batterydata/paper-abstracts huggingface dataset:
While Li-ion cells offer excellent electrochemical performance for several applications including electric vehicles, they also exhibit poor thermal transport characteristics, resulting in reduced performance, overheating and thermal runaway. Inadequate heat removal from Li-ion cells originates from poor thermal conductivity within the cell. This paper identifies the rate-limiting material-level process that dominates overall thermal conduction in a Li-ion cell. Results indicate that thermal characteristics of a Li-ion cell are largely dominated by heat transfer across the cathode-separator interface rather than heat transfer through the materials themselves. This interfacial thermal resistance contributes around 88% of total thermal resistance in the cell. Measured value of interfacial resistance is close to that obtained from theoretical models that account for weak adhesion and large acoustic mismatch between cathode and separator. Further, to address this problem, an amine-based chemical bridging of the interface is carried out. This is shown to result in in four-times lower interfacial thermal resistance without deterioration in electrochemical performance, thereby increasing effective thermal conductivity by three-fold. This improvement is expected to reduce peak temperature rise during operation by 60%. By identifying and addressing the material-level root cause of poor thermal transport in Li-ion cells, this work may contributes towards improved thermal performance of Li-ion cells.
A new nitrogen rich porous graphene-cross-linked melamine formaldehyde carbon cryogel (GCMFCC) was successfully prepared by a sol-gel poly condensation reaction catalyzed by Na2CO3; it was subsequently converted to a cryogel by freeze-drying. The melamine formaldehyde carbon cryogel (MFCC) and GCMFCC-x were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). XPS and BET analysis showed that the as- prepared GCMFCC-5% cryogel had a highest nitrogen content of 14.29% with surface area of 261.33 m2/g and unimodal meso-pore volume of 0.36 cm3/g. The electrochemical behavior of MFCC and GCMFCC-x samples was investigated by cyclic voltammetry and charge/discharge cycles. GCMFCC-5% achieved highest capacitance of 313.24 F/g. Hence, GCMFCC is a promising electric double-layer capacitor material with low production costs and the ability to avoid supercritical drying.
Highly flexible free-standing electrodes for flexible lithium-ion batteries (LIBs) are prepared by casting slurry on a glass substrate and detaching the film after drying. The slurry is composed of lithium cobalt oxide (LiCoO2) as a cathode material and Super-P as a conductive agent. These are currently used in conventional electrode fabricating. The flexible electrode contains the similar constituents and composition to the electrodes in commercial LIBs, but does not include metal foil as a current collector as that limits the flexibility of the LIB. Polyvinylidene fluoride (PVDF) with hexafluoropropylene (HFP) is used as a binder instead of PVDF alone due to its better mechanical properties (tensile stress, strain, and peel-off strength). In order to compensate for the low electronic conductivity of flexible electrodes without metal foil, a carbon nanotube (CNT) is incorporated into the electrode. The flexible electrodes offer great flexibility with the ability to be bent and folded without deforming. The flexible electrode exhibits high overpotential during charging/discharging process and inferior electrochemical performance (rate capability, energy density and cycling stability) to conventional electrodes with metal foil due to the low electronic conductivity but it delivers reasonable performance in a punch cell with an aluminum-deposited PET substrate as a current collector. Using CNT enhances the electrochemical properties of flexible electrodes, but weakens its mechanical strength at the same time. Therefore, the optimum amount of CNT needs to be determined.
A novel structure denoted as a “multiroom carbon hybrid”, which comprises empty voids dispersed in metal oxide-, sulfide-, and selenide-carbon composites is introduced. Multiroom-structured carbon hybrid microspheres of single component Co3O4 and NiO and multicomponent (Ni0.5Co0.5)Ox were successfully prepared using a one-pot spray pyrolysis process. Liquid-liquid phase segregation during the spray pyrolysis process is a key requirement for generating multiroom-structured metal oxide-carbon hybrid microspheres. Multiroom-structured CoSe2-graphitic carbon (GC) and CoS2-CoS-GC hybrid microspheres were also prepared using a simple post-treatment process. Multiroom-structured CoSe2-GC hybrid microspheres have superior sodium-ion storage properties to bare CoSe2 microspheres. The reversible discharge capacities of the CoSe2-GC and CoS2-CoS-GC hybrid microspheres for the 100th cycles at a current density of 0.2Ag−1 are 393 and 334mAhg−1, respectively. The discharge capacity of the multiroom-structured Co3O4-C hybrid microspheres for lithium-ion storage at a high current density of 3Ag−1 for the 150th cycle is 1243mAhg−1.
