batterydata/paper-abstracts huggingface dataset:
Cupric ion substituted LiFePO4/C composites were successfully synthesized via a two-step solid state reaction method. The SEM mapping demonstrates that cupric is well substituted in LiFePO4. Interestingly, the XRD spectra indicate that the substituted cupric could enlarge the interplanar distance of planes that parallelled to [010] direction of LiFePO4 crystallines, which could widens the diffusion channels of Li+ along [010] direction. For further research, Lithium ion storage behavior of as-synthesized cupric ion substituted LiFePO4/C products were investigated via various electrochemical strategies, and the highest capacity of 152.4, 144.4, 126.7 and 110.5mAhg−1 was achieved by LiFe0.985Cu0.015PO4/C at discharge rate of 1, 2, 5, and 10 C, respectively. Compared the result with that of LiFePO4/C, we can see that cupric ion substituted LiFePO4/C composites show enhanced electrochemical activity for Li+ storage with decreased overpotential and increased high rate capability for electrochemical reaction.
Based on the wide range of problems to effectively perform cardiopulmonary testing in young children, this study strives to develop a new cardiopulmonary exercise test for children using a mobile testing device worn in a backpack in order to test children during their natural movement habits, namely, running outdoors. A standard cardiopulmonary exercise ramp test on a cycle ergometer was performed by a group of twenty 7–10-year-old children. The results were compared with a self-paced incremental running test performed using a mobile cardiopulmonary exercise measuring device in an outdoor park. The children were able to reach significantly higher values for most of the cardiopulmonary exercise variables during the outdoor test and higher. Whereas a plateau in
Ruttan L, Martin K, Liu A, Colella B, Green RE. Long-term cognitive outcome in moderate to severe traumatic brain injury: a meta-analysis examining timed and untimed tests at 1 and 4.5 or more years after injury. Objectives To examine long-term outcome of moderate to severe traumatic brain injury (TBI) on timed and untimed cognitive tests using meta-analysis. Design Meta-analysis examining outcome at 2 epochs, 6 to 18 months postinjury (epoch 1) and 4.5 to 11 years postinjury (epoch 2). Setting Data source was published articles (1966–2007) identified through electronic and manual search. Participants A total of 1380 subjects with moderate to severe TBI participated in the 16 studies meeting inclusion criteria. Interventions Not applicable. Main Outcome Measures Timed and untimed neuropsychologic tests with quantitative results (means, SDs, t, and df tests) from studies containing a healthy comparison group and a mean time since injury falling within 1 of the 2 epochs. Results Patient versus control weighted effect sizes were medium to large at epoch 1 for both untimed tasks (r=−.46; confidence interval [CI], −.32 to −.65) and timed tasks (r=−.46; CI, −.35 to −.59). At epoch 2, effect sizes were slightly smaller for untimed tasks (r=−.38; CI, −.25 to −.60) and timed tasks (r=−.40; CI, −.32 to −.62). Conclusions Patients showed robust, persisting impairments on both timed and untimed tests at recovery plateau (ie, 6–18mo postinjury) and many years later. These findings converge with previous studies, though using an alternative approach that obviates some of the methodologic problems of longitudinal studies, such as selective attrition.
Employing linear carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as electrolyte solvents provides an opportunity to design appropriate electrolyte systems for high-performance sodium-ion batteries (SIBs). However, in practice, the use of linear carbonate-containing electrolytes is quite challenging because linear carbonates readily decompose at Na metal electrodes or sodiated anodes. One of the promising approaches is using an electrolyte additive to resolve the critical problems related to linear carbonates. Our investigation reveals that remarkable enhancement in electrochemical performance of Na4Fe3(PO4)2(P2O7) cathodes with linear carbonate-containing electrolytes is achieved by using a fluoroethylene carbonate (FEC) additive. Importantly, the initial Coulombic efficiency of the Na deposition/stripping on a stainless steel (SS) electrode is drastically improved from 16% to 90% by introducing the FEC additive into ethylene carbonate (EC)/propylene carbonate (PC)/DEC (5/3/2, v/v/v)/0.5 M NaClO4. The underlying mechanism of FEC at the electrode-electrolyte interface is clearly demonstrated by 13C nuclear magnetic resonance (NMR). In addition, the Na4Fe3(PO4)2(P2O7) cathode in EC/PC/DEC (5/3/2, v/v/v)/0.5 M sodium perchlorate (NaClO4) with FEC delivers a discharge capacity of 90.5 mAh g−1 at a current rate of C/2 and exhibits excellent capacity retention of 97.5% with high Coulombic efficiency of 99.6% after 300 cycles at 30 °C.
