the Oxygen Evolution Reaction (OER) hinders the efficient running of electrolyzer devices which convert water into molecular H2. This H2 can subsequently be used in a H2/O2 fuel cell for the renewable generation of electricity with only H2O as a by-product. However, this fuel cell process is not economy feasible due to the sluggish kinetics of the Oxygen Reduction Reaction (ORR) at the device cathode, even with expensive state-of-the-art electrocatalytic materials. As of late, the amount of interest in the OER and ORR, from research laboratories from all over the globe, has risen rapidly in order to find cheap and efficient catalysts to replace the expensive platinum based catalysts currently used in the two aforementioned energy conversion/generation technologies. Layered transition metal oxides, based on the cheap transition metal oxides Mn, Co, Ni and Fe have been reported as viable catalysts for the OER and ORR. Layered structures have an added advantage over non-layered materials as the surface area can be increase by means of exfoliation, with potential for tailoring electrocatalytic activity. It has been shown that the fabrication process and post-synthetic treatments, e.g. anion exchange or exfoliation, of these materials can alter the catalytic activity of these materials. Here we summarise various fabrication methods and modifications utilised in literature to tailor the performance of layered transition metal and hydroxide based catalysts for the ORR and OER toward that of the state-of-the-art materials for these technologies.
In this work, γ-MnO2 nanoparticles and α-MnO2 urchin-like nanostructures have been successfully synthesized by the microwave-assisted reflux as short as 5min under neutral and acidic conditions, respectively. The crystal structure, morphology and chemical composition of the MnO2 products were investigated be X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption. γ-MnO2 nanoparticles showed a smaller particle size, a higher specific surface area, and a larger pore volume than those of α-MnO2 urchin-like nanostructures. The electrochemical performance was investigated by using cyclic voltammetry and galvanostatic charge–discharge techniques. γ-MnO2 nanoparticles obtained from the neutral condition exhibited a capacitance of 311Fg−1 at a current density of 0.2Ag−1, which is much higher than that of α-MnO2 urchin-like nanostructures (163Fg−1). The specific capacitance retention and coulombic efficiency after 5000 cycles at 1Ag−1 were about 93% and almost 100% for γ-MnO2 nanoparticles, respectively, suggesting that it is a promising electrode material for supercapacitors.
In this study, polypyrrole/multi-walled carbon nanotube (PPy/MWCNT) composites were synthesized in water, dichloromethane and n-hexane solvents and the conducting composite materials were tested as symmetric 2-electrode electrochemical capacitors. The synthesis method, electrolyte type, and binder compositions had profound effects on the overall performance of the cells. The microscopic structure of the composites and hydrophilicity of the electrode materials also influenced the capacitor behavior. The cells assembled with the PPy/MWCNT composites had a high specific capacitance (165Fg−1) and excellent cycleability for up to 1000 cycles in 1.0M KCl electrolyte. The composite electrodes showed no capacitance loss due to the increase of internal resistance of the materials and thus, they exhibited ideal supercapacitor characteristics.
The structural stability of graphite electrodes in Li-ion cells, which were cycled at room temperature and 60°C was investigated. We observed gradual structural degradation of the graphite, which was most pronounced on the electrode surface but also extended into the bulk of the electrode. Graphite particles close to the Cu current collector remained almost unchanged, whereas those close to the electrode/electrolyte interface suffered significant structural damage. Structural degradation of the graphite led to an increased anode surface reactivity vs. the electrolyte. A thick layer of inorganic products from side reactions was observed on the disordered carbon areas of the anode.
