batterydata/paper-abstracts huggingface dataset:
We examined subclinical alterations of cerebral function during carotid endarterectomy (CEA) and predictability of minor cerebral damage by perioperative levels of biochemical markers of brain damage (S100B and neuron-specific enolase [NSE]). Twenty consecutive patients with ≥70% asymptomatic carotid stenosis undergoing elective CEA were enrolled. Pre- and postoperative testing included magnetic resonance imaging (MRI) of the head, a standardized neurological exam, a battery of neuropsychological tests, and measurement of serum levels of S100B and NSE. There were no major ischemic strokes. In one patient, a mild weakness of the contralateral lower extremity was discovered on neurological examination; in another individual, postoperative MRI revealed two new small subcortical lesions without clinical correlate. While S100B increased significantly early after opening of the carotid clamp (p = 0.015), the NSE increase did not reach statistical significance. As a group, participants obtained a significantly higher mean overall neuropsychological score at follow-up testing (p < 0.05). In one patient, a significant decline of cognitive function was observed. This was the only individual to obtain a consistently high S100B and NSE increase. Neuropsychological testing combined with measurements of S100B and NSE may improve sensitivity when assessing subtle cerebral damage following CEA.
A novel polymer membrane of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by the phase inversion technique with two different non-solvents, 1-butanol or hexane. The prepared films were analyzed by scanning electron microscope (SEM) and nitrogen absorption/desorption techniques. The change in the morphology and pore diameter of the films prepared with different non-solvents correlates with the structure of the non-solvents used. This electrolyte membrane was coupled with a nanocomposite LiAl0.01Co0.99O2 cathode which was prepared by a solid-state reaction method and subsequently by ball-milling. Lithium cells consisting of LiAl0.01Co0.99O2/polymer electrolyte/Li were assembled and their charge–discharge studies were investigated.
Uniform Ni3S2 nanobowls with an average size of 250nm and shell thickness of ~30nm wrapped by rGO sheets were firstly synthesized by a simple wet chemical method. The Ni3S2–rGO hybrid composite with spatial three-dimensional (3D) structure showed enhanced electrochemical properties in lithium-ion batteries, compared with Ni3S2 hollow chains. Its specific capacity could be up to 443mAhg−1 at 0.5C after 500 cycles (theoretical capacity of Ni3S2 is 462mAhg−1), while Ni3S2 hollow chains faded dramatically to 147mAhg−1 after 100 cycles. The improved cycle stability of the composite could be ascribed to the bowl structure with both exposed interior and exterior arch surfaces which could stand much more lithiation–delithiation than quasi-1D hollow chains. The novel stable bowl-like structure, the wrapped flexible rGO sheets served as buffers for the expansion of Ni3S2 bowls, the attachment sites provided by bowls keeping rGO from aggregation, and the improved electron transfer rate by rGO sheets, all synergetic effects made the composite a superior anode material. Furthermore, an efficient simple method was proposed to check componential transform during cycles by comparing the peak ratio in S2p spectrum when sulfides were used as electrode materials in LIBs.
The growing need for efficient vehicles has led many researchers to explore various ways to utilize waste heat from the Internal Combustion Engine (ICE) to improve vehicle fuel economy. Past efforts in Waste Heat Recovery (WHR) have focused primarily on recovering waste heat from Conventional Vehicles (CV), which dissipate more than two-thirds of the fuel energy as waste heat. In general, WHR has always been considered as a secondary component to the vehicle powertrain and as a result it has had little success, particularly in light-duty vehicles. This investigation explores WHR from a broader perspective to better understand the possibilities and limits of WHR from CVs to future highly hybridized vehicles. Fuel energy distribution in the ICE is used to evaluate the sources of waste heat and identify exhaust energy recovery as the most promising method for improving ICE thermal efficiency. Fundamental analysis of conventional and hybrid powertrain design is used to investigate how they impact the availability of exhaust energy from the ICE. Models and simulations of several engines and vehicles are used to validate the theory presented for effective WHR from light-duty vehicles. The analysis focuses on how available exhaust energy changes for different vehicles, how it varies with drive cycles, and how the induced back pressure from an exhaust energy recovery system affects ICE performance. The results indicate that effective WHR is difficult to achieve in light-duty conventional vehicles, but is viable in a highly hybridized vehicles, where ICE thermal efficiency can be increased by at least 15 percent over various drive cycles.