Cobalt(II,III) oxide (Co3O4), synthesized by gel-combustion method, thermally treated in air at temperatures 400, 600 and 800°C, was subjected to the reduction to metallic state in hydrogen atmosphere. The reduction was carried out at several constant heating rates and controlled by thermogravimetry. The mass vs. temperature curves were analyzed from the kinetic aspect. The two-step reduction was confirmed. Both the hydrogen partial pressure and the sample history influenced the reduction kinetics. The activation energies of both reduction steps were determined by means of Friedman isoconversional method and Kissinger methods, and the values obtained by Kissinger method were used to fit the experimental data by means of expanded Prout–Tompkins reaction model.
SnSb–Ag/Carbon nanonube (CNT) composites materials are synthesised using chemical reduction methods. The microstructure, morphologies and electrochemical properties of these materials are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), constant current charge/discharge tests and cyclic voltammetry tests. The results indicate that Ag promotes the entire charge–discharge process during the complex multi-step reaction process and, to some extent, prevent the reunion of nanoparticles. At the same time, CNTs, with a large space volume and form a network structure, prevent particles aggregation and increase the buffer space between the alloy particles, which greatly reduce the diffusion distance of lithium ions and the occurrence of lithium trapping in the active electrode materials. CNTs also have excellent mechanical properties and toughness, they effectively buffer enormous stresses during the volume expansion of alloy particles, weakening the forces between the particles and reducing the rate of formation of powder particles. All these factors cause the SnSbAg0.1/6% CNT composites exhibit excellent cycle life by controlling the lithiation of the anode material; the reversible capacity for the 50th cycle is 639.6 mAh g−1 between 0.05 and 1.5 V.
Improving the electron and ion transport in sulfur electrodes and suppressing the lithium polysulfide shuttle have been the two major challenges with lithium-sulfur (Li-S) batteries. Here, we present a composite paper electrode consisting of hollow Co3S4 polyhedra, activated carbon nanofibers (ACNF), and pure sulfur powder for Li-S batteries. The hollow Co3S4 polyhedra with a porous shell structure provide large spaces to accommodate the polysulfides, possess ideal polar chemisorptive capability for immobilizing the polysulfide species, and have a higher conductivity than many polar metal oxides, facilitating fast reaction kinetics with the Li-S batteries. The composite electrode exhibits high sulfur utilization and maintains superior cycling stability in Li-S batteries with a high sulfur areal mass. A high capacity of 953mAh g−1 at 1C rate could be achieved with a sulfur loading of 2.5mgcm−2, and the capacity remains at 610mAh g−1 after 450 cycles. Even with a high sulfur loading of 13.5mgcm−2, the composite electrode delivers a high areal capacity of 13mAhcm−2 at 0.3C rate.
