batterydata/paper-abstracts huggingface dataset:
Background The term epileptiform discharge typically refers to interictal paroxysmal activity that occurs more commonly during sleep. This type of paroxysmal activity does not include the electroencephalographic (EEG) activity observed during a seizure. The prevalence of epileptiform activity in the general pediatric population is unknown. Methods Polysomnographic (PSG) studies were conducted in otherwise healthy children recruited from the general population and with no previous history of seizures or any other medical conditions. All sleep studies included an eight-lead EEG montage. Spike and sharp waves, either alone or accompanied by slow waves, occurring singly or in bursts lasting <5s were considered as representing epileptiform activity. Results Nine hundred seventy children underwent overnight PSG. In 14 children, evidence of epileptiform activity, in the absence of any additional abnormality in the PSG, occurred. Thus, the prevalence of epileptiform activity was 1.45%. Epileptiform patterns found were either spike or spike and wave and were more prominent during non-rapid eye movement (NREM) sleep, with 11 patients presenting spike and spike and wave patterns in the centro-temporal regions. Four of the six children who underwent neurocognitive tests exhibited abnormal findings in areas of behavior, attention, hyperactivity, and learning. Conclusion Epileptiform activity in otherwise healthy children from the community is relatively frequent and, if confirmed by prospective studies, could be associated with suboptimal cognitive and behavioral functions. Increased awareness by sleep professionals and use of PSG montage that includes temporal leads and >2 standard EEG leads should facilitate the detection of epileptiform activity in children.
The kinetics of zinc dissolution in concentrated potassium hydroxide solution were determined as a function of KOH concentration, amount of added ZnO, and temperature through linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The measurements were evaluated with a simplified reaction scheme in which an intermediate ZnI species is formed on the electrode surface that subsequently reacts to a soluble ZnII species. Analysis of the LSV data with a two-step Butler–Volmer kinetics showed that the transfer coefficients and the surface coverage of the intermediate are approximately constant in the entire range of operation conditions, whereas the exchange current density for the first reaction step is about five times larger than for the second step. Analysis of the dynamic EIS measurements resulted in very similar current densities than obtained from the quasi-stationary LSV method. For the first time, activation energies describing the temperature dependence of the exchange current density were also determined.
It is challenging to probe ion dynamics in supercapacitor electrodes, which has significant implications in optimizing their performance. Here, the authors develop in situ diffusion NMR spectroscopy to measure and illustrate the diffusion of the charge-storing ions in working supercapacitors.
Lithium iron phosphate (LiFePO4) is a potentially high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and one-dimensional diffusion channel for lithium ions require small particle size and shape control during the synthesis. In this paper, well-crystallized and morphology-controlled LiFePO4 cathode material for lithium-ion batteries is successfully synthesized via a soluble starch-assisted hydrothermal method at 180 °C for 5 h, followed by calcining with phenolic resin at 750 °C for 6 h. In this study, we investigate the effect of five different concentrations of starch solution on controlling morphology of LiFePO4. Interestingly, the nano-sized LiFePO4 particles obtained in 0.075 mol L−1 starch solution exhibit a spheroidal microstructure, while the platelet shape LiFePO4 particles are synthesized in lower or higher concentration of starch solution. The mechanism and process of forming such spheroidal microstructure is discussed. These unique structural and morphological properties of LiFePO4 lead to high specific capacity and stable cycling performance. Analysis of the electrochemical impedance spectroscopy reveals that nano-sized carbon/polyacene coated LiFePO4 cathode materials play an critical role in achieving excellent electrochemical performance.
The Brazilian government aims at universal electricity access. The national rural electrification initiative has provided electricity services to more than 14 million people since 2003, mainly through grid extension. However, the initiative has not been able to reach remote areas in the Amazon, thus requiring a review of conditions for small scale off-grid power generation projects. As a result, new rules established under the national rural electrification program address the design and implementation of off-grid power generation projects with an installed capacity up to 100 kW. The objective of this paper is to explore the effects of the new set of rules on the levelized cost of electricity for different power generation solutions in the Amazon. Our study shows that the new rules may be beneficial to isolated communities, as they reduce the levelized cost of electricity, favor renewable energy technologies and may contribute to reduce CO2 emissions. In addition, the new rules may help engage new actors to provide rural electrification of the Amazon region. To fully take advantage of the current scheme, action at local level is required to define the most appropriate model for small-scale power generation projects and establish synergies between concessionaires and local energy providers.