The advance of battery technology in electric vehicle and large-scale energy storage applications drives the development of new battery materials, such as sodium iron silicate Na2FeSiO4. In this work, structural characteristics, deintercalation voltages, ionic conductivities, and mechanical properties of Na2FeSiO4 polymorphs are investigated by using potential-based lattice dynamics and density functional theory methods. To simulate the polymorphism of Na2FeSiO4, a total of 14 structural models are constructed from the structure types ABC2X4 of Na- and Li-based silicates. Free energies are calculated within the quasi-harmonic approximation to evaluate the relative stabilities of 13 dynamically stable structures under temperature and pressure conditions. The energetically favored structures reveal that Na2FeSiO4 polymorphs tend to form the structures with three-dimensional (3D) framework of FeO4 and SiO4 tetrahedra. In comparison with Li-equivalent, Na2FeSiO4 is predicted to have the characteristics of smaller volume change, lower deintercalation voltage, 3D or quasi-3D ionic mobility, and better mechanical property, which may deliver a prospect of higher electrochemical performance. The mechanism of substitution Na for Li on the effects of structural and electrochemical properties is also discussed. Helpful information is expected to provide for the preparation of high-performance cathode materials of Na-ion batteries and the fundamental understanding of Na-intercalation chemistry.
In this paper is proposed a nonlinear current-mode control for the fuel cell/battery/ultracapacitor hybrid power sources (HPS) that improves the ripple factor of the fuel cell current. The nonlinear current control is analyzed and designed using a systematic approach. The design goal is to generate an anti-ripple via buck current controlled source in order to mitigate the inverter current ripple. All the results have been validated in several simulations. The simulation results successfully show that nonlinear current-mode control determines in the low frequency-domain better performances than other current-mode control techniques, such as the hysteretic current-mode controller or the peak current-mode controller. The current ripple factor is one of the used performance indicators.
Magnetars are neutron stars (NSs) with extreme magnetic fields1 of strength 5 × 1013−1015 G. These fields are generated by dynamo action during the proto-NS phase, and are expected to have both poloidal and toroidal components2–6, although the energy of the toroidal component could be ten times larger7. Only the poloidal dipolar field can be measured directly, via NS spin-down8. The magnetic field provides heating and governs how this heat flows through the crust9. Magnetar thermal X-ray emission in quiescence is modulated with the rotational period of the NS, with a typical pulsed fraction 10–58%, implying that the surface temperature is substantially non-uniform despite the high thermal conductivity of the star’s crust. Poloidal dipolar fields cannot explain this large pulsed fraction10,11. Previous two-dimensional simulations12,13 have shown that a strong, large-scale toroidal magnetic field pushes a hot region into one hemisphere and increases the pulsed fraction. Here, we report three-dimensional magneto-thermal simulations of magnetars with strong, large-scale toroidal magnetic fields. These models, combined with ray propagation in curved spacetime, accurately describe the observed light curves of 10 out of 19 magnetars in quiescence and allow us to further constrain their rotational orientation. We find that the presence of a strong toroidal magnetic field is enough to explain the strong modulation of thermal X-ray emission in quiescence.