High capacity transition metal oxides have attracted much attention as potential sodium-ion batteries (SIBs) anodes. However, the fast capacity fading greatly limits their practical applications. In this study, highly crystallized mesoporous Fe3O4 nanoparticles encapsulated in the hollow nitrogen-doped carbon nanospheres (denoted as HCM-Fe3O4@void@N-C) have been synthesized and then explored as anode materials for SIBs. The resultant HCM-Fe3O4@void@N-C nanospheres possess a uniform particle size of ~ 180 nm with highly crystallized mesoporous Fe3O4 cores (~ 100 nm in diameter), a large surface area of ~ 250 m2 g−1 and a nitrogen-doped carbon shell (~ 7.6 wt%). Notably, a high discharge capacity of 372 mA h g−1 is obtained after the first five cycles at 160 mA g−1, which can gradually increase and be maintained at an ultrahigh specific capacity of 522 mA h g−1 even after 800 cycles. Besides, remarkable rate performance with a capacity of 196 mA h g−1 at a current density of 1200 mA g–1 and a high Coulombic efficiency (~ 100%) are obtained. Such good performance can be attributed to the unique yolk-shell nanostructure with a high crystallized mesoporous Fe3O4 core, a high conductive N-doped carbon shell, and a suitable void space, paving a new way to design and synthesize high-performance anode materials for SIBs.
Elucidating the role of interparticle Li transport and multi-particle (de)lithiation kinetics in nanoparticulate two-phase electrode materials such as LiFePO4 is a challenging task because of the small temporal and spatial scale associated with the process. Often, the relevant processes that determine the kinetics of (dis)charging an electrode are assumed to be exclusively those associated with Li transport to and from the counter-electrode, without a consideration of interactions between particles. However, the redistribution of Li between nanoparticles can have a strong influence on the overall cell rate performance. Using a continuum model to simulate the lithiation kinetics of a porous aggregate of LiFePO4 nanoparticles, we demonstrate the impact of cell architecture (in terms of ionic and electronic connectivities between active particles) and cycling rate on the multi-particle (de)lithiation kinetics. Specifically, the connectivity between particles is shown to have a strong effect on “interparticle phase separation,” a process by which active particles undergo additional cycling (charge during the overall discharge) and amplified reaction rates. We show that interparticle phase separation can be reduced or eliminated by improving (“homogenizing”) the connectivity between particles. Extensive comparisons to experimental literature and insights toward improving the performance of nanoparticulate electrodes are also provided.
Previous research has suggested that the left anterior insula, specifically the superior precentral gyrus of the insula (SPGI), is a critical brain region for the coordination of complex articulatory movements. However, previous studies have not determined which articulatory factors are specifically dependent on this brain region. In the current study, 33 left hemisphere stroke patients with varying degrees of speech impairment were asked to perform multiple repetitions of single words that varied along three separate dimensions: number of syllables, degree of articulatory travel (i.e., change between places of articulation for consonants), and presence/absence of an initial consonant cluster. The role of the SPGI in performance across the three conditions was determined using voxel-based lesion symptom mapping (VLSM), a statistical approach to lesion analysis that does not require separating patients based on lesion site or symptom profile. Rather, continuous performance data are entered, along with lesions reconstructed in normalized space. Based on preliminary analyses, there was adequate power to detect differences in the SPGI, which was the focus of our predictions. We found that the SPGI was critical for performance on the articulation task across all three conditions, namely, when words were multi-syllabic, required a high degree of travel, or involved an initial consonant cluster. As a control, we also generated a VLSM map for articulation of words with minimal articulatory complexity (i.e., single-syllable words with no initial cluster and a minimal change in place of articulation). In this case, the SPGI was not implicated. The current results suggest that the left SPGI is a critical area for intra- and inter-syllabic coordination of complex articulatory movements, prior to end-stage execution of speech commands.
The process of the gas phase treatment to remove CsOH and Cs2MoO4 radioactive aerosols labeled with cesium-137 (hereinafter, 137CsOH and 137Cs2MoO4) was studied using a setup containing elements of a submerged bed scrubber and a spiral filtering element. Water, basalt wool with a fiber diameter of 2.0 μm, perlite, and a mixture of perlite with Ca(OH)2 were used as the submerged bed. With this setup, it is possible to remove more than 99% of 137CsOH and 137Cs2MoO4 radioactive aerosols removed from the gas flow.
