batterydata/paper-abstracts huggingface dataset:
High charge and discharge rates are desired properties for Li-ion batteries of both macro- and micro-scale (i.e. a footprint area of < 1mm2). Under these conditions, a rise of the cell temperature can take place, leading to performance limitations and safety issues. Investigations of thermal effects in battery cells provide possible explanations of the limiting factors of cell performance and can suggest improvements. We present here extensive simulations with a fully coupled 3D thermal-electrochemical model of 3D microbatteries (3D-MBs) using Finite Element Methodology (FEM). 3D-MB architectures comprising pillar shaped, plate shaped and concentric electrode arrangements are simulated, using LiCoO2 and graphite as electrodes and solid polymer electrolytes with LiTFSI salt. Sensitivity analysis of the electrolyte diffusion coefficient, depending on the C-rate, is used to benchmark the performance of these 3D-MB cells. FEM simulations of the 3D-MB during operation provide a complete 3D time-dependent description of the thermal behavior of the cells. Temperature gradients in the cell highlight critical regions which are likely causing performance bottlenecks and safety hazards. The simulations clearly demonstrate that the highest heat sources appear near the regions with most active charge transfer processes, thereby providing insights for optimization of the cell geometry in terms of both performance and safety.
Electrochemical impedance spectroscopy (EIS) is one of the most important experimental techniques employed in electrochemistry because it can be used to deconvolve physico-chemical phenomena occurring at disparate timescales. Unfortunately, the analysis of EIS data is frequently challenging since it can require the selection of ad hoc equivalent circuits. The distribution of relaxation times (DRT) method is complementary to the approach of fitting equivalent circuits because the DRT maps the EIS data onto a function containing the timescale characteristics of the system under study. While conceptually simple, the DRT cannot be obtained by simple minimization of the least squares because the corresponding optimization problem is ill posed. Regularization methods, such as ridge/Tikhonov or Lasso regression, add a penalty term to the least squares minimization problem enabling the DRT deconvolution. In this work, we show that such regularization methods may be understood in a Bayesian context. For example, ridge/Tikhonov regression implicitly encapsulates the prior insight that the derivatives of the DRT are regular. We use this Bayesian approach as a starting point to extend the DRT regularization by considering frequency dependent oscillation levels. This approach is shown to be more robust with respect to both discontinuities and over smoothing than typical regularized DRT methods. Furthermore, the Bayesian approach is versatile and may be extended to include more informative priors.
The nanocrystalline LiFe x Mn2−x O4 (x =0.2–1.0) particles were prepared by ultrasonic spray pyrolysis method using nitrate salts of ingredients at 800°C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Besides, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the iron substituent amount on electrochemical behavior. Particle characterization studies show that nanocrystalline particles have spinel structure and they are in submicron size range with spherical morphology. The lowest iron doped sample (LiFe0.2Mn1.8O4) exhibits 117mAhg−1 cumulative discharge capacity at 0.5C and 88% capacity retention for 4V plateau after 50 cycles. At higher iron concentrations, substituent tends to occupy the 8a tetrahedral sites, which prevent the lithium transport in the lattice during charge–discharge process. Increasing of the iron amount in the spinel structure causes the deterioration of the electrochemical performance.
Word learning plays a central role in language development and is a key predictor for later academic success. The underlying neural basis of successful word learning in children is still unknown. Here, we took advantage of the opportunity afforded by diffusion-weighted magnetic resonance imaging to investigate neural plasticity in the white matter of typically developing preschool children as they learn words. We demonstrate that after 3 weeks of word learning, children showed significantly larger increases of fractional anisotropy (FA) in the left precentral white matter compared to two control groups. Average training accuracy was correlated with FA change in the white matter underlying the left dorsal postcentral gyrus, with children who learned more slowly showing larger FA increases in this region. Moreover, we found that the status of white matter in the left middle temporal gyrus, assumed to support semantic processes, is predictive for early stages of word learning. Our findings provide the first evidence for white matter plasticity following word learning in preschool children. The present results on learning novel words in children point to a key involvement of the left fronto-parietal fiber connection, known to be implicated in top-down attention as well as working memory. While working memory and attention have been discussed to participate in word learning in children, our training study provides evidence that the neural structure supporting these cognitive processes plays a direct role in word learning.