Carbon nanoarchitectures are versatile platforms for advanced electrode structures in which the carbon edifice serves multiple simultaneous functions: a massively parallel 3-D current collector with an interpenetrating structural flow field that facilitates the efficient transport of electrons, ions, and molecules throughout the structure for further functionalization or high-performance electrochemical operation. We fabricate carbon nanofoam papers by infiltrating commercially available low-density carbon fiber papers with phenolic resin. The polymer-filled paper is ambiently dried and then pyrolyzed to create lightweight, mechanically flexible, and electronically conductive sheets of ultraporous carbon with an electronic conductivity characteristic of the paper support (20–200 S cm−1) rather than RF-derived carbon (typically 0.1–1 S cm−1). The resulting composites comprise nanoscopic carbon walls that are co-continuous with an aperiodic, 3-D interconnected network of mesopores (2 to 50 nm) and macropores (50 nm to 2 µm). Macropores sized at 100–300 nm have not been adequately explored in the literature and offer ample headspace to modify internal carbon walls, thereby introducing new functionality without occluding the interconnected void volume of the nanofoam. Increasing the viscosity of the polymer sol and matching the surface energetics of the carbon fibers and aqueous sol is necessary to avoid forming a standard carbon aerogel pore–solid structure, where the pores are sized in the micropore (<2 nm) and mesopore range. Carbon nanofoam papers can be scaled in x, y, and z and are device-ready electrode structures that do not require conductive additives or polymeric binders for electrode fabrication. This one class of nanofoams serves as a high-surface-area scaffold that can be segued by appropriate modification into multifunctional nanoarchitectures that improve the performance of electrochemical capacitors, lithium-ion batteries, metal–air batteries, fuel cells, and ultrafiltration.
Flow cytometry is a valuable tool for the analysis of phytoplankton and other suspended particles because of its speed and quantitative measurements, but the method's oceanographic application has been limited by the need to take discrete water samples for analysis on board ship or in the laboratory. For this reason, we have developed an automated flow cytometer (FlowCytobot) that can operate in situ and unattended. The new instrument utilizes a diode-pumped 532nm laser and can measure light scattering and fluorescence of particles as small as Synechococcus cells. For operation at the LEO-15 mooring site off New Jersey, it is connected to shore by power and communications cables, and is controlled by a microcomputer whose programming can be loaded remotely. The sampling rate is adjustable; we have used from 12.5 to 50μlmin−1. Integrated signals from each particle (two light scattering angles and two fluorescence emission bands) are transmitted to a shore-based computer, where they are accessible by Internet and can be examined in real time. FlowCytobot was deployed at LEO-15 from late July to early October 2001, where it operated continuously (aside from occasional power or communications interruptions at the node) without outside intervention. Even after 2 months of in situ operation, FlowCytobot's measurements were similar to those of a conventional flow cytometer, as shown by analysis of a discrete water sample taken at the location of the sample inlet. In addition to documenting seasonal and event-scale changes in size distributions and population abundances in the pico- and nanophytoplankton, FlowCytobot will be useful for examining diel cycles in light scattering and pigment fluorescence of cells in situ that may allow estimation of rates of production by different phytoplankton groups.
LiCoO2, Mg-doped LiCoO2, and Zr doped LiCoO2, are manufactured by a sol–gel method, and are used as cathode active materials for lithium rechargeable batteries. The structural characteristics of the synthesized electrodes are analyzed by X-ray diffraction. The materials have a layered structure with the space gropu R 3 ¯ m of hexagonal systems. LiCoO2 prepared by sol–gel method shows a capacity decay over 4.3V but LiCoO2 doped with Mg and Zr give an improvement in charge–discharge cycling performance. This effect may attribute to the fact that Mg2+ and Zr4+ ions have the same size as the Li+ ion and they locate at the inter-slab space. Therefore, they provide a pathway for the intercalation–deintercalation of Li+ during the charge and the discharge processes and prevent distortion of the structure. Also, the formation of a solid solution on the surface of the electrode acts as the buffer to phase transition and the structure becomes very stable.