Magnesium aluminate (MgAl2O4)-incorporated poly(ethylene oxide) (PEO)–lithium hexafluorophosphate (LiPF6) based composite polymer electrolyte (CPE) membranes were prepared by a hot press for the first time. The membranes were subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TG), differential scanning calorimetry (DSC), tensile, impedance spectroscopy, compatibility and transport number studies. The incorporation of MgAl2O4 greatly enhanced the ionic conductivity, compatibility and mechanical integrity of the polymeric membrane. Finally, an all solid state lithium cell composed of Li/CPE/LiFePO4 was assembled and its cycling profile was analyzed at 70°C. The cells delivered a discharge capacity of 127mAhg−1 at 1C-rate with very good capacity retention up to 100 cycles which is found to be better than those reported earlier.
Spinel Li4Ti5O12 (LTO) has been intensively investigated as promising anode material for large-scale stationary electrochemical storage of energy produced from renewable sources due to its remarkable structural stability and excellent safety. In this paper, nanoparticles-constructed LTO with extra surface lithium storage capability is successfully prepared in air at 600°C via employing TiOSO4·2H2O as Ti source. The newly prepared nanoparticles-constructed LTO displays enhanced electrochemical performances, demonstrating ultrahigh reversible capacity of 173mAhg−1 at 0.5C and superior rate performance of more than 145mAhg−1 at 30C between 1.0 and 2.5V vs. Li+/Li. The influences of specific surface area and crystallinity on the extra surface lithium storage capability of the sintered samples for LIBs are investigated in detail in terms of reversible capacity, cyclability and rate capability. Our results reveal that not only specific surface area but also crystallinity and pored structure are vital for reducing electrode polarization and achieving extra surface lithium storage of LTO. We anticipate that the uniquely extra surface lithium storage reaction of LTO will get more attentions in the near future.
In this paper, we study underwater energy harvesting from bending vibrations of an annular ionic polymer metal composite (IPMC). The IPMC is clam-ped to a moving base, which harmonically excites the IPMC to vibrate along its fundamental axisymmetric mode shape. We model the IPMC as a thin plate, and the interaction with the surrounding fluid is described through a distributed hydrodynamic loading which is responsible for a marked reduction of the resonance spectrum through added mass effect. IPMC sensing is described though a lumped circuit model, comprising a resistor, a capacitor, a Warburg impedance, and a voltage source controlled by the mechanical curvature. In a series of experiments, the IPMC electrodes are shunted with a resistor, which is parametrically varied together with the excitation frequency to elucidate power harvesting. We also assess the effect of the IPMC geometry on power harvesting, by systematically varying the inner radius of the annulus to encompass five different configurations. Experimental results suggest that IPMC geometry has a primary role on its vibrations, whereby increasing the inner radius results into a significant increase of the resonance frequency. Such an increase does, in turn, produce a robust improvement in power harvesting that increases of two orders of magnitude as the ratio between the inner and the outer radius varies from 0.23 to 0.5.
The structure degradation of commercial Lithium-ion battery (LIB) graphite anodes with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystalline graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.
Two MgCo2O4 nanostructures in different morphologies have been synthesized by using two different structure-directing agents (urea (U) and nitrilotriacetic acid (NTA)) as new catalysts for water oxidation reactions. The properties of these nanostructures were discovered and characterized by a combination of analytical techniques, being TEM, SEM, EDX, XRD, XPS, and BET. While the urea-stabilized MgCo2O4 (U-MgCo2O4) nanostructures have spiky morphology, the NTA- stabilized ones (NTA-MgCo2O4) have wire-like structures. The synthesized nanostructures were utilized to modify glassy carbon electrodes (GCEs), and the electrochemical activities of the modified electrodes in water oxidation reactions were investigated in an alkaline medium by recording linear sweep voltammograms (LSVs). Even though both modified GCEs had almost the same onset potentials (1.67 V vs. RHE for U-MgCo2O4/GCE and 1.63 V vs. RHE for NTA-MgCo2O4/GCE), NTA-MgCo2O4/GCE required a lower overpotential (463 mV vs. 573 mV) to drive 10 mA cm− 2 catalytic current density. Besides being catalytically more active than U-MgCo2O4/GCE, NTA-MgCo2O4/GCE was also found to be more stable in constant potential electrolysis. Moreover, it demonstrated a comparable performance to that of RuO2 and has the advantage of being significantly economic.