This study aims at developing an analysis method for failure mode relating to material properties by considering simulated design specifications of a functional model. The proposed method contains the following procedures: (1) developing a simulated design specification of a functional model, (2) performing failure mode analyses by inserting deviation patterns into the design specifications and (3) identifying failure modes and root cause analysis to identify failure causes relating to material properties. The proposed procedure was applied in a pilot study using a simplified laser irradiation machine. The group who used the proposed model, which is based on design review based on failure modes, showed a higher rate of success in people detecting material-relating causes, compared with the group who used conventional failure mode and effect analysis. Therefore, the proposed model effectively supports users to identify causes of failure modes regarding material properties for functional materials.
During recent years intensive research activities involving both experimental and modeling approaches have appeared for different aspects of Lithium-air (Li-air) battery. Multi-phase transport phenomena including dissolved oxygen and lithium ions (Li+) in the liquid electrolyte, as well as electrons in the solid materials, are strongly coupled with the porous structures and various reactions, particularly the solid product grown in the porous cathode during battery discharge. Understanding the mechanisms of transport phenomena and accurate evaluation of effective transport properties are significant for improving the battery capacities and design, especially at high rate conditions. In this paper, the transport governing equations commonly used for macroscopic continuum models at porous-average level are outlined and highlighted, with a purpose to provide a general overview of the validity and the limitation of these approaches. The most often used models in the open literature are reviewed and discussed focusing on the effective properties involving tortuosity factors, solid product morphologies, as well as effects on the void space clogging, surface area reduction and passivation. Comments and suggestions are also provided for better understanding of multi-phase transport phenomena and implementation of the detailed models for solid product generation and morphology growth in Li-air battery cathodes.
Publisher Summary This chapter describes fuel cells that convert chemical energy into electric energy. All fuel cell types are in principle capable of operation in both directions, although a particular cell may have been optimized for a particular process. The basic ingredients of an electrochemical device are two electrodes, sometimes called anode and cathode, and an intermediate electrolyte layer capable of transferring positive ions from the negative to the positive electrode or negative ions in the opposite direction, while a corresponding flow of electrons in an external circuit from the negative to the positive electrode provides the desired power. Use has been made of solid electrodes and fluid electrolytes and fluid electrodes such as in high-temperature batteries and solid electrolytes such as ion-conducting semiconductors. The difference in electric potential between the electrodes corresponds to an energy difference for each electron. The total number of electrons that could traverse the external circuit may be expressed as the product of the number of moles of electrons and Avogadro's constant. Hydrogen gas is led to the negative electrode, which may consist of a porous material, allowing H + ions to diffuse into the electrolyte, while the electrons enter the electrode material and may flow through the external circuit. Gaseous oxygen (or oxygen-containing air) is similarly led to the positive electrode, where a more complex reaction takes place. Also at the positive electrode, the reaction rate can be stimulated by a catalyst. Instead of the porous material electrodes, which allow direct contact between the input gases and the electrolyte, membranes can be used like those found in biological material, membranes that allow H+ to diffuse through but not H2.