Hybrid electrochemical electrodes consisting of supercapacitive graphene nanosheets and pseudocapacitive conducting polymers such as polypyrrole (PPy) and polyaniline (PAni) are constructed layer-by-layer (LbL) via in-situ electropolymerization followed by electrochemical reduction of graphene oxide (ErGO) forming (PPy/ErGO)n=1 and (PAni/ErGO)n=1 bilayers, with subsequent multilayers up to n = 5. We investigated structural, physical and electrochemical properties and the hybrids prepared using this Scheme 1 showed excellent electro-chemo-mechanical stability and enhanced electrochemical performance attributed to appropriate polymer chain conformations and covalently tailored and chemically bridged interface-promoted synergistic effects. From cyclic voltammograms, we determined gravimetric specific capacitance (Cs) at scan rate 10 mV/s and at a discharge current density of 1.0 A g−1 that ranged 300–560 F g−1 outperforming other hybrid supercapacitors and capacity retention of ∼90% over 1000 cycles at a specific current density of 1.5 A g−1. From electrochemical impedance spectroscopy data fitting and circuit simulations we determined various equivalent circuit parameters including low frequency (Clf) and interfacial capacitance, charge transfer and solution resistance that helped to calculate gravimetric power and energy densities. We also prepared PAni/rGO multilayer pseudocapacitors by varying rGO weight loading by electrostatic LbL assembly (Scheme 2) and compared their electrochemical properties with those of Scheme 1. The findings reveal the significance of electro-processing and electrodeposition and clearly elucidate the role of engineered interfaces in enhancement of interfacial properties i.e. heterogeneous electron transfer, diffusion coefficient, mechanical strength and electrical double layer in Scheme 1 graphene-polymer hybrids.
This work presents a systematic study on how pore size and specific surface area (SSA) of carbon effect specific capacitance and frequency response behavior. Carbide derived carbons (CDC) produced by leaching metals from TiC and ZrC at temperatures from 600 to 1200°C have highly tailorable microstructure and porosity, allowing them to serve as excellent model systems for porous carbons in general. BET SSA and average pore size increased with synthesis temperature and was 600–2000m2 g−1 and 0.7–1.85nm, respectively. Maximum specific capacitance in 1M H2SO4 was found to occur at an intermediate synthesis temperature, 800°C, for both ZrC and TiC derived carbons and was 190 and 150Fg−1, respectively. Volumetric capacitance for TiC and ZrC derived carbons was maximum at 140 and 110Fcm−3. These results contradict an oft-reported axiom that increasing pore size and SSA, all other things being held constant, increases specific capacitance. A correlation between specific capacitance and SSA of micropores (less than 2nm in diameter) has been shown. As expected, increasing pore size was found to improve the frequency response. However, CDCs with similar pore size distributions but obtained from different starting materials showed noticeable differences in impedance behavior. This highlights the importance of not only the pore size and specific surface area measured using gas sorption techniques, but also the pore shape or tortuousity, which is non-trivial to characterize, on energy storage.
New composite materials based on polymer-derived SiCN ceramics and hard carbons were studied in view of its application as anodes for lithium-ion batteries. Two kinds of composites were prepared by pyrolysis of the preceramic polysilazane (HTT1800, Clariant) at 1000°C in Ar atmosphere mixed with hard carbons derived from potato starch (HC_PS) or with a hard carbon precursor, namely potato starch (PS), denoted as HTT/HC_PS and HTT/PS composites, respectively. Thermal gravimetric analysis suggests possible reactions between the preceramic polymer and the carbon precursor. The HTT/PS composites contain higher amount of oxygen and appear to be more homogeneous than that of the HTT/HC_PS composite. Raman analysis confirms the presence of highly disordered carbon in the composites by the appearance of the well-pronounced D band at 1347cm−1. The materials are amorphous with a significant fraction of single graphene sheets as confirmed by X-ray diffraction. The HTT/PS composite exhibits a high-recovered capacity (434mAhg−1 when charging with a current of 36mAg−1) and outstanding cyclability for 400 cycles even at high current rates (90mAhg−1 when charging with 3600mAg−1). These properties make the composite a candidate anode material for high power energy devices.