A simple, global model for the optimal combination of ultracapacitor and battery for electrical energy storage is developed. The goal for this hybrid storage technology is to reduce the system life-cycle cost by making use of an ultracapacitor’s claimed long cycling-life in order to supplement relatively cheap, but cycle-limited battery storage. The model is built up of two independent sub-models that allow flexibility in the relative proportion of system energy storage. An analysis performed in this paper indicates that ultracapacitor/battery storage systems may be cost effective for high-cycle applications.
Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) salt are potentially a good alternative to LiPF6 since it could both improve the chemical and thermal stability as salt for electrolyte. This work presents a systematic comparative study between LiPF6 and LiTFSI in a mixture of EC/DMC on the basis of some of their physicochemical properties. Transport properties (viscosity and conductivity) are compared at various temperatures from −20 to 80°C. Using Walden rule, we have demonstrated that LiTFSI 1M in EC/DMC is more ionic than LiPF6 1M in the same binary solvent. Moreover, the electrochemical storage properties of an activated carbon electrode were investigated in EC/DMC mixture containing LiTFSI or LiPF6. The specific capacitance C s of activated carbon was determined from the Galvanostatic charge–discharge curve between 2 and 3.7V, at low current densities. The capacitance values were found to be 100 and 90Fg−1 respectively for LiTFSI and LiPF6 electrolytes at 2mAg−1. On the basis of the physicochemical and electrochemical measurements, we have correlated the improvement of the specific capacitance with activated carbon to the increase of the ionicity of the LiTFSI salt in EC/DMC binary system. The drawback concerning the corrosion of aluminium collectors was resolved by adding a few percentage of LiPF6 (1%) in the binary electrolyte. Finally, we have studied the electrochemical behavior of intercalation–deintercalation of lithium in the graphite electrode with EC/DMC+LiTFSI as electrolyte. Results of this study indicate that the realization of asymmetric graphite/activated carbon supercapacitors with LiFTSI based electrolyte is possible.
A novel approach to effectively suppress the “polysulfide shuttle” in Li–S batteries is presented by designing a freestanding, three-dimensional graphene/1T MoS2 (3DG/TM) heterostructure with highly efficient electrocatalysis properties for lithium polysulfides (LiPSs). The 3DG/TM heterostructure is constructed by few-layered graphene nanosheets sandwiched by hydrophilic, metallic, few-layered 1T MoS2 nanosheets with abundant active sites. The porous 3D structure and the hydrophilic feature of 1T-MoS2 are beneficial for electrolyte penetration and Li-ion transfer, and the high conductivities of both graphene and the 1T MoS2 nanosheets facilitate electron transfer. These merits lead to a high electrocatalytic efficiency for LiPSs due to excellent ion/electron transfer and the presence of sufficient electrocatalytic active sites. Therefore, the cells with 3DG/TM exhibit outstanding electrochemical performance, with a high reversible discharge capacity of 1181 mA h g−1 and a capacity retention of 96.3% after 200 cycles. The electrocatalysis mechanism of LiPSs is further experimentally and theoretically revealed, which provides new insights and opportunities to develop advanced Li–S batteries with highly efficient electrocatalysts for LiPS conversion.
The switchable generation of hydrogen from a hydrazine solution was achieved with an electrochemical cell that has a cobalt anode and a platinum cathode. The H2 generator is based on the combination of hydrazine electro-oxidation on cobalt anode and H2O electro-reduction on platinum cathode. The rate of H2 generation was regulated by switching with no power supply. Slight electricity was generated from this cell along with H2. This cell uses selective anode and cathode catalysts, and hence a membraneless (one-compartment) structure could be realized for the regulation of H2 generation.