The structural stability and the redox mechanism of Li-rich layered oxides (LLOs) are two very important aspects for high energy density. The former is related to the irreversible loss of lattice oxygen and capacity fading during cycling, while the latter determines the overall capacity of the materials. This paper aims at clarifying the factors governing the structural stability, the extra capacity and the redox mechanism of LLOs upon Li-removal. The results show that the structural stability against oxygen vacancy formation is improved with increasing M–O covalency, while it decreases with increasing d-shell electron number and with electrochemical extraction of lithium from the lattice. The redox mechanism of Li2−xMO3 electrodes formed by 3d metals or by heavier metals with a d0 electronic configuration is related to the electron depletion from the oxygen lone-pairs (localized non-bonding O(2p) states) leading to an irreversible anionic redox ending with the reductive elimination of O2 upon cycling. For these phases, long-term cycling is predicted to be very unlikely due to the irreversible loss of lattice oxygen upon charging. For the electrodes formed by 4d and 5d metals with intermediate dn electronic configurations, reversible cationic and anionic redox activities are predicted, therefore enabling reversible extra-capacities. The very different redox mechanisms exhibited by Li2−xMO3 electrodes are then linked to the delicate balance between the Coulomb repulsions (U term) and the M–O bond covalency (Δ term) through the general description of charge-transfer vs. Mott–Hubbard insulators. The present findings will provide a uniform guideline for tuning the band structures of Li2MO3 phases and thus activating desired redox mechanisms, being beneficial for the design of high-energy density electrode materials for Li-ion battery applications.
A mathematical model of the impedance response of porous air electrodes in alkaline solutions, based on flooded agglomerate theory, was developed. The model results provides insight into characteristic features of the impedance spectra according to the relative rate of the various reactions and mass transfer processes occurring. The modelled spectra where dissolution, transport and reaction of oxygen dominates the impedance are close to ideal semicircles. With increasing contribution from ionic transport in the solution inside the pores, two distinct features occur, namely the appearance of a 45° branch at high frequencies, and an inductive loop at low frequenices. Examples from the literature where inductive loops occurs are given.
TiO2(B) nanowire arrays (TBNA) were synthesized directly on Ti foil substrate as a three-dimensional (3D) anode for lithium ion batteries. The crystal phase of TiO2(B) in the products was confirmed by X-ray diffraction and Raman spectroscopy. Observations from electron microscopy revealed uniform nanowires that were distributed regularly on the surface of the Ti metal foil forming an unique 3D nanowire array structure. TBNA exhibits promising electrochemical performance, the discharge capacity is extremely high even over the theoretical capacity of TiO2(B) at C/20, though it decays gradually, it is still high as 124.9mAh/g at 2C. The dramatic improvement in reversible capacity is ascribed to the unique structure of 3D nanowire array, which provides good electronic conductivity and accessible lithium ion paths, as well as a large surface area.
All-solid-state sulfur-based rechargeable lithium batteries have been expected to have superior energy density and high reliability so far. In general, the solid-solid interface between electrode and electrolyte particles has strong influence on the cell performance. Recently it is realized that all-solid-state lithium–sulfur batteries exhibit good cycling performance by reducing the particle size down to submicron scale. However, the origin of excellent reversibility has not been understood. Here we clearly demonstrate Li2S nanocomposites underlying high-capacity and cycling stability in all-solid-state lithium–sulfur batteries. Through high-resolution transmission electron microscopy (TEM) and energy-dispersed X-ray (EDX) spectroscopy experiments, reversible structural and morphological changes at the nanoscale during the full-electrochemical cycles in next-generation all-solid-state lithium–sulfur batteries have been revealed for the first time. Reversible variations during cycles between crystallization and amorphization of sulfur-based active nanoparticles are responsible for the feasibility of the high capacity and cycling stability. The smooth and adhesive interface between them is truly realized at the nanoscale, which is fabricated by mechanical milling technique. Our experimental findings will lead to new route to generate the sulfur-based rechargeable batteries with high-capacity and cycling stability.
The increasing use of rare-earth elements (REE) and their compounds has led to their accumulation in the environment and has raised concern about their safety. The toxic effects of REE such as lanthanum are largely unknown; genotoxicity studies have been limited and results are controversial. We evaluated the genotoxicity of lanthanum nitrate (La(NO3)3) in several in vitro and in vivo tests, including bacterial reverse mutation assay (Ames test), mouse bone marrow micronucleus assay, and chromosome aberration assay. La(NO3)3 was not mutagenic in the Ames test. La(NO3)3 did not increase the frequencies of bone marrow micronuclei or chromosome aberration in the mouse after repeated treatments at oral doses up to 735 (females) and 855mg/kg (males). The compound did not increase the frequency of chromosome aberrations in CHO cells in vitro. These results indicate that lanthanum is not a genotoxic hazard.