Keggin-structured phosphotungstic acid H3PW12O40 (HPW)-modified Ag@Pt/MWCNTs electrocatalysts were successfully prepared using a chemical impregnation method. Physical characterization by X-ray powder diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy revealed that the HPW molecules were incorporated into the Ag@Pt/MWCNT structure The diameter of the catalyst used was about 4.0 nm, and electrochemical investigation results indicated that HPW could ameliorate electrocatalytic activity. The catalyst with HPW content of 25 % displayed the best excellent electrocatalytic activity with an electrochemically active area of 83.62 m2 g−1 and a half-wave potential for the oxygen reduction reaction of 0.851 V, all ascribed to the high utilization of Pt and the protective effect of the HPW layer on the catalyst surface. The synergic effect of the HPW and Ag@Pt enhanced the rate of electron transfer and increased the catalytic efficiency of oxygen reduction reaction, influencing 4e− reduction reactions on Ag@Pt/MWCNTs-HPW catalysts.
The stability vs. aging of Li2FeSiO4 (LFS) cathode material in fluorine-based electrolytes, especially at elevated temperature, was studied in this work. The LFS powder was initially synthesized using a hydrothermal route and then aged at 60°C for 40 days in LiPF6 and LiBF4-based electrolytes. The residual powder and the electrolyte were investigated afterwards. In the case of LiPF6, a structural and compositional change of LFS to Li2SiF6 was observed by XRD. SEM images confirmed that this change led to a morphology change of the aged material. XPS, EDX and ICP-OES measurements showed a large increase of fluorine content inside the residual powder. NMR investigations indicated an accelerated decomposition of electrolyte in the presence of LFS compared to the electrolyte aged without LFS. Our results suggest a degradation of LFS to Li2SiF6 in the fluorine-based electrolyte at elevated temperatures while the electrolyte decomposition is accelerated.
Graphite and nano-silicon-based negative electrodes in lithium-ion batteries with low binder content were evaluated. The effectiveness of styrene butadiene rubber (SBR) and various types of cellulose containing electrodes were compared to standard electrodes containing PVdF as binder. The cycling performance of lithium-based half cells in EC:DMC (1:1), 1M LiPF6 shows that styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (Na-CMC), or both combined have a similar bonding ability as conventional poly(vinylidene fluoride) (PVdF). However, using Na-CMC the irreversible charge capacity in the first cycle decreased in comparison with electrodes containing PVdF binder. Nano-Si electrode containing 1% SBR/1% Na-CMC as binder show the same cycle stability as an identical electrode containing 10% PVdF binder.
Tin–antimony alloy (SnSb) particles dispersed in a conductive matrix comprised of TiC and carbon have been synthesized by high energy mechanical milling (HEMM) and explored as anodes for sodium-ion batteries. The SnSb–TiC–C samples have been prepared with different TiC and carbon contents in the composite, characterized by X-ray diffraction before and after sodiation and by high-resolution transmission electron microscopy, and compared to SnSb–C as a baseline. The SnSb–TiC–C anodes demonstrate better cyclic performance as well as better rate-capability compared to SnSb–C. In addition, the increase in TiC content in the composite leads to better electrochemical performance. SnSb–TiC(40%)–C(20%) and SnSb–TiC(40%)–C(30%) electrodes exhibit the best electrochemical performance, which could result from both the well-developed SnSb as an electrochemically active nanocrystalline material and the conductive matrix composed of a combination of TiC and carbon. Additionally, the use of FEC electrolyte additive results in much better electrochemical performance even at high-rate current density when combined with this material due to the formation of a stable and thin SEI layer.