Polymer gel electrolytes formed by hydroxyethylcellulose (HEC) plasticized with glycerol and containing lithium perchlorate were studied by nuclear magnetic resonance spectroscopy (NMR) and complex impedance spectroscopy. In heavily plasticized samples, results show that the addition of solvent enhances the conductivity, which reaches 6×10−5 S/cm at room temperature. The 7Li NMR results indicate that this enhancement is associated with a decoupling of the lithium-ion dynamics from the local motion of the polymer host, with the increase in the mobility of the ionic species, and with the increase of the charge carrier concentration resulting from the salt dissociation after addition of the solvent. The temperature dependence of the lithium NMR spin-lattice relaxation is interpreted assuming that there are two distinct lithium-ion dynamics. The corresponding NMR relaxation processes are characterized by activation energies of 0.3 and 0.12eV, respectively.
Equations governing the vibrations and buckling of multilayered orthotropic graphene sheets can be expressed as a system of n partial differential equations where n refers to the number of sheets. This description is based on the continuum model of the graphene sheets which can also take the small scale effects into account by employing a nonlocal theory. In the present article a variational principle is derived for the nonlocal elastic theory of rectangular graphene sheets embedded in an elastic medium and undergoing transverse vibrations. Moreover the graphene sheets are subject to biaxial compression. Rayleigh quotients are obtained for the frequencies of freely vibrating graphene sheets and for the buckling load. The influence of small scale effects on the frequencies and the buckling load can be observed qualiatively from the expressions of the Rayleigh quotients. Elastic medium is modeled as a combination of Winkler and Pasternak foundations acting on the top and bottom layers of the mutilayered nano-structure. Natural boundary conditions of the problem are derived using the variational principle formulated in the study. It is observed that free boundaries lead to coupled boundary conditions due to nonlocal theory used in the continuum formulation while the local (classical) elasticity theory leads to uncoupled boundary conditions. The mathematical methods used in the study involve calculus of variations and the semi-inverse method for deriving the variational integrals.
The impact of cycling at low temperatures on the thermal and mechanical abuse behavior of commercial 18650-type lithium ion cells was compared to fresh cells. Post-mortem analyses revealed a deposition of high surface area lithium (HSAL) metal on the graphite surface accompanied by severe electrolyte decomposition. Heat wait search (HWS) tests in an accelerating rate calorimeter (ARC) were performed to investigate the thermal abuse behavior of aged and fresh cells under quasi-adiabatic conditions, showing a strong shift of the onset temperature for exothermic reactions. HSAL deposition promotes the reduction of the carbonate based electrolyte due to the high reactivity of lithium metal with high surface area, leading to a thermally induced decomposition of the electrolyte to produce volatile gaseous products. Nail penetration tests showed a change in the thermal runaway (TR) behavior affected by the decomposition reaction. This study indicates a greater thermal hazard for LIB cells at higher SOC and experiencing aging at low temperature.
The present study proposes correlations between the silver content and the dendrite arm spacing of two distinct Pb–Ag alloys (1 and 2.4 wt.% Ag) with their resulting electrochemical corrosion responses. Samples having a wide range of dendritic spacings were obtained using a water-cooled unidirectional solidification system. EIS, potentiodynamic polarization curves and an equivalent circuit were used to characterize the corrosion behavior of these samples in a 0.5 M H2SO4 solution at 25°C. It was found that both the Ag alloying and the scale of secondary dendritic arm, λ2, have important roles on the electrochemical corrosion behavior. The current density decreased with the increase in λ2. The increase in silver content provoked only a slightly improvement in the corrosion resistance and its addition to a Pb alloy should meticulously be analyzed considering the ratio anode/cathode areas. Although the addition of silver increases considerably the final cost of Pb–Ag alloys, these alloys can be used as alternative materials for the manufacture of lead-acid battery components.
In this study, the impact of annealing treatment on the ionic transfer and storage stability of 70Li2S–30P2S5 glass-ceramic solid electrolyte (SE) pellets are investigated. The ionic conductivity is enhanced from 1 to 1.5 mS cm−1, while the total interfacial resistance of Li/SE/Li cell is reduced by over an order of magnitude with increasing annealing temperature up to 250 °C. Higher annealing temperature induced formation of a low conductivity Li4P2S6 phase, which increased ionic and interfacial resistances. Storage stability is also improved by annealing treatments. Preparation of exemplary Li4Ti5O12 (LTO) electrodes involving mechanical milling with SE particles undesirably induces formation of a TiS2 phase at the interfaces. Annealing the cells at 250 °C induces further reaction between LTO and SE, increasing TiS2 content and reducing cell rate performance. High reactivity between metal oxides and sulfide-based SE may be an obstacle for the preparation of high performance rechargeable solid state Li ion batteries.