In the present study, we propose a novel three-dimensional detached serpentine flow field. The flow field applies two staggered serpentine channels to the bipolar plate and electrode (near the membrane side), respectively. The detached inflow and outflow channels aim to enhance convective mass transfer of active species in both in-plane and through-plane directions of the electrode, thereby, leading to enhanced mass transfer, complete electrolyte penetration into the electrode, and reduced pressure loss. The combined effects via the detached flow field lead to the increases of approximately 4.2% and 3.2% in the voltage and energy (pump consumption included) efficiencies of a vanadium redox flow battery cell, respectively, when compared with those of the interdigitated flow field (under the current density corresponding to 100 mA cm−2 and flow rate corresponding to 20 mL min−1). The experimental results also reveal that the performance of the proposed design is more sensitive to the felt compression and electrolyte flow rate compared to the conventional interdigitated and serpentine flow fields. This is potentially due to the presence of the significant pressure gradient in the through-plane direction of the electrode by using the proposed detached serpentine flow field.
A new series of ionic liquids containing aliphatic tetraalkylammonium dications with alkyl linkage chains and TFSI anion as potential electrolytes were prepared and characterized. Some of the important physicochemical and electrochemical properties of these prepared ionic liquids, including melting point, density, solubility in common solvents, ionic conductivity, thermal and electrochemical stability, were investigated. These ammonium dicationic ionic liquids exhibited five types of phase transition behavior on heating and one stage decomposition behavior. The spacer length and the head group overall length were responsible for the solid/liquid transformation temperature, and the spacer length was more effective in lowering the solid/liquid transformation temperature than the head group overall length. The interesting findings for such dicationic ionic liquids was that they showed the lowest solid–liquid transformation temperatures among analogues with alkyl links, and belonged to the greatest thermal stable ionic liquids. The Arrhenius equation approximately described the relationship between conductivity and temperature for several prepared dicationic ionic liquids in the low temperature region studied. The electrochemical windows were about 4.3V for C9(N222)2-TFSI2 and C12(N222)2-TFSI2, and 4.7V for C6(N118)2-TFSI2 at room temperature.
Nano-sized Li4Ti5O12 powders with high dispersivity were fabricated by a sol–gel process using P123 as surfactant, which exhibited much better high rate performance towards Li+ insertion/extraction as compared to the densely aggregated Li4Ti5O12 particles although the primary grain sizes of both samples were almost the same. The Li4Ti5O12 electrode prepared from the well-dispersed nanopowders can preserve 88.6% of the capacity at 0.1Ag−1 when being cycled at 1Ag−1, which is obviously higher than that of the densely aggregated sample, in which only 30% capacity can be retained. By improving the dispersivity, the specific surface area of the Li4Ti5O12 nanoparticles, hence the electrode–electrolyte contact area was increased; meanwhile, more homogeneous mixing of the active materials with carbon black was achieved. All these factors might have resulted in the better high rate performance.
Highly controllable porous architecture is desirable to tailor the physical and chemical properties of functional materials in advanced lithium ion batteries. Here, porous microspheres of spinel lithium titanate (Li4Ti5O12), a promising alternative anode material for lithium ion batteries, are fabricated by mutual molten growth method in a controllable manner. The key role of the rigidity of the porous structure on the performance of the electrode materials in lithium ion batteries is demonstrated. Rigid framework of the materials is formed by second growth of the primary particles that fused together to generate an interconnected nanopore system inside the spheres, leading to better electrolyte diffusion and lower interparticle contact resistance, relative to the non-porous counterpart. The pristine Li4Ti5O12 microspheres with uniform pore distribution and continuous framework exhibit high tap density, remarkable reversible capacity and rate capability, as well as excellent cycling stability. The present method is scalable and may provide a new approach to fabricate other candidate electrode materials for applications that require both high power and high volumetric energy density.