In response to a stimulus, a soft material deforms, and the deformation provides a function. We call such a material a soft active material (SAM). This review focuses on one class of soft active materials: dielectric elastomers. When a membrane of a dielectric elastomer is subject to a voltage through its thickness, the membrane reduces thickness and expands area, possibly straining over 100%. The dielectric elastomers are being developed as transducers for broad applications, including soft robots, adaptive optics, Braille displays, and electric generators. This paper reviews the theory of dielectric elastomers, developed within continuum mechanics and thermodynamics, and motivated by molecular pictures and empirical observations. The theory couples large deformation and electric potential, and describes nonlinear and nonequilibrium behavior, such as electromechanical instability and viscoelasticity. The theory enables the finite element method to simulate transducers of realistic configurations, predicts the efficiency of electromechanical energy conversion, and suggests alternative routes to achieve giant voltage-induced deformation. It is hoped that the theory will aid in the creation of materials and devices.
Background Pediatric sleep-disordered breathing is known to negatively impact cognitive development. While a theoretical basis has been proposed for the developmental effect of pediatric sleep-disordered breathing on executive function specifically, this had not been directly examined among preschool-age children. This population may be particularly vulnerable if school-readiness is compromised. The purpose of the current study was to use a multi-dimensional approach to assessing executive function among preschool-age children at risk for sleep-disordered breathing. Methods Thirty-nine preschool children were administered executive function tasks assessing the dimensions of inhibition, working memory, and planning as part of a larger study. A parent or guardian completed a validated questionnaire concerning the child’s snoring and other behaviors indicating risk for sleep-disordered breathing. Results After controlling for age in a series of regressions, higher parent-reported risk for sleep-disordered breathing was associated with substantially lower performance on each executive function dimension. In comparing the group means of children at high and low risk for sleep-disordered breathing, the single snoring frequency item also showed that children who snored frequently or almost always had lower performance on each executive function dimension. Conclusions The results suggest that sleep-disordered breathing may be associated with impaired executive function in preschoolers, with its strongest impact on the inhibition dimension, further emphasizing the importance of early intervention for sleep-disordered breathing in this early age group.
Vanadium diselenide (VSe2) is a transition metal dichalcogenide with metallic conductivity, which makes it a potentially promising electrode material for electrochemical applications. However, the development of VSe2 electrodes for such applications has been severely hampered by the difficulty of preparing nanosized products. In this work, a new facile solvothermal synthesis process is developed and optimized to synthesize ultrathin VSe2 nanosheet assemblies. To obtain the ultrathin nanosheets, N-methyl pyrrolidone, which has similar surface energy to many transition metal dichalcogenides, was used as the solvent to limit the crystal growth along the c-axis direction. The resulting ultrathin VSe2 nanosheets exhibit good performance toward alkaline ion (Li+ and Na+) storage, which can be significantly enhanced by carbon coating. Specifically, the carbon-coated VSe2 nanosheets can deliver high capacities of 768 mA h g-1 (Li+ storage) and 571 mA h g-1 (Na+ storage) along with outstanding stability.
Introduction Changes in personality differ qualitatively and quantitatively among patients with different neurodegenerative diseases, likely due to divergent patterns of regional neurodegeneration. Regional damage to circuits underlying various cognitive and emotional functions have been associated with interpersonal traits like dominance, extraversion, and warmth in patients with neurodegenerative diseases, suggesting that personality may in part be mediated by these more basic neuropsychological functions. In this study, we hypothesized that different combinations of cognitive, neuropsychiatric, and emotional measures would predict different interpersonal traits in patients with neurodegenerative diseases. Methods A battery of cognitive, neuropsychiatric, and emotional measures was administered to 286 patients with various neurodegenerative diseases such as Alzheimer’s disease, behavioral variant frontotemporal dementia, semantic dementia, and progressive supranuclear palsy, and informants described patients’ dominance, extraversion, and warmth using the Interpersonal Adjective Scales (IAS) personality questionnaire. Regression modeling was performed to identify which neuropsychological factors uniquely predicted current personality, controlling for age, gender, and premorbid personality. Results Social dominance covaried with patients’ capacity for cognitive control and verbal fluency. Conversely, warmth did not rely on these executive or verbal skills, but covaried primarily with patients’ capacity for emotional responsiveness. Extraversion, representing a blend of dominance and warmth, demonstrated an intermediate degree of relationship to both executive/verbal and emotional functions. Conclusions These findings suggest that different personality traits are partly subserved by specific cognitive and emotional functions in neurodegenerative disease patients. While this study was performed in the context of brain damage, the results raise the question of whether individual differences in these neuropsychological abilities may also underlie variability in normal personality.