Background Social cognitive deficits contribute to functional disability in schizophrenia. Social cognitive tasks in healthy persons consistently evoke activation of medial prefrontal cortex, inferior frontal gyrus, temporoparietal gyrus, and posterior cingulate cortex/precuneus. We tested the hypothesis that patients with schizophrenia and their unaffected siblings share dysfunction of the same neural networks. Methods Neural activation during emotion processing (EP), theory of mind (ToM), and control tasks was measured using functional magnetic resonance imaging (fMRI) in 14 patients with schizophrenia, 14 nonpsychotic siblings of patients with schizophrenia, and 14 matched healthy subjects. Results Compared with healthy controls, patients with schizophrenia showed reduced activation of right hemisphere structures involved in EP and ToM including inferior frontal gyrus, middle frontal gyrus, and right temporoparietal junction. These deficits were shared, in part, by unaffected siblings. The latter group demonstrated deficits in bilateral precuneus activation during ToM, not present in patients. Conclusions Schizophrenia appears to be associated with a deficit in activation of right hemisphere components of a ToM network. Such deficits are shared in part by those at high genetic risk but unaffected by schizophrenia.
Rational design and facile preparation of non-noble trifunctional electrocatalysts with high performance, low cost and strong durability for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are highly demanded, but remain as a big challenge. Herein, we report a spontaneous gas-foaming method to prepare nitrogen doped ultrathin carbon nanosheets (NCNs) by simply pyrolysing a mixture of citric acid and NH4Cl. Under the optimized pyrolysis temperature (carbonized at 1000 °C) and mass ratio of precursors (1:1), the synthesized NCN-1000-5 sample possesses an ultrathin sheet structure, an ultrahigh specific surface area (1793 m2 g−1), and rich edge defects, and exhibits low overpotential and robust stability for the ORR, OER and HER. By means of density functional theory (DFT) computations, we revealed that the intrinsic active sites for the ORR, OER and HER are the carbon atoms located at the armchair edge and adjacent to the graphitic N dopants. When practically used as a catalyst in rechargeable Zn–air batteries, a high energy density (806 W h kg−1), a low charge/discharge voltage gap (0.77 V) and an ultralong cycle life (over 330 h) were obtained at 10 mA cm−2 for NCN-1000-5. This work not only presents a versatile strategy to develop advanced carbon materials with ultrahigh specific surface area and abundant edge defects, but also provides useful guidance for designing and developing multifunctional metal-free catalysts for various energy-related electrocatalytic reactions.
The present work focuses on the development of template-free mesoporous NiO nanoarrays with large surface area grown on 3D nickel foam networks by a seed mediated aqueous chemical growth technique and subsequent annealing process. The resultant binder-free, well-aligned and vertically grown NiO nanoarrays exhibits a micron-sized planar structure as well as an ultrathin thickness (∼7 nm). The unique surface and electronic structure facilitates surface-dependent electrochemical reaction processes with no dead volume. They deliver a high capacitance of 2065 F g−1 at a current density of 16 A g−1 as a three electrode system. A specific capacitance of 1247 F g−1 is maintained at a higher current rate of 70 A g−1 with 88.9% retention after 5000 cycles. Finally, in a solid-state asymmetric supercapacitor configuration using NiO//activated carbon, the device delivers an enhanced supercapacitive performance, with an energy density of 43.5 Wh kg−1 and power density of 2.1 kW kg−1. Thus, the current research paves the way for the use of NiO nanoarrays as an electrode material for practical supercapacitor devices with higher cycling retention and rate capacity.