Ground-penetrating radar is becoming increasingly popular for use as a non-destructive assessment method for investigating reinforced concrete structures. The amount of data collected however can be very large and take a significant level of subjective experience to interpret. This study focuses upon the use of a neural network approach to automate and facilitate the post-processing of ground penetrating radar results. The radar data is reduced to a simplified data set by using an edge detection routine. Signal reflections from reinforcing bars displaying a hyperbolic image format are detected using a multi-layer perceptron (MLP) network with a single hidden layer containing 8 nodes to recognise a simplified hyperbolic shape. Training and testing of the network was carried out making use of an emulsion analogue tank, simulating the properties of concrete, and using real concrete specimens. The results showed that the use of a MLP neural network approach could be quite effective in automating the identification and location of embedded steel reinforcing bars from a radar investigation. Accurate estimation of depth, or cover, requires a reliable knowledge of the dielectric properties of the concrete, and recent work using a specially-developed wideband horn antenna for direct determination of in situ properties is also outlined.
Energy storage systems (ESS) are the candidate solution to integrate the high amount of electric power generated by volatile renewable energy sources into the electric grid. However, even though the investment costs of some ESS technologies have decreased over the last few years, few business models seem to be attractive for investors. In most of these models, ESS are applied only for one use case, such as primary control reserve. In this study, a business model based on the sharing economy principle has been developed and analyzed. In this model, the energy storage operator offers its storage system to different kinds of customers. Each customer uses the ESS for their single use case. A set of different use cases has been identified to make the operation of the ESS profitable (e.g. peak shaving, self-consumption and day-ahead market participation). Different kinds of stationary batteries (lithium-ion, sodium-sulfur and vanadium redox-flow) have been considered as energy storage technologies, which differ both in their investment costs and their technical properties, such as round-trip efficiency. The simulation of the business model developed showed that a sharing economy-based model may increase the profitability of operating a battery storage system compared to the single use case business model. Additionally, larger battery dimensions regarding power and capacity were found to be profitable and resulted in an increased revenue stream.
With the rapid growth in renewable energy and battery storage technologies, there exists significant opportunity to improve energy efficiency and reduce costs through optimization. However, optimization algorithms must take into account the underlying dynamics and uncertainties of the various interconnected subsystems in order to fully realize this potential. To this end, we formulate and solve an energy management optimization problem as a Markov Decision Process (MDP) consisting of battery storage dynamics, a stochastic demand model, a stochastic solar generation model, and an electricity pricing scheme. The stochastic model for predicting solar generation is constructed based on weather forecast data from the National Oceanic and Atmospheric Administration. A near-optimal policy design is proposed via stochastic dynamic programming. Simulation results are presented in the context of storage and solar-integrated residential and commercial building environments. Results indicate that the near-optimal policy significantly reduces the operating costs compared to several heuristic alternatives. The proposed framework facilitates the design and evaluation of energy management policies with configurable demand-supply-storage parameters in the presence of weather-induced uncertainties.