Well-dispersed trimetallic-alloyed PdSnCo nanocrystals with an average size of 7nm are supported on nitrogen-doped reduced graphene (NG) nanosheets by a solvothermal method. The PdSnCo/NG nanocatalyst is characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. As a result, the PdSnCo/NG exhibits high catalytic activity toward oxygen reduction reaction and high electrochemical stability in alkaline medium, compared to commercial 10% Pd black, binary PdSn/NG, and PdCo/NG. Moreover, PdSnCo/NG nanocatalyst shows high discharge capacity of 6750mAhg−1, low charge voltage and predominant cycleability for lithium-air batteries.
The low cost wind turbines with timber blades represent a good solution for the decentralized energy production in off-grid regions of developing countries. This paper summarizes the results of investigations on the mechanical testing and choice of timber for wind blades, testing of different coatings and blades as well as installation and practical experience with wooden wind turbines in Nepal. The recommendations on the optimal choice of Nepali timber and coatings for low cost wind blades are summarized. The timber wood blades were designed and tested. On the basis of the recommendations, the wind turbines with timber (lakuri) wind blades were produced, and tested. The turbines with timber wind blades were installed on several locations around Nepal, and their usability was studied. It was demonstrated that the appropriate choice of timber and coatings ensures necessary reliability of the blades and turbines. It was further demonstrated that the low cost wind turbines with timber blades represent a promising and viable option for the decentralized energy production in developing countries, which also opens new areas for businesses.
To assess the effect of consuming a mid-morning almond snack (28 and 42 g) tested against a negative control of no almonds on acute satiety responses.
For reaching high-performance of electrode materials, it is generally believed that understanding the structure evolution and heterogeneous alignment effect is the key. Presently, a very simple and universally applicable self-healing method is investigated to prepare defect-free Prussian blue analogs (PBAs) that reach their theoretical capacity as cathode materials for sodium-ion batteries (SIBs). For direct imaging of the local structure and the dynamic process at the atomic scale, we deliver a fast ion-conductive nickel-based PBA that enables rapid Na+ extraction/insertion within 3 minutes and a capacity retention of nearly 100% over 4000 cycles. This guest-ion disordered and quasi-zero-strain nonequilibrium solid–solution reaction mechanism provides an effective guarantee for realizing long-cycle life and high-rate capability electrode materials that operate via reversible two-phase transition reaction. Unconventional materials and mechanisms that enable reversible insertion/extraction of ions in low-cost metal–organic frameworks (MOFs) within minutes have implications for fast-charging devices, grid-scale energy storage applications, material discovery, and tailored modification.
The comparative study of carbon cathodes with and without cobalt phthalocyanine (CoPc) in BCX cells (the Li/SOCl2 cell containing BrCl in the electrolyte) has been carried out by using electrochemical impedance spectroscopy (EIS), constant current discharge curves, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. It is shown that CoPc can improve both the capacity and the voltage of discharge for the BCX cell, and enhance the stability of the open-circuit voltage of the BCX cell. The addition of CoPc to carbon cathode of BCX cells can also decrease the impedance value of the porous carbon cathode, resulting in the considerable decrease of both film resistance and electron transfer resistance. The microstructure and composition of the discharge products on carbon cathodes have been studied using SEM/EDS and XPS analysis.