Impedance spectroscopy is one of the most promising methods for characterizing aging effects of portable secondary batteries online because it provides information about different aging mechanisms. However, application of impedance spectroscopy “in the field” has some higher requirements than for laboratory experiments. It requires a fast impedance measurement process, an accurate model applicable with several batteries and a robust method for model parameter estimation. In this paper, we present a method measuring impedance at different frequencies simultaneously. We propose to use a composite electrode model, capable to describe porous composite electrode materials. A hybrid method for parameter estimation based on a combination of evolution strategy and Levenberg–Marquardt method allowed a robust and fast parameter calculation. Based on this approach, an experimental investigation of aging effects of a lithium ion battery was carried out. After 230 discharge/charge cycles, the battery showed a 14% decreased capacity. Modeling results show that series resistance, charge transfer resistance and Warburg coefficient changed thereby their values by approximately 60%. A single frequency impedance measurement, usually carried out at 1kHz, delivers only information about series resistance. Impedance spectroscopy allows additionally the estimation of charge transfer resistance and Warburg coefficient. This fact and the high sensitivity of model parameters to capacity change prove that impedance spectroscopy together with an accurate modeling deliver information that significantly improve characterization of aging effects.
The toxicity analysis of combustion products from commercialized Li-ion batteries was performed in this work. More than 100 emitted gaseous products are identified, most of which are hazardous to the human beings and trigger negative impact on the environment. Moreover, the states of charge of battery was found to significantly affect the types of toxic combustion products, and the 100% state of charge even led to the most serious toxicity. The relationship between the concentration of toxic combustion products and battery capacity was also investigated. Interestingly, the concentration of carbon monoxide rose up rapidly up on the increase of the capacity instead of the toxic organic products. This investigation suggests that the efforts on effective battery emergency response could be potentially simplified to achieve cost down for manufacturers.
A composite of MoO2–Mo2C–C is fabricated through a facile ion-exchange route for the first time as an alternative anode material for lithium-ion batteries (LIBs). A macroporous cinnamic anion-exchange resin interacts with ammonium molybdate tetrahydrate in aqueous solution, and the product is then calcined under an inert gas atmosphere. The interaction between the resin and ammonium molybdate tetrahydrate results in an atomic level dispersion of the molybdenum over the organic carbon precursor (resin), while the calcination process allows the formation of MoO2 and Mo2C as well as the pyrolysis of resin to solid carbon. According to field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements, ultrafine MoO2 and Mo2C nanoparticles are uniformly dispersed but firmly attached within an amorphous carbon framework. When evaluated as an anode material, the as-synthesized sample exhibits superior electrochemical performance. The specific discharge capacity is as high as 1491 mA h g−1 in the first cycle and 724 mA h g−1 over 50 cycles at a current density of 0.2 A g−1. This simple, environmentally friendly, low-cost and easily scaled up method, has significant potential for mass industrial production of MoO2-based material as next-generation anode material of LIBs with wide application capability.
Single-crystalline Li4Ti5O12 nanorods have been successfully prepared through a molten salt method, followed by a precipitation method, and characterized with X-ray powder diffractometry, field-emission scanning electron microscopy, and transmission electron microscope. Their electrochemical properties have been studied by charge/discharge cycling and cyclic voltammetry. The results show that the single-crystalline Li4Ti5O12 nanorods reveal high capacity, excellent rate capability and cycle stability. The discharge capacity up to 176.4 mAh g−1 at 0.1 C rate is achieved. When tested at 10 C rate, the first discharge capacity reaches 135.9 mAh g−1, and the capacity retention is more than 61.5% after 1500 cycles. Furthermore, high rate capability Li4Ti5O12/LiMn2O4 full cells have been made using Li4Ti5O12 nanorods as the negative electrode, which display superior cycle stability at high rate. The discharge capacity and the mass energy density sequentially reach 40 mAh g−1 and 86.4 Wh kg−1 at 10 C rate, while the capacity retention is about 60% after 1000 cycles.