Energy storage devices have become vital parts of our routine life. Among the numerous candidates, lithium ion batteries are considered the most favorable energy storage systems. MoSe2 consists of Se–Mo–Se atom layers bounded with van-der Waals forces and is highly favored for lithium ion intercalation and extraction. This paper establishes a simple and economical one-pot chemical method to synthesize MoSe2 nanostructures for lithium ion battery anode material. Raman scattering confirmed the 1T@2H MoSe2 mixed phase structure, transmission electron microscopy showed 2H and 1T phase contours in the MoSe2 nanosheet, and scanning electron microscopy showed the nanograin honeycomb structured morphology. The 1T@2H MoSe2 nanostructures deliver enhanced primary discharge capacity 843 mAh/g at 100mA/g with 99% Coulombic efficiency after 100cycles. Electrochemical results confirmed the 1T@2H MoSe2 nanostructure would be an excellent anode material and a promising candidate for high performance lithium ion batteries.
In this article, we propose a trilayer graphene/polypropylene/Al2O3 (GPA) separator with dual function for high performance lithium–sulfur (Li–S) batteries. Graphene is coated on one side of polypropylene (PP) separator, which functions as a conductive layer and an electrolyte reservoir that allows for rapid electron and ion transport. Then Al2O3 particles are coated on the other side to further enhance thermal stability and safety of the graphene coated polypropylene (GCP) separator, which are touched with lithium metal anode in the Li–S battery. The GPA separator shows good thermal stability after heating at 157 °C for 10 min while both GCP and PP separators showing an obvious shrinkage about 10%. The initial discharge specific capacity of Li–S coin cell with a GPA separator could reach 1067.7 mAh g−1 at 0.2C. After 100 discharge/charge cycles, it can still deliver a reversible capacity of as high as 804.4 mAh g−1 with 75% capacity retention. The pouch cells further confirm that the trilayer design has great promise towards practical applications.
Lithium sulfur (Li-S) batteries have attracted considerable attention as the next generation rechargeable batteries owing to their much higher energy density in contrast to the conventional lithium ion batteries (LIBs). However, the inferior cycling performance as well as rate capability, resulted from the polysulfides shuttle effect and sluggish reaction kinetics, remains as major hurdles for its practical application. Herein, a high-rate and ultrastable Li-S battery has been demonstrated by using the multifunctional iron phosphide (FeP) nanocrystals as an efficient host material to anchor the polysulfides and regulate the polysulfide redox conversion. Density functional theory (DFT) calculations indicate that FeP can provide strong chemical bonding towards polysulfides. The FeP nanocrystals show high catalytic effect to facilitate the polysulfides conversion reaction and lower the Li2S nucleation energy. Additionally, the 3D rGO-CNTs scaffold enables fast and continuous long-distance electron transportation and accommodates large volumetric change during the charge/discharge processes. As a result, the FeP nanocrystals with intrinsic polysulfide affinity and catalytic activity suppress the polysulfide dissolution and enhance the redox reaction kinetics, enabling ultrastable cycling (0.04% capacity decay per cycle) and excellent rate performance (613.1 mAh g−1 at 3 C). Significantly, the enhanced Li-S performances provide significant insight for realizing high performance Li-S batteries by incorporating the metal phosphides into the sulfur cathode.