Lithium vanadium fluorophosphate, LiVPO4F, was utilized as both cathode and anode for fabrication of a symmetric lithium-ion LiVPO4F//LiVPO4F cell. The electrochemical evolution of the LiVPO4F//LiVPO4F cell with the commonly used organic electrolyte LiPF6/EC-DMC has shown that this cell works as a secondary battery, but exhibits poor durability at room temperature and absolutely does not work at increased operating temperatures. To improve the performance and safety of this symmetric battery, we substituted a non-flammable ionic liquid (IL) LiBF4/EMIBF4 electrolyte for the organic electrolyte. The symmetric battery using the IL electrolyte was examined galvanostatically at different rates and operating temperatures within the voltage range of 0.01–2.8V. It was demonstrated that the IL-based symmetric cell worked as a secondary battery with a Coulombic efficiency of 77% at 0.1mAcm−2 and 25°C. It was also found that the use of the IL electrolyte instead of the organic one resulted in the general reduction of the first discharge capacity by about 20–25% but provided much more stable behavior and a longer cycle life. Moreover, an increase of the discharge capacity of the IL-based symmetric battery up to 120mAhg−1 was observed when the operating temperature was increased up to 80°C at 0.1mAcm−2. The obtained electrochemical behavior of both symmetric batteries was confirmed by complex-impedance measurements at different temperatures and cycling states. The thermal stability of LiVPO4F with both the IL and organic electrolytes was also examined.
Nitrogen atoms doping was widely recognized as the promising technique to improve the electrochemical performances of various carbonaceous materials application for energy storage devices. Herein, we reported a facial fabrication of highly N-doped graphene-like carbon (NGC) through the carbonization of a mixture containing polypyrrole and g-C3N4 nanosheets, which was employed as sacrificial template and extra nitrogen source simultaneously. The resultant NGC material integrate a range of excellent features including high nitrogen contents (17.54 at%), large specific surface areas (635.73 m2 g−1) and abundant mesopores with high pore volume (1.9483 cm3 g−1). As anode material in Li-ions batteries, the NGC material exhibits an promising initial discharge capacity of 2749 mAh g−1 at a current density of 50 mA g−1 and encouraging cycling stability (1143 mAh g−1 after 200 cycles) as well as excellent rate performance (440 mAh g−1 at 2 A g−1). This feasible fabrication presents a new guidance to exploit high performance N-doped carbon materials for the applications in energy storage devices.
We couple the Leaky Membrane Model, which describes the diffusion and electromigration of ions in a homogenized porous medium of fixed background charge, with Butler-Volmer reaction kinetics for flat electrodes separated by such a medium in a simple mathematical theory of voltammetry. The model is illustrated for the prototypical case of copper electro-deposition/dissolution in aqueous charged porous media. We first consider the steady state with three different experimentally relevant boundary conditions and derive analytical or semi-analytical expressions for concentration profiles, electric potential profiles, current-voltage relations and overlimiting conductances. Next, we perform nonlinear least squares fitting on experimental data, consider the transient response for linear sweep voltammetry and demonstrate good agreement of the model predictions with experimental data. The experimental datasets are for copper electrodeposition from copper(II) sulfate solutions in a variety of nanoporous media, such as anodic aluminum oxide, cellulose nitrate and polyethylene battery separators, whose internal surfaces are functionalized with positively and negatively charged polyelectrolyte polymers.
Carboxylated graphene–ZnO (G-COOZn) composites were grown as ZnO nanoparticles onto graphene sheets by a one-step thermal method using carboxylated graphene (G-COOH) and Zn(NO3)2. G-COOH sheets were synthesized from graphene oxide (GO) and chloroacetic acid (Cl–CH2–COOH). GO was used as the starting material, as prepared by the Hummers’ method using graphite flakes. GO, G-COOH, and G-COOZn were characterized by XRD, AFM, SEM, TEM, FT-IR, 13C-NMR, and Raman spectroscopy. The electrochemical properties of the G-COOZn supercapacitor were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. The results show that the asymmetric supercapacitor has electrochemical capacitance performance within the potential range of 0–1V. The supercapacitor delivered a specific capacitance of ∼238Fg−1 at a current density of 50mAcm−2. This method provides an easy and straightforward approach to deposit ZnO nanoparticles onto graphene sheets, and may be readily extended to the preparation of other classes of hybrids based on GO sheets for specific technological applications.