Among existing energy management strategies (EMSs) for fuel cell hybrid electric vehicles (FCHEV), the equivalent consumption minimization strategy (ECMS) is often considered as a practical approach because it can be implemented in real-time, while achieving near-optimal performance. However, under real-world driving conditions with uncertainties such as hilly roads, both near-optimality and charge-sustenance of ECMS are not guaranteed unless the equivalent factor (EF) is optimally adjusted in real-time. In this paper, a methodology of extracting the globally optimal EF trajectory from dynamic programming (DP) solution is proposed for the design of EF adaptation strategies. In order to illustrate the performance and process of the extraction method, a FCHEV energy management problem under hilly road conditions is investigated as a case study. The main goal is to learn how EF should be adjusted and the impact of EF adaptation on fuel economy under several hilly road cases. Using the extraction method, the DP-based EF is computed, and its performance is compared with those of Pontryagin's minimum principle (PMP) and conventional ECMS. The results show that the optimal EF adaptation significantly improves fuel economy when the battery SoC constraint becomes active, and thus EF must be properly adjusted under severely hilly road conditions.
This work details the design and synthesis of novel urchin-like α-FeOOH@MnO2 core–shell hollow microspheres for high-performance electrode materials for supercapacitors. The core–shell heterostructures were constructed by growing strip-like MnO2 nanostructures onto the urchin-like α-FeOOH hollow microspheres that were composed of nanorods. Based on the synergetic effects and multi-functionalities of both the MnO2 shell and urchin-like α-FeOOH hollow cores, the resulting urchin-like α-FeOOH@MnO2 core–shell hollow microspheres exhibited excellent electrochemical performance with a high specific capacitance of 597 F g−1 at 1 A g−1, good rate capability (capacitance retention of 74.2% at 10 A g−1), and remarkable cycling stability (capacitance retention of 97.1% after 2000 cycles). Moreover, an asymmetric supercapacitor fabricated using α-FeOOH@MnO2 as positive electrode and activated carbon as negative electrode was found to deliver a high energy density of 34.2 W h kg−1 and power density of 815 W kg−1.
Gelatin-tethered iron oxide composites are facilely prepared as high-performance anode materials for Li-ion batteries (LIBs). The synthetic procedures are simple, eco-friendly, and reproducible in that gelatin-linked Fe3O4 is directly converted into nitrogen (N)-doped carbon modified iron oxides (N-Fe2O3@Carbon) at 400°C. The N-Fe2O3@Carbon exhibits an improved capacity retention and good rate capability. At a current density of 0.1C after 30 cycles, the N-Fe2O3@Carbon (400°C) shows a high capacity of ∼800mAhg−1 with a columbic efficiency of >99.5%. The excellent performance of N-Fe2O3@Carbon is mainly attributed to the conductive nitrogen and strong cross-linking force of gelatin, consequently leading to durable structural integrity of Li-storage iron oxides during charge/discharge processes. Since a small amount of gelatin with multiple amine groups delivers a high impact on the performance of Li-storage metal oxides, this chemical strategy is very useful to prepare cost-effective and environmentally benign electrode materials in the field of sustainable energy conversion and storage.
A molecular thermodynamic model based on both the theory of melting point depression and the lattice fluid model is developed to interpret the liquidus curves in the resulting phase diagram and predict the change of liquidus curve and an eutectic point with various pressures. Quantitative description according to the proposed model is in good agreement with the experimentally observed transition temperature of a given system and shows that an eutectic point moves toward higher T m and lower weight fraction of salt with increasing pressure.
We demonstrate that performance on an object recognition task can be explained in terms of observer-specific perceptual profiles. These profiles are derived from a battery of tests, including the effects of stereo, texture, outline (occluding contour), and motion cues on amplitude judgements of curved surfaces. Using a task in which observers learned to recognise ‘amoeboid’ objects, a multivariate regression analysis revealed that three psychometric variables derived from the test battery account for 74% of the variance in learning rate. These variables are choice reaction time, and the relative dependence of amplitude judgements on motion and outline cues. The implications of these findings for the existence of observer-specific perceptual profiles, and their relation to the fundamental psychophysical competences associated with object recognition are discussed.