This paper describes a highly structured assessment protocol with objective behavioral measures for joint attention responding and initiation. The assessment was given to 26 children diagnosed with autism spectrum disorders and 21 typically developing children, aged two to four years. Interobserver agreement was high for all behavioral measures. Children with autism had relatively minor deficits in joint attention responding and more severe deficits in joint attention initiation, relative to typically developing children. These results replicate those reported in previous research. The protocol can be used reliably to assess behavior indicative of joint attention responding and initiation in typically developing children and children with autism.
Using interlaced carbon nanotubes (CNTs) as framework, a novel three-dimensional (3D) networks structured Co(NO3)2·6H2O@CNTs with superior electrochemical performance is synthesized by an ultrasonic assisted hydrothermal and low-temperature conversion method. In the micro-/nanostructured composite, Co(NO3)2·6H2O particles, with an average size about 0.7μm, are homogeneously embedded in the CNTs 3D networks. The CNTs, with high electronic conductivity and outstanding mechanical flexibility, are effective to keep the stability of Co(NO3)2·6H2O micro-/nanostructures. Evaluated as anode material for lithium ion batteries, the micro-/nanostructured Co(NO3)2·6H2O@CNTs exhibits a high reversible capacity of 1460mAhg−1 at a current density of 50mAg−1 after 100 charge/discharge cycles. Even at 1000mAg−1, a superior stable capacity as high as 1089mAhg−1 could be maintained after 1000cycles. The improved reversible capacity, excellent cycling stability, and good rate capability of Co(NO3)2·6H2O@CNTs can be ascribed to the three dimensional structure and the synergistic effect between Co(NO3)2·6H2O and CNTs. Therefore, this Co(NO3)2·6H2O@CNTs micro-/nanocomposite can be considered as an attractive anode candidate in rechargeable lithium ion batteries.
With a mixture of a SiO2 sol and a solution of lithium and cobalt acetates as the precursor, nano-SiO2 modified LiCoO2 films were fabricated by the electrostatic spray deposition (ESD) technique. The SiO2 content of these films was 0, 5, 10, 15 and 20wt%, respectively. Their structure and electrochemical properties were characterized by means of X-ray diffraction, scanning electron microscopy, galvanostatic cell cycling, AC impedance spectroscopy and cyclic voltammetry. Li2CoSiO4 was found formed in the SiO2-containing films. The film with 15wt% SiO2 shows the best cycling stability with the capacity of 130mAh/g in the voltage range between 2.7 and 4.3V at the current density of 0.1mA/cm2. Due to its resulted small cell impedance, it has excellent rate capability. A LiCoO2 (shell)/SiO2 (core) structure model is proposed to explain the improved properties of these films.
Following the route of synthesis of β-MoO3 through soft chemistry methods a new amorphous material with composition MoO3·2H2O has been detected. The hydrated molybdenum oxide showed the capacity for electrochemical lithium insertion. The maximum amount of lithium incorporated in this material (∼3.3Li/Mo) leads to a specific capacity of 490Ahkg−1. The charge–discharge curve showed a good reversibility in the potential range from 3.2 to 1.1V versus Li+/Li0 where the cell voltage decreased monotonously as a function of the degree of lithium inserted. The electrochemical features of amorphous MoO3·2H2O suggest that it can be considered as a possible cathode candidate in rechargeable lithium batteries.
Han et al. comment on our recent paper “Geometry and fast diffusion of AlCl4 cluster intercalated in graphite” [Electrochim. Acta. 195 (2016) 158–165] and question the planar geometry of the AlCl4 cluster and thus the fast diffusion of the AlCl4 cluster in graphite. In this reply, we demonstrate that the planar geometry is reasonable and the ultrafast diffusion of the AlCl4 cluster is in good agreements with the experiments by Lin et al. [Nature 520 (2015) 325–328]. The reasons on why the graphite foam is better in terms of the rate performance than the natural graphite are also discussed.
Some recently developed ‘intelligent’ or advanced dressings, are reviewed and their mechanisms are detailed. Applications including the use of sensors, temperature control and non-contact dressings are described. The potential of such smart textiles in the treatment of particular wounds is explored.