Perfluorinated sulfonic acid (PFSA) ionomers have high proton conductivity and excellent mechanical-chemical stability under humid conditions in low temperature Polymer Electrolyte Membrane Fuel Cell (PEMFC) application. In this work, we compare performance and durability between long side chain (LSC) and short side chain (SSC) PFSA ionomers as a solid electrolyte membrane and as ionomer-additive in the electrodes. Membrane electrode assemblies (MEAs) are prepared combining the LSC/SSC membrane with the corresponding LSC/SSC ionomer in the catalyst layer. Thereby, their chemical compatibility could be determined. MEAs are tested in single cell test benches with segmented bipolar plate for long term degradation test with dynamic load-cycling. While maintaining uniform conditions, we have experienced that different MEAs show different behavior in short-term to long-term application. Owing to its stability in lower equivalent weight; SSC ionomer provides favorable proton conductivity leading to higher power density of the cell. Nevertheless, faster degradation of SSC than the LSC ionomer are encountered in this study likely due to the higher gas permeation of thinner SSC membranes and lower polytetrafluoroethylene content. This study contributes a significant insight in the behavior of ionomers in FC as function of time, and shows avenues for further improvement of durability.
We propose using a slide-ring (SR) gel electrolyte to achieve a gel polymer electrolyte with both sufficient mechanical strength and high ionic conductivity. The SR gel is made from polyrotaxane, which has a structure that consists of cyclic molecules, α-cyclodextrins (CDs), threaded by an axial polymer chain, polyethylene glycol (PEG), and cross-linked by divinyl sulfone. The SR gel electrolyte was made from SR gels which were swollen by an electrolyte solution (ES) prepared with lithium salt and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI). The swelling behavior of SR gel in the ES by the formation of coordination bonds between lithium cations and oxygen atoms on CDs was investigated. The swelling behavior and ionic conductivity of the SR gel swollen with ES had a peak at 0.8M lithium ion in the ES and the molar conductivity of the SR gel swollen with ES was 85% more than that of pristine ES. The puncture resistance of the SR gel electrolyte was also investigated; the puncture elongation was more than 1000% and the Young’s modulus increased with the lithium ion concentration due to an increase in the coordination bonds between lithium cations and the oxygen atoms on CDs.
In this present study, a novel material made up of p-benzoquinone (BQ) immobilized on a new composite of cellulose acetate and mixed metal oxides (CA/TiO2/Sb2O5) was applied to the electrocatalytic oxidation of ascorbic acid (H2AA). The material was prepared by a phase inversion process and characterized by several techniques including scanning electronic microscopy coupled with energy dispersive spectroscopy (SEM–EDS), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence. Ti and Sb mapping profiles on the surface showed a homogeneous distribution of the matrices. Ti2p and Sb3d doublet indicate that the formation of TiO2 and Sb2O5 is the presumed responsible for the good rigidity of the polymeric matrix. A carbon paste electrode of this material was used to study the electrocatalytic oxidation of ascorbic acid by cyclic voltammetric, chronoamperometric and differential pulse techniques. The electrode had a quick response time, showing great potential to be utilized as an electrochemical sensor for the determination of ascorbic acid in commercial samples.
In the present study, a type of polymer electrolyte (PE) based on a PVdF polymer network, MePrPipNTf2 +LiNTf2 ionic liquid (MePrPip: N-methyl-N-propylpiperidinium cation, NTf2 is bis(trifluoromethanesulphonyl)imide anion) and vinylene carbonate (VC) as the SEI forming additive was prepared by the casting technique. The produced PE working together with the LiFePO4 (LFP) and Li4Ti5O12 (LTO) was characterized by thermal gravimetry (TG), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic sweep voltammetry (CV) and galvanostatic charging/discharging. PE had a high ionic conductivity of 4.4 mS cm−1 at 25°C with an activation energy of 12.4kJmol−1. The membrane with IL showed a thermal decomposition temperature of 310°C. The LiFePO4 cathode showed good cyclability (161 mAh g−1 after 40 cycles) and coulombic efficiency (99%). Charge/discharge tests of Li4Ti5O12/PE/Li cells at different C rates exhibited a good specific capacity of 158 mAh g−1 and 133 mAh g−1 at C/5 and C/2, respectively. The efficiency of the full LFP/PE/LTO cell charging/discharging under study was high (ca. 151 mAh g−1 after 40 cycles).