Information on battery internal temperature is valuable to enhance the understanding of thermo-electrochemical reactions, to validate simulation models, and to refine battery thermal design. In this study, 12 thermocouples are embedded at strategically-chosen locations inside a 25 Ah laminated lithium-ion battery. Another 12 thermocouples are attached at the corresponding locations on the surface. The temporal and spatial variations of the temperature are measured at a series of discharge rates under different thermal conditions. The thermal response of these locations is also analyzed. The major findings include: First, the internal temperatures could differ from the surface for as large as 1.1 °C, even for a thin laminated cell. Second, the time constants of thermal response at the internal locations are generally dozens of seconds larger than on the surface. Third, the internal variation in the plane direction reaches above 10 °C under adiabatic 1.5 C discharge, much larger than in the through-plane direction, indicating the in-plane heat conductivity needs improvement. Finally, forced convection is effective to suppress the temperature rise as well as the variation. The direct measurement of internal temperature initiated in this study paves the way for implanting sensors/microchips in single cell to extract multiple physico-electrochemical signals simultaneously.
The present study reports the synthesis and morphological, structural and electrochemical characterization of ternary oxides mixture containing nickel, cobalt and tin. The ternary oxide is synthesized by Pechini method with subsequent deposition onto a titanium substrate in a thin-film form. XRD and EDS analysis confirm the formation of ternary film with amorphous nature. SEM analysis show that cracks on the film favor the gain of the surface area that is an interesting feature for electrochemical capacitors. The ternary film is investigated in KOH electrolyte solution using cyclic voltammetry and charge–discharge study with a specific capacitance of 328 F g−1, and a capacitance retention of 86% over 600 cycles. The values of specific power and specific energy was 345.7 W kg−1 and 18.92 Wh kg−1, respectively.
Objective This study examines the utility of new measures of event-related spatio-temporal waves in the EEG as a marker of ADHD, previously shown to be closely related to the P3 ERP in an adult sample. Methods Wave activity in the EEG was assessed during both an auditory Oddball and a visual continuous performance task (CPT) for an ADHD group ranging in age from 6 to 18 years and comprising mostly Combined and Inattentive subtypes, and for an age and gender matched control group. Results The ADHD subjects had less wave activity at low frequencies (∼1Hz) during both tasks. For auditory Oddball targets, this effect was shown to be related to smaller P3 ERP amplitudes. During CPT, the ∼1Hz wave activity in the ADHD subjects was inversely related to clinical and behavioral measures of hyperactivity and impulsivity. CPT wave activity at ∼1Hz was seen to “normalise” following treatment with stimulant medication. Conclusions The results identify a deficit in low frequency wave activity as a new marker for ADHD associated with levels of hyperactivity and impulsivity. Significance The marker is evident across a range of tasks and may be specific to ADHD. While lower ∼1Hz activity partly accounts for reduced P3 ERPs in ADHD, the effect also arises for tasks that do not elicit a P3. Deficits in behavioral inhibition are hypothesized to arise from underlying dysregulation of cortical inhibition.
Hierarchically nanostructured materials have proven their superiority in high performance lithium ion batteries. Herein, we successfully fabricate hierarchical vanadium pentoxide (V2O5) nanobelts by an economical and facile hydrothermal strategy followed by annealing treatment. A self-template growth of hierarchical V2O5 nanobelts was achieved from precursor VO2 (B) nanobelts, resulting in open structure of hierarchical V2O5 nanobelts composed of plate-like V2O5 nanocrystals and tiny haircuts. The hierarchical nanobelts deliver a high specific surface area of 137.5m2 g−1. When used as the cathode material for lithium ion battery, the hierarchical V2O5 nanobelts exhibit high discharge capacity of 288mAhg−1, which maintain 246mAhg−1 at the end of 50th cycle with capacity retention of 85.4 %.The present electrochemical results demonstrate the high discharge capacity, superior cycling stability and rate capability of the hierarchical V2O5 nanobelts, which could be attributed to the advantages of unique hierarchical nanobelt structure.